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

54321

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