Bones and Skeletal Tissues

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Bones and
Skeletal Tissues
Cartilage
• Location and basic structure
• Found throughout adult body
• Ear and epiglottis
• Articular cartilages and costal cartilage
• Larynx, trachea, and nose
• Intervertebral discs, pubic symphysis, and articular discs
Cartilage
• Is surrounded by perichondrium
• Consists primarily of water
• Resilient tissue—it springs back to original shape
Types of Cartilage
• Hyaline cartilage (glassy)
• Most abundant cartilage
• Provides support through flexibility
• Elastic cartilage—contains many elastic fibers
• Able to tolerate repeated bending
• Fibrocartilage—resists strong compression and strong
tension
• An intermediate between hyaline and elastic cartilage
Cartilages in the Adult Body
Growth of Cartilage
• Appositional growth
• Chondroblasts in surrounding perichondrium produce new
cartilage
• Interstitial growth
• Chondrocytes within cartilage divide and secrete new matrix
• Cartilage stops growing when the skeleton stops growing
Tissues in Bone
• Bones contain several types of tissues
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Dominated by bone CT
Contain nervous tissue and blood CT
Contain cartilage in articular cartilages
Contain ET lining blood vessels
Function of Bones
• Support—provides hard framework
• Movement—skeletal muscles use bones as levers
• Protection of underlying organs
• Mineral storage—reservoir for important minerals
• Blood-cell formation—bone contains red marrow
• Energy metabolism—osteoblasts secrete osteocalcin
Bone Tissue
• Bone tissue
• Organic components—cells, fibers, and ground substance
• Inorganic components—mineral salts that invade bony matrix
Extracellular Matrix
• Unique composition of matrix
• Gives bone exceptional properties
• 35%—organic components
• Contributes to flexibility and tensile strength
• 65%—inorganic components
• Provide exceptional harness, resists compression
Cells
• Three types of cells in bone produces or maintain bone
• Osteogenic cells—stem cells that differentiate into osteoblasts
• Osteoblasts—actively produce and secrete bone matrix
• Bone matrix is osteoid
• Osteocytes—keep bone matrix healthy
Cells
• Osteoclasts
• Responsible for resorption of bone
• Are derived from a line of white blood cells
• Secrete hydrochloric acid and lysosomal enzymes
Classification of Bones
• Long bones—longer than wide; a shaft plus ends
• Short bones—roughly cube-shaped
• Flat bones—thin and flattened, usually curved
• Irregular bones—various shapes, do not fit into other
categories
Gross Anatomy of Bones
• Compact bone—dense outer layer of bone
• Spongy (cancellous) bone—internal network of bone
Structure of a Typical Long Bone
• Diaphysis—―shaft‖ of a bone
• Epiphysis—ends of a bone
• Blood vessels—well vascularized
• Medullary cavity—hollow cavity filled with yellow marrow
• Membranes
• Periosteum, perforating fibers (Sharpey’s fibers), and endosteum
Structure of a Long Bone
Structure of Short, Irregular, and Flat Bones
• Flat bones, short bones, and irregular bones
• Contain bone marrow but no marrow cavity
• Diploë
• Internal spongy bone of flat bones
Gross Anatomy of Bones
• Bone design and stress
• Anatomy of a bone reflects stresses
• Compression and tension greatest at external surfaces
Bone Markings
• Superficial surfaces of bones reflect stresses on them
• There are three broad categories of bone markings
• Projections for muscle attachment
• Surfaces that form joints
• Depressions and openings
Microscopic Structure of Compact Bones
• Compact Bone
• Contains passage ways for blood vessels, lymph vessels, and
nerves
• Osteons—long cylindrical structures
• Function in support
• Structurally—resembles rings of a tree in cross-section
Microscopic Structure of Compact Bones
• Osteons contain:
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Lamellae
Central canal
Perforating canals
Canaliculi
Microscopic Structure of Compact Bones
• Spongy Bone
• Is less complex than compact bone
• Trabeculae contain layers of lamellae and osteocytes
• Are too small to contain osteons
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Bones and
Skeletal Tissues
Bone Development
• Ossification (osteogenesis)—bone-tissue formation
• Membrane bones—formed directly from mesenchyme
• Intramembranous ossification
• Other bones—develop initially from hyaline cartilage
• Endochondral ossification
Intramembranous Ossification
Endochondral Ossification
• All bones except some bones of the skull and clavicles
• Bones are modeled in hyaline cartilage
• Begins forming late in the second month of embryonic
development
• Continues forming until early adulthood
Stages in Endochondral Ossification
Anatomy of Epiphyseal Growth Areas
• In epiphyseal plates of growing bones:
• Cartilage is organized for quick, efficient growth
• Cartilage cells form tall stacks
• Chondroblasts at the top of stacks divide quickly
• Pushes the epiphysis away from the diaphysis
• Lengthens entire long bone
Anatomy of Epiphyseal Growth Areas
• Older chondrocytes signal surrounding matrix to calcify
• Older chondrocytes then die and disintegrate
• Leaves long trabeculae (spicules) of calcified cartilage on
diaphysis side
• Trabeculae are partly eroded by osteoclasts
• Osteoblasts then cover trabeculae with bone tissue
• Trabeculae finally eaten away from their tips by osteoclasts
Organization of Cartilage within
Epiphyseal Plate of Growing Long Bone
Postnatal Growth of Endochondral Bones
• During childhood and adolescence:
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Bones lengthen entirely by growth of the epiphyseal plates
Cartilage is replaced with bone CT as quickly as it grows
Epiphyseal plate maintains constant thickness
Whole bone lengthens
Hormonal Regulation of Bone Growth
• Growth hormone—produced by the pituitary gland
• Stimulates epiphyseal plates
• Thyroid hormone—ensures that the skeleton retains proper
proportions
• Sex hormones (estrogen and testosterone)
• Promote bone growth
• Later induces closure of epiphyseal plates
Postnatal Growth of Endochondral Bones
• As adolescence draws to an end:
• Chondroblasts divide less often
• Epiphyseal plates become thinner
• Cartilage stops growing
• Replaced by bone tissue
• Long bones stop lengthening when diaphysis and epiphysis fuse
Bone Remodeling
• Bone is dynamic living tissue
• 500 mg of calcium may enter or leave the adult skeleton each
day
• Cancellous bone of the skeleton is replaced every
3–4 years
• Compact bone is replaced every 10 years
Postnatal Growth of Endochondral Bones
• Growing bones widen as they lengthen
• Osteoblasts—add bone tissue to the external surface of the
diaphysis
• Osteoclasts—remove bone from the internal surface of the
diaphysis
• Appositional growth—growth of a bone by addition of bone
tissue to its surface
Bone Remodeling
• Bone deposit and removal
• Occurs at periosteal and endosteal surfaces
• Bone remodeling
• Bone deposition—accomplished by osteoblasts
• Bone reabsorption—accomplished by osteoclasts
Remodeling, Spongy Bone
Osteoclast—A Bone-Degrading Cell
• A giant cell with many nuclei
• Crawls along bone surfaces
• Breaks down bone tissue
• Secretes concentrated HCl
• Lysosomal enzymes are released
• Derived from hematopoietic stem cells
Repair of Bone Fractures
• Simple and compound fractures
• Treatment by reduction
• Closed reduction
• Open reduction
Stages of Healing a Fracture
Common Types of Fractures
Disorders of Bones
• Osteoporosis
• Characterized by low bone mass
• Bone reabsorption outpaces bone deposition
• Occurs most often in women after menopause
Osteoporosis
Disorders of Bones
• Osteomalacia
• Occurs in adults—bones are inadequately mineralized
• Rickets
• Occurs in children—analogous to osteomalacia
Disorders of Bones
• Paget’s disease
• Characterized by excessive rate of bone deposition
• Osteosarcoma
• A form of bone cancer
The Skeleton Throughout Life
• Cartilage grows quickly in youth
• Skeleton shows fewer chondrocytes in the elderly
• Bones are a timetable
• Mesoderm
• Gives rise to embryonic mesenchyme cells
• Mesenchyme
• Produces membranes and cartilage
• Membranes and cartilage ossify
The Skeleton Throughout Life
• Skeleton grows until the age of 18–21 years
• In children and adolescents, bone formation exceeds rate of
bone reabsorption
• In young adults, bone formation and bone reabsorption are in
balance
• In old age, reabsorption predominates
• Bone mass declines with age
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Bones, Part 1:
The Axial Skeleton
The Skeleton
• Consists of:
• Bones, cartilage, joints, and ligaments
• Composed of 206 named bones grouped into two divisions
• Axial skeleton (80 bones)
• Appendicular skeleton (126 bones)
The Axial Skeleton
• Formed from 80 named bones
• Consists of skull, vertebral column, and bony thorax
The Axial Skeleton
The Skull
• Formed by cranial and facial bones
The Cranium
• Is the body’s most complex bony structure
• Formed by cranial and facial bones
• The cranium
• Encloses and protects brain
• Provides attachment for head and neck muscles
The Face
• Facial bones serve to
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Form framework of the face
Form cavities for the sense organs of sight, taste, and smell
Provide openings for the passage of air and food
Hold the teeth in place
Anchor muscles of the face
Overview of Skull Geography
• Facial bones form anterior aspect
• Cranium is divided into cranial vault and the base
• Internally, prominent bony ridges divide skull into distinct
fossae
Overview of Skull Geography
• The skull contains smaller cavities
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Middle and inner ear cavities—in lateral aspect of cranial base
Nasal cavity—lies in and posterior to the nose
Orbits—house the eyeballs
Air-filled sinuses—occur in several bones around the nasal
cavity
Overview of Skull Geography
• The skull contains approximately 85 named openings
• Foramina, canals, and fissures
• Provide openings for important structures
• Spinal cord
• Blood vessels serving the brain
• 12 pairs of cranial nerves
Cranial Bones
• Formed from eight large bones
• Paired bones include
• Temporal bones
• Parietal bones
• Unpaired bones include
• Frontal bone
• Occipital bone
• Sphenoid bone
• Ethmoid bone
Parietal Bones and Sutures
• Parietal bones form superior and lateral parts of skull
• Four sutures of the cranium
• Coronal suture—runs in the coronal plane
• Located where parietal bones meet the frontal bone
• Squamous suture—occurs where each parietal bone meets a
temporal bone inferiorly
Parietal Bones and Sutures
• Four sutures of the cranium (continued)
• Sagittal suture—occurs where right and left parietal bones meet
superiorly
• Lambdoid suture—occurs where the parietal bones meet the
occipital bone posteriorly
Sutural Bones
• Small bones that occur within sutures
• Irregular in shape, size, and location
• Not all people have sutural bones
The Skull— Posterior View
Frontal Bone
• Forms the forehead and roofs of orbits
• Supraorbital margin—superior margin of orbits
• Glabella—smooth part of frontal bone between superciliary
arches
• Frontal sinuses within frontal bone
• Contributes to anterior cranial fossa
Occipital Bone
• Forms the posterior portion of the cranium and cranial base
• Articulates with the temporal bones and parietal bones
• Forms the posterior cranial fossa
• Foramen magnum located at its base
Occipital Bone
• Features and structures
• Occipital condyles
• Hypoglossal foramen
• External occipital protuberance
• Superior nuchal lines
• Inferior nuchal lines
Inferior Aspect of the Skull
Temporal Bones
• Lie inferior to parietal bones
• Form the inferolateral portion of the skull
• Term ―temporal‖ comes from Latin word for time
• Specific regions of temporal bone
• Squamous, temporal, petrous, and mastoid regions
Lateral Aspect of the Skull
The Temporal Bone
• The mastoid process
• Site for neck muscle attachment
• Contains air sinuses
• Petrous region
• Projects medially, contributes to cranial base
• Houses cavities of middle and internal ear
• Contributes to the middle and posterior cranial fossae
The Temporal Bone
• Foramina of the temporal bone
• Jugular foramen
• At boundary with occipital bone
• Carotid canal
• Formane lacerum
• Internal accoustic meatus
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Bones, Part 1:
The Axial Skeleton
The Sphenoid Bone
• Spans the width of the cranial floor
• Resembles a butterfly or bat
• Consists of a body and three pairs of processes
• Contains five important openings
• Is the ―keystone‖ of the cranium
The Ethmoid Bone
• Lies between nasal and sphenoid bones
• Forms most of the medial bony region between the nasal
cavity and orbits
The Ethmoid Bone
• Cribiform plate—superior surface of the ethmoid bone
• Contain olfactory foramina
• Crista galli—attachment for falx cerebri
• Perpendicular plate—forms superior part of nasal septum
The Ethmoid Bone
• Lateral masses—contain air cells
• Superior and middle nasal conchae
• Extend medially from laterial masses
The Ethmoid Bone
Facial Bones
• Unpaired bones
• Mandible and vomer
• Paired bones
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Maxillae
Zygomatic bones
Nasal bones
Lacrimal bones
Palatine bones
Inferior nasal conchae
Facial Bones
Mandible
• The lower jawbone is the largest and strongest facial bone
• Composed of two main parts
• Horizontal body
• Two upright rami
Mandible
Maxillary Bones
• Articulate with all other facial bones except the mandible
• Contain maxillary sinuses—largest paranasal sinuses
• Forms part of the inferior orbital fissure
• Are the ―keystone‖ bones of the face
Other Bones of the Face
• Zygomatic bones
• Form lateral wall of orbits
• Nasal bones
• Form bridge of nose
• Lacrimal bones
• Located in the medial orbital walls
• Palatine bones
• Complete the posterior part of the hard palate
Other Bones of the Face
• Vomer
• Forms the inferior part of the nasal septum
• Inferior nasal conchae
• Thin, curved bones that project medially form the lateral walls of
the nasal cavity
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Bones, Part 1:
The Axial Skeleton
Special Parts of the Skull
• Orbits
• Nasal cavity
• Paranasal sinuses
• Hyoid bone
Nasal Cavity
Nasal Septum
Paranasal Sinuses
• Air-filled sinuses are located within
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Frontal bone
Ethmoid bone
Sphenoid bone
Maxillary bones
• Lined with mucous membrane
• Lighten the skull
Orbits
The Hyoid Bone
• Lies inferior to the mandible
• The only bone with no direct articulation with any other bone
• Acts as a movable base for the tongue
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Bones, Part 1:
The Axial Skeleton
The Vertebral Column
• Formed from 26 bones in the adult
• Transmits weight of trunk to the lower limbs
• Surrounds and protects the spinal cord
The Vertebral Column
• Serves as attachment sites for muscles of the neck and back
• Held in place by ligaments
• Anterior and posterior longitudinal ligaments
• Ligamentum flavum
The Vertebral Column
Regions and Normal Curvatures
• The Vertebral column has five major regions
• 7 cervical vertebrae of the neck region
• 12 thoracic vertebrae
• 5 lumbar vertebrae
• Sacrum—five fused bones
• Inferior to lumbar vertebrae
• Coccyx—inferior to sacrum
Regions and Normal Curvatures
• Curvatures of the spine
• Cervical and lumbar curvatures
• Concave posteriorly
• Thoracic and sacral curvatures
• Convex posteriority
Regions and Normal Curvatures
• Curvatures increase resilience of spine
• Thoracic and sacral curvatures
• Primary curvatures
• Present at birth
• Lumbar curvature
• Develops when baby begins to walk
Ligaments of the Spine
• Major supporting ligaments
• Anterior longitudinal ligament
• Attaches to bony vertebrae and intervertebral discs
• Prevents hyperextension
• Posterior longitudinal ligament
• Narrow and relatively weak
• Attaches to intervertebral discs
Intervertebral Discs
• Are cushion-like pads between vertebrae
• Composed of
• Nucleus pulposus
• Anulus fibrosus
Intervertebral Discs
• Nucleus pulposus
• Gelatinous inner sphere
• Absorbs compressive stresses
• Anulus fibrosus
• Outer fings formed of ligament
• Inner rings formed of fibrocartilage
• Contain the nucleus pulposus
General Structure of Vertebrae
• Common structures to all regions
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Body
Vertebral arch
Vertebral foramen
Spinous process
Transverse process
Superior and inferior articular processes
Intervertebral foramina
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Bones, Part 1:
The Axial Skeleton
Regions Vertebral Characteristics
• Specific regions of the spine perform specific functions
• Types of movement that occur between vertebrae
• Flexion and extension
• Lateral flexion
• Rotation in the long axis
Cervical Vertebrae
• Seven cervical vertebrae (C1–C7)—smallest and lightest
vertebrae
• C3–C7 are typical cervical vertebrae
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Body is wider laterally
Spinous processes are short and bifid (except C7)
Vertebral foramen are large and triangular
Transverse processes contain transverse foramina
Superior articular facets face superoposteriorly
The Atlas
• C1 is termed the atlas
• Lacks a body and spinous process
• Supports the skull
• Superior articular facets receive the occipital condyles
• Allows flexion and extension of neck
• Nodding the head ―yes‖
The Axis
• Has a body and spinous process
• Dens (odontoid process) projects superiorly
• Formed from fusion of the body of the atlas with the axis
• Acts as a pivot for rotation of the atlas and skull
• Participates in rotating the head from side to side
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Bones, Part 1:
The Axial Skeleton
Thoracic Vertebrae (T1—T12)
• All articulate with ribs
• Have heart-shaped bodies from the superior view
• Each side of the body of T1–T10 bears demifacts for articulation
with ribs
• T1 has a full facet for the first rib
• T10–T12 only have a single facet
Thoracic Vertebrae
• Spinous processes are long and point inferiorly
• Vertebral foramen are circular
• Transverse processes articulate with tubercles of ribs
• Superior articular facets point posteriorly
• Inferior articular processes point anteriorly
• Allows rotation and prevents flexion and extension
Lumbar Vertebrae (L1—L5)
• Bodies are thick and robust
• Transverse processes are thin and tapered
• Spinous processes are thick, blunt, and point posteriorly
• Vertebral foramina are triangular
• Superior and inferior articular facets directly medially
• Allows flexion and extension—rotation prevented
Sacrum (S1—S5)
• Shapes the posterior wall of pelvis
• Formed from 5 fused vertebrae
• Superior surface articulates with L5
• Inferiorly articulates with coccyx
• Sacral promontory
• Where the first sacral vertebrae bulges into pelvic cavity
• Center of gravity is 1 cm posterior to sacral promontory
• Ala—develops from fused rib elements
Sacrum
• Sacral foramina
• Ventral foramina
• Passage for ventral rami of sacral spinal nerves
• Dorsal foramina
• Passage for dorsal rami of sacral spinal nerves
Coccyx
• Is the ―tailbone‖
• Formed from 3—5 fused vertebrae
• Offers only slight support to pelvic organs
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Bones, Part 1:
The Axial Skeleton
The Thoracic Cage
• Forms the framework of the chest
• Components
• Thoracic vertebrae—posteriorly
• Ribs—laterally
• Sternum and costal cartilage—anteriorly
• Protects thoracic organs
• Supports shoulder girdle and upper limbs
• Provides attachment sites for muscles
Sternum
• Formed from three sections
• Manubrium—superior section
• Articulates with medial end of clavicles
• Body—bulk of sternum
• Sides are notched at articulations for costal cartilage of ribs 2–
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• Xiphoid process—inferior end of sternum
• Ossifies around age 40
Sternum
• Anatomical landmarks
• Jugular notch
• Central indentation at superior border of the manubrium
• Sternal angle
• A horizontal ridge where the manubrium joins the body
• Xiphisternal joint
• Where sternal body and xiphoid process fuse
• Lies at the level of the 9th thoracic vertebra
Ribs
• All ribs attach to vertebral column posteriorly
• True ribs - superior seven pairs of ribs
• Attach to sternum by costal cartilage
• False ribs—inferior five pairs of ribs
• Ribs 11–12 are known as floating ribs
Disorders of the Axial Skeleton
• Cleft palate
• A common congenital disorder
• Right and left halves of palate fail to fuse medially
• Stenosis of the lumbar spine
• Narrowing of the vertebral canal
• Can compress roots of spinal nerves
Disorders of the Axial Skeleton
• Abnormal spinal curvatures
• Scoliosis—an abnormal lateral curvature
• Kyphosis—an exaggerated thoracic curvature
• Lordosis—an accentuated lumbar curvature; ―swayback‖
The Axial Skeleton Throughout Life
• Membrane bones begin to ossify in second month of
development
• Bone tissue grows outward from ossification centers
• Fontanels
• Unossified remnants of membranes
Fontanelles
The Axial Skeleton Throughout Life
• Many bones of the face and skull form by intramembranous
ossification
• Endochondral bones of the skull
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Occipital bone
Sphenoid
Ethmoid bones
Parts of the temporal bone
The Axial Skeleton Throughout Life
• Aging of the axial skeleton
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Water content of the intervertebral discs decreases
By age 55, loss of a few centimeters in height is common
Thorax becomes more rigid
Bones lose mass with age
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Bones,
Part 1: The Appendicular Skeleton
The Appendicular Skeleton
• Pectoral girdle
• Attaches the upper limbs to the trunk
• Pelvic girdle
• Attaches the lower limbs to the trunk
• Upper and lower limbs differ in function
• Share the same structural plan
The Pectoral Girdle
• Consists of the clavicle and the scapula
• Pectoral girdles do not quite encircle the body completely
• Medial end of each clavicle articulates with the manubrium and
first rib
• Laterally—the ends of the clavicles join the scapulae
• Scapulae do not join each other or the axial skeleton
The Pectoral Girdle
• Provides attachment for many muscles that move the upper
limb
• Girdle is very light and upper limbs are mobile
• Only clavicle articulates with the axial skeleton
• Socket of the shoulder joint (glenoid cavity) is shallow
• Good for flexibility, bad for stability
Articulated Pectoral Girdle
Clavicles
• Extend horizontally across the superior thorax
• Sternal end articulates with the manubrium
• Acromial end articulates with scapula
Clavicles
• Provide attachment for muscles
• Hold the scapulae and arms laterally
• Transmit compression forces from the upper limbs to the axial
skeleton
Scapulae
• Lie on the dorsal surface of the rib cage
• Located between ribs 2–7
• Have three borders
• Superior
• Medial (vertebral)
• Lateral (axillary)
• Have three angles
• Lateral, superior, and inferior
The Upper Limb
• 30 bones form each upper limb
• Grouped into bones of the:
• Arm
• Forearm
• Hand
Arm
• Region of the upper limb between the shoulder and elbow
• Humerus
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The only bone of the arm
Longest and strongest bone of the upper limb
Articulates with the scapula at the shoulder
Articulates with the radius and ulna at the elbow
Arm
• Humerus
• Many structures of the humerus provide sites for muscle
attachment
• Other structures of the humerus provide articulation sites for
other bones
Forearm
• Formed from the radius and ulna
• Proximal ends articulate with the humerus
• Distal ends articulate with carpals
Forearm
• Radius and ulna articulate with each other
• At the proximal and distal radioulnar joints
• The interosseous membrane
• Interconnects radius and ulna
• In anatomical position; the radius is lateral and the ulna is
medial
Ulna
• Main bone responsible for forming the elbow joint with the
humerus
• Hinge joint allows forearm to bend on arm
• Distal end is separated from carpals by fibrocartilage
• Plays little to no role in hand movement
Proximal Part of the Ulna
Radius and Ulna
Radius
• Superior surface of the head of the radius articulates with the
capitulum
• Medially—the head of the radius articulates with the radial
notch of the ulna
• Contributes heavily to the wrist joint
• Distal radius articulates with carpal bones
• When radius moves, the hand moves with it
Distal Ends of the Radius and Ulna
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Bones,
Part 1: The Appendicular Skeleton
Hand
• Includes the following bones
• Carpus—wrist
• Metacarpals—palm
• Phalanges—fingers
Carpus
• Forms the true wrist—the proximal region of the hand
• Gliding movements occur between carpals
• Composed of eight marble-sized bones
Carpus
• Carpal bones
• Are arranged in two irregular rows
• Proximal row from lateral to medial
• Scaphoid, lunate, triquetral, and pisiform
• Distal row from lateral to medial
• Trapezium, trapezoid, capitate, and hamate
• A mnemonic to help remember carpals:
• Sally left the party to take Carmen home
Bones of the Hand
Metacarpus
• Five metacarpals radiate distally from the wrist
• Metacarpals form the palm
• Numbered 1–5, beginning with the pollex (thumb)
• Articulate proximally with the distal row of carpals
• Articulate distally with the proximal phalanges
Phalanges
• Numbered 1–5, beginning with the pollex (thumb)
• Except for the thumb, each finger has three phalanges
• Proximal, middle, and distal
Bones of the Appendicular Skeleton
Pelvic Girdle
• Attaches lower limbs to the spine
• Supports visceral organs
• Attaches to the axial skeleton by strong ligaments
• Acetabulum is a deep cup that holds the head of the femur
• Lower limbs have less freedom of movement
• Are more stable than the arm
Pelvic Girdle
• Consists of paired hip bones (coxal bones)
• Hip bones unite anteriorly with each other
• Articulates posteriorly with the sacrum
Bones of the Pelvic Girdle
• A deep, basin-like structure
• Formed by:
• Coxal bones, sacrum, and coccyx
The Pelvic Girdle
• Consists of three separate bones in childhood
• Ilium, ischium, and pubis
• Bones fuse, retain separate names to regions of the coxal
bones
• Acetabulum
• A deep hemispherical socket on lateral pelvic surface
Ilium
• Large, flaring bone
• Forms the superior region of the coxal bone
• Site of attachment for many muscles
• Articulation with the sacrum forms sacroiliac joint
Ischium
• Forms posteroinferior region of the coxal bone
• Anteriorly—joins the pubis
• Ischial tuberosities
• Are the strongest part of the hip bone
Pubis
• Forms the anterior region of the coxal bone
• Lies horizontally in anatomical position
• Pubic symphysis
• The two pubic bones are joined by fibrocartilage at the midline
• Pubic arch—inferior to the pubic symphysis
• Angle helps distinguish male from female pelves
Lateral and Medial Views of the Hip Bone
True and False Pelves
• Bony pelvis is divided into two regions
• False (greater) pelvis—bounded by alae of the iliac bones
• True (lesser) pelvis—inferior to pelvic brim
• Forms a bowl containing the pelvic organs
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Bones,
Part 1: The Appendicular Skeleton
Pelvic Structures and Childbearing
• Major differences between male and female pelves
• Female pelvis is adapted for childbearing
• Pelvis is lighter, wider, and shallower than in the male
• Provides more room in the true pelvis
Female and Male Pelves
The Lower Limb
• Carries the entire weight of the erect body
• Bones of lower limb are thicker and stronger than those of
upper limb
• Divided into three segments
• Thigh, leg, and foot
Thigh
• The region of the lower limb between the hip and the knee
• Femur—the single bone of the thigh
• Longest and strongest bone of the body
• Ball-shaped head articulates with the acetabulum
Structures of the Femur
Patella
• Triangular sesamoid bone
• Imbedded in the tendon that secures the quadriceps muscles
• Protects the knee anteriorly
• Improves leverage of the thigh muscles across the knee
Leg
• Refers to the region of the lower limb between the knee and
the ankle
• Composed of the tibia and fibula
• Tibia—more massive medial bone of the leg
• Receives weight of the body from the femur
• Fibula—stick-like lateral bone of the leg
• Interosseous membrane
• Connects the tibia and fibula
Leg
• Tibia articulates with femur at superior end
• Forms the knee joint
• Tibia articulates with talus at the inferior end
• Forms the ankle joint
• Fibula does not contribute to the knee joint
• Stabilizes the ankle joint
Structures of the Tibia and Fibula
The Foot
• Foot is composed of
• Tarsus, metatarsus, and the phalanges
• Important functions
• Supports body weight
• Acts as a lever to propel body forward when walking
• Segmentation makes foot pliable and adapted to uneven ground
Tarsus
• Makes up the posterior half of the foot
• Contains seven bones called tarsals
• Body weight is primarily borne by the talus and calcaneus
• Trochlea of the talus
• Site of articulation with the tibia
• Other tarsals are:
• Cuboid and navicular
• Medial, intermediate, and lateral cuneiforms
Metatarsus
• Consists of five small long bones called metatarsals
• Numbered 1–5 beginning with the hallux
(great toe)
• First metatarsal supports body weight
Phalanges of the Toes
• 14 phalanges of the toes
• Smaller and less nimble than those of the fingers
• Structure and arrangement are similar to phalanges of fingers
• Except for the great toe, each toe has three phalanges
• Proximal, middle, and distal
Arches of the Foot
• Foot has three important arches
• Medial and lateral longitudinal arch
• Transverse arch
• Arches are maintained by
• Interlocking shapes of tarsals
• Ligaments and tendons
• ―Keystones‖ of arches
• Talus—medial longitudinal arch
• Cuboid—lateral longitudinal arch
Lower Limb and Pelvis
Disorders of the Appendicular Skeleton
• Bone fractures
• Hip dysplasia
• Head of the femur slips out of acetabulum
• Clubfoot
• Soles of the feet turn medially
The Appendicular Skeleton Throughout Life
• Growth of the appendicular skeleton
• Increases height
• Changes body proportions
• Upper/lower body ratio changes with age
• At birth, head and trunk are 1.5 times as long as lower limbs
• Lower limbs grow faster than the trunk
• Upper/lower body ratio of 1 to 1 by age 10
Changes in Body Proportions
The Appendicular Skeleton Throughout Life
• Few changes occur in adult skeleton until middle age, when
• Skeleton loses mass
• Osteoporosis and limb fractures become more common
9
Joints
Joints
• Rigid elements of the skeleton meet at joints or articulations
• Greek root ―arthro‖ means joint
• Structure of joints
• Enables resistance to crushing, tearing, and other forces
Classifications of Joints
• Joints can be classified by function or structure
• Functional classification—based on amount of movement
• Synarthroses—immovable; common in axial skeleton
• Amphiarthroses—slightly movable; common in axial skeleton
• Diarthroses—freely movable; common in appendicular skeleton
(all synovial joints)
Classifications of Joints
• Structural classification based on
• Material that binds bones together
• Presence or absence of a joint cavity
• Structural classifications include
• Fibrous
• Cartilaginous
• Synovial
Fibrous Joints
• Bones are connected by fibrous connective tissue
• Do not have a joint cavity
• Most are immovable or slightly movable
• Types
• Sutures
• Syndesmoses
• Gomphoses
Sutures
• Bones are tightly bound by a minimal amount of fibrous tissue
• Only occur between the bones of the skull
• Allow bone growth so the skull can expand with brain during
childhood
• Fibrous tissue ossifies in middle age
• Synostoses—closed sutures
Syndesmoses
• Bones are connected exclusively by ligaments
• Amount of movement depends on length of fibers
• Tibiofibular joint—immovable synarthrosis
• Interosseous membrane between radius and ulna
• Freely movable diarthrosis
Gomphoses
• Tooth in a socket
• Connecting ligament—the periodontal ligament
Fibrous Joints
Cartilaginous Joints
• Bones are united by cartilage
• Lack a joint cavity
• Two types
• Synchondroses
• Symphyses
Synchondroses
• Hyaline cartilage unites bones
• Epiphyseal plates
• Joint between first rib and manubrium
Symphyses
• Fibrocartilage unites bones; resists tension and compression
• Slightly movable joints that provide strength with flexibility
• Intervertebral discs
• Pubic symphysis
• Hyaline cartilage—present as articular cartilage
Symphyses
Synovial Joints
• Most movable type of joint
• All are diarthroses
• Each contains a fluid-filled joint cavity
General Structure of Synovial Joints
• Articular cartilage
• Ends of opposing bones are covered with hyaline cartilage
• Absorbs compression
• Joint cavity (synovial cavity)
• Unique to synovial joints
• Cavity is a potential space that holds a small amount of synovial
fluid
General Structure of Synovial Joints
• Articular capsule—joint cavity is enclosed in a two-layered
capsule
• Fibrous capsule—dense irregular connective tissue, which
strengthens joint
• Synovial membrane—loose connective tissue
• Lines joint capsule and covers internal joint surfaces
• Functions to make synovial fluid
General Structure of Synovial Joints
• Synovial fluid
• A viscous fluid similar to raw egg white
• A filtrate of blood
• Arises from capillaries in synovial membrane
• Contains glycoprotein molecules secreted by fibroblasts
• Reinforcing ligaments
• Often are thickened parts of the fibrous capsule
• Sometimes are extracapsular ligaments—located outside the
capsule
• Sometimes are intracapsular ligaments—located internal to the
capsule
General Structure of Synovial Joints
• Richly supplied with sensory nerves
• Detect pain
• Most monitor how much the capsule is being stretched
General Structure of Synovial Joints
• Have a rich blood supply
• Most supply the synovial membrane
• Extensive capillary beds produce basis of synovial fluid
• Branches of several major nerves and blood vessels
Synovial Joints with Articular Discs
• Some synovial joints contain an articular disc
• Occur in the temporomandibular joint and at the knee joint
• Occur in joints whose articulating bones have somewhat
different shapes
9
Joints
How Synovial Joints Function
• Synovial joints—lubricating devices
• Friction could overheat and destroy joint tissue
• Are subjected to compressive forces
• Fluid is squeezed out as opposing cartilages touch
• Cartilages ride on the slippery film
Bursae and Tendon Sheaths
• Bursae and tendon sheaths are not synovial joints
• Closed bags of lubricant
• Reduce friction between body elements
• Bursa—a flattened fibrous sac lined by a synovial membrane
• Tendon sheath—an elongated bursa that wraps around a
tendon
Bursae and Tendon Sheaths
Movements Allowed by Synovial Joints
• Three basic types of movement
• Gliding—one bone across the surface of another
• Angular movement—movements change the angle between
bones
• Rotation—movement around a bone's long axis
Gliding Joints
• Flat surfaces of two bones slip across
each other
• Gliding occurs
between
• Carpals
• Articular
processes
of vertebrae
• Tarsals
Angular Movements
• Increase or decrease angle between bones
• Movements involve
• Flexion and extension
• Abduction and adduction
• Circumduction
Rotation
• Involves turning movement of a bone around its long axis
• The only movement allowed between atlas and axis vertebrae
• Occurs at the hip and shoulder joints
Rotation
Special Movements
• Elevation—lifting a body part superiorly
• Depression—moving the elevated part inferiorly
Special Movements
• Protraction—nonangular movement anteriorly
• Retraction—nonangular movement posteriorly
Special Movements
• Supination—forearm rotates laterally, palm faces anteriorly
• Pronation—forearm rotates medially, palm faces posteriorly
• Brings radius across the ulna
Special Movements
• Opposition—thumb moves across the palm to touch the tips
of other fingers
9
Joints
Special Movements
• Inversion and eversion
• Special movements at the foot
• Inversion—turns sole medially
• Eversion—turns sole laterally
Special Movements
Special Movements
• Dorsiflexion and plantar flexion
• Up-and-down movements of the foot
• Dorsiflexion—lifting the foot so its superior surface approaches
the shin
• Plantar flexion—depressing the foot, elevating the heel
Special Movements
Synovial Joints Classified by Shape
• Plane joint
• Articular surfaces are flat planes
• Short gliding movements are allowed
• Intertarsal and intercarpal joints
• Movements are nonaxial
• Gliding does not involve rotation around any axis
Plane Joint
Synovial Joints Classified by Shape
• Hinge joints
•
•
•
•
Cylindrical end of one bone fits into a trough on another bone
Angular movement is allowed in one plane
Elbow, ankle, and joints between phalanges
Movement is uniaxial—allows movement around one axis only
Hinge Joint
Synovial Joints Classified by Shape
• Pivot joints
• Classified as uniaxial – rotating bone only turns around its long
axis
• Examples
• Proximal radioulnar joint
• Joint between atlas and axis
Pivot Joint
Synovial Joints Classified by Shape
• Condyloid joints
• Allow moving bone to travel
• Side to side—abduction-adduction
• Back and forth—flexion-extension
• Classified as biaxial—movement occurs around two axes
Condyloid Joint
Synovial Joints Classified by Shape
• Saddle joints
• Each articular surface has concave and convex surfaces
• Classified as biaxial joints
• 1st carpometacarpal joint is a good example
• Allows opposition of the thumb
Synovial Joints Classified by Shape
9
Joints
Synovial Joints Classified by Shape
• Ball-and-socket joints
• Spherical head of one bone fits into round socket of another
• Classified as multiaxial—allow movement in all axes
• Shoulder and hip joints are examples
Ball-and-Socket Joint
Factors Influencing Stability of Synovial Joints
• Articular surfaces
• Shapes of articulating surfaces determine movements possible
• Seldom play a major role in joint stability
• Exceptions that do provide stability
• Hip joint, elbow joint, and ankle
Factors Influencing Stability of Synovial Joints
• Ligaments
• Capsules and ligaments prevent excessive motions
• On the medial or inferior side of a joint – prevent excessive
abduction
• Lateral or superiorly located—resist adduction
Factors Influencing Stability of Synovial Joints
• Ligaments (continued)
• Anterior ligaments—resist extension and lateral rotation
• Posterior ligaments—resist flexion and medial rotation
• The more ligaments, usually stronger and more stable
Factors Influencing Stability of Synovial Joints
• Muscle tone
• Helps stabilize joints by keeping tension on tendons
• Is important in reinforcing:
• Shoulder and knee joints
• Supporting joints in arches of the foot
Selected Synovial Joints
• Sternoclavicular joint
• Is a saddle joint
• Four ligaments surround the joint
• Anterior and posterior sternoclavicular ligaments
• Interclavicular ligament
• Costoclavicular ligament
• Performs multiple complex movements
Selected Synovial Joints
• Temporomandibular Joint
•
•
•
•
Is a modified hinge joint
The head of the mandible articulates with the temporal bone
Lateral excursion is a side-to-side movement
Two surfaces of the articular disc allow
• Hinge-like movement
• Gliding of superior surface anteriorly
9
Joints
Selected Synovial Joints
• Shoulder (glenohumeral) joint
• The most freely movable joint lacks stability
• Articular capsule is thin and loose
• Muscle tendons contribute to joint stability
Glenohumeral Joint
Glenohumeral Joint
• The rotator cuff is made up of four muscles and their
associated tendons
•
•
•
•
Subscapularis
Supraspinatus
Infraspinatus
Teres minor
• Rotator cuff injuries are common shoulder injuries
The Shoulder Joint
The Shoulder Joint
Selected Synovial Joints
• Elbow joint
• Allows flexion and extension
• The humerus’ articulation with the trochlear notch of the ulna
forms the hinge
• Tendons of biceps and triceps brachii provide stability
Wrist Joint
• Stabilized by numerous ligaments
• Composed of radiocarpal and intercarpal joint
• Radiocarpal joint—joint between the radius and proximal
carpals (the scaphoid and lunate)
• Allows for flexion, extension, adduction, abduction, and
circumduction
• Intercarpal joint—joint between the proximal and distal rows or
carpals
• Allows for gliding movement
Selected Synovial Joints
• Hip joint
• A ball-and-socket structure
• Movements occur in all axes
• Limited by ligaments and acetabulum
• Head of femur articulates with acetabulum
• Stability comes chiefly from acetabulum and capsular ligaments
• Muscle tendons contribute somewhat to stability
Selected Synovial Joints
• Knee joint
•
•
•
•
•
•
The largest and most complex joint
Primarily acts as a hinge joint
Has some capacity for rotation when leg is flexed
Structurally considered compound and bicondyloid
Two fibrocartilage menisci occur within the joint cavity
Femoropatellar joint—shares the joint cavity
• Allows patella to glide across the distal femur
Knee Joint
• Capsule of the knee joint
• Covers posterior and lateral aspects of the knee
• Covers tibial and femoral condyles
• Does not cover the anterior aspect of the knee
• Anteriorly covered by three ligaments
• Patellar ligament
• Medial and lateral patellar retinacula
Anterior View of Knee
Knee Joint
• Ligaments of the knee joint
• Become taut when knee is extended
• These extracapsular and capsular ligaments are
• Fibular and tibial collateral ligament
• Oblique popliteal ligament
• Arcuate popliteal ligament
Posterior View of Knee Joint
Knee Joint
• Intracapsular ligaments
• Cruciate ligaments
• Cross each other like an ―X‖
• Each cruciate ligament runs from the proximal tibia to the distal
femur
• Anterior cruciate ligament
• Posterior cruciate ligament
Anterior View of Flexed Knee
Knee Joint
• Intracapsular ligaments
• Cruciate ligaments—prevent undesirable movements at the knee
• Anterior cruciate ligament—prevents anterior sliding of the
tibia
• Posterior cruciate ligament—prevents forward sliding of the
femur or backward displacement of the tibia
Stabilizing function of cruciate ligaments
The “Unhappy Triad”
• Lateral blows to the knee can tear:
• Tibial collateral ligament and medial meniscus
• Anterior cruciate ligament
The “Unhappy Triad”
Selected Synovial Joint
• Ankle joint
• A hinge joint between
• United inferior ends of tibia and fibula
• The talus of the foot
• Allows the movements
• Dorsiflexion and plantar flexion only
The Ankle Joint
• Medially and laterally stabilized by ligaments
• Medial (deltoid) ligament
• Lateral ligament
• Inferior ends of tibia and fibula are joined by ligaments
• Anterior and posterior tibiofibular ligaments
Disorders of Joints
• Structure of joints makes them prone to traumatic stress
• Function of joints makes them subject to friction and wear
• Affected by inflammatory and degenerative processes
Joint Injuries
• Torn cartilage—common injury to meniscus of knee joint
• Sprains—ligaments of a reinforcing joint are stretched or torn
• Dislocation—occurs when the bones of a joint are forced out
of alignment
Inflammatory and Degenerative Conditions
• Bursitis—inflammation of a bursa due to injury or friction
• Tendonitis—inflammation of a tendon sheath
Inflammatory and Degenerative Conditions
• Arthritis—describes over 100 kinds of joint-damaging
diseases
• Osteoarthritis—most common type of ―wear and tear‖ arthritis
• Rheumatoid arthritis—a chronic inflammatory disorder
• Gouty arthritis (gout)—uric acid build-up causes pain in joints
• Lyme disease—inflammatory disease often resulting in joint
pain
The Joints Throughout Life
• Synovial joints develop from mesenchyme
• By Week 8 of fetal development, joints resemble adult joints
• Outer region of mesenchyme becomes fibrous joint capsule
• Inner region becomes the joint cavity
The Joints Throughout Life
• During youth—injury may tear an epiphysis off a bone shaft
• Advancing age—osteoarthritis becomes more common
• Exercise—helps maintain joint health
10
Muscle Tissue
Muscle
• Muscle—a Latin word for ―little mouse‖
• Muscle is the primary tissue in the:
• Heart (cardiac MT)
• Walls of hollow organs (smooth MT)
• Skeletal muscle
• Makes up nearly half the body’s mass
Overview of Muscle Tissue
• Functions of muscle tissue
• Movement
• Skeletal muscle—attached to skeleton
• Moves body by moving the bones
• Smooth muscle—squeezes fluids and other substances
through hollow organs
Overview of Muscle Tissue
• Functions of muscle tissue (continued)
• Maintenance of posture—enables the body to remain sitting or
standing
• Joint stabilization
• Heat generation
• Muscle contractions produce heat
• Helps maintain normal body temperature
Functional Features of Muscles
• Functional features
• Contractility
• Long cells shorten and generate pulling force
• Excitability
• Electrical nerve impulse stimulates the muscle cell to contract
• Extensibility
• Can be stretched back to its original length by contraction of
an opposing muscle
• Elasticity
• Can recoil after being stretched
Types of Muscle Tissue
• Skeletal muscle tissue
• Packaged into skeletal muscles
• Makes up 40% of body weight
• Cells are striated
Types of Muscle Tissue
• Cardiac muscle tissue—occurs only in the walls of the heart
• Smooth muscle tissue—occupies the walls of hollow organs
• Cells lack striations
Similarities of Muscle Tissue
• Cells of smooth and skeletal muscle
• Are known as fibers
• Muscle contraction
• Depends on two types of myofilaments (contractile proteins)
• One type contains actin
• Another type contains myosin
• These two proteins generate contractile force
Similarities of Muscle Tissues
• Plasma membrane is called a sarcolemma
• Cytoplasm is called sarcoplasm
Skeletal Muscle
• Each muscle is an organ
• Consists mostly of muscle tissue
• Skeletal muscle also contains
• Connective tissue
• Blood vessels
• Nerves
Basic Features of a Skeletal Muscle
• Connective tissue and fascicles
• Sheaths of connective tissue bind a skeletal muscle and its
fibers together
• Epimysium—dense regular connective tissue surrounding
entire muscle
• Perimysium—surrounds each fascicle
(group of muscle fibers)
• Endomysium—a fine sheath of connective tissue wrapping
each muscle cell
Basic Features of a Skeletal Muscle
• Connective tissue sheaths are continuous with tendons
• When muscle fibers contract, pull is exerted on all layers of
connective tissue are tendon
• Sheaths provide elasticity and carry blood vessels and nerves
Connective Tissue Sheaths in Skeletal Muscle
Basic Features of a Skeletal Muscle
• Nerves and blood vessels
• Each skeletal muscle supplied by branches of
• One nerve
• One artery
• One or more veins
Basic Features of a Skeletal Muscle
• Nerves and blood vessels (continued)
• Nerves and vessels branch repeatedly
• Smallest nerve branches serve:
• Individual muscle fibers
• Neuromuscular junction—signals the muscle to contract
Basic Features of a Skeletal Muscle
• Muscle attachments
• Most skeletal muscles run from one bone to another
• One bone will move, other bone remains fixed
• Origin—less movable attachment
• Insertion—more movable attachment
Basic Features of a Skeletal Muscle
• Muscle attachments (continued)
• Muscles attach to origins and insertions by CT
• Fleshy attachments—CT fibers are short
• Indirect attachments—CT forms a tendon or aponeurosis
• Bone markings present where tendons meet bones
• Tubercles, trochanters, and crests
Microscopic and Functional Anatomy
of Skeletal Muscle Tissue
• The skeletal muscle fiber
• Fibers are long and cylindrical
• Are huge cells—diameter is 10–100µm
• Length—several centimeters to dozens of centimeters
• Each cell formed by fusion of embryonic cells
• Cells are multinucleate
• Nuclei are peripherally located
Diagram of Part of a Muscle Fiber
Myofibrils and Sarcomeres
• Striations result from internal structure of myofibrils
• Myofibrils
•
•
•
•
Are long rods within cytoplasm
Make up 80% of the cytoplasm
Are a specialized contractile organelle found in muscle tissue
Are a long row of repeating segments called sarcomeres
(functional unit of Skeletal MT)
Sarcomere
• Basic unit of contraction of skeletal muscle
• Z disc (Z line)—boundaries of each sarcomere
• Thin (actin) filaments—extend from Z disc toward the center of
the sarcomere
• Thick (myosin) filaments—located in the center of the
sarcomere
• Overlap inner ends of the thin filaments
• Contain ATPase enzymes
Sarcomere Structure
• A bands—full length of the thick filament
• Includes inner end of thin filaments
• H zone—center part of A band where no thin filaments occur
• A bands and I bands refract polarized light differently
• A bands—anisotropic
• I bands—isotropic
Sarcomere Structure (continued)
• M line—in center of H zone
• Contains tiny rods that hold thick filaments together
• I band—region with only thin filaments
• Lies within two adjacent sarcomeres
Sarcomere Structure (continued)
Sarcoplasmic Reticulum and T Tubules
• Sarcoplasmic reticulum
• A specialized smooth ER
• Interconnecting tubules surround each myofibril
• Some tubules form cross-channels called terminal cisternae
• Cisternae occur in pairs on either side of a
t tubule
Sarcoplasmic Reticulum and T Tubules
• Sarcoplasmic reticulum
• Contains calcium ions—released when muscle is stimulated to
contract
• Calcium ions diffuse through cytoplasm
• Trigger the sliding filament mechanism
• T tubules—deep invaginations of sarcolemma
• Triad—T tubule flanked by two terminal cisterns
Mechanism of Contraction
• Two major types of contraction
• Concentric contraction—muscle shortens to do work
• Eccentric contraction—muscle generates force as it lengthens
• Muscle acts as a ―brake‖ to resist gravity
• ―Down‖ portion of a pushup is an example
Mechanism of Contraction
• Sliding filament mechanism
• Explains concentric contraction
• Myosin head attach to thin filaments at both ends of a
sarcomere
• Then pull thin filaments toward the center of the sarcomere
• Thin and thick filaments do not shorten
• Initiated by release of calcium ions from the SR
• Powered by ATP
Sliding Filament Mechanism
• Contraction changes the striation pattern
• Fully relaxed—thin filaments partially overlap thin filaments
• Contraction—Z discs move closer together
• Sarcomere shortens
• I bands shorten, H zone disappears
• A band remains the same length
Microscopic and Functional Anatomy
of Skeletal Muscle Tissue
• Muscle extension
• Muscle is stretched by a movement opposite that which
contracts it
• Muscle fiber length and force of contraction
• Greatest force produced when a fiber starts out slightly stretched
• Myosin heads can pull along the entire length of the thin
filaments
The Role of Titin
• Titin—a spring-like molecule in sarcomeres
• Resists overstretching
• Holds thick filaments in place
• Unfolds when muscle is stretched
Innervation of Skeletal Muscle
• Motor neurons innervate skeletal muscle tissue
• Neuromuscular junction is the point where nerve ending and
muscle fiber meet
• Axon terminals—at ends of axons
• Store neurotransmitters
• Synaptic cleft—space between axon terminal and sarcolemma
The Neuromuscular Junction
Motor Units
10
Muscle Tissue
Types of Skeletal Muscle Fibers
• Skeletal muscle fibers are categorized according to two
characteristics
• How they manufacture energy (ATP)
• How quickly they contract
• Oxidative fibers—produce ATP aerobically
• Glycolytic fibers—produce ATP anaerobically by glycolysis
Types of Skeletal Muscle Fibers
• Skeletal muscle fibers
• Are divided into three classes
• Slow oxidative fibers
• Red slow oxidative fibers
• Fast glycolytic fibers
• White fast glycolytic fibers
• Fast oxidative fibers
• Intermediate fibers
Types of Skeletal Muscle Fibers
• Slow oxidative fibers
•
•
•
•
•
•
Red color due to abundant myoglobin
Obtain energy from aerobic metabolic reactions
Contain a large number of mitochondria
Richly supplied with capillaries
Contract slowly and resistant to fatigue
Fibers are small in diameter
Types of Skeletal Muscle Fibers
• Fast glycolytic fibers
•
•
•
•
•
Contain little myoglobin and few mitochondria
About twice the diameter of slow-oxidative fibers
Contain more myofilaments and generate more power
Depend on anaerobic pathways
Contract rapidly and tire quickly
Types of Skeletal Muscle Fibers
• Fast oxidative fibers
•
•
•
•
•
•
Have an intermediate diameter
Contract quickly like fast glycolytic fibers
Are oxygen-dependent
Have high myoglobin content and rich supply of capillaries
Somewhat fatigue-resistant
More powerful than slow oxidative fibers
Disorders of Muscle Tissue
• Muscle tissues experience few disorders
• Heart muscle is the exception
• Skeletal muscle
• Remarkably resistant to infection
• Smooth muscle
• Problems stem from external irritants
Disorders of Muscle Tissue
• Muscular dystrophy
• A group of inherited muscle destroying disease
• Affected muscles enlarge with fat and connective tissue
• Muscles degenerate
• Types of muscular dystrophy
• Duchenne muscular dystrophy
• Myotonic dystrophy
Disorders of Muscle Tissue
• Myofascial pain syndrome
• Pain is caused by tightened bands of muscle fibers
• Fibromyalgia
• A mysterious chronic-pain syndrome
• Affects mostly women
• Symptoms—fatigue, sleep abnormalities, severe
musculoskeletal pain, and headache
Muscle Tissue Throughout Life
• Muscle tissue develops from myoblasts
• Myoblasts fuse to form skeletal muscle fibers
• Skeletal muscles contract by the seventh week of development
Muscle Tissue Throughout Life
• Cardiac muscle
• Pumps blood three weeks after fertilization
• Satellite cells
• Surround skeletal muscle fibers
• Resemble undifferentiated myoblasts
• Fuse into existing muscle fibers to help them grow
Muscle Tissue Throughout Life
• With increased age
• Amount of connective tissue increases in muscles
• Number of muscle fibers decreases
• Loss of muscle mass with aging
• Decrease in muscular strength is 50% by age 80
• Sarcopenia—muscle wasting
11
Muscles of the Body
Muscles of the Body
• Skeletal muscles
• Produce movements
• Blinking of eye, standing on tiptoe, swallowing food, etc.
• General principles of leverage
• Muscles act with or against each other
• Criteria used in naming muscles
Arrangement of Fascicles in Muscles
• Skeletal muscles—consist of fascicles
• Fascicles—arranged in different patterns
• Fascicle arrangement—tells about action of a muscle
Arrangement of Fascicles in Muscles
• Types of fascicle arrangement
• Parallel—fascicles run parallel to the long axis of the muscle
• Strap-like—sternocleidomastoid
• Fusiform—biceps brachii
Arrangement of Fascicles in Muscles
• Types of fascicle arrangement
• Convergent
• Origin of the muscle is broad
• Fascicles converge toward the tendon of insertion
• Example—pectoralis major
Arrangement of Fascicles in Muscles
• Types of fascicle arrangement
• Pennate
• Unipennate—fascicles insert into one side of the tendon
• Bipennate—fascicles insert into the tendon from both sides
• Multipennate—fascicles insert into one large tendon from all
sides
Arrangement of Fascicles in Muscles
• Circular
• Fascicles are arranged in concentric rings
• Surround external body openings
• Sphincter—general name for a circular muscle
• Examples
• Orbicularis oris and orbicularis oculi
Lever Systems: Bone-Muscle Relationships
• Movement of skeletal muscles involves leverage
•
•
•
•
Lever—a rigid bar that moves
Fulcrum—a fixed point
Effort—applied force
Load—resistance
Lever Systems: Bone-Muscle Relationships
• Bones—act as levers
• Joints—act as fulcrums
• Muscle contraction—provides effort
• Applies force where muscle attaches to bone
• Load—bone, overlying tissue, and anything lifted
Lever Systems: Bone-Muscle Relationships
• Levers allow a given effort to
• Move a heavier load
• Move a load farther
• Mechanical advantage
• Moves a large load over small distances
• Mechanical disadvantage
• Allows a load to be moved over a large distance
Lever Systems: Bone-Muscle Relationships
• First-class lever
• Effort applied at one end
• Load is at the opposite end
• Fulcrum is located between load and effort
Lever Systems: Bone-Muscle Relationships
• Examples—seesaws, scissors, and lifting your head off your
chest
Lever Systems: Bone-Muscle Relationships
• Second-class lever
•
•
•
•
Effort applied at one end
Fulcrum is at the opposite end
Load is between the effort and fulcrum
Examples—wheelbarrow or standing on tiptoe
• An uncommon type of lever in the body
• Work at a mechanical advantage
Lever Systems: Bone-Muscle Relationships
• Third-class lever
• Effort is applied between the load and the fulcrum
• Work speedily
• Always at a mechanical disadvantage
Lever Systems: Bone-Muscle Relationships
• Most skeletal muscles are third-class levers
• Example—biceps brachii
• Fulcrum—the elbow joint
• Force—exerted on the proximal region of the radius
• Load—the distal part of the forearm
Organization Scheme Based on Embryonic Development
• Overview based on
• Embryonic origin
• General function
• Muscles develop from mesoderm
• Myotomes
• Somitomeres
• The first seven myotomes of the head
• Splanchnic mesoderm
Development and Basic Organization of the Muscles
Organization Scheme Based on Embryonic Development
• Muscles organized into four groups
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Musculature of the visceral organs
Pharyngeal arch muscles
Axial muscles
Limb muscles
Organization Scheme Based on Embryonic Development
• Musculature of the visceral organs
• Includes smooth and cardiac muscle
• Develops from splanchnic mesoderm
• Pharyngeal arch muscles
• Includes
• Skeletal muscles of the pharynx
• Muscles of the head and neck
• Develop from the fourth to seventh somitomeres
Pharyngeal Arch Muscles
Axial Muscles
• Lie anterior and posterior to the body axis
• Muscles of the
• Thorax, abdomen, and pelvis
• Many muscles of the
• Neck and some of the head
• Function to move the trunk and maintain posture
Axial Muscles
• Develop from myotomes and some somitomeres
• Dorsal regions of myotomes—deep muscles of the back
• Ventral regions of myotomes—muscles of the trunk and neck
• Respiratory muscles
• Anterior abdominal wall muscles
• Muscles of the pelvic floor
Axial Muscles
Limb Muscles
• Limb muscles arise from lateral parts of nearby myotomes
• Extensors
• Muscle mass dorsal to limb bones
• Flexors
• Muscle mass ventral to limb bones
Limb Muscles
Muscle Actions and Interactions
• A muscle cannot reverse the movement it produces
• Another muscle must undo the action
• Muscles with opposite actions lie on opposite sides of a joint
Muscle Actions and Interactions
• Prime mover (agonist)
• Has major responsibility for a certain movement
• Antagonist
• Opposes or reverses a movement
• Synergist—helps the prime mover
• By adding extra force
• By reducing undesirable movements
• Fixator
• A type of synergist that holds a bone firmly in place
Muscle Compartments of the Limbs
• Dense fibrous connective tissue divides limb muscles into
compartments
• Muscles in opposing compartments are
• Agonist and antagonist pairs
• Each compartment is innervated by a single nerve
Muscle Compartments of Arm and Forearm
• The upper limb has anterior and posterior compartments
• Anterior arm compartment muscles
• Flex the shoulder or arm
• Innervation is the musculocutaneous nerve
• Anterior forearm compartment muscles
• Flex the wrist and digits
• Innervation is the median or ulnar nerve
Muscle Compartments of the Thigh
• Posterior compartment muscles
• Extend the hip and flex the knee
• Innervation is the tibial branch of the sciatic nerve
• Anterior compartment muscles
• Flex the hip and extend the knee
• Innervation is the femoral nerve
• Medial compartment
• Adduct the thigh
• Innervation is the obturator nerve
Muscle Compartments of the Thigh and Leg
Compartments of the Leg
• Posterior compartment muscles
• Contains digital and plantar flexors
• Innervation is the tibial nerve
• Anterior compartment muscles
• Contains digital extensors and dorsiflexors
• Innervation is the deep fibular nerve
• Lateral compartment muscles
• Plantar flex and evert the foot
• Innervation is the superficial fibular nerve
Naming the Skeletal Muscles
• Location
• Example—the brachialis is located on the arm
• Shape
• Example—the deltoid is triangular
• Relative size
• Maximus, minimus, and longus indicate size
• Example—gluteus maximus and gluteus minimus
Naming the Skeletal Muscles
• Direction of fascicles and muscle fibers
• Name tells direction in which fibers run
• Example—rectus abdominis and transversus abdominis
• Location of attachments—name reveals point of origin and
insertion
• Example—brachioradialis
Naming the Skeletal Muscles
• Number of origins
• Two, three, or four origins
• Indicated by the words biceps, triceps, and quadriceps
• Action
• The action is part of the muscle’s name
• Indicates type of muscle movement
• Flexor, extensor, adductor, or abductor
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Muscles of the Body
Superficial Muscles of the Body—Anterior View
Superficial Muscles of the Body—Posterior View
Muscles of the Head—Facial Expression
• Muscles of facial expression
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Lie in the face and scalp
Thin and variable in shape
Often insert in the skin—not on bones
Innervated by cranial nerve VII—the facial nerve
Muscles of the Head—Facial Expression
Muscles Mastication and Tongue Movement
• Four main pairs of muscles involved in mastication
• Innervated by mandibular division of the trigeminal nerve (cranial
nerve V)
• Prime movers of jaw closure
• Masseter and temporalis
• Side-to-side movement
• Pterygoid muscles
• Compression of cheeks
• Buccinator muscles
Muscles Mastication and Tongue Movement
• Extrinsic muscles of the tongue
• Move tongue
• Laterally
• Anteriorly
• Posteriorly
• All innervated by cranial nerve XII—the hypoglossal nerve
Muscles of the Anterior Neck and Throat—Swallowing
• The neck is divided into anterior and posterior triangles
• Anterior triangle
• Divided into suprahyoid and infrahyoid muscles
• Participate in swallowing
• Pharyngeal constrictors
• Squeeze food into the esophagus
Muscles of the Neck and Vertebral Column
• Head movement
• Sternocleidomastoid
• Splenius capitis and splenius cervicis
Muscles of the Neck and Vertebral Column
• Trunk extension
• Deep muscles of the back
• Maintain normal curvatures of the spine
• Form a column from sacrum to the skull
• Erector spinae group
• Largest of the deep back muscles
Deep Muscles of the Thorax—Breathing
• Deep muscles provide movements for breathing
• External intercostal muscles
• Lift the rib cage
• Internal intercostal muscles
• Aid expiration during heavy breathing
Deep Muscles of the Thorax—Breathing
• Diaphragm
• Most important muscle of respiration
• Flattens as it contracts
• Increases the volume of the thoracic cavity
Muscles of the Abdominal Wall
• Lateral and anterior abdominal wall
• Formed from three flat muscle sheets
• External oblique
• Internal oblique
• Transversus abdominis
• Fourth muscle pair
• Rectus abdominis
• Inserts at the linea alba
Muscles of the Pelvic Floor
• Pelvic floor (pelvic diaphragm)
• Sheet of two muscles
• Both support pelvic organs
• Levator ani
• Formed from iliococcygeus, puborectalis, and pubococcygeus
• Coccygeus
Muscles of the Pelvic Floor
Muscles of the Perineum
• Inferior to the muscles of the pelvic floor
• Urogenital diaphragm formed from:
• Sphincter urethrae and the deep transverse perineus
Muscles of the Perineum
• Muscles of the superficial perineal space
• Ischiocavernosus
• Bulbospongiosus
• Superficial transverse perineus
Muscles of the Perineum
Superficial Muscles of the Anterior Thorax
• Movements of the scapula
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Pectoralis major
Pectoralis minor
Serratus anterior
Subclavius
Superficial Muscles of the Posterior Thorax
• Movements of the scapula
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Trapezius
Levator scapulae
Rhomboid major
Rhomboid minor
Muscles Crossing the Shoulder Joint
• Movements of the arm
• Deltoid
• Pectoralis major
Muscles Crossing the Elbow Joint
• Posterior muscles—extensors of the forearm
• Triceps brachii
• Anconeus
• Anterior muscles—flexors of the forearm
• Biceps brachii—also supinates the forearm
• Brachialis
• Brachioradialis
Muscles of the Forearm
• Movements of the wrist, hand, and fingers
• Tendons are anchored by
• Flexor and extensor retinacula
• Most forearm muscles arise from the distal humerus
• Movements at the wrist include
• Flexion, extension, abduction, and adduction
• Wrist and fingers are ―operated‖ by muscles in the forearm
Muscles of the Forearm
• Flexors
• Anterior flexor compartment
• Innervated by median and ulnar nerves
• Originate from a common tendon
• Medial epicondyle of the humerus
Superficial Anterior Muscles of the Forearm
• Pronator teres
• Flexor carpi radialis
• Palmaris longus
• Flexor carpi ulnaris
• Flexor digitorum superficialis
Deep Anterior Muscles of the Forearm
• Flexor pollicis longus
• Flexor digitorum profundus
• Pronator quadratus
Deep Anterior Muscles of the Forearm
Muscles of the Forearm
• Extensors
• Posterior compartment of the forearm
• Innervated by the radial nerve
• Originate at a common tendon
• Lateral epicondyle of the humerus
Superficial Posterior Muscles of the Forearm
• Brachioradialis—flexes forearm
• Extensor carpi radialis longus
• Extensor carpi radialis brevis
• Extensor digitorum
• Extensor carpi ulnaris
Deep Posterior Muscles of the Forearm
• Supinator
• Abductor pollicis longus
• Extensor pollicis brevis and longus
• Extensor indicus
Intrinsic Muscles of the Hand
• Fine movement of the fingers
• All located in the palm
• Control precise movements
• Include muscles of
• Adduction, abduction, and opposition
Intrinsic Muscles of the Hand
• Thenar muscles—ball of thumb
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Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis
Adductor pollicis
• Hypothenar muscles
• Abductor digiti minimi
• Flexor digiti minimi
• Opponens pollicis
Intrinsic Muscles of the Hand
Intrinsic Muscles of the Hand
• Midpalmar muscles
• Lumbricals
• Palmar interossei
• Dorsal interossei
Intrinsic Muscles of the Hand
Muscles Crossing the Hip and Knee Joints
• Thigh and leg movements
• Anterior muscles
• Flex the thigh and extend the leg at the knee
• Posterior muscles
• Extend the thigh and flex the leg
Muscles Crossing the Hip and Knee Joints
• Thigh and leg movements
• Adductor muscles—on medial aspect of thigh
• Adduct the thigh only
• Deep fascia of the thigh
• Surrounds and encloses all three groups
Muscles Crossing the Hip and Knee Joints
• Movements at the hip joint
• Muscles that flex the thigh
• Originate on vertebral column or pelvis
• Muscles that extend the thigh
• Arise posterior to the hip joint
• Adductors originate medial to the hip joint
• Abductors originate lateral to the hip joint
Anterior and Medial Muscles
• Origin on pelvis or vertebral column
• Iliacus
• Psoas major
• Sartorius
• Muscles of the medial compartment
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Adductor longus
Adductor brevis
Adductor magnus
Pectineus
Gracilis
Anterior and Medial Muscles
Muscles of the Anterior Compartment of the Thigh
• Quadriceps femoris
• Has four separate heads
• Has a common insertion at the quadriceps tendon
• Powerful knee extensors
• Rectus femoris
• Vastus lateralis
• Vastus medialis
• Vastus intermedius
• Tensor fasciae latae
Muscles of the Anterior Compartment of the Thigh
Posterior Muscles
• Origin on pelvis or sacrum
• Gluteus maximus
• Gluteus medius
• Gluteus minimus
• Lateral rotators
• Piriformis
• Obturator externus
• Obturator internus
• Superior and inferior gemellus
• Quadratus femoris
Posterior Muscles
Muscles of the Posterior Compartment of the Thigh
• Hamstrings
• Biceps femoris
• Semitendinosus
• Semimembranosus
Muscles of the Leg
• Fascia lata of the leg surrounds muscles
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Tightly binds muscles
Prevents swelling during exercise
Aids venous return
Divides leg into three compartments
• Tendons are held in place by
• Extensor, fibular, and flexor retinacula
• Muscle movement at ankle and intertarsal joints
Muscles of the Anterior Compartment
• Tibialis anterior
• Extensor digitorum longus
• Fibularis tertius
• Extensor hallucis longus
Muscles of the Lateral Compartment
• Fibularis longus
• Fibularis brevis
• Flexor hallucis longus
• Extensor hallucis longus
• Fibularis tertius
Muscles of the Posterior Compartment
• Superficial muscles
• Triceps surae
• Gastrocnemius
• Soleus
• Plantaris
Muscles of the Posterior Compartment
• Deep muscles
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Popliteus
Flexor digitorum longus
Flexor hallucis longus
Tibialis posterior
Intrinsic Muscles of the Foot
• Toe movement and foot support
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Help to flex, extend, abduct, and adduct the toes
Support the arches of the foot
Single muscle on dorsal aspect of the foot
Many muscles on the plantar aspect
Muscles of the Foot
• Muscle on the dorsum of the foot
• Extensor digitorum brevis
• Muscles on the sole of the foot
• First layer
• Flexor digitorum brevis
• Abductor hallucis
• Abductor digiti minimi
Muscles of the Foot
• Second layer
• Flexor accessorius
• Lumbricals
Muscles of the Foot
• Third layer
• Flexor hallucis brevis
• Adductor hallucis
• Flexor digiti minimi brevis
• Fourth layer
• Plantar and dorsal interossei
Muscles of the Foot
Surface Anatomy
• Palpation—feeling internal structures through the skin
• ―Living anatomy‖—provides information about
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Palpation of arterial pulses
Skeleton, muscles, and blood vessels
Sounds of the heart and lungs
Where to give injections
The Head
• Cranium—selected structures felt through the skin
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Superciliary arches
External occipital protuberance
Mastoid process
Temporalis muscle—at temple region
Frontalis muscle
• Feel wrinkling of the forehead when eyebrows are raised
Surface Anatomy of Lateral Aspect of the Head
The Head
• Face—selected structures felt through the skin
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Lacrimal fossa
Root and bridge of the nose
Auricle of the ear
Zygomatic arch
Masseter muscle
Mandible
Temporomandibular joint
The Neck
• Skeletal landmarks
• Spinous processes of cervical vertebrae
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• C7 is particularly prominent (vertebra prominens)
Hyoid bone—in the anterior superior neck
Laryngeal prominence—the ―Adam’s Apple‖
Cricoid cartilage—inferior to the laryngeal prominence
Jugular notch—depression in the superior part of the sternum
The Neck
Muscles of the Neck
• Sternocleidomastoid—most prominent neck muscle
• Sternal head
• Clavicular head
• Deep to the sternocleidomastoid
• Common carotid artery
• Internal jugular vein
• Trapezius—posterior aspect of the neck
Triangles of the Neck
• The sternocleidomastoid muscles divide
the neck
• Anterior triangle
• Posterior triangle
The Thorax
• Sternum—portions felt through the skin
• Manubrium, xiphoid process, and sternal angle
• Midaxillary line—line from the center of the axilla onto the
lateral thoracic wall
• Midclavicular line—vertical line from midpoint of the clavicle to
the groin
Muscles of the Thorax
• Pectoralis major
• Serratus anterior
The Anterior Thorax and Abdomen
The Abdomen
• Structures felt through the skin
• Iliac crest
• Anterior superior iliac spine
• Inguinal ligament
• Runs medially from anterior superior iliac spine to the pubic
tubercle
• Pubic crest
Muscles and other Abdominal Surface Features
• Linea alba
• The ―white line‖ extending from xiphoid process to the pubic
symphysis
• Rectus abdominis
• Linea semilunaris—lateral margin of rectus abdominis
The Pelvis and Perineum
• Four bony structures define the perineum
• Pubic symphysis
• Two ischial tuberosities
• Coccyx
The Back
• Posterior median furrow—vertical groove along the midline
• Spinous processes of vertebrae
• Spine of the scapula
• Medial end is opposite T3
• Medial border of the scapula
The Back
• Inferior angle of the scapula
• Iliac crests
• Supracristal line—intersects L4
• Sacrum—superior to cleft in the buttocks
• Coccyx—posterior to the anus
Surface Anatomy of the Back
Muscles of the Back
• Trapezius
• Latissimus dorsi
• Erector spinae
Surface Anatomy of the Back
Upper Limb and Shoulder
• The axilla
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Base of the axilla—where armpit hair grows
Deep to the axilla—axillary lymph nodes and blood vessels
Anterior axillary fold—pectoralis major
Posterior axillary fold—latissimus dorsi and teres major
Shoulder and Arm
The Shoulder
• Acromion—lateral end of the spine of the scapula
• Acromioclavicular joint
• Deltoid muscle
• Covers the greater tubercle of the humerus
The Arm
• The region between the shoulder and elbow
• Humerus
• Palpated through skin along its entire length
• Biceps brachii
• Medial bicipital groove
• The medial boundary of the biceps brachii
• Triceps brachii
The Arm
The Elbow
• Lateral and medial epicondyles of the humerus
• Ulnar nerve—―funny bone‖ runs across medial epicondyle
• Olecranon process of the ulna
• Cubital fossa—(antecubital fossa)
• Forms anterior surface of forearm
The Anterior Surface of the Forearm and Fist
Forearm
• Bones
• Ulna—palpate entire length
• Styloid process and head—distal end
• Radius—partly covered in muscle
• Head of the radius—proximal end
• Styloid process—distal end
Muscles of the Forearm
• Flexor muscles—anterior forearm
• Flexor carpi radialis
• Palmaris longus
• This muscle is absent in about 30% of people
• Extensor muscles—posterior forearm
Muscles of the Forearm
Other Structures of the Forearm
• Anatomical snuff box bordered by
• Extensor pollicis brevis
• Extensor pollicis longus
The Hand
• Dorsum of hand
• Dorsal venous network
• Tendons of extensor digitorum
Gluteal Region
• Iliac crests
• Posterior superior iliac spine
• Sacroiliac joint
• Prominences of the buttocks
• ―Cheeks‖ of the buttocks
• Formed from subcutaneous fat and the gluteal muscles
The Gluteal Region
Lower Limb and Gluteal Region
• Natal cleft (gluteal cleft)
• Vertical midline groove between ―cheeks‖
• Gluteal fold
• Horizontal fold below each ―cheek‖
• Ischial tuberosities
• Greater trochanter of the femur
• Located at the lateral hip
Lower Limb and Gluteal Region
Thigh
• Medial and lateral condyles of the femur
• Patella
• Three groups of muscles
• Quadriceps femoris—anterior thigh
• Vastus lateralis—injection site
• Adductors—medial thigh
• Hamstrings—posterior thigh
Thigh
The Thigh
• The femoral triangle
• Superior border—inguinal ligament
• Inferior borders
• Sartorius
• Adductor longus
• Popliteal fossa
• Diamond-shaped hollow on posterior knee
• Defined by borders of ―hamstring‖ tendons and gastrocnemius
Leg and Foot
• Palpate patella to find the patellar ligament
• Structures of the proximal leg
• Tibial tuberosity
• Lateral and medial condyles of the tibia
• Head of the fibula
• Structures of the distal leg
• Medial malleolus
• Lateral malleolus
Leg and Foot
Muscle Groups of the Leg
• Posterior calf muscles
• Gastrocnemius and soleus
• Calcaneal tendon—inferior end of the soleus and
gastrocnemius
• Anterior compartment muscles
• Tibialis anterior
• Extensor digitorum
• Fibularis
Muscle Groups of the Leg
Foot
• Tendons on the dorsal surface of the foot
• Extensor digitorum longus tendon
• Extensor hallucis longus
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