
○ Objectives

Describe anatomical position. Why is it significant?
 Identify the planes of reference used to locate the structure of the body
 Define and be able to properly use descriptive and directional anatomical terms
○ Anatomical Position – standing erect, palms forward
○ Supine – reclining, face up
○ Prone – reclining, face down
○ Body Regions

Axial region – contains thorax and abdomen

Appendicular regions
Upper limb
Arm – shoulder to elbow
Lower Limb
Thigh – hip to knee
Forearm – elbow to wrist Leg – knee to ankle
Wrist, hand, fingers Ankle, foot, toes
○ Anatomical Planes

Saggital – divides into right and left halves

Midsaggital – right at midline

Coronal (frontal) – divides into anterior and posterior
 Transverse (horizontal) – divides top and bottom
○ Terms of Position

Ventral (anterior) – front of body

Dorsal (posterior) – back of body

Superior (cranial) – toward the head

Inferior (caudal) – toward the feet

Midline

Medial – toward the midline

Lateral – away from the midline

Core

Internal – toward the core

External – away from the core

Surface

Superficial – toward the surface

Intermediate – between the surface

Deep – away from the surface

Attachment

Proximal – close to the point of attachment

Distal – away from the point of attachment
Latin Singular vs Plural
Singular Plural
-a
-ax
-en
-ex
-is
-is
-ae
-aces
-ina
-ices
-es
-ides
-ix -ices
○ Terms of Movement

Angle
-ma
-on
-um
-mata
-a
-a

Flexion – decrease the angle between two bones

Extension – increase the angle between two
-us
-us
-us
-era
-i
-ora bones

Midline

Abduction – moving away from midline

Adduction – moving toward the midline

Rotation – movement around a long axis
-x
-y
-yx
-ges
-ies
-ices

Circumduction – circular movement where the structure forms a cone

Palms
Example
Axilla, axillae
Thorax, thoraces
Lumen, lumina
Cortex, cortices
Diagnosis, diagnoses
Epididymis, epididymides
Appendix, appendices
Carcinoma, carcinomata
Ganglion, ganglia
Spetum, septa
Vicus, viscera
Villus, villi
Corpus, corpora
Phalanx, phalanges
Ovary, ovaries
Calyx, calices


Because radius and ulna rotate over each other

Supination – turning palms up

Pronation – turning palms down

Foot

Dorsiflexion – bring foot up

Plantar flexion – push foot down

Sole of Foot

Inversion – turn sole of foot medially

Eversion – turn sole of foot laterally
○ Select Surface Landmarks in Anatomical Position
Cephalic – head Acromial – shoulder
Cervical – neck
Cheek – buccal
Axillary – arm pit
Brachial – arm
Mental – chin
Inguinal – groin
Olecranal – back of elbow
Popliteal – hollow behind the knee
Sural – calf of leg
Femoral - thigh
Cubital
Pollex
Coxal
Tarsal
– hollow of elbow
Antebrachial – forearm
– thumb
– hip joint
Hallux
– ankle
– great toe
Calcaneal – heel of foot

○
Objectives
 Describe the basic anatomical organization of the nervous system
 Diagram a typical neuron and list its parts. Identify distinguishing characteristics of motor and sensory neurons

Describe the gross anatomical features of the spinal cord
 Describe the location, organization and structure of the spinal meninges
 Diagram a cross section through the spinal cord. Be able to label all of the parts as described in class
 Describe the components of a typical spinal nerve and explain the normal branching pattern

Explain the numbering of spinal nerve pairs
 Give the definition of a spinal cord segment. Explain the difference between the spinal cord segment and the vertebral level
 Define the term dermatome and state its clinical significance
 Give the anatomical basis for administering a successful lumbar puncture
○ Two ways to organize

Functional Organization

Somatic components – somatic afferents (receive sensory information) and somatic efferents (send muscle information)

Visceral (autonomic) components – visceral afferents and efferents that innervate smooth muscle, cardiac muscle and glands

Anatomical Organization – more common

Central Nervous System – brain and spinal cord

Peripheral Nervous System
○ Cranial Nerves – mostly directly attached to brain

12 pair; Innervate head and neck
○ Spinal Nerves – 31 pair, attached to spinal cord; innervate everything else
○ Types of Neurons

Multipolar – many processes; motor neurons

Pseudounipolar - primary sensory neurons

Peripheral process - „dendrite‟

Central process – „axon‟
○ Definitions

Nucleus – collection of neuronal cell bodies within the CNS (collected because they do the same thing)

Ganglion – collection of neuronal cell bodies outside the CNS


Tract – nerve processes (axons) bundled together in CNS
 Nerve – nerve processes bundled together in in PNS

Gray matter – unmyelinated
○ Spinal Cord

Connects brain to body; responsible for spinal reflexes; continuous with brain

Afferent (sensory) – receives from body

Efferent (motor) – sends away from CNS

Size and shape

In general it tapers as it gets down to coccyx since less information is transmitted as you go down

Cervical Enlargement – between C4-T1 , due to upper limb connections

Lumbar Enlargement – between L3-S3 , due to lower limb connections
 Conus Medullaris – tapered inferior end of spinal cord

Cauda equina - „horse tail‟ – a continuation of dorsal & ventral rootlets for spinal nerves below vL2
(where spinal cord stops)

Protection

Vertebral Column – spinal cord housed in vertebral foramen

Meninges – three connective tissue coverings that surround the brain and spinal cord
○ Dura mater – (tough mother) outermost layer, dense CT

Continues into sacrum to vS2 (it is longer than spinal cord) and is anchored to coccyx
○ Arachnoid mater – thin transparent membrane with thin weblike extensions that connect to pia mater

Normally contacts dura mater

Ends at S2 with the dura mater
○ Pia mater – (delicate mother), very thin layer of CT which can‟t be taken off spinal cord

Follows every contour of CNS

Filum Terminale – inferior extension of the pia mater from the conus medularis
○ Attached inferiorly to inferior part of dura at vS2
○ Inferior anchor for spinal cord

Denticulate Ligaments – lateral extensions of pia mater
○ Act as lateral anchors (and connect to dura mater?)

Spaces Between Meninges
○ Epidural Space – between dura and bone
○ Subdural Space – between arachnoid and dura mater
 only a potential space , nothing is there normally
○ Subarachnoid Space – between arachnoid and pia

Contains CSF

Internal Structure of Spinal Cord

Gray and white matter

Dorsal horn – contains axons involved with sensory reception

Ventral horn – contains nuclei of multipolar motor neurons

Lateral horn – contains autonomic neurons
○ only in T1-L2 & S2-S4

Spinal Nerves

Formation of Spinal Nerves
○ Dorsal Root – sensory, between dorsal horn and dorsal root ganglion
○ Dorsal Root Ganglion – where nuclei of pseudounipolar sensory neurons are housed
○ Ventral Root – contains axons of motor neurons
○ Spinal Nerve – DRG and ventral root unite and form spinal nerve
 Are mixed nerves because they have afferent and efferent neurons
○ Intervertebral foramen – where spinal nerve comes out

Only visible when two vertebra are stacked on top of each other


Branches of Spinal Nerve
○ Each branch of the spinal nerve is still a mixed nerve
○ Dorsal primary ramus – innervates skin and muscles of back
○ Ventral primary ramus – innervates all other skin and muscles (trunk, limbs, etc.)

Is much bigger because it innervates more things

Number of Spinal Nerves
○ 31 pairs
○ Numbering – all spinal nerves (except the cervical ones) exit below the vertebra they are named after (ex. T1 exits below T1)

Exception – C1 spinal nerve exits above vC1, C2 spinal nerve exits below vC1
○ C8 exits below vC7
○ Cervical – 8
○ Thoracic – 12
○ Lumbar – 5
○ Sacral – 5
○ Coccygeal – 1

Spinal cord level vs Vertebral level
○ Spinal Cord Segment – portion of spinal cord that contributed to the formation of the spinal nerve
○ Vertebral Level – anatomical landmark that is associated with a specific vertebrae

Ex. Spinal cord ends at vertebral level L2
○ Why? At birth spinal cord and vertebral column end at same place, but vertebra grows

Dermatome – area of skin supplied by a single spinal nerve

Lumbar Puncture – done in area of cauda equina so that spinal cord is not affected

This allows for CSF to be sampled from the dural sac

○ Objectives
 Vertebral Column

Define the normal and basic pathological spinal (postural) curvatures

Identify the features of typical vertebra

Distinguish the characteristics of vertebrae from different regions of the vertebral column

Describe the joints and ligaments of the vertebral column. Understand how these contribute to movements of the vertebral column

Describe the craniovertebral joints (atlanto-occipital; ligaments between atlas, axis and occiput)

Understand how spinal nerves emerge from the vertebral column.

Describe the relationship between the number of spinal cord segments/spinal nerves and vertebral level

Describe how the length of the spinal cord changes during development relative to the length of the vertebral canal

Explain the blood supply of the spinal cord and vertebral column and identify the sources
 Muscles of the Back

Define the muscle groups associated with the back. Contrast their actions and innervation

Identify the attachments and compare the functions of the superficial (extrinsic) back muscles; trapezius, latissimus dorsi; levator scapulae and rhomboids (these will also be considered with the upper extremity)

Identify the attachments and compare the functions of the basic attachments of intrinsic back muscles
○ Movements of the Back
 Extension, flexion, lateral flexion, rotation
○ Vertebral Column

31-33 Vertebrae

7 Cervical, 12 Thoracic, 5 Lumbar, 5 Sacral (fused), 2-4 Coccygeal (fused)

Sacral Hiatus – opening in the inferior portion of the sacrum that you can feel

Closed by a membrane

Contains – filum terminale (which passes through to coccyx) and fat

Important for caudal anesthetic

Curvatures of the Vertebral Column


Types
○ Kyphosis – anteriorly concave curvature of the vertebral column

Occurs normally in thoracic and sacral regions

Abnormal exaggeration occurs in the thoracic region
○ Lordosis – anteriorly convex curvature of vertebral column

Occurs normally in cervical and lumbar regions

Abnormal exaggeration usually occurs in lumbar region
○ Scoliosis – abnormal lateral curvature of the spine

Development of Curvature
○ Primary curvature – anything that is kyphotic (thoracic, sacral)

Early in development all curvature is kyphotic
○ Secondary curvature – anything that is lordotic (cervical, lumbar)

This curvature is associated with weight bearing

First to develop is lumbar (right around birth)

Typical Vertebra

Vertebral Body –

Pedicle – attaches directly to vertebral body

Lamina – connects pedicle to spinous process

Vertebral Arch = lamina + pedicle

Vertebral foramen = lamina + pedicle + vertebral body

Spinous process

Transverse process

Superior and Inferior articular processes

Zygapophyseal joint – superior articular process + inferior articular process from above
○ One on each side of the spinous process

Superior vertebral notch + inferior vertebral notch = intervertebral foramen
○ Spinal nerve passes through intervertebral foramen (so does DRG)

Distinguishing Characteristics of Vertebrae

Cervical (8)
○ Transverse foramen – hole in transverse process where vertebral artery passes through
○ Transverse process has posterior tubercle and anterior tubercle
○ Spinous process is bifid
○ Vertebral body is more square

Thoracic (12)
○ Has facets for the ribs (flat connecting points)

Each rib has three contact points, one on the transverse process, one on the superior facet of vertebral body, one on inferior facet of vertebral body on the vertebra above

Ribs are only in the thorax
○ Spinous process is angled inferiorly
○ Vertebral body is heart-shaped

Lumbar (5)
○ No transverse foramen or rib facets
○ Spinous process is short and sturdy
○ Vertebral body is large and kidney-shaped
 Special Vertebral Bones

Both have transverse foramen just like other cervical vertebrae

Atlas (C1) – “holds world on shoulders” – the skull rests on it
○ Lacks vertebral body – has anterior and posterior arches instead
○ Superior articular facet touches skull

Axis (C2) –
○ Dens (odontoid process) – used to be the vertebral body of C1, but now it is fused to C2


Vertebral Ligaments

Anterior Longitudinal – on anterior side of vertebral body

Posterior Longitudinal – on posterior side of vertebral body, inside vertebral canal

Supraspinous ligament – on dorsal side, connects spinous processes
○ From cervical region on up this ligament is called the nucal ligament

Here it becomes triangle shaped? And fills up a greater area

Interspinous ligament – in between spinous processes (lots of CT)

Ligamentum Flavum – covers vertebral arch
○ Connects adjacent laminae
○ Flavum = yellow
 Intervertebral Discs

Numbering – eg L4-5 disc is between L4 and L5

There is no disc between C1 & C2

Anulus Fibrosis – outermost part of disc
○ Contains fibrocartilage rings that are thinner posteriorly (where rupture occurs)
○ Vascularized

Nucleus Pulposus – inner part of disc
○ Contains mucoid – made of reticular & collagen fibers

Avascular

70%-90% water

Water content decreases with age and is associated with decrease in height, decrease in compresibility and increased probability of rupture

Disc Herniation
○ Nucleus pulposus protrudes through annulus fibrosis
○ Occurs most frequently in cervical and lumbar regions
○ Most frequent site = in posterolateral direction (often to either side of the posterior longitudinal ligament)

This will compress the spinal nerve
○ Affects lower spinal nerve root

Ex. L4-5 disc herniation affects L5 nerve root

Atlanto-Occipital Joint

Anterior Atlanto-occipital membrane - ?

Posterior Atlanto-occipital membrane – connects posterior skull to posterior portion of C1
○ Covers spinal cord

Internal Ligaments (plate 22)
○ Tectorial Membrane – continuation of posterior longitudinal ligament starting at C2
○ Cruciform ligament – where the bands cross it holds posterior of dens in place, composed of three bands

Superior longitudinal band – connects to skull?

Transverse band – connects laterally to C1

Inferior longitudinal band – connects to vertebral body of C2
○ Alar Ligaments – laterally connect dens to skull (two of them)
○ Apical ligament of dens – connect anterior of dens to skull
○ Back Muscles

Origin – more medial, less movement
 Insertion – more lateral, more movement

Overview of Musculature

Extrinsic Back Muscles (quick overview)
○ Control Upper Limb
 Trapezius – connects shoulder to neck

Latissimus dorsi – connects lower back to side?

 Rhomboid mm (major and minor) – connects shoulder blade to spine
 Levator Scapulae –
○ Accessory respiratory mm

Serratus posterior inferior muscle – lower ribs to lower back

Serratus posterior superior muscle
○ Innervation

Ventral rami of spinal nerves

Accessory n (CN XI) for Trapezius

Intrinsic Back Muscles
○ True back muscles, maintain posture, move vertebral column and head
○ Superficial Layer

Looks like one bundle, but splenius cervicis is inferior

Spine to head
○ Intermediate Layer
 Erector spinae mm
○ Deep Layer
 Transversospinal (starts on TP ends in spine?)
○ All extend spine or head
○ All rotate to opposite side
○ All are TP to SP
○ Innervation
○ Dorsal rami of spinal nerves
Origin
Insertion Action
Splenius Capitis – more medial than cervicis
Splenius Cervicis
SP (T3-C3) -superior nuchal line
-mastoid process
SP (T3-6) TP (C1-3)
-Bilateral – extends head
-Unilateral – laterally flexes and rotates head to same side
-Bilateral – extends head
-Unilateral – laterally flexes and rotates cervical spine to same side
SP SP Bilateral – extends spine & head
Unilateral – lateral flexion
Spinalis - most medial
Capitis
Cervicis
Thoracis
Longissimus
Iliocostalis - most lateral
Capitis
Cervicis TP & AP
Thoracis
-Sacrum
-iliac crest
(common tendon)
-SP and TP
Cervicis ribs
Thoracis ribs
Lumborum
-Sacrum
-iliac crest
(common tendon)
-TF
Semispinalis - highest
TP & AP mastoid process
TP
-Ribs
-TP
TP ribs
-ribs
-deep TF rotates head to same side
Bilateral – extends spine & head
Unilateral – lateral flexion (only acts against gravity)
Bilateral – extends spine
Unilateral – lateral flexion
TP SP Bilateral – extends spine & head
Unilateral – lateral flexion ,

Multifidis – mostly in lumbar
TP SP rotates to opposite side
Note - origin and insertion 2-4 vertebrae apart
Rotatores TP SP Note - Origin is 1 vert below insertion
○ Note – SP = spinous process, TP = transverse process, AP = articular process, TF = thoracolumbar fascia
○ Note – thoracolumbar fascia is the covering of deep back muscles

Innervation
○ Dorsal Rami innervate

Intrinsic back muscles

Middle skin of back
○ Sensory Innervation

Dorsal rami – innervates middle of back

Ventral rami – innervates lateral parts of back
○ Ex. Supraclavicular nerves (from cervical plexus)
○ Ex. Lateral branches of intercostal nerves

Vasculature (Plates 171 & 172)
○ Arteries

Neck
○ Vertebral Artery – supplies vertebral column in the neck
○ Ascending cervical artery -
○ Deep cervical artery -

Posterior intercostals artery - in thorax

Lumbar arteries – in abdomen (a small branch goes into the canal)

Lateral sacral arteries – in pelvis
○ Feeder Arteries
 Two Paths
○ Thoracic aorta → posterior intercostals artery → spinal branch →
 radicular artery → ant and post segements to dorsal and ventral roots
 segmental medullary artery → ant and post segements to dorsal and ventral roots → spinal arteries
 From there both the radicular and segmental medullary arteries split into posterior and anterior segments and supplies dorsal
(including DRG) and ventral roots
 The segmental medullary then goes on to supply the spinal cord (via spinal arteries), the radicular artery does not

Extra notes
○ Spinal branch – at posterior aspect of vertebral body and vertebral arch
○ Segmental medullary artery varies in level of origin and number
 Average 8 anterior and 12 posterior

Great anterior segmental medullary artery – supplies 2/3rds of spinal cord

Mainly in thoracolumbar region
○ Spinal arteries – 2 posterior and 1 anterior
○ Veins (plate 173)

Drainage of spinal cord
○ anterior and posterior spinal veins (inside pia mater, right between halves of spinal cord)
→ radicular and segmental medullary veins (they look the same) → internal venous plexus (inside vertebral canal in extradural fat) → external venous plexus (surrounds vertebral column

Extra notes
○ Veins inside the spinal cord (and head and neck) are valveless , but radicular and medullary veins do have valves

○ Clinical point – due to the low venous pressure (since no valves?) venous stasis can cause dangerous change in pressure within the spinal cord

Clinical signs include gait disturbances, spastic paralysis and sensory deficits

○ Objectives
 Define and describe: hypoblast, epiblast, primitive streak, primitive node, notochordal process, prochordal plate, cloacal plate, notochord, ectoderm, mesoderm, endoderm
 Describe the formation of the bilaminar embryonic disc from the inner cell mass
 Describe the formation of the extraembryonic mesoderm

Describe the formation of the primary and secondary yolk sacs
 Describe the formation of the body (connecting) stalk
 List three functions of the secondary yolk sac
 Define and describe: lacuna, intervillous space, deciduas basalis, deciduas capsularis, deciduas parietalis, amnion, chorion

Describe the formation of the amnion and the chorion

List the functions of the placenta
 Describe the morphological changes that occur during the development of placental villi
 Describe the components of the placental membrane or “barrier”
 Describe the formation of the amniotic fluid

List several functions of the amniotic fluid
 Define amniocentesis and list several indications for the procedure

○ Objectives
 List and describe the morphology and function of the layers in the skin
 List and describe the morphology and arrangement of the layers and components in the epidermis, dermis and hypodermis
 List and describe the morphological and functional changes in epidermal cells as they move from the basal lamina to be sloughed off at the surface of the stratum corneum

List and describe the morphology and function of all cells in the epidermis
 Describe the morphology of the epidermis/dermal junction and its functional significance
 Define and describe the cleavage linds of Langer and their clinical significance
 Describe the arrangement of the blood supply to the skin and relate it to temperature regulation

List and describe the functions of the skin
 Integrate the morphology of the skin to its functions
 List and describe the arrangement and location of skin appendages (hair, glands, nails)

List and describe the arrangement of the parts and layers of the hair and hair follicle
 Relate the layers of the epidermis to those of the hair follicle and nails
 Define and describe terminal, vellus hair and lanugo hair; give their distribution over the body
 List the parts and describe the growth cycle of hair
 Describe the process by which a hair shaft increases in length

Integrate the morphology of hair and its function
 List and describe the morphology, function and secretion of the 3 types of glands (sebaceous, sudoriferous and ceruminous)
 List the distribution of different types of glands across the body
 List and describe the morphology and function of the parts of nails
 List and describe the morphology, function and location of the sensory receptors of the skin (free epidermal nerve endings,
Merkel endings, Pacinian corpuscle, and Meissner‟s corpuscle)
○ Integument Overview

Consists of Two Components

Appendages of Skin – derived from the epidermis and associated with the skin
○ Hair, glands (sweat, sebaceous, ceruminous), nails

Skin (Integument)
○ Covers entire surface of body
○ Variable thickness across body, thicker on dorsal surface , thickest between shoulders on back
○ Continuous with mucosal linings of the body orifices
○ Mucocutaneous junction – (ie. lips) reddish due to blood in capillaries and lack of keratin in cells

Basic Structure of Skin
Epidermis Dermis Hypodermis

Stratified squamous keratinized epithelium
Derived from ectoderm
Avascular
Sits on basement membrane
Has 5 layers
Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum
Stratum Corneum
Dense irregular connective tissue
Derived from mesenchyme
Vascular – supplies nutrients to epidermis
Has 2 Layers
Papillary Layer – superficial layer immediately underneath epidermis
Characterized by dermal papillae
Reticular Layer – deepest and thickest layer, contains skin appendages is not part of the skin
Areolar connective tissue
(loose CT with fat in it)
Other names - subcutaneous/superficial fascia and panniculus adiposus (when in abdomen)
 Dimples – where dermis is tightly attached to underlying deep fascia or bone

Functions of the Skin

Mechanical Protection – trauma, bacteria, UV

Maintenance of Body Fluids – prevents dessication (waterproof), prevents absorption
○ Excretion – sweat glands secrete water, ions, urea, ammonia (just like kidney)

Maintenance of Body Temperature – sweat cools body, blood vessels bring warm blood to surface to radiate heat, adipose tissue insulates

Synthesis of Vitamin D
○ In Skin: Vit D precursor + UV → another precursor (cholecalciferol)
○ In Liver: cholecalciferol → 25 hydroxy cholecalciferol
○ In Kidney: 25 hydroxy cholecalciferol → vitamin D
○ Function – Vit D stimulates Ca and PO absorption in gut

Immunity – contains wandering cells of immune system

Reception of Sensory Stimuli
○ Communication – embarrassed, nervous, cyanosis, jaundice, age, nerve damage

Repair – repairs and forms scars

Morphology of Skin

Epidermis
○ Layers of Epidermis

" B all S tate G irls L ove C ock"

Stratum Basale (Germanitivum)
○ Deepest layer
○ Diagnostic Characteristic – single layer of cells sit upon basement membrane
○ Shape - Cuboidal to columnar
○ Mitosis occurs here (constantly resupplies epidermis with new cells)

Stratum Spinosum
○ Diagnostic Characteristic – spiny appearance, the „spines‟ are where desmosomes attach and hold adjacent cells toether into one unified sheet
○ Several layers
○ Shape - irregularly shaped cells
○ Artifact – gaps between cells form due to shrinkage during tissue processing

Stratum Granulosum
○ Diagnostic Characteristic – contains numerous, darker staining keratohyalin granules
(which are involved in keratinization)
○ Narrow layer, 3-5 cells thick
○ Shape – flattened with nuclei disappearing (as you get more superficial)

Stratum Lucidum
○ Diagnostic Characteristic – cells and nuclei are not visible at light level


At EM level, the cells are indistinguishable from stratum corneum (thus can be considered part of stratum corneum )
○ 2-3 cells thick

Stratum Corneum
○ Diagnostic Characteristic – no nuclei visible
○ Numerous layers of dead cells
○ Cells filled with keratin
○ Stratum disjunctivum – part of stratum corneum where superficial cells slough off
○ Types of Epidermis

Thick (Glabrous) Skin – lacks hair and sebaceous glands
○ Refers to thickness of epidermis only , not thickness of entire skin with dermis
○ Epidermis more than 1mm thick
○ Found only on palms and soles

Thin (hairy/non-glabrous) Skin – characterized by presence of hair & sebaceous glands
○ Another Diagnostic Characteristic – reduced thickness of stratum corneum, granulosum & spinosum (basically the three outermost)
○ Stratum lucidum is absent
○ Found everywhere else
○ Epidermal Cell Types

Keratinocyte – produces keratin, main cell of epidermis
○ Derived from ectoderm

Melanocyte – pigmented cell
○ Found only in stratum basale
○ Derived from neural crest cells

Langerhans cell – mobile immune system cells scattered in stratum spinosum
○ Appearance - Stellate shape with many branches, clear cytoplasm
○ Present antigens to helper T cells

Merkel cell – cutaneous mechanoreceptors responsible for light touch
○ In stratum basale
○ Appearance – small clear cell
○ Do not contain catecholamiens (why is this important?), innervated by single axon
○ Keratinocytes in More Detail

Create the protective, waterproof barrier

Cytomorphosis – differentiation and maturation (takes 26-30 days)
○ Keratinocytes do this, they start in the stratum basale and move to stratum corneum
 As keratin builds up the cells start to die, this is the degeneration phase

Keratin – fibrous proteins that make up intermediate filaments
○ Amount of keratin in the cell increases as it migrates toward surface

Keratinization in Each Layer
○ Fibronectin in basement layer regulates rate of keratinization
○ Epidermal growth factor – stimulates proliferation of keratinocytes
○ The cytology of cells in different layers reflects maturation and keratinization
○ Stratum Basale

Main function is mitosis (mitotic structures present)

Tonofilaments - Small bundles of keratin (start to appear here)

Desmosomes – attatch cells to other cells
 Hemidesmosomes – attach cells to extracellular matrix
○ Stratum Spinosum

More keratin is produced to make more tonofilaments

Tonofibrils – tonofilaments eventually form these

Lamellar granules – membrane bound granules rich in glycolipids.

Appear as light and dark bands.


Extruded as cells approach top (to make waterproof barrier)
○ Stratum Granulosum

Keratohyalin granules – irregularly-shaped, dense staining inclusions in cytoplasm

Eventually extruded

Tonofilaments continue to increase in cytoplasm

Filaggrin – a protein that cross-links tonofilaments

Involucrin – attachment to cell membrane, crosslinking done by transglutaminase.
Creates water impermeable cell membrane that helps cause cell death

Lamellar Granules increase in the intercellular space

Because they are glycolipids, they form a waterproof barrier between cells

Move from synthesis phase → degenerative phase

Cell nuclei begin to disappear
○ Creating the waterproof barrier

Impermeability due to buildup of keratin in cells

Thickening of cell membrane due to involucrin

Presence of glycolipids between keratinocytes
○ Stratum Lucidum - Keratinocytes are dead, lack nuclei, lots of waterproofing
○ Stratum Corneum – the cells in this layer are called squames

There are no keratohyalin granules or lamellar granules remaining

Epidermal Proliferation Unit (EPU) - The original keratinocyte and all its progeny?
○ Original stem cell produces 10ish basal cells which migrate laterally?

As more proliferation occurs the unit of cells moves upward as a group?
○ Melanocytes in more Detail
 Artifact - Actually looks clear at LM level because it doesn‟t have desmosomes and shrinks

Highly branched

Normal Skin – about 1000 melanocytes/mm

Pigmented Skin (areolae, genital, etc.) – about 2000 melanocytes/mm

Different Races – have same number of melanocytes just have different # of melanin granules

Skin Color Caused By
○ Melanin – only pigment produced by skin
○ Carotene – yellow exogenous plant pigment deposited in stratum corneum and adipose
○ Oxyhemaglobin – red protein in blood

Melanin Epidermal Unit – melanocyte and associated keratinocytes (keratinocytes that have melanin made by that melanocyte)
○ Located in the stratum basale and spinosum

Production of Melanin
○ Tyrosinase – converts tyrosine → melanin in melanocyte vesicles
○ Premelanosomes – small vesicles containing a little bit of melanin. Arise from Golgi
○ Melanosomes – more developed with more melanin
○ Melanin Granules – mature melanosomes

Migrate out to ends of branches??

The end of the process is pinched off into the cytoplasm of the keratinocytes??
 cytocrine secretion ??
○ Melanosome Complex – forms after keratinocyte and melanin granules fuse with lysosomes. These form a cap over the nucleus

Slowly degenerate

Dark skinned races: 1. Produce more melanin, 2. have longer lasting melanosome complexes, 3. have granules in all layers

Function of Melanin
○ Protects nucleus from UV rays
○ UVA – 320 nm (short)


Causes wrinkling, sagging of skin, skin cancer
 does not burn the skin (tanning salons use it)
○ UVB – 370 nm (long, this gets in farther)

Causes sunburn – induces inflammation of blood vessels in dermis

Most sunscreens only block this

Melanin Related Clinical Applications
○ Tanning – darkening of melanin with exposure to sunlight and increased tyrosinase activity over several days of continued exposure
○ Albino – lack of tyrosinase but same number of melanocytes
○ Vitiligo – depigmentation genetic disorder in skin and hair characterized by scattered patches of white skin and white hair

Melanocytes are destroyed
 Michael Jackson
○ Freckle – patch of skin with slightly higher concentration of melanin granules
○ Nevus (mole) – benign localized overgrowth of melanocytes arising during early life
○ Malignant melanoma – very malignant
○ Diseases of the Epidermis

Psoriasis – chronic condition characterized by patches of red-brown area with whitish scales
○ Due to excessive proliferation of keratinocytes
○ Takes 1 week, instead of 4 for keratinocytes to reach top, they aren‟t mature when at top

Waterproof barrier not formed because cells not fully keratinized, lamellar granules not secreted
○ Cause unknown

Eczema – characterized by edema, exudation, crusting & severe itching
○ Dermis also affected (edema and infiltration of immune cells)
○ Cause thought to be immunological

Phemphigus – autoimmune disease against desmosome proteins in epidermis resulting in severe blistering and loss of fluids
○ Makes it easier for infectious agents to enter
○ Potentially fatal

Basal Cell Carcinoma – cancer of the keratinocytes in the stratum basale
○ Most common of all skin cancers, but does not readily metastasize

Squamous Cell Carcinoma –
○ Second most common skin cancer, readily metastasizes

Not a disease – DMSO – a penetrating agent used for arthritis (unofficially) that can bring foreign substances into the body

Dermis
○ Papillary Layer – composed of modified areolar CT

Immediately below epidermis, and is the thinner of the 2 dermal layers

Epidermal-Dermal Junction – interdigitation of dermal papillae and epidermal pegs or ridges to prevent side shearing forces from separating the two layers
○ Dermal papillae – fingerlike projections of CT of dermis into epidermis

Thin vs. Thick Skin
○ Thin Skin – dermal papillae present but are simply rounded bumps or mounds of CT
○ Thick Skin – has more pronounced ridges (makes fingerprints and improves grip)
 interpapillary peg of epidermis divides primary dermal ridge into 2 secondary ridges
 the primary dermal ridges correspond to the epidermal ridges?
○ Reticular Layer – composed of dense irregular CT and is rich in collagen and elastic fibers

Bundles of collagen fibers interwoven and oriented in all directions to resist shearing

Thickest layer in dermis


Cleavage lines of Langer – predominant direction of the bundles of collagen in a region of the body
○ Important for surgery – if parallel incision then little scar, if across then big scar
○ Stretch Marks – tear of the dermis but epidermis remains, due to skin being too tight

Gap is repaired by scar tissue

Blood Supply for Skin
○ Blood supply derived from arteries in the hypodermis (subcutaneous fascia)
○ 3 Layers

Subcutaneous Plexus – located in the hypodermis
○ The deepest layer; all the blood supply originates here
 Cutaneous Plexus – located in the dermal-hypodermis junction

Subpapillary Plexus – located just below the papillary layer
○ Capillary loops run up into the dermal papillae
○ Vasculature and Temperature Regulation

A-V Shunts – control blood flow and are located between cutaneous and subpapillary plexi
○ Found in Apical Skin, not Non-Apical Skin???

Apical Skin – found in finger and toe tips, nail beds, nose and lips

Normal Temp – AV shunts partially closed to allow warm blood to flow near surface

High Temp – AV shunts completely closed and vessels dilate passively to increase skin blood

Cold Temp – AV shunts completely closed and precapillary sphincter closes to prevent blood from going to surface

Norepinephrine – causes vasoconstriction , released by sympathetic nervous system

Acetylcholine – usually causes vasodilation
○ Clinical Applications

Decubitus Ulcers (bedsores) – compromised circulation in area of skin usually due to compression of vessels

Contusion (bruise) – leakage of blood out of capillaries

Erythema – redness of skin due to enlarged capillaries

Capillary hemangioma (birth mark) – benign vascular tumor of dermal capillaries

Appendages of Skin

Hair
○ Hard keratinous epithelial fiber composed of keratinocytes
○ Hair Follicle – where the hair is anchored, tubular invagination of the epidermis which extends down through the dermis to the hypodermis
 Enters skin obliquely

Surroundings
○ Dermal Sheath – CT surrounding follicle
○ External Root Sheath – extension of the stratum basale and spinosum , completely surrounds
○ Internal Rooth Sheath – derived from outside region of matrix

Goes only half way up, cells slough off before sebaceous gland

Contains soft keratin

Subdivisions
○ Hair Shaft – the actual hair above the surface

Cuticle of Hair – outer single layer of hard keratin

Cortex – inner bulk of hair, hard keratin

Medulla – center area made of soft keratin
○ Root of Hair – from center of follicle down to bulb
○ Bulb – nutrient supply to hair follicle, enlargement at deep end

Contains dermal papillae composed of CT

Zones

○ Matrix/germativum Zone – where proliferation of keratinocytes occurs, equivalent of stratum basale in epidermis

From here keratinocytes move upward and differentiate via keratinization
○ Keratogenous Zone – where cells become fully keratinized

Hard Keratin – has more disulfide bonds than soft keratin
○ Hair Color

Melanocytes in matrix produce pigment which is transferred to the keratinocytes

Pheomelanin – yellow, develops from tryptophan

Eumelanin – brown & black, develops from tyrosine

Gray Hair – melanocytes lack tyrosinase (which is responsible for producing melanin)

White Hair – pigment lacking + air pockets that reflect light
○ Associated Structures
 Errector Pili Muscles – smooth muscle which connects basement membrane of dermal papillae to dermal sheath

Sebaceous Gland – oil gland in acute angle of hair shaft near top
○ Hair Cycle

Hair does not grow continuously, it grows in cyclic stages

All hairs are in different phases of the cycle

Anagen Phase (growth phase) – due to proliferation of matrix
○ Different length of growth phase in different areas of body

Catagen Phase (transitional phase) – growth stops, but hair remains in follicle (short time)

Telogen Phase (resting phase) – hair shaft falls out and bulb involutes

Glands
○ Sebaceous – secrete sebum , oily substance

Associated with hair follicles

Morphology – simple or branched alveolar
○ Secretory unit – single alveolus (IS THIS REDUNDANT??)

Duct – single duct opening into hair follicle

Mode – holicrine (entire cell degenerates and is secreted)

Clinical Connection – when infected by bacteria they cause acne
○ Sex hormones at puberty increase secretion
○ Sudiferous Glands – sweat glands

Eccrine Sweat Glands – secrete serous and mucus substance, most common sweat gland
○ Separate from hair follicle
○ Morphology - simple coiled tubular glands
○ Duct – open at top of friction ridges (when they are present)
○ Mode – merocrine (secreted through exocytosis)
○ Function – temp regulation, excrtetion of ions (like a kidney)
○ Types of Cells

Clear Cells – serous

Dark Cells – mucous

Myoepithelial cells – help expel secretions
○ Hyperhidrosis – excessive sweating

Apocrine Sweat Glands – secrete serous substance
○ Duct opens into hair follicle
○ Morphology - simple coiled tubular glands
○ Mode - merocrine, not apocrine
○ Don‟t function until puberty
○ Located in axilla, pubic region, etc.
○ Modified Glands

Meibomian (tarsal) Glands – secrete oily substance
○ Modified sebaceous glands on inner surface of eyelids


Ceruminous Glands – secrete wax (cerumen)
○ Modified apocrine sweat glands in external auditory canal

Mammary Glands – modified apocrine glands

Nails
○ Nail Plate – main body of nail containing keratinocytes with hard keratin

Replaces stratum corneum

Lateral Nail Groove – lateral edge of nail plate

Nail Root – proximal portion where nail plate starts
○ Nail Matrix – portion near nail root where keratinocytes proliferate to form nail

Lunula – whitish crescent that is distal-most part of nail matrix
○ Nail Bed – portion of epidermis where nail plate lies

Continuous with strata basale & spinosum
○ Eponychium – flap of skin that grows over the root of the nail
○ Hyponychium – excess stratum corneum under free edge of nail

Sensory Receptors

It is difficult to match functional classification with morphological classification because they mix

Functional Classification
○ Mechanoreceptor – touch, pressure, stretch
○ Thermoreceptor
○ Nociceptor – pain, itch, etc.

Morphological Classification
Free Nerve Ending Lack Schwann cells and myelin at terminal end
Merkel Cell Ending Between keratinocytes in stratum basale
Meissner’s Corpuscle Located in dermal papillae of papillary layer
Pacinian Corpuscle Large onion-like structure in lower dermis and hypodermis
Thermoreceptors & nociceptors
Light touch mechanoreceptor
Light touch mechanoreceptor
Pressure and vibration mechanoreceptor
Free nerve ending
Unmyelinated nerve terminating on Merkel cell
Encapsulated
Encapsulated
Ruffini Corpuscle Elongated in lower dermis and hypodermis
Tension mechanoreceptor
Encapsulated
Krause End Bulb Located in conjunctiva, oral Unknown Delicate capsule (axon cavity, tongue branches within capsule)

○ Objectives

Define and describe: hypoblast, epiblast, primitive streak, primitive node, notocordal process, prochrodal plate, cloacal plate, notocord, ectoderm, mesoderm, and endoderm.
 Describe the formation of the bilaminar embryonic disk from the inner cell mass.

Describe the formation of the notocord.
 Descirbe the formation of the intraembryonic mesoderm.
 List the derivatives of each of the three basic germ layers.
 Describe a somite and its derivatives.
 Briefly describe the intraembryonic coelom and its formation.
 Briefly describe the folding processes that occur in the embryo and the consequences of these processes.
 Briefly describe the changes in appearance of the embryo and the fetus during development.

○ Objectives
 Describe the results of the lateral and longitudinal folding processes that occur in the embryo

Define: coelom, mesentery, septum transversum

Describe/define the adult structures derived from the primitive intraembryonic coelom
 Describe/define the origin of the cells lining the intraembryonic coelom and its definitive derivatives
 Describe the configuration of the intraembryonic coelom following the development of the head fold

Describe/define the pleuropericardial membranes and the pleuroperitoneal membranes
 Describe the relative position of the (thoracoabdominal) diaphragm during early development

 List the four major tissue sources contributing to the definitive diaphragm. Correlate each with the related area of the definitive diaphragm

Describe the probable developmental errors that produce: congenital posterolateral diaphragmatic hernia, congenital hiatal hernia, congenital retrosternal hernia

○
Objectives
 List the embryological origin of the epidermis, dermis and skin appendages
 Relate the types of wound healing and burns to the morphology and function of the skin

Define and describe the periderm and vernix caseosa. Be able to describe their origin, formation and function
 Describe the origin and usual destination of melanocytes. Describe what occurs if migration and proliferation fail. Be able to describe what determines skin color
 Describe the process of hemangioma formation
 Describe the formation of sweat glands, sebaceous glands and mammary glands. Relate the causes of polythelia and polymastia
 Describe the formation of the hair follicle and hair shaft
 Describe the formation of a fingernail/toenail
○ Embryology

Just Know Chronology, not specific weeks

Epidermis and Dermis

Epidermis - derived from ectoderm

Dermis - derived from mesoderm

Development of Layers
○ 3 Weeks – single layer of ectodermal cells resting on layer of mesenchyme
○ 4-5 Weeks – surface ectoderm forms two layered structure

Periderm – superficial layer of squamous epithelium
○ Cells undergo keritinization and are sloughed off
○ Secretes amniotic fluid

Basal Germanitive Layer – layer of basal cells that make periderm
○ 11 Weeks - Intermediate Layer forms and makes up bulk of skin
○ 21 Weeks – periderm stops sloughing off and forms normal stratum corneum

This is influenced by many factors (epidermal growth factor, etc.)

Vernix caseosa (greasey layer) – forms now to cover fetus and protect it from amniotic fluid
○ Turns baby into greased pig
○ Contains sloughed periderm cells and sebum

Clinical Application – hyperkeratinization
○ Lamellar Icthyosis – scale-like appearance of skin, usually lacks hair and sweat glands
○ Harlequin Icthyosis – extreme hyperkeratinization, „alligator skin‟, deep fissures, fetus dies

Fingerprints – form at 10 weeks, completed by 17 weeks

Other Cells
○ 1 st
, Langerhans Cells – arise from bone marrow and enter epidermis
○ 2 nd
, Neural Crest Cells – arise from neuroectoderm and enter dermis

Once in dermis → melanoblasts → once in basal layer then melanocytes
○ 3 rd
, Merkel Cells – appear in stratum basale

Hair

Hair follicle is formed by both epidermis and dermis

Stages (hair germ → hair bud → hair bulb)
○ Stage 1 – hair germ forms (slight invagination of epidermis into dermis)
○ Stage 2 – elongation of the bud into hair bud
○ Stage 3 – characterized as club-shaped and is called hair bulb (looks like full follicle)

Types of Hair
○ Lanugo Hair – first hair to form

Very fine and covers entire fetus by 5 months. Falls out before birth
○ Vellus Hair – found on fetus at birth. Very downy, (65% of adult female hair)

○ Terminal Hair – coarse hair of scalp, pubic & eyebrows (95% of male body hair)

Hirsutism – excessive hairiness in women & children due to vellus hair turning into terminal hair by increased androgen

Hypertrichosis – excessive hairiness due to excessive hair follicles or persistence of them

Glands

Apocrine and sebaceous glands form with hair follicle

Eccrine sweat glands are not associated with hair follicles
○ Epidermal bud elongates to dermis
→
cells form coil
→
central cells degenerate to form lumen
→ outer cells differentiate into secretory cells
○ All eccrine sweat glands are formed prior to birth
 Nails (about 10 weeks)

Nail starts on palmar surface of digit, but migrates to dorsal surface quickly

Primary nail field forms nail bed → nail field drives wedge of cells into dermis → wedge forms nail matrix which produces nail plate → eventually nail folds show

Periderm/epidermis covering of nail eventually degenerates by birth

Nail plate only reaches end of finger tip by 32 weeks
○ If nail plate isn‟t at end of the finger then it is an indicator of prematurity
○ Wound Healing

Epidermal Wound Healing Process

Note - Only epidermis is affected

Clot Formation – blood clot is formed by leakage of blood from capillaries in underlying dermis
○ Platelets and fibronectin in clot provide matrix for macrophages and keratinocytes
○ Platelets release a bunch of growth factors to start wound closure

Activation/Proliferation - chemotactic factors recruit neutrophils and monocytes
○ These enter via extravasation , which requires p-selectin
○ Neutrophils cause keratinocytes and fibroblasts to proliferate
○ A bunch of growth factors are released

Migration – keratinocytes migrate along bottom of wound towards its center via diapedesis
○ Migration occurs beneath or through clot
○ Requires metalloproteinases to break hemidesmosomes of basal lamina (like a basement membrane)
○ Plasmin is also used

Maturation – keratinocytes meet in the center of the wound and stop proliferating via contact inhibition
○ Now normal keratinization takes over to resurface the epidermis
○ Basal lamina synthesis occurs. Scab eventually sloughed off

Deep Wound Healing Process

Note - Dermis is also affected

Inflammation Phase – blood clot forms and vasodilation of capillaries (due to histamine) cause extravasation of neutrophils and macrophages

Proliferative Phase – fibroblasts and keratinocytes proliferate due to growth factors
○ These cells begin to secrete matrix to form granulation tissue

Migratory Phase – keratinocytes and fibroblasts migrate through blood clot to form granulation tissue
○ Blood vessels grow into granulation tissue
○ Fibroblasts at edge are transformed into myofibroblasts which produce actin and myosin in cells to cause contraction of the wound

Maturation Phase – granulation tissue slowly turned into dense irregular CT

Note - Scars are lighter because melanocytes don‟t migrate into them

Burns


1 st
Degree Burns – only epidermis is affected
○ Causes redness and mild pain (like a sunburn)

2 nd
Degree Burns – epidermis and upper part of dermis affected
○ Causes blisters, pain and edema (touching stove)

3 rd
Degree Burns – full thickness of skin is affected
○ Causes charred skin, no pain in center of burn, just around edges where pain receptors intact
○ Systemic effects are greater threat to life than the local effects

Dehydration, bacterial infection, renal shut down (due to ↓ removal of urea), shock (blood circulation is reduced due to loss of fluid, reduced urine production due to low blood volume)

○
Objectives
 Define the skeletal and ligamentous elements of the shoulder girdle. What is the shoulder girdle?
 Define the muscles acting on the shoulder: extrinsic, intrinsic, pectoral, serratus anterior, arm muscles

Know their origins, insertions, innervations and primary actions
 Identify the shoulder muscles that comprise the “rotator cuff” and discuss their function

Identify the boundaries and contents of the quadrangular and triangular spaces
○ Shoulder Movements

Scapular Movements - Very flexible, but this causes lack of stability

Abduction (protraction) and Adduction (retraction)

Elevation and depression

Upward/downward rotation – reference point is glenoid cavity (if it rotates, then it is rotation)

Glenohumeral movements – joint between arm and scapula

Flexion/extension – tends to deviate to middle with flexion (not completely perpendicular to body)

Abduction/adduction – only to 90

Medial/lateral rotation

Circumduction
○ Skeleton

Scapula (has superior, medial and lateral border, superior and inferior angle) superior angle is closer to medial border than superior border

Acromion – highest point of scapula, comes out posteriorly

Spine of Scapula
– on posterior surface, continuous with acromion

Coracoid process – comes out anteriorly

Suprascapular notch –
○ Superior transverse scapular ligament – goes across the suprascapular notch to form supracapular foramen
○ Suprascapular artery – goes over the ligament
○ Suprascapular nerve – goes below the ligament
 “
A rmy goes over the bridge, N avy goes under the bridge”

Supraspinous and Infraspinous Fossa – cavities above and below spine of scapula

Subscapular fossa – on anterior of scapula

Greater scapular notch – things go through here (under one end of spine of scapula)

Glenoid cavity – where arm attaches
○ Supra- and infraglenoid tubercles – above and below glenoid cavity

Humerus

Head of humerus – where it contacts glenoid cavity
○ Much bigger than the glenoid cavity (gives more flexibility, but less stability)

Anatomical neck – just surrounding head of humerus

Surgical neck – many fractures occur here

Posterior View – can see greater tuberosity

Anterior View
○ Lesser tuberosity – more medial

○ Bicipital groove (interubercular sulcus)
– biceps brachii goes through this
○ Greater tuberosity – more lateral
○ Deltoid tuberosity – midway down bone, in line with bicipital groove. Where deltoid attaches
○ Synovial Joint

Fibrous capsule – outermost part

Synovial membrane - contains synovial fluid which surrounds joint and bathes hyaline cartilage on bone

Synovial Fluid – produced by synoviocytes , contains hyaluronic acid

Cushions, lubricates and nourishes via diffusion which requires movement
○ Shoulder Joint
 Sternoclavicular Joint – true to name (connects sternum to clavicle)
 only bony attachment of upper limb to axial skeleton

Sternoclavicular ligament (anterior and posterior) – true to name

Interclavicular ligament – true to name

Costoclavicular ligament – attaches to rib

Acromioclavicular Joint (AC Joint) – true to name

Acromioclavicular ligament - if torn → shoulder separation

Coracoclavicular ligament – attaches coracoid to the last quarter of the clavicle

Coracoacromial Arch – prevents superior displacement of humerus
○ Coracoid process
○ Coracoacromial ligament – just forms roof so humerus doesn‟t displace (connections on same bone)
○ Acromion

Glenohumeral Joint - true to name

Shoulder dislocation – disruption of this joint

Fibrous Joint Capsule
○ Glenohumeral ligaments – strengthen anterior part of capsule

Contains thickenings called superior, middle, and inferior
○ Coracohumeral ligament – strengthens superior part of capsule

Transverse humeral ligament – strengthens superior part of capsule
○ Holds tendon of biceps in bicipital groove

Glenoid labrum – fibrocartilage ring around circumference of glenoid cavity, deepening it

Bursae – a synovial sac which facilitates movement of a structure over bone
○ Subacromial & subdeltoid bursa – looks like shoulder pads over just the shoulder

Does not communicate with glenohumeral joint cavity
○ Subtendinous bursa of subscapularis – over glenohumeral ligaments and does communicate with glenohumeral joint cavity
○ Muscles

Extrinsic Muscles
Insertion
Action Nerve Origin
→
Pectoralis minor ribs (3-5) coracoid process medial and lateral pectoral nerve
Serratus anterior – curves around ribs to inner part of scapula ribs (upper 8) medial border of scapula
-stabilize scapula
-protraction
-pull tip of shoulder downward
-holds scapula against thorax, protraction (abduction)
-rotates scapula to direct glenoid cavity upwards
-essential for raising arm above head long thoracic nerve

Trapezius -ligamentum nuchae
-SP of vertebrae
Levator scapulae
C1-C4
-spine and acromion of scapula
-lateral portion of clavicle
(wraps around front)
superior angle of scapula
medial border of scapula
-elevate and depress scapula
-retraction (adduction) of scapula
-rotate glenoid process of scapula ↑
-elevate scapula
-rotate glenoid cavity ↓
-If insertion point is fixed then it can laterally flex neck
-retracts (adducts) scapula
-accessory nerve
(motor)
-C3-4 (proprioception) dorsal scapular nerve
Rhomboid major & minor
SPs of thoracic vertebra
→
medial border of scapula
Pectoralis major
Latissimus dorsi
-clavicular head
-sternocostal head
-T7 to sacrum
-iliac crest lateral lip of bicipedal groove
Intertubercular sulcus
-adductor of arm
-medial rotation of arm dorsal scapular nerve medial and lateral pectoral nerve thoracodorsal nerve -Adducts arm
-medial rotator of arm
-extends arm
→
Subclavius rib 1 clavicle -depression of clavicle
-anchoring of clavicle
nerve to subclavius
Serratus posterior superior
SP (C7-T3) Ribs 2-5 Expands ribs Ventral rami
Serratus posterior inferior
SP (T11-L2) Ribs (last 4) Expands ribs Ventral rami

Note – "Lady between two Majors"
○ The latissimus dorsi has its insertion point in bicipital groove (intertubercular sulcus) which is between two insertions of 'major' muscles on the medial and lateral edge of bicipital groove

Note - „medial‟ and „lateral‟ pectoral nerve based on origin of nerve, not what they innervate

Intrinsic Muscles

Origin – all scapula

Insertion – all humerus

Action – all act on humerus and help stabilize joint
Origin Insertion Action Nerve
Rotator Cuff – group of muscles and tendons that stabilize glenohumeral joint by attaching the scapula to the humerus
Teres Minor
Infraspinatis
Supraspinatus – goes through scapular notch
Subscapularis
Scapula –
lateral border
Scapula –
Scapula – fossa
supraspinous greater tuberosity lateral rotation
infraspinous fossa greater tuberosity lateral rotation
Axillary
Suprascapular greater tuberosity abduction (initiates) Suprascapular
Scapula –
subscapular fossa lesser tuberosity medial rotation Subscapular
Deltoid
Teres Major
Other Intrinsic Muscles of Shoulder
Scapula (front and back)
lateral 1/3 of clavicle
acromion
spine of scapula deltoid tuberosity -Abduction
-extends
-flexes
-medial & lateral rotation
Scapula –
lateral border medial edge of bicipital groove
-medial rotation
-(a little adduction)
Axillary
Lower subscapular

○ Scapular Rotation with Humeral Abduction
 0-30 Degrees - Abduction at glenohumeral joint only via supraspinatus

30-120 Degrees – abduction at glenohumeral joint via supraspinatus & deltoid
 scapular rotation via trapezius & serratus anterior

>120 Degrees – scapular rotation only
 (humerus has hit acromion and can‟t move anymore

○ Objectives

Axilla

Define the skeletal and muscular boundaries of the axilla

Identify the contents of the axilla. From what structure is the axillary sheath derived? What structures are included in the axillary sheath
 Brachial Plexus and Axillary Vasculature

Define the typical branching pattern of the brachial plexus. What landmarks can be used to find each level of the plexus: roots (ventral rami) → trunks → divisions → cords → terminal nerves
○ What are the supra clavicular branches and what do they innervate? What are the infra clavicular branches and what do they innervate?
○
What are the terminal nerves of the brachial plexus? Which groups of muscles do they innervate
 Autonomics of the Upper Extremity

At which spinal levels do preganglionic sympathetic fibers destined for the upper extremity arise?

Do parasympathetic fibers innervate vasculature of the upper extremity?

Blood Supply of the Upper Extremity

Which branches of the subclavian artery supply structures of the shoulder?

Where does the subclavian artery change its name to the axillary artery?

Which branches of the axillary artery supply structures of the shoulder and upper arm?

Understand the concept of collateral circulation and its application to this region
 Lymphatics of the Upper Extremity

Understand the basic lymphatic drainage of the upper extremity. How does lymph from the right upper extremity reach the right brachiocephalic vein?

How does lymph from the left upper extremity reach the left brachiocephalic vein
○ Borders of the Axilla

Apex – rib 1, upper edge of scapula & clavicle
 Base – skin (subcutaneous tissue and deep fascia)

Anterior Wall – pec major and minor, subclavius muscles & clavipectoral fascia

Posterior Wall – scapula, subscapularis, latissimus, teres major, long head of tricep

Medial Wall – ribs 1-4, intercostal and serratus anterior muscles

Lateral Wall – humerus
○ Contents of Axilla
 Axillary Artery – continuation of subclavian

Axillary Vein – thinner walled than axillary artery

Axillary lymphatics and nodes – most common site of breast metastasis. In axillary fat
 Axillary Sheath – extension of prevertebral fascia

Contains – brachial plexus, axillary artery, axillary vein

Brachial Plexus – C5-T1 nerves (ventral rami)
○ Brachial Plexus
 “Randy Travis Drinks Cold Beer”

Made of ventral rami of spinal nerves



Note – Posterior cord is posterior to axillary artery

Note – Radial nerve goes medial, axillary nerve goes lateral

Outline

Roots – in posterior cervical triangle, contains 5

Trunks – at/above clavicle , contains 3

Divisions – posterior to clavicle, lots of crosses

Cords – around axillary artery, back to 3

Terminal Branches – 5 named mixed nerves
Vertebral Motor Sensory
Axillary C5-6
Musculocutaneous C5-7
Median C5-T1 shoulder arm flexors mainly forearm, but a little hand
Over deltoid
Anterolateral forearm
Palmar surface lateral 3.5 digits
Ulnar C8-T1 mainly hand, but a little forearm Palmar surface medial 1.5 digits
Radial C5-T1 extensors of arm and forearm (and a few others)
Posterior forearm & dorsolateral hand
○ Note – motor innervation for radial nerve “BEST – brachioradialis, extensors, supinator, triceps”
○ Note – musculocutaneous pierces coracobrachialis (a good place to orient yourself)
○ Note – the more caudal the spinal nerve that innervates a terminal branch the more likely it is to innervate a distal structure
 When testing for damage of the brachial plexus, you can test sensory areas or muscles. When testing muscles remember that as you move distally on the arm you test lower aspects of the brachial plexus

Other Nerves
 Don‟t worry about specific spinal nerves, just know groupings
Supraclavicular Nerves Infraclavicular Nerves
1. Dorsal scapular – C5 5. Lateral pectoral – C5-7
2. Suprascapular – C5-6 6. Medial pectoral – C8-T1
3. Subclavian – C5-6 7. Medial cutaneous nerve of arm – C8-T1
4. Long Thoracic – C5-7 8. Medial cutaneous nerve of forearm – C8-T1
9. Upper subscapular – C5
10. Thoracodorsal – C6-8
11. Lower subscapular – C6

Note – medial pectoral pierces pec minor and innervates pec major

Note – medial cutaneous nerve of the arm joins the intercostalbrachial nerve (a branch of T2)


Areas of Dermatome to test specific spinal cord levels of the Brachial
Plexus

C5 – upper lateral arm

C6 – pad of thumb

C7 – pad of index finger

C8 – pad of little finger

T1 – medial elbow
○ Axillary Artery

Subclavian artery
→ lateral border of rib 1
→
axillary artery
→
ends at lower border of teres major → brachial artery
Parts
1 pec minor
2
-
-
Proximal
Posterior to pec minor
to
Branches
Superior thoracic a.
Thoracoacromial a.
Lateral thoracic a.
Structures Supplied Notes
-Pectoral mm
-Thoracic wall mm
-Serratus anterior m
C lavicular branch
A cromial branch
D eltoid branch
P ectoral branch
-Serratus anterior m.
-Pectoralis minor
-Mammary glands
This supplies branches
"Cadavers Are Dead People"
Not always there
“L-L”
L ateral goes with
L ong thoracic nerve
3 - Distal to pec minor
Subscapular a.
Subscapularis m
Circumflex scapular a.
posterior scapula
teres minor
infraspinatus
Thoracodorsal a.
latissimus dorsi
-Deltoid
-triceps brachii mm
Largest branch of axillary artery
Anterior humerial circumflex a
Smaller
Posterior humerial -Deltoid Larger circumflex a -triceps brachii mm

Note – "Screw The Lawyer, Save A Patient"

Note – the two humerial circumflex arteries go around humerus and eventually join
○ Spaces and Intervals
Triangular Space
Quadrangular
Space
Triangular
Interval
Contents
-Circumflex scapular a
(deep to it)
-Axillary nerve
-Posterior circumflex
-humeral a.
(these go through)
-Profunda brachii a.
-Radial n.
(deep to it)
Boundaries
-Teres major
-Teres minor
-Long head of tricep
-Teres major
-Teres minor
-Long head of tricep
Lateral head of tricep
-Teres major
-Long head of tricep
-Lateral head of tricep


○ Scapular Arterial Anastomoses

End to end joining of blood vessels which provides redundancy

Basically, two blood vessels venture down, one branches off and connects head on with the other

Suprascapular ↔ circumflex scapular artery

Posterior circumflex artery ↔ anterior circumflex artery?

Dorsal scapular artery ↔ posterior intercostals arteries
○ Venous Drainage
 Superficial Veins

Both originate on the dorsum of the hand

Basilic vein – continues as axillary, becomes a deep vein (so it is both a deep and superficial vein)
○ On medial side of arm

Cephalic vein – on lateral side of arm, joins axillary after going through the clavipectoral triangle
○ Clavipectoral triangle – made by deltoid, pectoral and clavicle

Deep Vein?

Paired and on either side of accompanying arteries (vein, artery, vein)
○ Lymphatic Drainage

Are not within the axillary sheath

Lateral & Anterior & Posterior → Central → Apical → Subclavian lymph trunk → venous system

Note - apical lymph node drains all other nodes and the mammary glands

○ Objectives

Briefly explain why the conceptus is not immunologically rejected by the mother during and following the process of implantation
 Define/describe homeotic genes (homeobox genes). What is their role in development? How are they regulated?

Define the term critical (sensitive) period of development. List several examples of critical periods and the results of alterations in the regional microenvironment within the embryo/fetus during them
 Describe the principle of cranio-caudal and proximo-distal growth sequences
 Define induction and give two examples of induction during embryonic development
 Describe the following processes that are important in development: tissue aggregation, cell death, differentiation, growth and regeneration
 Define teratology
 Give and example of a defect caused by each of the following classes of teratogen:

Environmental: infectious agents, radiation or chemical, hormonal

Chromosomal or genetic: autosomal abnormalities, sex chromosome abnormalities

○ Objectives
 Veins of the Upper Extremity

What are they and where are they?
 Arteries of Upper Extremity

What is the course and branching pattern of the brachial artery?


Which arteries contribute to collateral (and recurrent) circulation of the elbow?

What happens to the brachial artery as it passes into the forearm?

Compartments of the Arm

Which muscles are found in the flexor (anterior) compartment?
What are their attachments and what are their primary actions?
What nerve innervates the muscles of the flexor compartment?

Which muscles are found in the extensor (posterior) compartment?
What are their attachments and what are their primary actions?
What nerve innervates the muscles of the extensor compartment?

Compartments of the Forearm

What are the boundaries and contents of the cubital fossa?

Which muscles make up the Flexor-Pronator group?
What are their attachments and what are their primary actions?
What nerves innervate these muscles?

Which muscles make up the Extensor-Supinator group?
What are their attachments and what are their primary actions?
What nerves innervate these muscles?
○ Movements of the Arm and Forearm
 Glenohumeral Movements

Flexion – extension

Abduction – adduction

Medial rotation – lateral rotation

Circumduction

Elbow and Forearm

Flexion – Extension

Pronation – supination
○ Arm/Elbow

Skeleton

Foramen for nutrient artery – hole for a blood vessel into bone

Radial Groove – where radial nerve travels along the bone

Distal Humerus
○ Lateral suprachondylar ridge –
○ Radial fossa – for radial head, on anterior side
○ Coranoid fossa – for coranoid process of ulna, on anterior side
○ Capitulum – a round protrusion, on anterior side
○ Trochlea – a „valley‟ on the distal end
○ Lateral epichondyle –
○ Medial epichondyle – ulnar nerve passes behind it
○ Olecranon fossa – on posterior side, accepts olecronon of ulna

Forearm
○ Ulna – the stable bone

Olecranon process – what you feel at the elbow
 Trochlear notch – on the other side of the olecranon process (huh?)

Coranoid process – outside of the other end of the notch (huh?)

Radial notch – accepts radius

Ulnar tuberosity – accepts brachialis insertion

Styloid process – on distal end of ulna
○ Interosseous membrane – connects radius and ulna and has openings at top and bottom
○ Radius – the rotator

Head of radius –

Neck of radius –

Radial tuberosity – accepts biceps tendon
 Styloid process – on distal end, the ulna also has one

Elbow Joint


Fibrous Capsule – all the CT holding the joint together
○ Radial Collateral Ligament – thickening on lateral/radial side
○ Ulnar Collateral Ligament – thickening on medial/ulnar side

Anular ligament of radius – wraps around radius like a „ring‟ to hold it in place while letting it rotate

Muscles around Humerus
Biceps brachii
Brachialis
Coracobrachialis
Origin Insertion Action
Short Head – coracoids process
Humerus – body
Coracoid
Anterior (Flexor) Compartment
Long Head -
Supraglenoid tubercle
-biceps tendon to radial tuberosity
-bicipital aponeurosis
(which blends with deep fascia)
Elbow - Flexor
Elbow - Supinator
Ulna – ulnar tuberosity Elbow - Flexor (Pure)
Humerus – medial body -Arm – flexor
-Arm – adductor
Nerve
Musculocutaneous
Posterior (Extensor) Compartment
Triceps brachii
Long Head
infraglenoid tubercle
Lateral Head
humerus – shaft
Medial Head
(same as lateral head?)
Humerus – lateral epichondyle
Ulna – olecronon Elbow - extensor
Aconeus
Ulna – proximal Elbow – extensor
Stabilizer
○ Note – humerus is mainly in anterior compartment
○ Note – Long head of biceps brachii is based on the length of the tendon
○ Note – brachialis is covered by bicep

Cross Section
○ Lateral intermuscular septum – separates anterior (flexor) from posterior (extensor) compartment
○ Brachial Fascia – a “deep fascia” which surrounds
Radial both compartments
 maintains integrity of the muscles; allows them to function as one;

Arteries helps venous return

At inferior part of teres major the axillary artery becomes the brachial artery

The profunda brachii artery branches off the brachial artery and then becomes the radial collateral

The brachial artery branches just after passing under the bicipital aponeurosis into the radial artery and the ulnar artery

Redundancy
○ The proximal end of the elbow joint is supplied by three collaterals

○ The distal end is supplied by three recurrent arteries
○ All of these connect at the elbow to form anastamoses

Veins

Paired brachial veins – deep to the bicep

Medial cubital vein – the cephalic and basilic vein merge to form this
○ A good place for drawing blood

Nerves

Musculocutaneous – is motor in the proximal portion, but sensory in the distal portion (the forearm)
○ Penetrates the coracobrachialis
○ When in the forearm it is only sensory and is called the cutaneous portion of the musculocutaneous nerve

Median – no major branches in arm

Ulnar – no major branches in arm, travels behind the medial epichondyle

Note – medial and ulnar travel with the brachial artery in the arm

Radial – is motor in the posterior arm compartment and sensory in lateral and posterior arm?

See cross section
○ Note – paired brachial veins, radial nerve barely sits in the radial groove, “deep artery and veins of arm” = profunda brachii
○ Forearm
 Note – basically, when a muscle passes over a joint it will play a part in moving it

Compartments

Lateral intermuscular septum – between radius and deep fascia

Interosseous membrane – between radius and ulna

Medial intermuscular septum - between ulna and deep fascia

Flexor-Pronator

Note – superficial muscles have origin on medial epichondyle or humerus OR proximal-anterior radius/ulna
Pronator teres
Flexor carpi ulnaris
Palmaris longus
Flexor digitorum superficialis – beneath the other superficial muscles
Flexor carpi ulnaris
Origin
Insertion Action
– have origin on medial epichondyl
Ulna – head
Radius - middle
2 nd
metacarpal
Pronator
Flexor - elbow
Flexor – wrist
Radius - body
Palmar aponeurosis
(deep fascia in palm)
Flexor – wrist
Middle phalanges Flexor – digits
(and wrist)
Nerve
Flexor digitorum profundus
Flexor pollicis longus
Wrist – pisiform bone
Flexor – wrist Ulnar
– have origin on radius and ulna on anterior side
-Ulna
(-Radius)
Distal phalanges Flexor – digits
(and wrist)
-Radius
(-Ulna)
Distal phalanx of thumb
Flexor – thumb
Ulnar side = ulnar
Radial side = median

Pronator Ulna – distal Radius – distal quadratus
○ Note – „carpi‟ = wrist
○ Note – 'quadtratus' looks like a quadrangle

Extensor-Supinator
Origin
Pronator
Insertion Action
Brachio-radialis suprachondylar ridge Radius – styloid process Flexor – elbow
Extensor carpi radialis longus suprachondylar ridge II metacarpal Extensor – wrist
Radial deviation (abduction) - wrist
Extensor carpi radialis brevis
Extensor digitorum
III metacarpal Extensor – wrist
Radial deviation (abduction) - wrist
Distal phalnx of fingers Extensor – fingers and wrist
Extensor carpi ulnaris
Extensor digiti minimi
V metacarpal
V distal phalanx
Extensor – wrist
Ulnar deviation (adduction) – wrist
Extensor – pinky
Nerve
Supinator -Lateral epichondyle
-Ulna
Extensor Indicis -Ulna
-Interosseus membrane
Radius – proximal
II distal phalanx (index finger)
Supinate
Extensor – index finger
Abductor pollicis longus
-Radius
-Interosseus membrane
I metacarpal Extensor – base of thumb
Extensor pollicis brevis
-Radius
-Interosseus membrane
I base of proximal phalanx
Extensor – middle of thumb
Extensor pollicis Ulna I distal phalanx Extensor – end of thumb longus

Note – Superficial muscles have origin on lateral epichondyle OR proximal-anterior radius/ulna

Note – „pollex‟ = thumb

Note – the „brevis‟ vs. „longus‟ refers to the tendon
○ Cubital Fossa

Space at elbow that contains biceps tendon, brachial artery (and its radial and ulnar branches), brachial vein, parts of median and radial nerves

Boundaries

Superior – intercondylar line (imaginary)

Lateral – brachioradialis muscle

Medial – pronator teres muscle

Floor – brachialis & supinator muscles

Roof – deep fascia including bicipital aponeurosis & skin
○ Note that the median cubital vein is also here (the place for drawing blood)
○ Arteries (skipped hand arteries)


Brachial artery branches in cubital fossa →

Radial artery – basically goes to hand

Ulnar artery – branches just past elbow into:
○ Common interosseous – can be very short; branches into:

Anterior Interosseous – supplies deep flexors of forearm

Posterior Interosseous – supplies extensors of forearm

Note – he made a big point of this
○ Nerves (skipped hand nerves)

Median

Ulnar

Radial

Deep Branch – muscular, goes through supinator (goes through posterior interosseous???)

Superficial Branch – cutaneous

○ Objectives
 Define and describe the location of three types of muscle tissue: skeletal, cardiac and smooth
 List and describe the differences between the developmental origins for the skeletal muscle of the body: trunk muscles, pharyngeal arch muscles, ocular muscles, tongue muscles and muscles of the limbs

Define and/or describe: epaxial musculature, hypaxial musculature
 Describe the process of muscle cell maturation
 List the major regulatory factors that influence muscle cell maturation

List/describe the origin of cardiac and smooth muscle
○ Initial formation of the muscular system is independent from skeletal system, but later maturation is closely tied
○ Phases of Development

Commitment to myogenic lineage

Activation of a myogenic program

Proliferation of myogenic precursors

Specification of specific myogenic cells
 Fusion of mononucleated precursors to form multinucleated fibers

Organization of contractile proteins of the sarcomere
○ Formation from Mesoderm

Muscle system develops mainly from mesoderm

Exception – muscles of iris and ciliary body

Mesoderm condenses into 3 layers

Paraxial – around axis
○ Head
○ Somite

Sclerotome – cartilage, ribs and vertebrae of axial skeleton

Myotome – axial muscle tissue
 Dermatome - dermis

Intermediate → kidney & gonads

Lateral
○ Somatic (dorsal layer) → CT & vascular smooth muscle
○ Splanchnic (ventral layer) → smooth muscle of GI and cardiac muscle

Somitogenesis

Somitomeres – unsegmented mesoderm that develop into somites which are segmented
○ Differentiation is helped by somitomere expression of adhesion proteins causing compaction
○ Initiated by tyrosine kinase receptors called Eph which receive Ephrin signal molecules from surrounding tissue
○ After about 20 somitomeres form, then the 8 th
one begins to differentiate into a somite

This development starts rostrally and ends caudally (rostral → caudal)


The first 7 somitomeres do not develop into somites
○ These first 7 → muscles of face, jaw and throat

Axial Specification of Somites

Sclerotome somites (skeletal) that are experimentally moved to a different region will make the structure they are programmed to make in that new region.
○ Myotome somites don‟t do this, they are more influenced by the signals in the tissue which they migrate to

Somites are programmed where to go before being fully formed
○ Cells within a somite are only told to differentiate into a specific muscle after the somite is fully formed
 Somite Differentiation

Cells within a somite will need to differentiate into sclerotome, myotome and dermatome

The ventral region of somite wall forms the sclerotome

The dorsal wall forms the dermomyotome , this differentiates into:
○ Dermatome – forms dermis of back
○ Myotome – forms below dermatome in two stage process

1

2 st nd
– MyoD and Myf5 cause some cells in dermomyotome to commit to myogenic lineage
– myogenic precursors move away from dermomyotome to form their own layer
○ the myotomic cells then split into an epaxial region and a hypaxial region

Epaxial Myotome – found dorsomedially
○ Forms extensor muscles of neck & deep muscles of the back (ex. Erector spinae, transversospinosus)
○ Innervated by dorsal ramus of spinal nerves

Hypaxial Myotome – found ventrolaterally
○ Forms muscles of lateral and ventral body wall, limbs, tongue

Flex trunk and rotate vertebral column
○ Innervated by ventral ramus of spinal nerves
○ Extends aroundish the developing embryo

Pharyngeal Myotome – from the 1 st
7 somitomeres which didn‟t develop into somites
○ Forms muscles of mastication, facial expression, pharynx and larynx

Myogenesis

MyoD & Myf5 continue to influence myotome
○ Induce specification to myogenic fate (this is already accomplished)
○ Promote fusion of myogenic cells to form muscle fibers
○ Direct the organization of contractile proteins within the maturing muscle fibers

Somites in different rostro-caudal levels form appropriate muscle groups

Limb Muscles

Limb buds form from mesenchyme overlain by ectodermal tissue

Limb muscles form from the lateral portions of limb level somites, specifically the hypaxial area
○ These differentiate into myoblasts and then myotubules

Upper limb buds form around day 24 from C5-T1 somites

Lower limb buds form around day 28 from L2-S3 somites

Within a limb bud the myoblasts form two masses
○ Dorsal Limb Bud Mass – forms all limb extensor muscles (upper limb suppinators, all lower limb abductors)

Innervated by dorsal branch of ventral rami
○ Ventral Limb Bud Mass – forms all limb flexor muscles (upper limb pronators, lower limb adductors)

Innervated by ventral branch of ventral rami?

Limb bud masses eventually split to form specific muscles

○ Which muscle they become is not an intrinsic property of the myoblast, instead they get their cues from the surrounding CT
○ Muscle fiber type (fast, slow, red, white) is specified by intrinsic properties of myoblasts

Craniofacial Muscles

Pharyngeal Arches – 4 archlike masses of neuroectodermal cells which help create the face, mouth, nasal cavities, larynx and pharynx and differentiate into head and deep neck muscles
○ Form during the 4 th
and 5 th
weeks of gestation
○ Form from unsegmented somitomeres
○ Aggregate into pre-muscle masses
○ CT elements lay down tracks so that these somitomeres can migrate to the proper place to form the pharyngeal arches (this is a long way)
○ Innervated by cranial nerves once they make the pharyngeal arch, these nerves stay with the myoblasts as they move to their final destination
Pharyngeal Arch Cranial Nerve Muscles
1 st
2 nd
3 rd
4 th
V
VII
IX
X-XI
 Muscle Cell Fusion

Myoblasts → Skeletal Muscle Fibers
Mastication
Facial Expression
Stylopharyngeus
Larynx, pharynx
○ 1. Fusion of myoblasts to form multinucleated myotubules

Two classes of progenitor cells form
○ Founder Cells – primary cells which seed a distinct muscle
○ Fusion-Competent Cells – secondary cells which aggregate around the founder cell and fuse with them to form myotubules

Fusion requires – cell-cell recognition and attraction, adhesion, alignment, fusion
○ 2. Expression of contractile proteins and arrangement of sarcomeres
 Here the fiber type is established
○ CT sheath plays a part in expression of proteins for different fiber types? (contradiction??)

Muscle Cell Regeneration

Satellite Cells – mononuclear mygenic precursors that can divide at a slow rate to sustain self renewal and growth of muscle tissue
○ Replicate themselves due to Pax7
○ Differentiate into proper muscle cells via MyoD and Myf5

Regeneration is rare, but can happen after mechanical tearing or muscular disease
○ Smooth Muscle

Derived primarily from splanchnic mesoderm

GI – splanchnic mesoderm surrounding primordial gut

Vessels – somatic mesoderm

Iris & Ciliary Body – ectoderm

Mammary & sweat glands – myoepithelial cells derived from somatic endoderm

Note – splanchnic and somatic mesoderm from lateral plate mesoderm
○ Cardiac Muscle

Develops from splanchnic mesoderm surrounding the developing heart tube

Do not undergo fusion, instead they develop cell-to-cell connections (gap jnx, intercalcated discs)

○ Objectives
 Skeleton of Hand and Wrist

What are the bones of the hand and wrist? Be able to identify them in bone specimens as well as on X-rays

What is the carpal tunnel and what are its contents? What nerve is affected in carpal tunnel syndrome?

What is the Canal of Guyon and what are its contents?

 Blood Supply of the Hand

Where is the radial artery at the wrist and how does it enter the hand?

Where is the ulnar artery at the wrist and how does it enter the hand?

How do the radial and ulnar arteries contribute to the collateral circulation of the hand?
 Cutaneous Innervation of the Hand

What spinal levels innervate the thumb?

What spinal levels innervate the little finger?

Which portion of the hand would you test for median nerve innervation?

Which portion of the hand would you test for ulnar nerve innervation?

Which portion of the hand would you test for radial nerve innervation?
 Muscles of the Hand

What are the extrinsic muscles of the hand and what are their primary actions?

What are the intrinsic muscles of the hand and what are their primary actions?

What are the snuff box muscles and what are their primary actions?

What intrinsic hand muscles are innervated by the median, ulnar, and radial nerves?
 Clinical Conditions
 What nerve is damaged in “crutch palsy”?

What are the typical effects of an upper brachial plexus paralysis?

What are the typical effects ini the hand of a lower brachial plexus paralysis?
○ Skeleton

Carpal Bones – “Some lovers try positions that they cannot handle”

Start at thumb on lower level

Proximal - Scaphoid (skiff boat), Lunate , Triquetrum (3 sides), Pisiform (you can feel this?)

Distal – Trapezium , Trapezoid , Capitate (little head), Hamate (hook)

Metacarpals – I-V starting with thumb

Phalanges – Proximal , Middle and Distal (though thumb only has proximal and distal)

Note – radius is big at the wrist
 Scaphoid Fracture

Scaphoid bone is the most common wrist bone to be fractured if you catch fall with hands

Blood comes into scaphoid at its distal end and so if fracture happens below that circulation may be compromised and nonunion or avascular necrosis could develop
○ This can lead to arthritis
○ Surgery necessary to treat this
○ Movements of the Wrist and Fingers

Wrist – remember that the palm is face up in anatomical position

Extension/Flexion

Abduction ( radial deviation )/Adduction ( ulnar deviation )

Fingers – think of the middle finger as the midline

Abduction (away from middle finger)/Adduction (toward middle finger)

Extension/Flexion

Thumb

Extension/Flexion – tricky, „main flexion action of thumb‟

Abduction (move thumb anterior to 4 fingers)/adduction

Opposition – movement unique to thumb and pinky
○ Joints of the Fingers

Metacarpophalangeal Joint (MP Joint) – 1 st
knuckle

Proximal Interphalangeal Joint (PIP Joint) – 2 nd
knuckle

Distal Interphalangeal Joint (DIP Joint) – Knuckle sandwich
○ Aponeurosis and Synovial Sheaths
 Palmar Aponeurosis – a condensation of deep fascia which protects the palm

Comes from the tendon of palmaris longus

Common Sheath – underneath palmar aponeurosis and protects tendons, contains synovial fluid

Fibrous Digital Sheaths – on inner side of fingers, contains synovial fluid

○ Muscles
Origin
Insertion Action Nerve
Abductor digiti minimi
Flexor digiti minimi
Opponens digiti minimi
Pisiform
-Hamulus
-Flexor retinaculum
-Hamulus
-Flexor retinaculum
Abductor pollicis brevis
Flexor pollicis brevis
-Scaphoid
-Trapezium
-Flexor retinaculum
Superficial Head: flexor retinaculum
Deep Head: capitate & trapezium
Opponens pollicis Trapezium
Proximal phalanx
Proximal phalanx
5 th
metacarpal
1 st
metacarpal
Abductor
Flexor
Oppose
Abductor
Flexor
Oppose
Ulnar
(deep branch)
Median nerve
(recurrent branch)
Except deep head, it is ulnar
Dorsal interosseous mm
(4)
Palmar interosseus mm (3)
Metacarpals
Metacarpals
-Proximal Phalanx
-dorsal expansion
“extensor hood”
-Proximal Phalanx
-dorsal expansion
“extensor hood”
A b ducts
A d ducts
Ulnar
(deep branch)
Adductor pollicis -Metacarpal III
-Capitate
Lumbricals (4) Tendons of flexor digitorum profundum
Proximal phalanx of thumb
Extensor hood
A d ducts
-Flexes MP joint
-Extends DIP and PIP Joints
Ulnar and
Median

Dorsal interosseous mm – “DAB” – d orsal interosseous ab ducts

Proximal interosseous mm – “PAD” – p almar interosseous ad ducts

Note – note the number of each deep muscle

Note – lumbricals on palmar side, superficial to interosseous
○ Extensor Hood

Muscles attaching to it

Lumbricals, dorsal interosseous, palmar interosseous, abductor digiti minimi, adductor pollicis, abductor pollicis brevis

Lots of the muscles involved in handwriting
○ Arterial Supply
 Radial and Ulnar arteries anastamose on the palmar side of the wrist and give off branches for the fingers

Both are underneath palmar aponeurosis

Superficial Palmar Arch – a little more distal than deep palmar arch

Mainly supplied by ulnar artery

Ulnar artery
→
Superficial palmar arch
→ common palmar digital arteries (single in the middle)
→ proper palmar digital arteries (two on sides)
○ " USC P oonani"


Deep Palmar Arch – proximal to superficial palmar arch

Mainly supplied by radial artery (which is on the thumb side)

Deep palmar arch → palmar metacarpal arteries → proper palmar digital arteries
○ Nerves

Superficial Branch of Radial Nerve – sensory only in hand

Ulnar Nerve

Deep Branch of Ulnar – motor to intrinsic hand muscles

Superficial Branch of Ulnar – sensory

Palmal Branch of Ulnar – sensory
 Median Nerve

Recurrent Branch of Median – supplies thenar muscles
○ Goes through carpal tunnel

Palmar Branch of Median – sensory
○ Goes through carpal tunnel

Digital Branch of Median – sensory

Dermatome Hotspots

C6 – palmar tip of thumb

C7 – palmar tip of index finger

C8 – palmar tip of pinky
○ Carpal Tunnel

Flexor retinaculum covers palmar area containing tendons and nerves

Connects to Scaphoid (1), Pisiform (4), Trapezium (5) and Hamate (8)

Contents

4 Tendons of flexor digitorum superficialis – superficial

4 Tendons of flexor digitorum profundus – deeper

Median Nerve – thumb side near surface (except digital branch)

Tendon of flexor pollicis longus – thumb side deeper than median

Other Tunnels not part of Carpal Tunnel

Ulnar Tunnel – contains ulnar artery and nerve, is above the flexor retinaculum

Tendon of flexor carpi radialis – inside flexor retinaculum on thumb side
○ Anatomical Snuff Box
 Boundaries

Palmar – tendons of extensor pollicis brevis and abductor pollicis longus

Dorsal – tendon of extensor pollicis longus

Proximal – extensor retinaculum

Floor – scaphoid & trapezium

Roof – superficial fascia containing branches of superficial branch of radial nerve
 Contains the radial artery
○ Clinical Connections

Brachial Plexus Injuries

Erb-Duschenne Palsy – upper plexus injury (C5-6)
○ Caused by stretching arm or neck in funny ways
○ Nerves

Injures axillary, musculocutaneous & suprascapular nerves


Suprascapular prone to injury because it is fixed at suprascapular notch
○ Note - Supraspinatous and infraspinatous muscles are paralyzed most often
○ Symptoms

Arm lacks normal abduction and external rotation

Arm cannot be raised over head because deltoid (axillary) and supra- infraspinatous muscles
(suprascapular) are paralyzed

Elbow flexion weakened because biceps (musculocutaneous) is paralyzed

If roots damaged above their junction then additional paralysis of rhomboids (dorsal scapular) and serratus anterior (long thoracic) producing weakness in scapular retraction and protraction

Klumpke Paralysis – lower plexus injury (C8-T1), much less common, short hand muscles affected
○ Results in claw hand

Median Nerve Paralysis – results in atrophy of thenar muscles – Abductor pollicis brevis, Opponens pollicis

Flexor pollicis brevis maintains some function because deep head is innervated by ulnar

Ulnar Nerve Paralysis – results in interosseous muscle atrophy

Wrist deviates to radial side since no flexor carpi ulnaris

Hyperextension of 4 th
and 5 th
MP joints

Flexor digitorum profundus weakend – cannot flex 4 th

Flexion of 2 nd
and 3 rd
DIP
and 5 th
DIP
 Dupuytren’s Contracture
– thickening of palmar aponeurosis

Shortening and thickening of digital bands pulls fingers into flexion (esp ring and pinky)
 Colle’s Fracture – fracture of wrist resulting from falling on outstretched hand

Force transmitted through thenar eminence to lateral carpal bones and end of radius

Distal fragment displaced posteriorly („dinner fork deformity‟)

○ Objectives
 Understand how mesoderm and neural crest contribute to skeletal system formation
 Understand the basic processes involved in development of the axial skeleton

Understand the principal molecules and genes involved in somite differentiation that relate to skeleton development

Vertebrae and Ribs
○ Describe how vertebrae and ribs are formed by endochondral ossification of sclerotome regions of somites
○ Describe the formation of intervertebral discs
○
Understand the principal molecules and genes involved in development of vertebral column
 What are brevicollis, spina bifida, and scoliosis; what are some of the causes for these defects
○ Describe how ribs form from lateral processes of thoracic vertebrae
○
Describe how the sternum and clavicle are formed
 What is cleidocranial dysplasia?
 Understand the basic processes involved in development of the appendicular skeleton

Describe how somatic lateral plate mesoderm forms the skeleton of the appendages – the limb bones and appendicular girdles

Describe how the appendicular skeleton is formed by endochondral ossification of cartilage models

Understand the role of the apical ectodermal ridge (AER), zone of polarizing activity (ZPA), and the molecules that establish axes of polarity in the limb

Describe how digits (fingers and toes) are formed. What is the role of cell death?

Describe limb rotation and the consequences for muscle compartments

What are Amelia, meormelia, and achondroplasia?

What are the epiphyses and diaphyses and what are their significance?
 Describe how synovial joints are formed
○ Derivatives of Mesoderm

Paraxial Mesoderm – forms somites (mesoderm around a small cavity)

Gives rise to sclerotome which forms the axial skeleton

Intermediate Mesoderm – connects paraxial and lateral plate mesoderm

Lateral Plate Mesoderm – lines intraembryonic cavity, becomes parietal and visceral layers


Forms appendicular skeleton
○ Skeletal Development

Begins during week 4

Many develop from pre-existing cartilage
○ Development of Axial Skeleton

Somitic sclerotome – forms all cartilages and bones of axial skeleton

Somite Development and Axial Skeleton

Somites develop into dermomyotome (which becomes dermatome and myotome) and sclerotome

Cells migrate ventromedially (toward notochord) to make sclerotome

Sclerotome formation induced by notochord and neural tube via noggin and sonic hedgehog

Sclerotome then expresses Pax1 which initiates cartilage and bone forming gene expression

Origin of Specific Bones

Vertebrae
○ Formed by endochondral ossification
○ Develops in cranial
→
caudal sequence from 42-44 somite pairs

Which vertebrae a somite becomes influenced by cominations of Hox genes

4 Occipital Somites – 1 degenerates

8 Cervical Somites – the 1

12 Thoracic st
cervical and remaining 3 occipital fuse to form skull base

5 Lumbar
 5 Sacral – fuse to form sacrum

8-10 – coccygeal fuse to form coccyx (last 5-7 degenerate)
○ Development of Individual Vertebra
 Sclerotome from each side of body converge to make each vertebrae and disc

Developing spinal nerve splits each somite and causes Cranial + Caudal parts of adjacent somites to combine and form vertebra

Ventromedial part of each vertebra forms centrum (future vertebral body)
○ Influenced by sonic hedgehog

Dorsal part of each vertebra forms costal processes (future TP) and vertebral arch
○ Influenced by roof plate of neural tube

Why Resegment?
○ Causes myotomes to span intervertebral discs (allows muscles to move vertebra)
○ Intersegmental arteries (which were originally between sclerotomes) pass over middle of vertebral body
○ Spinal nerves near intervertebral disks pass through intervertebral foramen
○ Development of Intervertebral Discs

Developed from lower somite (ex. C5-C6 disc is from C6 somite)

Nucleus Pulposis – derived from notochord (notochord regresses from area of vert. body)

Annulus Fibrosis – formed by condensation of other sclerotome cells

Thus, the disc has two origins, notochord and sclerotome
○ Vertebral Defects

Klippel-Feil Syndrome (Brevicollis) – congenital failure to segement cervical vert
(especially C2 & C3)
○ Causes – short neck, ↓ cervical motion, low hairline, scoliosis, hearing loss
○ Gene locus on Ch 8

Faulty Hox Gene Expression
○ Due to ↑ retinoic acid consumption or metabolic disturbances in mother
○ Results in messed up cranial-caudal gradient

Ex. If ↑ retinoic acid then type of vertebrae shift more caudally

Spina Bifida – incomplete development of vertebral arch
○ 1° Cause – failure of normal vertebral induction

○ 2° Cause – failure of neural tube to close dorsally
○ Can result in herniation of spinal cord and/or meninges

Scoliosis – defective formation of one side of vertebral column

Formation of Atlas and Axis
○ The last occipital somite and the first cervical combine to form proatlas which makes basioccipital bone and the top of the dens
○ Remember that the atlas does not form a vertebral body (called centrum in dev), thus cells that would normally form the centrum of C1 fuse with axis of C2 to form the dens

Ribs – form as outgrowths of thoracic vertebrae during month 2
○ Sclerotome cells migrate within somatic lateral plate mesoderm around body curvature toward ventral surface

Sternum – forms from unification of ventral aspect of ribs 1-7 (via migrating sclerotome cells)
○ Join with two vertical cartilaginous bands
○ Costal Cartilage joins ribs to sternum
○ Then segments into elements
○ Split xiphoid process is a common malformation

Clavicle
○ Forms by intramembranous ossification (different from most others)
○ Ossification begins earlier than most bones (weeks 5-6) and is the last to complete the process
(around 21-25 years)
○ Cleidocranial Dysplasia – aplasia or hypoplasia (poorly formed) clavicles
 Also affects development of head (flat nose) and teeth (too many and they don‟t fall out)
○ Note - somitic mesoderm is in somites, somatic mesoderm is in the body
○ Origin of Appendicular Skeleton

Made of appendicular girdles (shoulder and pelvic) and intrinsic limb bones

All formed by endochondral ossification except clavicle

All formed from somatic lateral plate mesoderm (including cartilage)

Note – upper limbs form before lower limbs

Overview of Limb Development

Mesenchyme core develops

Ectoderm surrounds and apical ectodermal ridge is formed

Limb bud develops

Cartilage mesenchyme condenses

Cartilage models begin to form

Cartilage models completed and ossification begins

Active ossification of fetal limbs

Limb Bud

Initially consists of:
○ Mesenchyme from lateral plate mesoderm – forms skeleton, CT and some BV
○ Mesenchyme from somites – forms muscle
○ Neural crest cells – form Schwann cells and melanocytes

Apical ectodermal ridge (AER) – thickened distal border which prevents mesenchyme from differentiating and instead causes it to proliferate rapidly (so that limb elongates)
○ Expresses SER2
○ Causes limb outgrowth and induced by factors from lateral plate mesoderm

These factors are different depending on which limb it is
○ If AER is experimentally removed then limb will stop proliferating and start differentiating

The entire limb bud is covered by ectoderm
○ Dorsal part expresses radical fringe
○ Ventral part expresses engrailed (just know that different things are expressed on either side)

The Process (mainly just understand the point)
○ Bone morphogenic factors (BMPs) in ventral ectoderm induce AER formation

○ AER restricted to distal tip of limb by radical fringe
○ Radical fringe induces SER2 expression in AER
○ Engrailed represses expression of radical fringe to maintain the polarization
○ AER then expresses FGF4 & 8 to proliferate cells
○ As limb elongates, the proximal mesenchymal cells start to differentiate as the AER gets farther away from them

Zone of Polarizing Activity (ZPA) – cluster of cells at caudal border of limb that establish the cranio-caudal polarization (proper location of digits etc.)
○ Produces retinoic acid which initiates expression of sonic hedgehog

Absence of SHH causes regression of AER (Why???)
○ As limb grows the ZPA moves distal to keep up with the AER

Dorsoventral Axis – regulated by BMPs in ventral ectoderm
○ BMPs cause expression of engrailed on ventral side, which represses stuff that is secreted by dorsal side
○ LMX1 specifies cells to be dorsal

HOXd Expression Patterns in Limb
○ Pattern limb along proximodistal axis
○ Influenced by combinations of SHH and others
○ ↑ number means more distal

Development of Digits
○ Process
 Apoptosis in specific parts of AER creates separate ridge for each digit

Apoptosis in interdigital spaces separates digits
○ If cell death does not occur → syndactyly (abnormal digit formation, too many or too few)
○ Apoptosis also important for separation of radius/ulna & tibia/fibia & axilla
○ Digit Specification - BMP concentration is highest between digit 4&5 and this causes digit 4 to be digit 4. BMP concentration is lowest between 1&2 and this causes 1 to become 1

Limb Rotation
○ At first all limbs are oriented so that flexors are on one side and extensors on the other
○ Then upper limb rotates laterally and lower limb rotates medially so that the muscles are in the right spot

Amelia – complete absence of limbs

Meromelia – partial absence of limb
○ Phocomelia – proximal structures small or absent

Epiphyseal Plates – temporary plate of cartilage between the diaphysis (middle of bone) and epiphysis (end of bone)
○ Long bones have one at each end, small bones only have one, irregular bones have multiple
○ Achondroplasia (dwarfism) – abnormal ossification of cartilage that mainly affects long bones

Epiphyseal growth retarded and ceases early

Joint Formation
○ Cartilage present and differentiated
○ Joint “interzone” created by cells proliferating and increasing in density
○ Joint cavity formed by cell death, but surrounding cells stay to form joint capsule

Blood
○ Objectives (she emphasized these)

Identify the components of the blood and describe their functions
 Identify sites of hematopoesis and describe what happens there

Explain the importance of stem cells and how they relate to hematopoiesis

Describe the functional anatomy of the bone marrow

Distinguish the developmental stages of formed elements

Describe the functions of granulocytes

○ Funciton – transport gases, buffer, transport hormones, produce & transport antibodies
○ Hematocrit – RBC % after centrifugation

Usually 45% RBCs, though in women it is lower

1% of it is WBCs and platelets, forming buffy coat
○ neutrophils > lymphocytes > monocytes > eosinophils > basophils
○ Granular leukocytes – neutrophils, eosinophils, basophils
○ Agranular leukocytes – monocytes, lymphocytes (T cells, B cells)
○ Nice picture??

The other 65% is plasma , just water, proteins and solutes

7% proteins – created in liver and confined to bloodstream
○ albumin – maintains blood osmotic pressure
○ immunoglobulins – antibodies
○ fibrinogen – for clotting

1-2% - electrolytes, nutrients, hormones, waste products, gases
○ RBCs

Important Structures

Band 3 – ion transporter & site for ankyrin to hold onto

Spectrin + Band 4.1 + actin – lets RBC be pliable

Reticulocytes – immature RBCs in circulation

Identifiable because they have a thin band of ribosomes

Anemia – deficiency in hemoglobin

Normochromic anemia
○ Hereditary spherocytosis – abnormal spectrin causes RBC shape deformity
○ Sickle Cell Disease – Valine substituted for glutamate. Can have reverisibly and non-reversibly sickled RBCs

Hypochromic anemia – Iron deficiency of some sort (poor diet, blood loss)

Polycythemia – net increase in RBCs resulting in ↑ hematocrit and ↑ blood viscosity

Can be caused by stem cell disorder or ↑ erythropoietin
○ WBCs
Type
Neutrophils
Picture % Diameter Targets
60-70 10-12 -Bacterial first defense
-phagocytes
Nucleus Look multilobed Clear granules you can‟t see
Eosinophils
Basophils
2-4
<1
10-12
12-15
-antiparasitic
-inhibits histamine
-phagocytizes antigenantibody complexes
-Inflammatory
-Allergic
Bilobed bilobed
Pink granules
Dark blue granules
Lymphocytes 20 7-8 T-Cells
B-Cells
Takes up much of the cell
Big nucleus, very dark because of dense chromatin

Monocytes 3-8 14-17 biggest
-precursors to macrophages
Kidney shaped
-can find nucleolus in each lobe
-chromatin not condensed
Megakaryocyte Huge -doesn‟t circulate
-makes
Complex, multilobed,
<64N platelets

Note – neutrophils don‟t circulate, they marginate in capillaries and organs and sit there until needed

Note – eosinophil chemoattraction inhibited by steroids
 Note – basophils involved with inflammatory response by release of histamine, heparin and serotonin

Serotonin and heparin are main culprits for anaphylactic shock since they help relax muscles?

Basophils also involved with allergic response via release of leukotrienes

Note – Monocytes are antigen presting cells, osteoclasts in bone, and Kupffer cells in liver (which help recycle RBCs)

Lymphocytes

T-Lymphocytes – cell mediated immunity, many made as children and live forever
○ immune memory, 90% in blood
○ Present antigen to B-Cells

B-Lymphocytes – 4-10% in blood, mediate humoral immunity
○ Synthesize and secrete antibodies

Platelets

Hyalomere – outer visible ring containing microtubules allowing it to be contractile

Granulomere – internal structure of platelet (no nucleus)
○ Surface-opening tubule – where granules are released
○ Dense tubular system – machinery of platelets

Cytoplasm of megakaryocytes just buds off and platelets are formed

Thromboembolism – platelets blocking vessels

Coagulation disorders can be caused by Vitamin K deficiency, hemophilia

Thrombocytopenia – low # of platelets
○ Can be caused by leukemia, cancer, chemo drugs
○ Can result in petichiae (little bruises) and ecchymoses (big hemorrhages)

Types of Granules

All granulocytic leukocytes have azurophilic granules which are part of the lysosome and are clear

Neutrophils have three types of granules, but all are clear

Major Basic Protein – a specific granule found in eosinophils that helps fight against parasites
○ Bone Marrow

Clavicle is 1 st
place where bone marrow is formed

Cells in bone marrow ↓ with age

All cells in bone marrow are derived from one stem cell?

Megakaryocytes are always located near sinuses

Erythroblastic island – where RBCs are formed

Nurse cell – in the middle that phagocytizes old RBCs (a macrophage)
 Hematopoetic cord – the cellular part

Adventitial Cells – can make fat and turn marrow into yellow marrow , this is reversible if necessary

These are the big clear cells in bone marrow

Reticular fiber used to hold everything together

Hematopoesis

Stem cells can make anything

Progenitor cells – high mitotic activity, self-renewing. Often have „forming cell‟ in the name


Precursor cells – high mitotic activity, not self-renewing. Often have „blast‟ or „myelocyte‟ in name

Mature cells - no mitotic activity , first cells to be seen in blood

Erythropoiesis
○ Cell gets smaller at each stage
○ Amount of RNA ↓ and amount of hemoglobin ↑ as process progresses
○ Proerythroblast – first cell you can visually identify

Responds to erythropoietin (only one to do so) which is released by kidney
○ Basophilic erythroblast – lots of protein (hemoglobin) and RNA synthesis
○ Polychromatophilic erythroblast – RNA becomes visible and nucleus darkens

Concentration of ribosomes and hemoglobin is equal
○ Orthochromatophilic erythroblast - Mitosis occurs up until this stage, afterwards nucleus is extruded and mitosis stops

Nucleus is near one side

Granulopoiesis
○ Promyelocyte – gives rise to all granule cells. oval nucleus with nucleoli
○ Myelocyte stage – granules specific to each cell begin to form
○ Metamyelocyte stage – nucleus changes shape, more granules present
○ ( Band Cell ) – specific to neutrophils, nucleus like a horseshoe
○ Mature phenotype


Monopoiesis (difficult to find)
○ Monoblast
→
promonocyte
→
monocyte
→
differentiates into macrophage
○ Promonocyte has well developed golgi, RER, mitochondria, lysosomes


Lymphopoiesis (hard to identify)
○ Lymphoblast → prolymphocyte → T-cell & B-Cell
○ T-Cells differentiate outside bone marrow, B-Cells differentiate inside bone marrow
