The Skeletal System
CH. 6 & 7, p. 139-190
Organization of the Skeletal System
p. 129-131
The Axial Skeleton
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The Skull - cranial and facial bones
Auditory Ossicles - 3 total bones
Hyoid Bone - located above the larynx
Vertebral Column - 26 bones in the adult
Rib Cage/Sternum
The Appendicular Skeleton
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Pectoral Girdle - scapula and clavicles
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cingulum membri superioris - girdle - articulates with sternum and vertebral column
Upper Extremities - humerus, radius, ulna, carpal bones, metacarpals and phalanges
Pelvic Girdle - 2 ossa coxae, cingulum membri inferioris - articulates with sacrum
Lower Extremities - femur, tibia, fibula, tarsal bones, metatarsals and phalanges
Functions of the Skeletal System
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1) Support - rigid framework
2) Protection
3) Body Movement - levers
4) Provide an Anchoring Point for Muscles
5) Calcium/Phosphorus metabolism
6) Hematopoiesis
Terminology, p. 133, Table 6.2
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Condyle - a large rounded projection or knob
Facet - a flattened or shallow articulating surface
Head - a prominent rounded articulating bone end
Alveolus - a deep pit or socket
Foramen - a hole or rounded opening
Fissure - a narrow slit like opening
Sinus - a cavity or hollow space in a bone
Sulcus - a groove
Crest - a narrow ridge like projection
Terminology, cont.
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Epicondyle - a projection located superior to a condyle
Process - any boney protuberance
Spine - a sharp slender process
Trochanter - a massive process, on the femur
Tubercle - a small rounded process
Tuberosity - a large roughened process
Fossa - a flattened or shallow surface, depression
Shapes of Bones
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Long Bones - longer than wide
Short Bones - somewhat cube shaped
Flat Bones - cranial bones, ribs, scapula
Irregular Bones - vertebrae and certain
bones of the skull
Accessory Bones - extra bones
Wormian Bones - sutural bones
Structure of a Typical Long Bone
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Shaft - Diaphysis
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a) Periosteum - dense regular connective tissue
• 1) Sharpey’s fibers - connect periosteum to bone
Epiphysis - spongy bone on each end of the diaphysis
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a) Epiphyseal plate - growth center
b) Articular cartilage - hyaline cartilage
c) Red Marrow - hematopoiesis
Medullary cavity - central cavity within the diaphysis - lined with endosteum and filled with fat
(yellow marrow)
Bone Cells
Osteogenic cells - in periosteum and endosteum,
clasts
can become blast or
Osteoblasts - lay down osteoid
Osteocytes - mature bone cells, reside in lacunae,
stream
regulate calcium release into blood
Osteoclasts - break down bone
Bone-Lining cells - derived from osteoblasts along
Ca/P movement
the surface of most bones, reg.
Spongy and Compact Bone
Spongy Bone - trabecular bones, located deep to
compact bone.
Compact Bone - forms external portion of bone, very dense, composed of cylindrical columns
of bone.
– Haversian System - osteon
• Lamellae - concentric rings of bone
• Central Canal - contains artery, vein and lymphatics
• Lacunae - spaces where osteocytes reside
• Canaliculi - small channels which connect lacunae
• Perforating canals - Volkmann’s canals
Bone Growth
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Endochondral Ossification - long bones, etc.
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Intramembranous Ossification - flat bones
Homeostasis and Physiologic Function of Bone
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Hematopoiesis
Calcium Storage and Release
– Function of Calcium
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• Blood clotting
• Nerve transmission
• Muscle contraction
Control of Calcium Levels in the Blood
• Bone
• Kidney
• Parathyroid Glands
• Diet/GIT
Disorders of Calcium Metabolism
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Hypocalcemia - tetany
pH is proportional to HCO3/CO2
Hypercalcemia
Essential Nutrients for Bone Development
– calcium, phosphorus, magnesium
– Vit D - absorption of Ca
– Vit. A - osteoblast function
– Vit C - necessary for osteoid synthesis
– protein
The Axial Skeleton
p. 139-160
The Skull
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Divisions of the Skull
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a) Cranial Bones - 8 bones in all
• 1) Cranial Cavity - where the brain is
– a) Calvaria - roof of the cranial vault
– b) Cranial fossa - floor of the cranial cavity
b) Facial bones - 14 bones are not in contact with the brain. All paired except for vomer
and mandible
Fontanels
Anterior - Frontal - bregmatic, closes by 18-24
Posterior - Occipital, closes by 2months - becomes
months
the lambda
Anterolateral - Sphenoidal - closes by 3 months of
age, becomes the pterion
Posterolateral - Mastoid - closes by 1 year of age,
becomes the asterion
Sutures
Sagittal Suture
Coronal Suture
Lambdoidal Suture
Squamous Suture
Metopic Suture - extends from anterior fontanel
6 years
rostrally to the glabella, closes by age
The Cranial Bones
p. 146 - 149
Frontal Bone
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Frontal Squama - flattened portion of the forehead
Supraorbital Margin - arch, ridge
Supraorbital foramen - supraorbital nerve
Roof of the orbit
Supracilliary Ridge - deep to eyebrow
Glabella - most forward projecting part of head, AKA mesophryon, antinion, intercilium
Metopic Suture –closed by age 6
Bregma
Frontal Sinus
Parietal Bones
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Coronal Suture
Sagittal Suture
Parietal Foramina - emissary veins
Temporal Lines - origin of temporalis m.
Temporal Bones
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Squamous Suture
Squamous Portion
– a) zygomatic process
– b) mandibular fossa
– c) groove for the middle temporal artery
Tympanic Portion
– a) external acoustic meatus - ear canal
– b) styloid process
Temporal bones, cont.
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Mastoid Portion
– a) Mastoid process
– b) Mastoid foramen
– c) Stylomastoid foramen - CN VII
– d) Mastoid sinus
Petrous portion
– a) Groove for the Sigmoid Sinus
– b) Carotid canal - internal carotid artery
– c) Bones of the middle ear - malleus, incus, stapes
– d) internal acoustic meatus - CN VII and VIII
– e) Jugular foramen - CN IX, X, XI, internal jugular v.
Occipital Bone
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Lambdoid Suture
Foramen magnum - SC, CN XI, Vertebral aa., meninges
Occipital condyles
Hypoglossal canal - CN XII
Condyloid canal - emissary veins
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External occipital protuberance - inion
Nuchal lines
Clivus - from dorsum sellae to foramen magnum
Pharyngeal Tubercle
Groove for the Transverse Sinus
Sphenoid Bone - the wedge
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Greater wing
– Groove for the middle meningeal artery
Lesser wing
– Anterior clinoid ( = to resemble 4 poster bed) process
Body
– sphenoidal sinus - pernasal sinus
– jugum or yoke, connects the lesser wings
– Chiasmatic groove
– Groove for the internal Carotid a.
Pterygoid Plates - lateral wall of nasal cavity
Optic canal - CN II
Superior Orbital Fissure - CN III, IV, VI and V1 (ophthalmic division of CN V)
Foramen Rotundum - V2 - maxillary div.
Foramen Ovale - V3 - mandibular div.
Foramen Spinosum - middle meningeal a.
13 bones of the skull that do not touch the sphenoid
2 nasal, 2 lacrimal, 6 ear bones, 2 inferior nasal conchae, 1 mandible
Ethmoid Bone
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Perpendicular plate
Ethmoidal air cells - ethmoid sinus
Crista Galli - anterior attachment for falx cerebri
Superior and Middle Nasal Conchae - AKA turbinates
Cribriform Plate - CN I
Facial Bones
p. 149 - 152
Maxilla
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Alveolar Process - area around alveolus
Palatine Process - Horizontal Plate - Hard Palate
Median Palatine Suture
Incisive Foramen - Nasopalatine nerve
Infraorbital Foramen - branch of V2
Maxillary Sinus
Frontal Process
Zygomatic Process
Intermaxillary suture
Inferior Orbital Fissure - V2
Palatine Bones
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Horizontal Plate - posterior 1/3 of hard palate
Greater Palatine Foramen
Lesser Palatine Foramen
Zygomatic Bones
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Temporal Process
Zygomaticofacial Foramen - Zygomatic n.
Lacrimal Bones
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Lacrimal Sulcus
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Nasolacrimal Canal
Facial bones, cont.
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Nasal Bones
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Internasal Suture
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Inferior Nasal Conchae
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Vomer Bone
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Inferior portion of the nasal septum
Does not touch the occipital bone
Mandible
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Jawbone - to chew - only movable bone in the skull
Body
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symphysis menti - fuses at 1-2 years of age
mental (chin) protuberance
mental tubercle
mental foramen - mental nerve - branch of V3
Angle of the mandible
Ramus
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condylar process
• head
• neck
• pterygoid fossa
Coronoid (crow’s beak) process
Mandibular notch
Mandibular foramen - inferior alveolar nerve
Lingula
Hyoid Bone
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Body
Greater Cornu (Horn)
Lesser Cornu - stylohyoid ligament
Bones Which Form the Orbit
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Frontal Bone
Ethmoid Bone
Sphenoid Bone
Maxillary Bone
Lacrimal Bone
Zygomatic bone
Palatine Bone
Auditory Ossicles
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Three small paired bones within the middle ear cavity of the petrous portion of the temporal
bone
malleus - hammer - touches the tympanic membrane
incus - anvil
stapes - stirrup
Bones Which Enclose the Nasal Cavity
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Ethmoid Bone
Frontal Bone
Maxilla
Palatine Bone
Nasal Bone
Bones which do not touch the sphenoid bone
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There are 13 of them and they are………..
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Hint - they are all paired except one (this list does not include the hyoid bone)
2 nasal, 2 lacrimal, 6 ear bones, 2 inferior nasal conchae, 1 mandible
Holes in the Skull
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Supraorbital foramen - supraorbital nerve
Cribriform plate - Olfactory nerve (CN I)
Optic canal - Optic nerve (CN II)
Superior orbital fissure - CN III, IV, VI and V1
Foramen rotundum - Maxillary nerve (V2)
Foramen ovale - Mandibular nerve (V3)
Foramen spinosum - middle meningeal vessels
Foramen lacerum - loop of internal carotid artery
Carotid canal - internal carotid artery
Internal acoustic meatus - CN VII and CN VIII
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Stylomastoid foramen - CN VII
Jugular foramen - CN IX, X and XI, and sigmoid sinus
Hypoglossal canal - CN XII
Foramen magnum - Spinal cord, meninges, vertebral arteries, spinal roots of CN XI
Greater palatine - greater palatine nerve
Incisive foramen - nasopalatine nerve
Inferior orbital fissure - maxillary div. of CN V
Mandibular foramen - inferior alveolar nerve
Mental foramen - mental nerve
Nasolacrimal duct - nasolacrimal (tear) duct
Zygomaticofacial foramen - zygomaticofacial n.
The Vertebral Column
p. 153 - 159
The Vertebral Column
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Functions
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Support and Weight Bearing
Provide attachments for muscles
Protection of Spinal Cord
Permit passage of spinal nerves
Motion
Shock absorption
Human Vertebral Formula
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C7, T12, L5, S5, Cy 3-6
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Spinal Curves
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Primary Curves - present at birth - kyphotic - posterior curves - thoracic and sacral
Secondary Curves - develop at 3 months of age and as baby begins to stand erect Lordotic - anterior curves - cervical and lumbar
A typical vertebra looks like the other ones in that group
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Body - weight bearing portion
Neural Arch = 2 pedicles + 2 lamina
– pedicles
– lamina
– vertebral notches
• Intervertebral foramen - ovoid holes formed by the superior vertebral notch of one
vertebra and the inferior vertebral notch of the superior vertebra.
• Flexion verses extension
• First pair between C2 and C3, and last one between L5 and S1
Vertebral foramen - neural ring
– vertebral canal - neural canal
– Boundaries
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• posterior portion of the vertebral body
• vertebral arch
Shape
• cervical, lumbar and sacral regions - triangular
• thoracic region - circular, smallest
Transverse process - from lamina-pedicle junction
Superior and Inferior Articular processes
Articular facets
Joints of the Spine
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Zygapophyseal Joint - synovial, multiaxial, plane,
gliding
Intervertebral Joint - symphysis, amphiarthrotic
– IVD - intervertebral disc
• 23 in total - first one between C2 and C3, last one L5 and S1
• Function
– shock absorption
– attach vertebral bodies together
– form secondary curves to the vertebral column
– form anterior wall of the IVF ( intervertebral foramen)
• Components - nucleus pulposus and annulus fibrosus
Cervical Vertebrae
p. 156 - 157
The Atlas, C1
Lateral mass - no body
Superior and Inferior Articular processes
Anterior Arch
– anterior tubercle
– articular facet for the dens
Transverse process
– transverse foramen
– costotransverse bar - intertubercular bar
– anterior and posterior tubercles
Posterior Arch
– groove for the vertebral artery
– posterior tubercle
Axis, C2, Epistropheus
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Odontoid process - dens
– Anterior Articular Facet for the Atlas
– Posterior Articular Facet for the Transverse Ligament of the Atlas
– attachments for the alar ligaments on lateral aspects
Lateral Mass
Body - lip on anterior surface that overlaps superior surface of the body of C3
Bifid Spinous process - can palpate 2 inches below the EOP
Facts about Cervical Vertebrae
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Typical Cervical Vertebrae - C3,4,5,6
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Bifid Spinous process
Transverse foramen
Atypical Cervical Vertebrae - C1,2,7
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First IVF - between C2 and C3
First IVD - between C2 and C3
Facts about Cervical Vertebrae
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Uncinate process
– hook shaped process on the lateral borders of the superior surface of the bodies of C3-T1
– prevents posterior linear movement (translation) of the vertebral bodies and limits lateral
flexion
C7
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Vertebral Prominens
transverse processes do not posses a costotransverse bar
the vertebral artery does not go through the transverse foramen, but the vein does
no anterior lip to overlap T1
all mammals have 7 cervical vertebrae with 3 exceptions: duck billed platybus, 3 toed sloth,
sea manatec
Thoracic Vertebrae
Also called Dorsal vertebrae
Humans have 12; 2-8 are typical
Spinous processes are directed inferiorly
Costal Facets - where ribs articulate, most have 3 on each side
Surfaces of the articular process are aligned on a frontal plane
T1, 9, 10, 11 and 12 are atypical
• All have transverse costal facets except T11 and T12
• Bodies have whole facet of 1/2 facet called a demifacet
• T1 has a whole superior facet and an inferior demifacet and articulates with the first and
second rib respectively
• T2-T8 have 2 demifacets on each side of their bodies.
• T9 has a single superior demifacet on each side
• T10, T11 and T12 have whole facets on either side of their bodies. Each articulate with only
one pair of ribs
Atypical thoracic vertebrae
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T1 - articulates with rib 1 and 2
T9 - may have no demifacets and articulate with rib 9, or it may have superior and inferior
demifacets and articulate with 2 ribs
T10 - has only a full pair of facets, rib 10
T11 - has only a full pair of facets, no transverse costal facets, short spinous process,
articulates with rib 11
T12 - no transverse costal facets, articulates with rib 12, inferior articular facets face laterally
Lumbar Vertebrae
Mamillary processes - on superior facets
Accessory processes - on inferior base of TP
The surfaces of the articular facets are oblique to a sagittal plane - superior facets are
concave and face posteromedial, inferior facets are convex and face anterolateral
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L5 - largest circumference but not as thick as other lumbars, atypical as it has a wedge
shaped body (anterior portion of body is of greater height than the posterior region
The Sacrum
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Auricular surface
Sacroiliac joint
Median Sacral Crest
Anterior and Posterior Sacral Foramina
Sacral Canal
Superior articular process
Sacral Tuberosity
Transverse lines
Sacral Promontory
Lateral masses
Ligaments of the Spine
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Anterior Longitudinal Ligament
– anterior aspect of vertebral bodies and IVD
– axis to first sacral segment
Posterior Longitudinal Ligament
– attaches axis (continuous with the Tectorial membrane) to the first sacral segment
– inside of the neural canal
– attaches body to body and IVD’s
Interspinous Ligament
– connects adjacent spinous processes
Supraspinous Ligament
– attach the tips of the spinous processes, C7 to S1
Ligamentum Nuchae
– superior continuation of the supraspinous ligament
– triangular in shape
– attaches to the EOP and the median nuchal line, posterior tubercle of the atlas, and
spinous processes of the cervical vertebrae
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Ligamentum Flavum
– connects adjacent lamina, one on each side, elastic lig.
 Ligamentum Flavum
- connects adjacent lamina, one on each side, elastic ligament
The Rib Cage
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Sternum
– Manubrium
• Jugular notch
• clavicular notch
• costal notch
• manubriosternal joint - sternal angle, Angle of Louis
– Body of the Sternum
• Costal notches
– Xiphoid Process
Costal Margin - fusion of cartilage of ribs 8,9,10
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Costal Angle - formed by the 2 costal margins
Sternum
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Manubrium
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Jugular notch
Clavicular notch
Costal notch
Manubriosternal joint
Body of the Sternum
Xiphoid Process
Ribs
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12 pairs of ribs
Ribs 1 thru 7 - Vertebrosternal (True) ribs
Ribs 8 thru 10 - Vertebrocondral (False) ribs
Ribs 11 ans 12 - Floating ribs
Components of a typical rib
– Head
– Tubercle
– Neck
– Angle
Body
Costal groove
Intercostal space
Costochondral joint
The Appendicular Skeleton
CH. 7, p. 169 - 188
The Pectoral Girdle
p. 169 - 172
The Clavicle - Collar Bone
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Acromial Extremity - lateral end
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Conoid Tubercle - coracoclavicular ligament
Sternal Extremity
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Costal Tuberosity - costoclavicular ligament
Groove for the Subclavius muscle
The Scapula
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Spine of the scapula
– acromion - lateral end of spine
Fossae of the Scapula
– supraspinous fossa - supraspinatus m.
– infraspinous fossa - infraspinatus m.
– subscapular fossa
Glenoid cavity
– supraglenoid tubercle - long head of biceps brachii m.
– infraglenoid tubercle - long head of triceps brachii m.
Coracoid process - 3 muscles attach here
The Scapula, cont.
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Margins (borders) of the scapula
– lateral border (axillary margin)
– medial border (vertebral margin)
– superior border
• suprascapular notch - scapular notch - suprascapular nerve
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Angles of the Scapula
– inferior angle
– medial angle
– superior angle
Neck
The Humerus
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Head
Anatomic neck vs. surgical neck
Greater tubercle
Lesser Tubercle
Intertubercular groove
Deltoid Tuberosity
Radial groove - spiral groove - musculospiral
groove - radial nerve
Medial epicondyle - flexors of carpus and digits
The Humerus, cont.
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Lateral epicondyle - extensor muscles of the carpus and digits
Medial and lateral supracondylar crests
Trochlea
Capitulum
Coronoid fossa
Olecranon fossa
The Ulna
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Olecranon process
Semilunar notch - trochlear notch
Coronoid process
Ulnar tuberosity
Radial notch
Styloid process
Interosseous margin
Posterior border of ulna
The Radius
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Head
Radial tuberosity
Styloid process
Ulnar notch
Grooves on the posterior surface
– groove for ECRL and ECRB mm.
– dorsal tubercle
– groove for the Ex Pollicis Longus m.
– groove for the Ex Dig. And Ex. Indicis mm.
The Carpus
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Proximal Row of Carpal Bones - medial to lateral
– Pisiform - sesamoid bone in the tendon of FCU m.
– Triquetral - triangular bone
– Lunate - articulates with radius
– Scaphoid bone - navicular bone, articulates with radius
Distal Row - medial to lateral
– Hamate bone - hamulus
– Capitate - Os Magnum
– Trapezoid - Lesser multangular
– Trapezium - Greater multangular
Metacarpal Bones and Phalanges
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Metacarpal bones
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Base
Body
Head
Phalanges
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Proximal, middle and distal
Digits are numbers form lateral to medial, 1-5
The Pelvic Girdle
Formed by two Ossa Coxae - hip bones
Greater pelvis (false) - superior to pelvic brim
Lesser (true) pelvis - inferior to brim of pelvis
Pelvic Brim
Pelvic Inlet
Bones of the Pelvis
p. 177 - 180
Ilium
• External surface
• Iliac crest
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– anterior superior iliac spine and anterior inferior iliac spine
– posterior superior iliac spine and posterior inferior iliac spine
Gluteal Lines
Iliac Fossa
Greater Sciatic Notch
Auricular Surface for the sacrum
Iliac tuberosity
Inguinal ligament - pubic tubercle to ASIS
Ischium
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Spine of the Ischium
Ischiatic tuberosity
Lesser Sciatic Notch
Body
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Ramus of the Ischium
Pubis
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Superior Pubic Ramus
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pubic tubercle
pecten pubis
obturator groove
Inferior Pubic Ramus
Symphysis
The Pelvis, cont.
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Obturator Foramen
Acetabulum
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acetabular notch
acetabular fossa
lunate surface
Sex related differences in the pelvis
The Femur
• Head
– fovea capitis
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Neck
Greater and lesser trochanter
Shaft
Linea aspera
Gluteal tuberosity - third trochanter
Epicondyles
Adductor tubercle
Condyles
Intercondylar fossa
Popliteal fossa
Patellar surface
The Tibia
• Medial Condyle
• Lateral Condyle
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– Gerdy’s tubercle - insertion of the iliotibial tract
Tibial Plateau
– Intercondylar eminence
• Medial and lateral intercondylar tubercle
Tibial Tuberosity
Shaft
Interosseous crest
Medial Malleolus
Inferior Articular surface
Fibular notch
The Fibula
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Head
Interosseous border
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Lateral Malleolus
The Tarsal Bones
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Talus
– posterior process
• groove for the FHL m.
• medial and lateral tubercles
Calcaneus
– tuberosity
– sustentaculum tali
– groove for the FHL m.
Navicular
Cuboid - groove for the peroneus longus m.
Cuneiform bones
Metatarsals and Phalanges
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Metatarsals
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base, body, head
Mt 5 has a tuberosity on its base
Phalanges
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proximal, middle and distal
Hallux has only two phalanges
Arches of the Foot
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Longitudinal Arch
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medial portion is more elevated than lateral portion. The talus is the keystone of the medial
portion and the cuboid is keystone for the lateral portion.
Transverse Arch
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extends across the width of the foot. Formed by the calcaneus, navicular, cuboid and all 5
Mt’s.