Transcript Ch7-8.Axial._.Appendicular.Skeleton

The Axial Skeleton (contd.) &
The Appendicular Skeleton
Human Anatomy
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 Column
C1
2
3
4
5
6
7
T1
2
3
4
Cervical curvature
(concave)
7 vertebrae, C1 – C7
Spinous
process
Transverse
processes
Thoracic
curvature
(convex)
12 vertebrae,
T1 – T12
5
6
7
8
9
10
11
12
L1
2
3
4
5
Anterior view
Intervertebral
discs
Intervertebral
foramen
Lumbar
curvature
(concave)
5 vertebrae, L1 – L5
Sacral
curvature
(convex) 5 fused
vertebrae sacrum
Coccyx
4 fused vertebrae
Right lateral view
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
Ligaments of the Spine
Supraspinous ligament
Transverse process
Sectioned
spinous process
Intervertebral
disc
Anterior
longitudinal
ligament
Ligamentum flavum
Intervertebral foramen
Posterior longitudinal
ligament
Interspinous
ligament
Anulus fibrosus
Nucleus pulposus
Inferior articular process
(a)
Sectioned body
of vertebra
Median section of three vertebrae, illustrating the composition
of the discs and the ligaments
Posterior longitudinal
ligament
Anterior longitudinal
ligament
Body of a vertebra
Intervertebral disc
(b) Anterior view of part of the spinal column
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 cord
Spinal nerve root
Nucleus pulposus
of intact disc
Transverse
process
Herniated portion
of disc
Anulus fibrosus
of disc
Nucleus
pulposus
of disc
Herniated nucleus
pulposus
(c) Superior view of a herniated intervertebral disc
(d) MRI of lumbar region of vertebral column in
sagittal section showing normal &
herniated discs
General Structure of Vertebrae
Posterior
Lamina
Spinous
process
Transverse
process
Vertebral
arch
Superior
articular
process
and
facet
Pedicle
Vertebral
foramen
Body
(centrum)
Anterior
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
Cervical Vertebrae
Dens of axis
Transverse ligament
of atlas
C1 (atlas)
C2 (axis)
C3
Inferior articular
process
Bifid spinous
process
Transverse processes
C7 (vertebra
prominens)
(a) 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
C1
Posterior
Posterior tubercle
Posterior arch
Lateral
masses
Anterior arch
Transverse
foramen
Superior articular
facet
Anterior tubercle
(a) Superior view of atlas (C1)
The Atlas
C1
Posterior
arch
Transverse
process
Posterior
Posterior tubercle
Lateral
masses
Transverse foramen
Facet for dens
(b) Inferior view of atlas (C1)
Inferior
articular
facet
Anterior
arch
Anterior tubercle
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 Axis
C2
Posterior
Inferior
articular
process
Transverse
process
Dens
(c) Superior view of axis (C2)
Spinous process
Lamina
Pedicle
Superior
articular
facet
Body
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
Lumbar Vertebrae
Superior
articular
process
Transverse
process
Body
Intervertebral
disc
Inferior
articular
process
Spinous
process
(c) 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
Sacral promontory
Ala
Sacral
canal
Body of
first
sacral
vertebra
Facet of superior
articular process
Auricular
surface
Transverse
ridges (sites
of vertebral
fusion)
Apex
Median
sacral
crest
Anterior
Posterior
sacral
sacral
foramina
foramina
Coccyx
(a) Anterior view
Coccyx
(b) Posterior view
Lateral
sacral
crest
Sacral
hiatus
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
The Thoracic Cage
Jugular notch
Clavicular notch
Manubrium
Sternal angle
Body
Xiphisternal
joint
Xiphoid
process
True
ribs
(1–7
False
ribs
(8–12)
Intercostal
spaces
L1
Vertebra
Floating ribs (11, 12)
(a) Skeleton of the thoracic cage, anterior view
Costal cartilage
Costal margin
Sternum
The Thoracic Cage
T2
Jugular notch
T3
T4
Sternal angle
Heart
T9
Xiphisternal
joint
(b) Midsagittal section through the thorax, showing
the relationship of surface anatomical landmarks
of the thorax to the vertebral column
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
Shaft
Facets for articulation
with vertebrae
Junction with
costal cartilage
Head
Costal groove
Neck
Articular facet
on tubercle
Costal angle
(a) A typical rib (rib 6, right), posterior view
Angle
of rib
Transverse costal facet
(for tubercle of rib)
Superior costal facet
(for head of rib)
Body of vertebra
Head of rib
Intervertebral disc
Neck of rib
Tubercle of rib
Shaft
Crosssection
of rib
Costal groove
Sternum
Costal cartilage
(b) Vertebral and sternal articulations of a typical true rib
Ribs
Articular facet
on tubercle of rib
Spinous process
Shaft
Ligaments
Neck of rib
Head of rib
Superior costal facet
(for head of rib)
Transverse
costal facet
(for tubercle
of rib)
Body of
thoracic
vertebra
(c) Superior view of the articulation between a rib and a
thoracic vertebra
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
Frontal suture
Frontal bone
Ossification
center
Posterior fontanelle
(a) Superior view
Anterior
fontanelle
Parietal bone
Occipital
bone
Fontanelles
Parietal bone
Frontal bone
Ossification
center
Sphenoidal
fontanelle
Temporal bone
(squamous
portion)
Posterior
fontanelle
Mastoid
fontanelle
Occipital bone
(b) Lateral view
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
Articulated Pectoral Girdle
Acromioclavicular
joint
Clavicle
Scapula
(a) Articulated pectoral girdle
Clavicles
• Extend horizontally across the superior
thorax
• Sternal end articulates with the manubrium
• Acromial end articulates with scapula
Clavicles
Sternal (medial)
end
Posterior
Anterior
Acromial (lateral)
end
(b) Right clavicle, superior view
Acromial end
Anterior
Trapezoid line
Posterior
Sternal end
Tuberosity for
costoclavicular
ligament
(c) Right clavicle, inferior view
Conoid tubercle
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 Scapula
Acromion
Suprascapular notch
Coracoid
process
Superior border
Superior
angle
Glenoid
cavity
Lateral border
Subscapular
fossa
Medial border
(a) Right scapula, anterior aspect
Inferior angle
Structures of the Scapula
Suprascapular notch
Coracoid process
Acromion
Superior
angle
Supraspinous
fossa
Spine
Glenoid
cavity
at lateral
angle
Infraspinous
fossa
Medial border
(b) Right scapula, posterior aspect
Lateral border
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
Head of humerus
Head of humerus
Anatomical neck
Anatomical neck
Greater tubercle
Surgical neck
Intertubercular
sulcus
Radial groove
Deltoid tuberosity
Deltoid tuberosity
Medial supracondylar
ridge
Lateral supracondylar
ridge
Radial fossa
Capitulum
Coronoid fossa
Olecranon fossa
Medial epicondyle
Medial epicondyle
Trochlea
Trochlea
(a) Anterior view
Lateral epicondyle
(b) Posterior view
Structures of the Humerus of the
Right Arm
Humerus
Coronoid
fossa
Capitulum
Medial
epicondyle
Head of
radius
Radial
tuberosity
Radius
(c) Anterior view at the elbow region
Trochlea
Coronoid
process of
ulna
Radial notch
Ulna
Humerus
Olecranon
fossa
Olecranon
process
Medial
epicondyle
Lateral
epicondyle
Head
Neck
Ulna
(d) Posterior view of extended elbow
Radius
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
The Radius & Ulna
Radial notch
of the ulna
Head
Neck
Radial
tuberosity
Olecranon process
Head of radius
Trochlear notch
Neck of radius
Coronoid process
Proximal radioulnar
joint
Interosseous
membrane
Ulna
Radius
Styloid process
of radius
(a) Anterior view
Olecranon
process
Ulnar notch of
the radius
Head of ulna
Distal radioulnar joint
Styloid process of ulna
Interosseous
membrane
Ulna
Ulnar notch
of the radius
Radius
Head of ulna
Styloid process
of ulna
(b) Posterior view
Styloid process
of radius
Radius & Ulna
Olecranon process
Trochlear notch
View
Coronoid process
Radial notch
(c) Proximal portion of ulna, lateral view
Ulnar notch of radius
Articulation
for lunate
Articulation
for scaphoid
Styloid
process
View
Head of
ulna
Styloid
process
(d) Distal ends of the radius & ulna at the wrist
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
Phalanges
Distal
Middle
Proximal
Carpals
Hamate
Capitate
Pisiform
Triquetrum
Lunate
Ulna
5
4 3 2
Metacarpals
Head
Shaft
Base
Sesamoid
bones
1
Carpals
Trapezium
Trapezoid
Scaphoid
Radius
(a) Anterior view of right hand
1
2
3
4 5
Carpals
Hamate
Capitate
Triquetrum
Lunate
Ulna
(b) Posterior view of right hand
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
Bones of the Pelvic Girdle
• Consists of paired hip bones (coxal bones)
• Hip bones unite anteriorly with each other
• Articulates posteriorly with the sacrum
• Pelvic girdle  a deep, basin-like structure
• Formed by:
– Coxal bones, sacrum, & coccyx
Bones of the Pelvic Girdle
Base of sacrum
Iliac crest
Iliac fossa
llium
Coxal
bone
(os coxae
or hip
bone)
Pubis
Sacroiliac
joint
Anterior
superior
iliac spine
Sacral
promontory
Anterior
inferior iliac
spine
Sacrum
Coccyx
Ischium
Pelvic brim
Acetabulum
Pubic
tubercle
Pubic crest
Pubic arch
Pubic
symphysis
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
Tubercle of
the iliac crest
Anterior gluteal
line
Ilium
Ala
Iliac crest
Posterior
gluteal line
Posterior
superior
iIiac spine
Anterior
superior
iliac spine
Inferior
gluteal line
Anterior inferior
iliac spine
Posterior inferior
iliac spine
Greater sciatic
notch
Acetabulum
Ischial body
Ischial spine
Lesser sciatic
notch
Pubic body
Pubis
Ischium
Ilium
Ischial
tuberosity
Ischium
Ischial ramus
Pubis
(b) Lateral view, right hip bone
Inferior ramus
of pubis
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
Structures of the Femur
Fovea
capitis
Neck
Greater
trochanter
Head
Lesser trochanter
Intertrochanteric
line
Intertrochanteric
crest
Gluteal tuberosity
Linea aspera
Medial and
lateral supracondylar lines
Intercondylar fossa
Lateral
condyle
Lateral
epicondyle
Medial condyle
Lateral
epicondyle
Adductor tubercle
Medial
epicondyle
Patellar
surface
Anterior view
Posterior view
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
Bones of the Foot
Phalanges
Distal
Middle
Proximal
1
Medial
cuneiform
2
3 4
Metatarsals
5
Intermediate
cuneiform
Lateral
cuneiform
Navicular
Cuboid
Tarsals
Talus
Trochlea
of talus
Calcaneus
(a) Superior view
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
The (Talus)
Caring (Calcaneus)
– Cuboid
Nurse (Navicular)
Covers (Cuboid)
– Medial Cuneiform
Me (Medial Cuneiform)
– Intermediate Cuneiform
In (Intermed. Cuneiform)
Love (Lateral Cuneiform)
– 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
Facet for
lateral malleolus
Navicular
Intermediate cuneiform
Lateral cuneiform
Talus
Calcaneus
(c) Lateral view
Cuboid
Fifth metatarsal
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 Skeleton
Mon Lecture: Append Skeleton
contd. & Joints/Joint Movements
Mon Lab: Finish Skeleton;
Joints/Joint Movements