the axial skeleton (contd.) & the appendicular skeleton human anatomy sonya schuh-huerta, ph.d
TRANSCRIPT
The Axial Skeleton (contd.) &The Axial Skeleton (contd.) &The Appendicular SkeletonThe Appendicular Skeleton
Human AnatomyHuman AnatomySonya Schuh-Huerta, Ph.D.Sonya Schuh-Huerta, Ph.D.
The Vertebral Column
• Formed from 26 bones in the adult
• Transmits weight of trunk to lower limbs
• Surrounds & protects spinal cord
The Vertebral Column
• Serves as attachment sites for muscles of the neck and back
• Held in place by ligaments– Anterior & posterior longitudinal ligaments – Ligamentum flavum
The Vertebral ColumnCervical curvature
(concave)7 vertebrae, C1 – C7
Thoracic curvature(convex)
12 vertebrae,T1 – T12
Lumbarcurvature(concave)
5 vertebrae, L1 – L5
Sacralcurvature
(convex) 5 fusedvertebrae sacrum
Coccyx4 fused vertebraeAnterior view Right lateral view
C1
T1
2
3
4
5
6
7
8
9
10
11
12
L1
2
3
4
5
2
3
4
567
SpinousprocessTransverseprocesses
Intervertebraldiscs
Intervertebralforamen
Regions & Normal Curvatures
• The Vertebral column has 5 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 & Normal Curvatures
• Curvatures of the spine– Cervical & lumbar curvatures
• Concave posteriorly
– Thoracic & sacral curvatures• Convex posteriorly
Regions & Normal Curvatures
• Curvatures increase resilience of spine
• Thoracic & sacral curvatures– Primary curvatures
• Present at birth
• Lumbar curvature– Develops when baby begins to walk (~1 year)
Ligaments of the Spine
• Major supporting ligaments– Anterior longitudinal ligament
• Attaches to bony vertebrae & intervertebral discs• Prevents hyperextension
– Posterior longitudinal ligament• Narrow & relatively weak• Attaches to intervertebral discs
Posterior longitudinalligament
Anterior longitudinalligament
Body of a vertebra
Intervertebral disc
(b) Anterior view of part of the spinal column
Ligaments of the Spine
Supraspinous ligamentIntervertebraldisc
Anteriorlongitudinalligament
Intervertebral foramenPosterior longitudinalligament
Anulus fibrosus
Nucleus pulposus
Sectioned bodyof vertebra
Transverse process
Sectionedspinous process
Ligamentum flavum
Interspinousligament
Inferior articular process
(a) Median section of three vertebrae, illustrating the compositionof the discs and the ligaments
Intervertebral Discs
• Are cushion-like pads between vertebrae– Composed of:
• Nucleus pulposus• Anulus fibrosus
Intervertebral Discs
• Nucleus pulposus
• derived from notocord– Gelatinous inner sphere– Absorbs compressive stresses
• Annulus fibrosus– Outer rings formed of ligament– Inner rings formed of fibrocartilage– Surround the nucleus pulposus
Intervertebral Disc
Vertebral spinous process(posterior aspect of vertebra)
Spinal nerve root
Anulus fibrosusof disc
Herniated portionof disc
Nucleuspulposusof disc
Spinal cord
(c) Superior view of a herniated intervertebral disc
Transverseprocess
(d) MRI of lumbar region of vertebral column in sagittal section showing normal & herniated discs
Nucleus pulposus of intact disc
Herniated nucleuspulposus
General Structure of VertebraePosterior
Anterior
Lamina
Superior articularprocessandfacet
Transverseprocess
Pedicle
Spinousprocess
Vertebralarch
Vertebralforamen
Body(centrum)
General Structure of Vertebrae
• Common structures to all regions– Body– Vertebral arch– Vertebral foramen– Spinous process– Transverse process– Superior & inferior articular processes– Intervertebral foramina
Movement of the Vertebrae
• Specific regions of the spine perform specific functions
• Types of movement that occur between vertebrae– Flexion & extension– Lateral flexion– Rotation in the long axis
Cervical Vertebrae
• 7 cervical vertebrae (C1–C7) smallest & lightest vertebrae
• C3–C7 are typical cervical vertebrae – Body is wider laterally– Spinous processes are short & bifid
(except C7)– Vertebral foramen are large & triangular– Transverse processes contain transverse
foramina– Superior articular facets face superoposteriorly
Cervical Vertebrae
Dens of axis
Transverse ligamentof atlasC1 (atlas)
C2 (axis)
C3
Bifid spinousprocess
Transverse processes
C7 (vertebraprominens)
(a) Cervical vertebrae
Inferior articularprocess
Cervical Vertebrae
The Atlas
• C1 is termed atlas
• Lacks a body & spinous process
• Supports the skull – Superior articular facets receive the occipital
condyles
• Allows flexion & extension of neck – Nodding the head “yes”
The Atlas
Anterior arch
Superior articularfacet
Transverse foramen
Posterior arch
Posterior tubercle
Anterior tubercle
Posterior
Lateralmasses
(a) Superior view of atlas (C1)
C1
The Atlas
Facet for dens
Transverseprocess Lateral
masses
Transverse foramen
Posterior arch
Posterior tuberclePosterior
Anterior tubercle
Anterior arch
(b) Inferior view of atlas (C1)
Inferiorarticularfacet
C1
The Axis
• Has a body & 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 & skull– Participates in rotating the head from side to
side (‘nodding no’)
The AxisC2
Posterior
Dens
(c) Superior view of axis (C2)
Inferiorarticularprocess
Body
Superior articularfacet
Transverseprocess
Pedicle
LaminaSpinous process
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
Thoracic Vertebrae
• Spinous processes are long & 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 & prevents flexion and
extension
Lumbar Vertebrae (L1—L5)
• Bodies are thick & robust
• Transverse processes are thin & tapered
• Spinous processes are thick, blunt, & point posteriorly
• Vertebral foramina are triangular
• Superior & inferior articular facets directly medially
• Allows flexion & extension rotation prevented
Lumbar Vertebrae
Superiorarticularprocess
Transverseprocess
Spinousprocess
Intervertebraldisc
Body
Inferiorarticularprocess
(c) Lumbar vertebrae
Lumbar Vertebrae
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
Sacrum
Body offirstsacralvertebra
Transverse ridges (sites of vertebralfusion)
Coccyx Coccyx
AnteriorsacralforaminaApex
Posteriorsacralforamina
Mediansacralcrest
Sacral promontorySacralcanal
Sacralhiatus
BodyFacet of superiorarticular process
Lateralsacralcrest
Auricularsurface
Ala
(a) Anterior view (b) Posterior view
Coccyx
• Is the “tailbone”
• Formed from 3–5 fused vertebrae
• Offers only slight support to pelvic organs
• Easily injured
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
Intercostalspaces
True ribs(1–7
Falseribs(8–12)
Jugular notchClavicular notch
Manubrium
Sternal angleBody
XiphisternaljointXiphoidprocess
L1
VertebraFloating ribs (11, 12)
(a) Skeleton of the thoracic cage, anterior view
Sternum
Costal cartilageCostal margin
The Thoracic Cage
The Thoracic Cage
XiphisternalXiphisternaljoint
Heart
Sternal angle
Jugular notch
(b) Midsagittal section through the thorax, showingthe relationship of surface anatomical landmarksof the thorax to the vertebral column
T2
T4
T3
T9
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 2–7
– 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
Ribs
Junction withcostal cartilage
Shaft Head NeckArticular faceton tubercle
Costal angleCostal groove
Facets for articulationwith vertebrae
(a) A typical rib (rib 6, right), posterior view
Transverse costal facet (for tubercle of rib) Superior costal facet
(for head of rib)
Body of vertebra
Head of rib
Intervertebral disc
Tubercle of rib
Neck of rib
Shaft Sternum
Angleof rib
Cross-sectionof rib Costal groove
(b) Vertebral and sternal articulations of a typical true rib
Costal cartilage
Spinous processArticular faceton tubercle of rib
Shaft
Ligaments
Neck of rib
Head of rib Body ofthoracicvertebra
Transversecostal facet(for tubercleof rib)
Superior costal facet(for head of rib)
(c) Superior view of the articulation between a rib and athoracic vertebra
Ribs
Disorders of the Axial Skeleton
• Cleft palate– A common congenital
disorder– Right & left halves of palate
fail to fuse medially– Can involve entire palate & lip – minor to severe
• 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
Occipitalbone
Parietal bone
Anteriorfontanelle
Frontal suture
Frontal bone
Ossificationcenter
(a) Superior view
Posterior fontanelle
Fontanelles
Frontal bone
Sphenoidalfontanelle
(b) Lateral view
Posteriorfontanelle
Mastoidfontanelle
Parietal bone
Ossificationcenter
Occipital bone
Temporal bone(squamous portion)
The Axial Skeleton Throughout Life
• Many bones of the face & skull form by intramembranous ossification
• Endochondral bones of the skull are:– Occipital bone– Sphenoid – Ethmoid bones– Parts of the temporal bone
The Axial Skeleton Throughout Life
• Aging of the axial skeleton:– 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
The Appendicular Skeleton, Ch 8(also to be used as Lab Guide)
The Appendicular Skeleton
• Pectoral girdle– Attaches the upper limbs to the trunk
• Pelvic girdle– Attaches the lower limbs to the trunk
• Upper & lower limbs differ in function– Share the same structural plan
The Pectoral Girdle
• Consists of the clavicle & 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 & 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
ClavicleAcromio-clavicularjoint
Scapula
(a) Articulated pectoral girdle
Articulated Pectoral Girdle
Clavicles
• Extend horizontally across the superior thorax
• Sternal end articulates with the manubrium
• Acromial end articulates with scapula
Clavicles
Acromial (lateral)end
(b) Right clavicle, superior view
Posterior
Sternal (medial)end
Anterior
Acromial end
Trapezoid line
Conoid tubercle
Anterior
Posterior
Sternal end
(c) Right clavicle, inferior view
Tuberosity forcostoclavicularligament
Clavicles
• Provide attachment for muscles
• Hold the scapulae & 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 3 borders– Superior– Medial (vertebral)– Lateral (axillary)
• Have 3 angles– Lateral, superior, & inferior
Structures of the ScapulaAcromion
Coracoidprocess
Suprascapular notch Superior border
Superiorangle
Subscapularfossa
Medial border
Inferior angle
Glenoidcavity
Lateral border
(a) Right scapula, anterior aspect
Superiorangle
Medial border
Coracoid processSuprascapular notch
Acromion
Glenoidcavityat lateralangle
Lateral border
Infraspinousfossa
Spine
(b) Right scapula, posterior aspect
Supraspinousfossa
Structures of the Scapula
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 & elbow
• Humerus– The only bone of the arm– Longest & strongest bone of the upper limb– Articulates with the scapula at the shoulder– Articulates with the radius & 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
Structures of the Humerus of the Right Arm
Greater tubercle
Lesser tubercle
Intertubercularsulcus
Lateral supracondylarridgeRadial fossa
Capitulum
Head of humerus
Anatomical neck
Deltoid tuberosity
Coronoid fossa
Medial epicondyle
Trochlea
(a) Anterior view
Head of humerus
Anatomical neck
Radial groove
Olecranon fossa
Medial epicondyle
Trochlea
Surgical neck
Deltoid tuberosity
Greater tubercle
Lateral epicondyle
Medial supracondylarridge
(b) Posterior view
Structures of the Humerus of the Right Arm
Coronoid fossa
Radius
Radialtuberosity
Head ofradius
Capitulum
Trochlea
(c) Anterior view at the elbow region
Humerus
Medialepicondyle
Coronoidprocess ofulna
Ulna
Radial notch
Olecranonfossa
Ulna
Olecranonprocess
Medialepicondyle
(d) Posterior view of extended elbow
Humerus
Lateralepicondyle
Head
Radius
Neck
Forearm
• Formed from the radius & ulna
• Proximal ends articulate with the humerus
• Distal ends articulate with carpals
Forearm
• Radius & ulna articulate with each other – At the proximal & distal radioulnar joints
• The interosseous membrane– Interconnects radius & 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
Radial notch of the ulna
Olecranon process
Trochlear notch
Coronoid process
Proximal radioulnarjoint
Distal radioulnar joint
Ulnar notch of the radiusHead of ulna
Styloid process of ulna
Interosseousmembrane
Ulna
HeadNeckRadialtuberosity
Radius
Styloid processof radius
(a) Anterior view
Olecranonprocess
Styloid processof radius
Radius
Neck of radius
Head of radius
Ulnar notchof the radius
Head of ulna
Styloid processof ulna
Interosseousmembrane
Ulna
(b) Posterior view
The Radius & Ulna
(c) Proximal portion of ulna, lateral view
Olecranon process
Trochlear notch
Coronoid process
Radial notch
View
(d) Distal ends of the radius & ulna at the wrist
Ulnar notch of radius
Head ofulna
Styloidprocess
Articulationfor scaphoid
Articulationfor lunate
Styloidprocess
View
Radius & 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
Hand
• Includes the following bones:– Carpus (carpals) wrist – Metacarpals palm – Phalanges fingers
Carpus
• Forms the true wrist the proximal region of the hand
• Gliding movements occur between carpals
• Composed of 8 marble-sized bones
Carpus
• Carpal bones– Are arranged in 2 irregular rows– Proximal row from lateral to medial:
• Scaphoid, lunate, triquetral, & pisiform
– Distal row from lateral to medial:• Trapezium, trapezoid, capitate, & hamate
– A mnemonic to help remember carpals:• Sally Left The Party To Take Carmen Home!
Bones of the Hand
TrapezoidTrapezium
ScaphoidTriquetrumLunate
CapitateHamate
5 4 3 2 1 54321
Phalanges
Metacarpals
CarpalsCarpals
(a) Anterior view of right hand (b) Posterior view of right hand
Radius Ulna
Sesamoidbones Base
Shaft
ProximalMiddleDistal
Head
Ulna
TriquetrumLunate
CapitateHamate
Pisiform
Carpals
Metacarpus
• 5 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 3 phalanges– Proximal, middle, & distal
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
• Consists of paired hip bones (coxal bones)
• Hip bones unite anteriorly with each other
• Articulates posteriorly with the sacrum
Bones of the Pelvic Girdle
• Pelvic girdle a deep, basin-like structure
• Formed by:– Coxal bones, sacrum, & coccyx
Bones of the Pelvic Girdle
Coxal bone(os coxaeor hip bone)
llium
Sacroiliacjoint
Iliac fossa
Pubis
Ischium
Sacrum
Base of sacrum
Sacralpromontory
Pelvic brimAcetabulum
Pubic crest
Pubic symphysis
Iliac crest
Coccyx
Pubic arch
Anteriorinferior iliacspine
Anteriorsuperior iliac spine
Pubic tubercle
The Pelvic Girdle
• Consists of 3 separate bones in childhood– Ilium, ischium, & 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
Bones of the pelvic girdle
Ilium
Ischium
Pubis
Ilium
Ala
Tubercle ofthe iliac crest
Anterior glutealline
Posterior gluteal line
PosteriorsuperioriIiac spine
Greater sciaticnotch
Posterior inferioriliac spine
Ischial body
Ischial spine
Lesser sciatic notch
Ischialtuberosity
Ischium
Ischial ramus
Inferiorgluteal line
Acetabulum
Pubic body
Iliac crest
Anterior superioriliac spine
Anterior inferioriliac spine
Pubis
Inferior ramusof pubis
(b) Lateral view, right hip bone
True & False Pelves
• Bony pelvis is divided into 2 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
Pelvic Structures & Childbearing
• Major differences between male & female pelves:– Female pelvis is adapted for childbearing
• Pelvis is lighter, wider, & shallower than the male’s• Provides more room in the true pelvis
The Lower Limb
• Carries the entire weight of the erect body
• Bones of lower limb are thicker & stronger than those of upper limb
• Divided into 3 segments– Thigh, leg, & foot
Thigh
• The region of the lower limb between the hip and the knee
• Femur the single bone of the thigh– Longest & strongest bone of the body– Ball-shaped head articulates with the
acetabulum
Neck Foveacapitis Greater
trochanter
Inter-trochantericcrest
Lateralcondyle
Lateralepicondyle
Head
Intertrochantericline
Lesser trochanter
Gluteal tuberosity
Linea aspera
Intercondylar fossa
Medial andlateral supra-condylar lines
Medial condyle
Medialepicondyle
Adductor tubercle
Anterior view Posterior view
Lateralepicondyle
Patellarsurface
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 & the ankle
• Composed of the tibia & 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 & 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– It stabilizes the ankle joint
Structures of the Tibia & Fibula
The Foot
• Foot is composed of– Tarsus, metatarsus, & the phalanges
• Important functions– Supports body weight– Acts as a lever to propel body forward when
walking– Segmentation makes foot pliable & adapted to
uneven ground
Medialcuneiform
Phalanges
Metatarsals
Tarsals
Navicular
Intermediatecuneiform
Talus
Calcaneus
(a) Superior view
Cuboid
Lateralcuneiform
Proximal
Middle
Distal
Trochleaof talus
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Bones of the Foot
Tarsus• Makes up the posterior half of the foot
• Contains 7 bones called tarsals
• Body weight is primarily borne by the talus & calcaneus
• Trochlea of the talus
– Site of articulation with the tibia
• Other tarsals are:
– Navicular
– Cuboid
– Medial Cuneiform
– Intermediate Cuneiform
– Lateral Cuneiform
The (Talus)Caring (Calcaneus)Nurse (Navicular)Covers (Cuboid)Me (Medial Cuneiform)In (Intermed. Cuneiform)Love (Lateral Cuneiform)
Metatarsus
• Consists of 5 small long bones called metatarsals
• Numbered 1–5 beginning with the hallux (=big toe)
• First metatarsal supports body weight
Phalanges of the Toes
• 14 phalanges of the toes– Smaller & less nimble than those of the
fingers– Structure & arrangement are similar to
phalanges of fingers– Except for the big toe, each toe has 3
phalanges• Proximal, middle, & distal
Bones of the Foot
(c) Lateral view
Intermediate cuneiform
Lateral cuneiform
Fifth metatarsal
Facet forlateral malleolus
Talus
Navicular
CuboidCalcaneus
Lower Limb & 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 & 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
The Appendicular Skeleton Throughout Life
• Few changes occur in adult skeleton until middle age, when – Skeleton loses mass– Osteoporosis & limb fractures become more
common
Questions…?
What’s Next?Wed Lab: Appendicular SkeletonMon Lecture: Append Skeleton contd. & Joints/Joint MovementsMon Lab: Finish Skeleton; Joints/Joint Movements