Download Parts of a Long Bone - Perry Local Schools

Chapter 6
The Skeletal System
Copyright 2010, John Wiley & Sons, Inc.
Bone Function





Support
Protection
Assist in movements
Mineral homeostasis
Blood cell production


Hemopoiesis - red bone marrow
Triglyceride storage
Copyright 2010, John Wiley & Sons, Inc.
Types of Bones

Long bones: longer than wide


Short bones: almost cube shaped


Most wrist and ankle bones
Flat bones: thin and extensive surface


Such as thigh, leg, arm, forearm, fingers and toes
Such as cranial bones sternum, ribs and scapulas
Irregular bones:

Such as vertebrae and some facial bones
• Sesamoid Bones
• develop within a tendon
Copyright 2010, John Wiley & Sons, Inc.
Macroscopic Structure

Parts of a long bone



Diaphysis: shaft of long bone; made up mostly of
compact bone
Epiphysis: broad end of long bone; mostly
spongy bone
Metaphysis: growth area between diaphysis and
epiphysis

Epiphyseal line = remnant of epiphyseal disk/plate

Cartilage at the junction of the diaphysis and epiphyses
(growth plate)
Copyright 2010, John Wiley & Sons, Inc.
Parts of a Long Bone
•
•
•
•
•
Periosteum: fibrous covering over most of bone
Endosteum: membrane lining medullary cavity
Contains layer of osteoblasts (bone-forming
cells) &
osteoclasts (bone-destroying cells)
Medullary cavity: (yellow marrow) with fat and blood
cells
Nutrient Foramen = perforating canal allowing blood
vessels to enter and leave bone
Articular cartilage = pad of hyaline cartilage on the
epiphyses where long bones articulate or join
Copyright 2010, John Wiley & Sons, Inc.
Long Bones
Copyright 2010, John Wiley & Sons, Inc.
Microscopic Structure of Bone

Matrix


25% water, 25% collagen fibers, 50% mineral salts
Osteogenic cells in periosteum

Osteoblasts



Secrete collagen fibers
Build matrix and become trapped in lacunae
Osteoclasts are formed from monocytes

Digest bone matrix for normal bone turnover
Copyright 2010, John Wiley & Sons, Inc.
Histology of Bones
Copyright 2010, John Wiley & Sons, Inc.
Compact Bone Structure

Arranged in osteons (haversian systems)


Central canal through center of osteon



Cylinders running parallel to long axis of bone
Contains blood vessels, nerves, lymphatics
Concentric lamellae: layers of matrix
Lacunae:

Contain osteocytes (bone cells)
Copyright 2010, John Wiley & Sons, Inc.
Compact Bone Structure

Canaliculi (“little canals”)




Contain extensions of osteocytes
Permit flow of ECF between central canal and
lacunae
Compact bone is covered by periosteum
Perforating (Volkmann’s) canals


Carry blood and lymphatic vessels and nerves from
periosteum
They supply central (Haversian) canals and also bone
marrow
Copyright 2010, John Wiley & Sons, Inc.
Histology of Bones
Copyright 2010, John Wiley & Sons, Inc.
Spongy Bone Structure


Not arranged in osteons
Irregular latticework of trabeculae



These contain lacunae with osteocytes and
canaliculi
Spaces between trabeculae may contain red
bone marrow
Spongy bone is lighter than compact bone,
so reduces weight of skeleton
Copyright 2010, John Wiley & Sons, Inc.
Long Bones
Copyright 2010, John Wiley & Sons, Inc.
Bone Formation


Known as ossification
Timeline

Initial bone development in embryo and fetus




initial “skeleton” replaced by bone tissue beginning at 6
weeks of embryonic life
Growth of bone into adulthood
Remodeling: replacement of old bone
Repair if fractures occur
Copyright 2010, John Wiley & Sons, Inc.
Bone Formation
Two different methods of ossification

Intramembranous: bone forms in sheets
1.

Few bones: flat bones of the skull, lower jawbone
(mandible), and part of clavicle
Endochondrial: forms hyaline cartilage then
develops into bone
2.

All other bones form by this process
Copyright 2010, John Wiley & Sons, Inc.
Intramembranous Ossification

Four steps
1. Development of ossification center


Mesenchyme cells  osteogenic osteoblasts
Osteoblasts secrete organic matrix
2.Calcification: cells become osteocytes


In lacunae they extend cytoplasmic processes to each other
Deposit calcium & other mineral salts
3.Formation of trabeculae (spongy bone)

Blood vessels grow in and red marrow is formed
4.Periosteum covering the bone forms
from mesenchyme
Copyright 2010, John Wiley & Sons, Inc.
Flat bone
of skull
Blood capillary
Ossification center
Mesenchymal cell
Osteoblast
Mandible
Collagen fiber
1 Development of ossification center
Mesenchyme
condenses
Osteocyte in lacuna
Blood vessel
Canaliculus
Spongy bone
trabeculae
Osteoblast
Osteoblast
Newly calcified bone
matrix
2 Calcification
3 Formation of trabeculae
Periosteum
Spongy bone tissue
Compact bone tissue
Copyright 2010, John Wiley & Sons, Inc.
4 Development of the periosteum
Endochondrial Ossification

Six Steps
1. Formation of cartilage model of the “bone”

As mesenchyme cells develop into chondroblasts
2. Growth of cartilage model



Cartilage “bone” grows as chondroblasts secrete
cartilage matrix
Chondrocytes increase in size, matrix around them
calcifies
Chondrocytes die as they are cut off from nutrients,
leaving small spaces (lacunae)
Copyright 2010, John Wiley & Sons, Inc.
Endochondrial Ossification
3. Primary ossification center


Perichondrium sends nutrient artery inwards into
disintegrating cartilage
Osteogenic cells in perichondrium become osteoblasts
deposit bony matrix over remnants of calcified cartilage 
 spongy bone forms in center of the model


As perichondrium starts to form bone, the membrane is
called periosteum
Copyright 2010, John Wiley & Sons, Inc.
Endochondrial Ossification
4. Medullary (marrow) cavity



Spongy bone in center of the model grows towards
ends of model
Octeoclasts break down some of new spongy bone
forming a cavity (marrow) through most of diaphysis
Most of the wall of the diaphysis is replaced by a collar
of compact bone
Copyright 2010, John Wiley & Sons, Inc.
Endochondrial Ossification
5. Secondary ossification center



Similar to step 3 except that nutrient arteries enter ends
(epiphyses) of bones and osteoblasts deposit bony
matrix 
spongy bone forms in epiphyses from center outwards
Occurs about time of birth
6. Articular cartilage and epiphyseal cartilage


Ends of epiphyses becomes articular cartilage
Epiphyseal (growth) plate of cartilage remains between
epiphysis and diaphysis until bone growth ceases
Copyright 2010, John Wiley & Sons, Inc.
Perichondrium
Perichondrium
Proximal
epiphysis
Proximal
epiphysis
Uncalcified
Uncalcified
matrix matrix
Hyaline
Hyaline
cartilage cartilage
Periosteum
Periosteum
Calcified
Calcified
matrix matrix
Periosteum
Primary
Primary Periosteum
(covering
ossification
ossification(covering
compact
compact
bone) bone)
center
center
Medullary
Medullary
Spongy
Spongy cavity cavity
bonebone
Uncalcified
Uncalcified
matrix matrix
Diaphysis
Diaphysis
Distal
epiphysis
Distal
epiphysis
CalcifiedCalcified
matrix matrix
Nutrient
Nutrient
artery
artery
NutrientNutrient
artery and
artery
vein
and vein
1
Development
Development of
1 of
cartilage model
cartilage model
2
Growth
of
of
2 Growth
cartilage
cartilage
modelmodel
33 Development
Developmentofof
primary
primaryossification
ossification
center
center
4 Development
4 Development
of
of
the medullary
the medullary
cavity
cavity
Articular cartilage
Secondary
ossification
center
Epiphyseal
Epiphyseal
artery
artery
and
and
vein
vein
Secondary
ossification
center
Spongy bone
Uncalcified
Uncalcified
matrix
matrix
Epiphyseal plate
Nutrient
Nutrient
artery and veinartery and vein
5
Copyright
2010, John
5 Development
Development
of secondary
of secondary
ossification
ossification
center center
Wiley &
Inc. of articular cartilage
Formation
6 Sons,
and epiphyseal plate
Growth in Length



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Chondrocytes divide and grow more cartilage
on epiphyseal side of the epiphyseal plate
Chondrocytes on the diaphyseal side die and
are replaced by bone
Bone grows from diaphyseal side towards
epiphyseal side
Growth in length stops between 18-25 years

Cartilage in epiphyseal plate is completely
replaced by bone (epiphyseal line)
Copyright 2010, John Wiley & Sons, Inc.
Growth in Thickness

As bones grow in length, they must
also grow in thickness (width)


Perichondrial osteoblasts lay down
additional lamellae of compact bone
Simultaneously, osteoclasts in the
endosteum destroy interior bone to
increase width of the marrow
Copyright 2010, John Wiley & Sons, Inc.
Remodeling and Repair

Remodeling in response to use



Resorption by osteoclasts and
Deposition by osteoblasts
Repair after a fracture


Dead tissue removed
Chondroblasts  fibrocartilage 
spongy bone deposited by osteoblasts 
remodeled to compact bone
Copyright 2010, John Wiley & Sons, Inc.
Types of Fractures




Partial: incomplete break (crack)
Complete: bone broken into two or more
pieces
Closed (simple): not through skin
Open (compound): broken ends break skin
Copyright 2010, John Wiley & Sons, Inc.
• green stick
• fissured
• comminuted
• transverse
• oblique
• spiral
Types of Fractures
7-62
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Factors Affecting Growth



Adequate minerals (Ca, P, Mg)
Vitamins A, C, D
Hormones




Before puberty: hGH + insulin-like growth factors
Thyroid hormone and insulin also required
Sex hormones contribute to adolescent growth
spurt
Weight-bearing activity
Copyright 2010, John Wiley & Sons, Inc.
• Deficiency of Vitamin A – retards bone development
• Deficiency of Vitamin C – results in fragile bones, scurvy
• Deficiency of Vitamin D – rickets (children), osteomalacia (adults)
• Insufficient Growth Hormone – dwarfism
• Excessive Growth Hormone – gigantism, acromegaly
• Insufficient Thyroid Hormone – delays bone growth
•Physical Stress – stimulates bone growth
7-11
Copyright 2010, John Wiley & Sons, Inc.
Calcium Homeostasis




Blood levels of Ca2+ controlled
Negative feedback loops
Parathyroid hormone (PTH) increases
osteoclast activity + decreases loss of Ca2+ in
urine
Calcitonin decreases osteoclast activity
Copyright 2010, John Wiley & Sons, Inc.
Negative Feedback
Copyright 2010, John Wiley & Sons, Inc.
Exercise & Bone Tissue


Bone strengthened in response to use
Bone reabsorbed during disuse; examples:



During prolonged bed rest
Fracture with cast/immobilizer
Astronauts without gravity
Copyright 2010, John Wiley & Sons, Inc.
Divisions of Skeletal System

Two divisions: axial and appendicular

Axial: bones around body axis


Examples: skull bones, hyoid, ribs, sternum, vertebrae
Appendicular: bones of upper and lower limbs
plus shoulder and hip bones that connect them

Examples: collar bone (clavicle), arm (humerus),
forearm (radius and ulna), thigh bone (femur)
Copyright 2010, John Wiley & Sons, Inc.
Divisions of the
Skeletal System
Copyright 2010, John Wiley & Sons, Inc.
Skull & Hyoid Bone

Eight Cranial bones


Frontal, 2 parietal, 2 temporal, occipital, sphenoid,
and ethmoid
Fourteen Facial bones


2 nasal, 2 maxilla, 2 zygomatic, 2 lacrimal
2 palatine, 2 inferior nasal conchae, 1 mandible,
1 vomer
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Skull
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Skull
Frontal (1)
• forehead
•frontal sinuses
• supraorbital foramen
• coronal suture
7-17
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Skull
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Skull
Parietal (2)
• side walls of cranium
• roof of cranium
• sagittal suture
7-18
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Skull
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Skull
Temporal (2)
•squamosal suture
• external acoustic meatus
• mandibular fossa
• mastoid process
• styloid process
• zygomatic process
7-19
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Skull
Occipital (1)
• back of skull
• foramen magnum
• occipital condyles
• lambdoidal suture
7-20
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Skull
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Skull
Sphenoid (1)
• sella turcica
• sphenoidal sinuses
7-21
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Sphenoid Bone
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Skull
Ethmoid (1)
•cribiform plates
• perpendicular plate
• superior and middle nasal conchae
• ethmoidal sinuses
• crista gallis
7-22
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Ethmoid Bone
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Ethmoid Bone
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Facial Skeleton
Maxillary (2)
• upper jaw
•alveolar processes
• maxillary sinuses
• palatine process
7-23
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Facial Skeleton
Palatine (2)
• posterior roof of mouth
7-24
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Facial Skeleton
Zygomatic (2)
• prominences of cheeks
• temporal process
7-25
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Facial Skeleton
Lacrimal (2)
• medial walls of orbits
Nasal (2)
• bridge of nose
7-26
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Facial Skeleton
Vomer (1)
• inferior portion of nasal
septum
7-27
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Facial Skeleton
Inferior Nasal Conchae
(2)
• extend from lateral walls
of nasal cavity
7-28
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Facial Skeleton
Mandible (1)
• lower jaw
• body
• ramus
• mandibular
condyle
• coronoid process
• alveolar process
• mandibular
foramen
• mental foramen
7-29
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
hyoid
Copyright 2010, John Wiley & Sons, Inc.
Unique Features of Skull

Sutures: immovable joint between skull
bones


Paranasal sinuses: cavities


Coronal, sagittal, lambdoidal, squamous
Located in bones near nasal cavity
Fontanels: soft spot in fetal skull


Allow deformation at birth
Calcify to form sutures
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Paranasal Sinuses
Copyright 2010, John Wiley & Sons, Inc.
Vertebrae

Functions




Encloses spinal cord
Supports head
Point of attachment for muscles of back, ribs
and pelvic girdle
Regions (from superior to inferior)




7 cervical
12 thoracic
5 lumbar
1 sacrum and 1 coccyx
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Normal Curves in Column

Four normal curves



Cervical and lumbar curves are convex (bulge
anteriorly)
Thoracic and sacral curves are concave (bulge
posteriorly)
Curves increase strength, help in balance
and absorb shocks
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Vertebral
Column
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Vertebral Column
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Structure of Vertebra


Body: disc-shaped anterior portion
Vertebral arch: posteriorly back from body


With the body, creates a hole called vertebral foramen
Seven processes from this arch



Transverse process extending laterally on each side
Spinous process extending dorsally
Two each of superior and inferior articular processes
that form joints with vertebrae
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Structure of Vertebra
Copyright 2010, John Wiley & Sons, Inc.
Vertebral Column
•rib facets
•intervertebral discs
• intervertebral foramina
7-32
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Cervical Area

Cervical (C1-C7 from superior to inferior)


C1: atlas



Spinous process often bifid with transverse foramina
on transverse processes
Articulates with head, specialized to support head
Lacks body and spinous process
C2: axis


Has body and spinous process
Called dens (“tooth”) that creates a pivot for head
rotation
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Cervical
Vertebrae
Copyright 2010, John Wiley & Sons, Inc.
Other Vertebrae

Thoracic (T1-T12 )



Lumbar (L1-L5)


Largest and strongest; spinous processes short and
thick
Sacrum (S1-S5 fused into one unit)



Larger than cervical
Have facets for articulations with ribs
Foundation for pelvic girdle
Contain sacral foramina for nerves and blood vessels
Coccyx: 4 coccygeal vertebrae fused into 1
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Lumbar Vertebrae
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Sacrum and Coccyx
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Thorax


Thoracic cage: sternum, costal cartilages,
ribs and bodies of T1-T12
Sternum: 3 portions fused by about age 25



Manubrium, body, xiphoid process
True ribs #1-7: articulate with sternum by
costal cartilages
False ribs #8-12: articulate with coastal
cartilage of true ribs

2 - Floating Ribs (no attachment)
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Rib Structure
• Shaft
• Head – articulates
with vertebrae
• Tubercle
• Costal cartilage
7-40
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Thorax
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Pectoral Girdle


Function: attach bones of upper limbs to axial
skeleton
Clavicles and scapulas: bilateral
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Right Pectoral (Shoulder) Girdle
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Clavicles
• articulate with
manubrium
• articulate with scapulae
(acromion process)
7-43
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Scapula
• spine
• supraspinous fossa
• infraspinous fossa
• acromion process
• coracoid process
• glenoid cavity
7-44
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Upper Limb

Humerus: arm bone




Articulates with scapula (glenoid cavity)
Articulates with radius and ulna at elbow
Ulna: medial bone
Radius: lateral bone (thumb side)
Copyright 2010, John Wiley & Sons, Inc.
Right
Humerus
Copyright 2010, John Wiley & Sons, Inc.
Humerus
• head
• greater tubercle
• lesser tubercle
• anatomical neck
• surgical neck
• deltoid tuberosity
• capitulum
• trochlea
• coronoid fossa
• olecranon fossa
•Lateral epicondyle
•Medial epicondyle
7-46
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Right Ulna
and Radius
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Radius
• lateral forearm bone
• head
• radial tuberosity
• styloid process
7-47
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Ulna
• medial forearm bone
• trochlear notch
• olecranon process
• coronoid process
• styloid process
7-48
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Right Ulna and Radius
Copyright 2010, John Wiley & Sons, Inc.
Wrist and Hand


Carpals (wrist): 8 bones
Metacarpals: 5 bones of palm of hand


Number 1-5 starting with thumb
Phalanges: 14 bones of fingers

Each finger except thumb has proximal, middle
and distal phalanges; thumb lacks middle phalanx
Copyright 2010, John Wiley & Sons, Inc.
Right Wrist
and Hand
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Wrist and Hand
Carpals
• trapezium
• trapezoid
• capitate
• scaphoid
• pisiform
• triquetrum
• hamate
• lunate
7-49
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Pelvic (Hip) Girdle

Pelvic girdle includes two hip (coxal) bones




Joined anteriorly at pubic symphysis
+ sacrum and coccyx
False (greater) pelvis: broad region superior
to pelvic brim; contains abdominal organs
True (lesser) pelvis: small region inferior to
pelvic brim; contains urinary bladder +
internal reproductive organs
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Pelvic Girdle (Female)
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Pelvic Girdle (Female)
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Parts of Each Hip (Coxal) Bone

3 separate bones fuse by age 23 to form a
hip bone




Ilium: largest and most superior
Ischium: lower posterior part
Pubis: lower anterior part
acetabulum - socket for head of femur
Copyright 2010, John Wiley & Sons, Inc.
Right
Hip
Bone
Copyright 2010, John Wiley & Sons, Inc.
Lower Limb

Femur : largest bone in the body



Patella: kneecap in anterior of knee joint
Tibia: shin bone


Articulates with hip proximally and with the tibia and
patella distally
Large medial, weight-bearing bone of leg
Fibula: longest, thinnest bone in body


Lateral to tibia and smaller
Does not articulate with femur
Copyright 2010, John Wiley & Sons, Inc.
Right Femur
Copyright 2010, John Wiley & Sons, Inc.
Femur
• head
• fovea capitis
• neck
• greater trochanter
• lesser trochanter
• linea aspera
• condyles (medial/lateral)
• epicondyles (medial/lateral)
7-55
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Patella
• flat sesamoid bone
located in a tendon
7-56
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Right Tibia
and Fibula
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Tibia
• medial to fibula
• condyles
• tibial tuberosity
• anterior crest
• medial malleolus
7-57
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Fibula
• lateral to tibia
• head
• lateral
malleolus
• does not bear
any body weight
Insert figure 7.54
7-58
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Ankle and Foot

Tarsals (ankle) - 7 bones







Large talus (ankle bone) and
Calcaneus (heel bone)
navicular
cuboid
lateral cuneiform
intermediate cuneiform
medial cuneiform
Copyright 2010, John Wiley & Sons, Inc.
Ankle and Foot
Metatarsals (foot bones)
• Numbered 1 to 5 from medial to lateral
Phalanges (toe bones)
• Big toe has proximal and distal phalanges while others
have proximal, middle and distal phalanges.
7-59
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Right
Foot
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Arches of the Right Foot
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Male and Female Differences



Males usually have heavier bones
Related to muscle size and strength
Female pelvis is wider and shallower than
male pelvis: allows for birth
Copyright 2010, John Wiley & Sons, Inc.
Aging and Skeletal System




Birth through adolescence: more bone
formed than lost
Young adults: gain and loss about equal
As levels of sex steroids decline with age:
bone reabsorption > bone formation
Bones become brittle and lose calcium
Copyright 2010, John Wiley & Sons, Inc.
Life-Span Changes
• decrease in height at about age 30
• osteoclasts outnumber osteoblasts
• spongy bone weakens before compact bone
• hip fractures common
• bone loss rapid in menopausal women
•After age 70 bone loss between sexes is similar
•vertebral compression fractures common
7-61
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Homeostatic Disorders
Sickle Cell Disease
Osteoporosis
Cleft Palate
Polydactyly
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Osteoporosis
Copyright 2010, John Wiley & Sons, Inc.