UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
LEARNING OUTCOMES:
7.1
7.2
7.3
Bone Shape and Structure
1.
Classify bones according to their shapes, and name an example from each group.
(p. 200)
2.
Describe the macroscopic and microscopic structure of a long bone, and list the
functions of these parts. (pp. 200-202)
Bone Development and Growth
3.
Distinguish between intramembranous and endochondral bones, and explain how
such bones develop and grow. (p. 202-207)
4.
Describe the effects of sunlight, nutrition, hormonal secretions, and exercise on
bone development and growth. (pp. 207-210)
Bone Function
5.
7.4
Discuss the major functions of bones. (p. 210-211)
Skeletal Organization
6.
Distinguish between the axial and appendicular skeletons, and name the major
parts of each. (p. 212-215)
7.5 Skull – 7.11 Lower Limb
7.12
7.
Locate and identify the bones and the major features of the bones that comprise
the skull, vertebral column, thoracic cage, pectoral girdle, upper limb, pelvic
girdle, and lower limb. (pp. 215-245)
8.
Describe the differences between male and female skeletons. (p. 241)
Life-Span Changes
9.
Describe life-span changes in the skeletal system. (p. 245-246)
7-1
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
INTRODUCTION:
The skeletal system organs include the bones of the skeleton and the structures that connect
bones to other structures including ligaments, tendons and cartilages. The general functions of
the skeletal system include support and protection softer tissues. providing points of attachment
for muscles, housing blood-producing cells, and storing inorganic salts.
7.1
BONE SHAPE AND STRUCTURE
A.
Bone Shapes: See Figure 7.1, page 200.
1.
Long bones consist of a shaft with two ends.
Examples include:
a.
thigh bone = femur
b.
upper arm bone = humerus
2.
Short bones are cube-like.
Examples include:
a.
wrist bones = carpals
b.
ankle bones = tarsals
3.
Flat bones are thin and usually curved.
Examples include:
a.
most skull bones
b.
breast bone = sternum
c.
shoulder blades = scapulae
d.
ribs
4.
Irregular bones are not long short or flat.
Examples include:
a.
vertebrae
b.
auditory ossicles
5.
Sesamoid bones develop within a tendon.
The patella is a human sesamoid bone.
7-2
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.1
BONE SHAPE AND STRUCTURE
B.
Parts of a Long Bone
See Figure 7.2 page 201 and Figure 7.3a and b, page 202.
1.
Diaphysis = shaft.
a.
b.
2.
Epiphyses (pl) = expanded ends.
a.
b.
c.
3.
consist mainly of spongy bone
surrounded by a thin layer of compact bone.
proximal epiphysis vs. distal epiphysis
Epiphyseal line = remnant of epiphyseal disc/plate.
a.
4.
consists of a central medullary cavity (filled with yellow marrow)
surrounded by a thick collar of compact bone.
cartilage at the junction of the diaphysis and epiphyses (growth
plate).
Periosteum = outer fibrous protective covering of diaphysis.
a.
richly supplied with blood & lymph vessels nerves (nutrition):

5.
b.
Osteogenic layer contains osteoblasts (bone-forming cells) and
osteoclasts (bone-destroying cells)
c.
serves as insertion for tendons and ligaments.
Endosteum = inner lining of medullary cavity.
a.
6.
Nutrient Foramen = perforating canal allowing blood
vessels to enter and leave bone.
contains layer of osteoblasts & osteoclasts.
Articular cartilage = pad of hyaline cartilage on the epiphyses where
long bones articulate or join.
a.
"shock absorber".
7-3
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.1
BONE SHAPE AND STRUCTURE
LONG BONE STRUCTURE SUMMARY (Keyed at the end of this outline)
Long Bone Part
Description
Function
7-4
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.1
BONE SHAPE AND STRUCTURE
C.
Microscopic Structure
1.
Compact Bone is solid dense and smooth. The structural unit of compact
bone is the Osteon or Haversian system.
See Fig 7.4 and Fig 7.5 page 203.
2.
a.
Compact bone is composed of elongated cylinders cemented
together to form the long axis of the bone.
b.
Components of Osteon (Haversian system):

osteocytes (spider-shaped bone cells that lie in "lacunae")
that have laid down a

matrix of collagen and calcium salts in

concentric lamellae (layers) around a

central canal (Haversian canal) containing

blood vessels and nerves
c.
Communicating canals within compact bone:

Canaliculi connect the lacunae of osteocytes

Perforating (Volkmann's) canals connect the blood &
nerve supply of adjacent osteons together.
1.
run at right angles to and connect adjacent central
canals (Haversian canals).
Spongy (Cancellous) Bone
See Fig 7.3b and c page 202.
a.
b.
c.
d.
e.
consists of poorly organized trabeculae (small needle-like pieces
of bone)
with a lot of open space between them
nourished by diffusion from nearby Haversian canals
filled with red bone marrow, so hematopoiesis occurs in spongy
bone
located within flat bones and in epiphyses of long bones
7-5
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.2
BONE DEVELOPMENT AND GROWTH (Osteogenesis/ossification)
A.
Introduction
1.
The "skeleton" of an embryo is composed of fibrous CT membranes
(formed from mesenchyme and hyaline cartilage) that are loosely shaped
like bones.
2.
This "skeleton" provides supporting structures for ossification to begin.
3.
At about 6-7 weeks gestation ossification begins and continues throughout
adulthood.
4.
Ossification follows one of two patterns:
a.
b.
B
Intramembranous Ossification is when a bone forms on or within a fibrous CT
membrane.
1.
2.
C.
intramembranous ossification or endochondral ossification
Both mechanisms involve the replacement of preexisting
connective tissue with bone.
Flat bones are formed in this manner (i.e. skull bones, clavicles)
See Fig 7.8, page 205 and left side of Table 7.1, page 205.
Endochondral Ossification occurs when a bone is formed from a hyaline
cartilage model.
1.
2.
3.
4.
Most bones of the skeleton are formed in this manner.
Primary Ossification center hardens as fetus and infant.
Secondary Ossification centers develop in child and harden during
adolescence and early adulthood.
See Fig 7.9, page 206, and right side of Table 7.1, page 205.
*
See Fig 7.6, page 204 which show both patterns of ossication in a fetus.
*
During infancy and childhood long bones lengthen entirely by growth at the
epiphyseal plates (called longitudinal growth) and all bones grow in thickness by
a process called appositional growth.
7-6
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.2
BONE DEVELOPMENT AND GROWTH
D.
Growth at the Epiphyseal Plate
1.
2.
See Fig 7.10 page 206.
Structure of the Epiphyseal Plate or Disc (4 zones):
a.
Zone of resting cartilage

near epiphysis

small scattered chondrocytes

anchor plate to epiphysis.
b.
Zone of proliferating cartilage

larger chondrocytes that resemble a stack of coins

Chondrocytes divide to replace those that die at the
diaphyseal surface of the epiphysis.
c.
Zone of Hypertrophic cartilage

extremely large chondrocytes that are arranged in columns

maturing cells.
d.
Zone of calcified cartilage

only a few cells thick

consists of dead cells within calcified matrix

This calcified matrix is destroyed by osteoclasts.
Osteoclasts are large multinucleated cells that originate
from white blood cells called monocytes, and are
responsible for bone resorption. See Fig 7.11, page 207.
a.
secrete lysosomal enzymes that digest the organic
matrix
b.
secrete acids that decompose calcium salts into Ca2+
and PO4- ions which can then enter blood.

This matrix is then invaded by bone-building cells,
osteoblasts, which lay down bone on the calcified cartilage
that persists.

As a result the diaphyseal border of the plate is firmly
cemented to the bone of the diaphysis.
The epiphyseal plate allows for bone lengthening. As a child grows
a.
Cartilage cells are produced by mitosis on epiphyseal side of plate.
b.
They are then destroyed and replaced by bone on diaphyseal side
of plate. Therefore thickness of the plate remains almost constant
while the bone on the diaphyseal side increases in length.
c.
The cartilage of epiphyseal plate is replaced by bone forming the
epiphyseal line.
d.
Ossification of most bones is completed by age 25.
*
See box and Figure 7.12 on page 207 re: growth plate damage in
childhood and Ossification Timetable 7.2, page 207.
7-7
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.2
BONE DEVELOPMENT AND GROWTH
D.
E.
F.
Bone Thickening / Appositional Growth
Along with increasing in length bones increase in thickness or diameter.
1.
occurs in osteogenic layer of periosteum
2.
Osteoblasts lay down matrix (compact bone) on outer surface.
3.
This is accompanied by osteoclasts destroying the bone matrix at the
endosteal surface.
Homeostasis of Bone Tissue
1.
Once bones are formed, the actions of osteoclasts and osteoblasts
continually remodel them.
2.
Bone remodeling occurs throughout life.
a.
Osteoclasts resorb bone
b.
Osteoblasts replace the bone
c.
These opposing processes are highly regulated so that total mass of
bone tissue in adult skeleton normally remains constant, even
though 3%-5% of bone calcium is exchanged each year.
Factors Affecting Bone Development Growth and Repair
A number of factors influence bone development, growth, and repair. These
include nutrition, exposure to sunlight, hormonal secretions, and physical
exercise.
1.
Nutrition
a.
Vitamin D greatly increases intestinal absorption of dietary
calcium & retards its urine loss.
o
Deficiency causes rickets in children and osteomalacia in
adults.
o
Vitamin D is found in dairy products
o
Vitamin D is synthesized in the skin with exposure to
sunlight.
b.
Vitamin A is required for bone resorption controls the activity
distribution and coordination of osteoblasts & osteoclasts during
development.
c.
Vitamin C helps maintain bone matrix (collagen synthesis)
o
Deficiency causes scurvy.
2.
Exposure to sunlight – See F.1.a (above)
3.
Hormonal Secretions:
a.
human Growth Hormone (hGH) from the pituitary gland is
responsible for the general growth of all tissues. In bone it
stimuates reproduction of cartilage cells at epiphyseal plate.
o
Hyposecretion in childhood results in pituitary dwarfism.
o
Hypersecretion in childhood results in pituitary gigantism.
o
Hypersecretion in adulthood results in acromegaly.
These disorders are discussed in greater detail in Chapter 13.
7-8
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.2
BONE DEVELOPMENT AND GROWTH
F.
Factors Affecting Bone Development Growth and Repair
3.
4.
7.3
Hormonal Secretions:
b.
Thyroid hormones
 T4 = Thyroxine stimulates replacement of cartilage by bone in
epiphyseal plate.
 Calcitonin acts on several sites to decrease blood calcium levels
(see 7.3, C. 3. on next page)
c.
Parathyroid Hormone (PTH)
 from parathyroid glands stimulates osteoclasts to resorb bone.
d.
Sex hormones from the male and female gonads (testosterones
and estrogens, respectively)

are abundant at puberty and cause considerable long bone
growth (aid osteoblast activity and promote new bone
growth)

also degenerate cartilage cells in epiphyseal plate (i.e. close
epiphyseal plate).

Estrogen effect is greater than androgen effect
Physical Exercise
a.
Physical stress stimulates bone growth = hypertrophy.
b.
Lack of exercise = atrophy or bone tissue waste.
c.
See Fig 7.13, page 210, re: muscle attachments on bones with exercise.
*
See Clinical Application 7.1, Fractures on pages 208-209 and Clinical
Application 7.2, Preventing Fragility Fractures, page 212.
BONE FUNCTION
A.
Support, Protection, and Movement
1.
Support:
a.
The bones in legs and pelvis support the trunk
b.
The atlas (1st vertebra) supports the skull etc.
2.
Protection of underlying organs
a.
The skull protects the brain
b.
The rib cage protects the heart and lungs etc.
3.
Body Movement – discussed in Chapters 8 and 9
a.
Skeletal muscles are attached to bones by tendons.
b.
serve as levers to move bones
B.
Blood Cell Formation - Hematopoiesis
a.
All blood cells are formed in the red marrow of spongy bone in flat
bones and epiphyses of long bones.
7-9
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.3
BONE FUNCTION
C.
Inorganic Salt Storage
1.
2.
3.
Hydroxyapatite, which is primarily calcium phosphate [Ca3(PO4)2.(OH)2]
gives bone its hardness or rigidity.
Calcium is required for many metabolic processes, including
a.
muscle contraction
b.
nerve impulse conduction
Blood calcium homeostasis must be maintained
a.
Bone remodeling directly affects blood calcium homeostasis
because the primary matrix of bone is calcium.
Recall that once a bone is formed it is continuously being remodeled
throughout life. This process involves the action of osteoblasts and
osteoclasts (see above) two hormones (calcitonin & parathyroid
hormone) and in turn affects blood calcium homeostasis. See Figure
7.14, page 211.
a.
Parathyroid hormone (PTH) which is secreted by the parathyroid
glands when blood calcium levels are low:

stimulates osteoclast activity (resorption of bone occurs)
which releases Ca2+ into the blood

causes kidney tubules to reabsorb Ca2+ back into the blood

causes intestinal mucosa to increase dietary absorption of
Ca2+ and therefore

causes an increase in blood calcium levels (back to
normal).
b.
Calcitonin which is secreted by the thyroid gland when blood
calcium levels are high:

inhibits bone resorption increases osteoblast activity (i.e.
causes a deposition of bone matrix)

causes the kidney tubules to secrete excess Ca2+ into the
urine and therefore

results in a decrease in blood calcium levels (back to
normal).
7-10
7.3
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
BONE FUNCTION
C.
Inorganic Salt Storage
3.
Blood Calcium Homeostasis: See Fig 7.14 page 211.
Add arrows to complete negative feedback loop below.
Thyroid Gland
Hormone: Calcitonin
1. Osteoclasts are inhibited.
2. Osteoblasts use excess
Ca++ to lay down bone
matrix.
3. Kidney tubules secrete
excess Ca++ into
urine.
Stimulus: ↑ blood Ca++
↓ blood Ca++
Normal Blood Ca++
Set Point = 8.4-10.3dL
↑ blood Ca++
Stimulus: ↓ blood Ca++
1. Osteoclasts resorb bone matrix.
2. Kidney tubules reabsorb Ca++
back into bloodstream.
3. Intestinal mucosa absorbs Ca++.
Parathyroid Glands
Parathyroid Hormone
7-11
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.4.
SKELETAL ORGANIZATION
A.
Number of Bones
The skeletal system consists of 206 bones and joints that allow for the many
functions discussed in the introduction and previous section.
B.
Divisions of the Skeletal System
The skeleton is divided into two major divisions: axial and appendicular
portions. See Table 7.3 page 213 and Figure 7.16, page 214.
1.
2.
*
7.5
The axial skeleton includes the bones of the skull, hyoid bone, vertebral
column, and thoracic cage.
The appendicular skeleton includes the limbs of the upper and lower
extremities and the bones that attach those limbs to the trunk (pectoral
and pelvic girdles).
In the next sections we will not only name and locate the bones of the
skeleton but we will study the structure of each. See Table 7.4, page 215:
Terms Used to Describe Skeletal Structures.
SKULL = cranium (brain case) and facial bones
All the bones of the skull (except the mandible) are firmly interlocked along structures
called sutures.
*
A suture is the area where skull bones fuse together or articulate (join).
*
Sutural (wormian) bones are tiny bones within the skull that lie between major
skull bones. See Fig 7.15 page 213.
1.
Cranium = brain case or helmet. See Cranial Bones Table 7.5 page 218.
The cranium is composed of eight bones including the frontal, occipital, sphenoid,
and ethmoid bones, along with a pair of parietal and temporal bones.
a.
Frontal bone = forehead. See Fig 7.18, page 216.
○
articulates with parietal bones along coronal suture
See Fig 7.19 page 216.
○
forms superior portion of orbit
See Fig 7.20 page 217.
○
contains 2 frontal (paranasal) sinuses
See Fig 7.21 page 217.
7-12
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.5
SKULL
1.
Cranium (continued)
b.
Parietal bones = bulging sides of skull behind frontal bone
o
See Fig 7.19 page 216.
o
Articulations:
1.
anteriorly with frontal bones at coronal suture
2.
posteriorly with occipital bone at lambdoid suture
3.
laterally with temporal bones at squamous suture
4.
between bones at sagittal suture
c.
Occipital bone = base of skull. See Fig 7.22 page 219 and
Fig. 7.19 page 216.

articulates with paired parietal bones along the lambdoid suture

Foramen magnum ("large hole") = opening in occipital bone
where nerve fibers pass from brain into spinal cord.

Occipital condyles = rounded processes on either side of foramen
magnum which articulate with the first vertebra (atlas).
d.
Temporal bones lie inferior to parietal bones at squamous suture.
See Fig. 7.19 page 216.

Zygomatic process = bar-like extension that meets the zygomatic
bone

External acoustic meatus = opening in tympanic region which
opens to the inner portions of the ear.

Styloid process = needle-like extension (attachment for some neck
muscles)

Mastoid process = a rounded process that extends down from
mastoid region of temporal bone (attachment for neck muscles).

See box on page 218 re: mastoiditis.

Mandibular fossa = depression where mandibular condyle
articulates.
e.
Sphenoid bone = butterfly shaped bone that spans the length of the
cranial floor. See Fig 7.26, page 221.

lateral portions are wedged between many other skull bones =
"keystone". See Fig. 7.19 page 216.

contains two sphenoid (paranasal) sinuses
See Fig 7.21 page 217.

Sella turcica (Fig. 7.23, page 219 and Fig 7.26, page 221) =
portion of sphenoid bone which rises up and forms a saddle-shaped
mass that houses the pituitary gland.
7-13
7.5
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
SKULL
1.
Cranium (continued)
f.
2.
Ethmoid bone = complex shaped bone composed of two masses on either
side of the nasal cavity. See Fig. 7.24, page 220.

contains two ethmoid (paranasal) sinuses, See Fig 7.21 page 217.

Cribriform or horizontal plate connects two masses of ethmoid
bone horizontally.

Perpendicular plate projects downward from cribriform plate to
form superior portion of nasal septum, See Fig 7.18, page 216.

Superior and middle nasal conchae = delicate scroll-shaped
plates that project into nasal cavity. See Fig 7.18, page 216.

Crista galli = process that extends from horizontal plate that
serves as the attachment for meninges (membranes) that surround
the brain. See Fig 7.24b, page 220 and Fig 7.26, page 221.
Facial Skeleton
The facial skeleton shapes the face and provides attachment for various muscles
that move the jaw and control facial expressions.
See Fig 7.18 and Fig 7.19 page 216, and Table 7.6, page 224.
a.
b.
c.
d.
e.
f.
g.
h.
Maxillae = upper jaw bones.

contain two maxillary (paranasal) sinuses.
Palatine bones = complete posterior portion of hard palate

See Fig 7.25, page 220 and Fig 7.27, page 221.

See box on page 221 re: Cleft palate.
Zygomatic bones = cheek bones.

temporal processes project posteriorly and articulate with the
zygomatic processes of temporal bone. These two processes
compose the zygomatic arch. See Fig 7.19, page 216.
Lacrimal bones = median walls of orbit.

Contains lacrimal foramen for tear drainage.
Nasal bones = bridge of nose.
Vomer = inferior portion of nasal septum.

The perpendicular plate of the ethmoid bone forms the superior
portion of nasal septum.
Inferior Nasal Conchae
Mandible = lower jaw. See Fig 7.30, page 223.

largest strongest bone in the face

mandibular condyle articulates with the mandibular fossa of the
temporal bone at temporomandibular joint (TMJ).

only movable bone in the skull.
7-14
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.5
SKULL
3.
Orbit – composed of seven bones. See Fig 7.20, page 217.
4.
Infantile Skull- differs from the adult skull in the following ways
a.
b
c
*
5.
*
7.6
Fontanels

soft spots

allow “molding” of skull in birth canal
Large forehead and small face
Larger orbits
See Fig 7.32, page 225.
Hyoid Bone See Fig 7.17, page 214.
a.
Location:
b.
Function:
in neck between lower jaw and larynx
held in place by muscles and ligaments
supports tongue
In addition to the figures presented in this chapter please refer to Human Skull
Reference Plates Twenty-Six through Fifty-Four on pages 252-266.
Vertebral Column: See Fig. 7.33, page 226 and Table 7.8, page 231.
1.
Introduction: The vertebral column is composed of 33 infantile or 26 adult
irregular bones called vertebrae. These bones are divided into five regions and in
the sagittal plane, four curvatures exist. The vertebrae are separated by
intervertebral discs, made of fibrocartilage.
2.
A Typical Vertebra: See Fig 7.34 page 227.
a.
b.
c.
d.
e.
body = discoid shaped anterior region
vertebral arch = posterior region

pedicle = short bony posterior projection

lamina = flattened plates that articulate posteriorly into spinous
process
vertebral foramen = opening between body and vertebral arch through
which the spinal cord passes
spinous process = midline posterior projection
transverse processes = laterally from pedicle.
Sketch a typical vertebra below:
7-15
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.6
Vertebral Column: See Fig. 7.33, page 226 and Table 7.8, page 231.
3.
Cervical Vertebrae
a.
b.
c.
d.
4.
Thoracic Vertebrae
a.
b.
c.
5.
5 large vertebrae in abdominal cavity.
See typical thoracic vertebra structure in Fig 7.37c, page 229.
Sacrum
a.
b.
7.
12 vertebrae of thoracic cavity
posterior articulation site of ribs
See typical thoracic vertebra structure in Fig 7.34, page 227 and Fig 7.37b,
page 229.
Lumbar Vertebrae
a.
b.
6.
7 vertebrae (bones) in neck. See Fig 7.33, page 226, Fig 7.36, page 228,
and Fig 7.37a, page 229.
First is atlas
Second is axis
See Fig 7.35, page 228.
5 fused vertebrae that articulate with coxal bones of pelvis
See Fig 7.38, page 230.
Coccyx
a.
b.
4 vertebrae which makeup the tailbone.
See Fig 7.38, page 230.
*
See Clinical Application 7.3, page 230, Disorders of the Vertebral Column.
*
See box on page 227 re: spina fibida.
*
See box on page 229 re: spondylolisthesis.
*
In lab you will be able to study and distinguish between cervical, thoracic, and
lumbar vertebrae, in addition to studying sacrum and coccyx.
7-16
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.7
Thoracic Cage
The thoracic cage includes the ribs, sternum, thoracic vertebrae, and costal cartilages.
See Fig 7.39 page 232.
1.
Ribs:
a.
12 pairs



articulate anteriorly with sternum through costal (hyaline)
cartilage
articulate posteriorly with thoracic vertebrae
Three types:
1.
2.
3.

True ribs = upper 7 pairs that articulate directly with
sternum
False ribs = remaining 5 pairs of ribs
Floating ribs = 11th and 12th pair
These ribs do not articulate anteriorly
Typical Rib Structure:
Fig 7.40, page 233.
1.
Head
2.
Neck
3.
Tubercle
4.
Costal Angle
5.
Costal groove
6.
Body
2.
Sternum: See Fig 7.39a, page 232.
a.
Three parts:

Manubrium = upper portion.
1.
resembles handle
2.
articulates with clavicle and first rib

Body = middle vertical portion.
1.
site where most ribs articulate anteriorly

Xiphoid process = lower extension from body.
7-17
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.8
Pectoral Girdle
The pectoral (shoulder) girdle connects the upper limbs to the rib cage and consists of
two pairs of bones.
See Fig 7.41, page 234.
1.
Anterior clavicles (2) = collar bones.
a.
b.
c.
2.
medial sternal ends
lateral acromial ends
provide attachments for many muscles
Posterior scapulae (2) = shoulder blades.
See Fig 7.42, page 234.
a.
b.
c.
d.
e.
f.
g.
h.
7.9
flattened triangular bones
glenoid cavity (fossa) = small fossa that articulates with the head of the
humerus
coracoid process = anterior projection of superior portion (looks like a
bent finger) attachment for biceps muscle
acromion = uppermost point of shoulder
spine = diagonal posterior extension
body = flattened triangular region
medial & lateral Border
inferior angle
Upper Limb: See Figure 7.43, page 235.
1.
Humerus = upper arm bone: See Fig 7.44, page 236.
a.
b.
typical long bone
note location of:

proximal head

distal capitulum and trochlea (articulate with radius and ulna,
respectively)

greater/lesser tubercles

deltoid tuberosity

body

medial/lateral epicondyles

olecranon fossa
7-18
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.9
Upper Limb
2.
Radius = forearm bone on same side as thumb (lateral)
See Fig 7.45 page 237.
a.
3.
Note location of
o
head
o
neck
o
radial tuberosity
o
ulnar notch (distal)
o
styloid process (lateral prominence)
Ulna = forearm bone on same side as pinky (medial)
See Fig 7.45 page 237.
a.
Note location of
o
o
o
o
o
3.
olecranon (process)= prominence of elbow
trochlear notch = receives trochlea of humerus
coronoid process (Fig 7.45b)
head (distal)
styloid process (medial prominence)
Hand – wrist, palm, and fingers
See Fig 7.46, page 238.
a.
Carpus = 8 carpals (wrist, short) bones.
b.
Metacarpus = 5 metacarpals (hand, long) bones.
c.
Phalanges (plural) phalanx (singular) = finger bone or digit.
o
o
o
Thumb (pollex) = 2 phalanges
Fingers = 3 phalanges
Total per limb = 14 phalanges
See Fig 7.47, page 239 illustrating polydactyly, and box describing the
condition.
*
See Table 7.9, page 237 summarizing Bones of the Pectoral Girdle and Upper Limbs.
7-19
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.10
Pelvic Girdle = two coxal bones that connects lower limbs to the vertebral column
See Fig 7.48, page 239.
1.
2.
Hip Bones (pair of coxal bones)
a.
articulate anteriorly at the pubic symphysis and posteriorly with the
sacrum.
b.
Each coxal bone consists of 3 separate bones during childhood but these
bones are securely fused in adults:
See Fig 7.49, page 240.
2.
Ischium = lowest L-shaped portion of coxal bone (i.e. area we sit
on).

Note ischial spine
3.
Pubis = anterior portion of coxal bone, bladder rests upon it.
*
The pubis (coxal) bones articulate anteriorly at the pubic
symphysis (fibrocartilage disc). See Fig 7.48a, page 239.
Pelvic brim is border between the greater (false) and lesser (true) pelvis.
Lesser (true) pelvis is passageway for fetus during birth.
Differences Between Male and Female Pelves
a.
b.
c.
d.
*
Ilium = largest uppermost flaring portion of coxal bone.
iliac crest = prominence of the hip (i.e. hands on hips).

The socket that articulates with head of femur is called the
acetabulum.

The hole in each coxal bone is called the obturator
foramen.

Note iliac spine.

See box re: hip pointer on page 239.
True (Lesser, Lower) and False (Greater, Upper) Pelves
a.
b.
3.
1.
Female ilium is more flared.
Female has wider pubic arch.
Pelvic curvature is flatter in female.
See Figure 7.50, page 240.
See Table 7.10 page 241, Differences Between the Male and Female Skeletons.
7-20
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
7.11
Lower Limb
See Fig 7.51, page 242.
1.
Femur = thigh bone: See Fig 7.52, page 243.
a.
largest, longest, strongest bone in skeleton
b.
note the location of:

head

neck

greater & lesser trochanters (attachment for thigh and buttocks
muscle)

linea aspera

lateral & medial condyles (tibia)

epicondyles

patellar surface (patella).
2.
Patella = knee cap; a sesamoid bone.
a.
See Fig 7.51a and b, page 242.
b.
See box on page 243 re: patellar dislocation.
3.
Tibia = shin bone:
See Fig 7.53 page 243.
a.
very strong
b.
note location of:

medial/lateral condyles

tibial tuberosity

medial malleolus (bulge of ankle).
4.
Fibula = thin bone lateral to tibia: See Fig 7.53 page 243.
a.
Note the location of:

head

lateral malleolus (lateral ankle bulge).
5.
Foot – ankle, instep, and toes: See Fig 7.54, and Fig 7.55, page 244.
a.
Tarsus = 7 tarsal (ankle) bones.
Body weight is carried on 2 largest tarsals:

Talus = uppermost tarsal which articulates with the tibia and fibula

Calcaneus = heel bone.
b.
Metatarsus = 5 metatarsal (foot) bones.
c.
Phalanges = toe bones or digits (14 total).
*
See box re: clubfoot on page 245.
*
See Table 7.11, page 245 for summary of Bones of the Pelvic Girdle and Lower Limbs.
7-21
7.12
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
LIFE SPAN CHANGES
A.
Age related skeletal changes are apparent at the cellular and whole body level.
1.
Height begins to decrease incrementally at around age 33.
2.
Bone loss gradually exceeds bone replacement.

After menopause females lose bone more rapidly than males.

By age 70 bone loss between sexes is similar.
3.
Fractures increase as bones age.

See Table 7.12 page 246, Possible Reasons for Falls Among
Elderly.
OTHER INTERESTING TOPICS:
A.
A.
B.
C.
D.
THE WHOLE PICTURE. See page 199.
CAREER CORNER: Radiologic Technician, see page 201.
Bone pain in sickle cell disease. See box on page 202.
Noncollagenous Proteins in Bone. See box on page 209.
Bone Marrow Transplants. See box on page 211.
INNERCONNECTIONS of the skeletal system with other organ systems: See page 247.
CHAPTER SUMMARY – see pages 246, 248--249.
CHAPTER ASSESSMENTS – see page 250.
INTEGRATIVE ASSESSMENTS/CRITICAL THINKING – see page 251.
HUMAN SKULL REFERENCE PLATES – see pages 252-266.
7-22
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
SUMMARY TABLE (See partial sample key at the end of the outline)
NAME OF
BONE:
SCIENTIFIC
COMMON
AXIAL OR
APPENDICULAR
SKELETON?
CLASSIFICATION BY SHAPE
HOW MANY IN
SKELETON?
SPECIAL
FEATURES OR
MARKINGS
SPECIFIC
ARTICULATION
(S)
SPECIAL
FUNCTIONS
7-23
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
SUMMARY TABLE (See partial sample key at the end of the outline)
NAME OF BONE:
SCIENTIFIC
COMMON
AXIAL OR
APPENDICULAR
SKELETON?
CLASSIFICATION
BY SHAPE
HOW MANY IN
SKELETON?
SPECIAL
FEATURES OR
MARKINGS
SPECIFIC
ARTICULATION
(S)
SPECIAL
FUNCTIONS
7-24
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
CHAPTER 7: THE SKELETAL SYSTEM
OVERVIEW OF LONG BONE STRUCTURE
LONG BONE PART
DESCRIPTION
FUNCTION
Diaphysis
long shaft of bone;
collar of compact bone
surrounding medullary
cavity filled with yellow
marrow (fat storage)
rigidity
Epiphyses
expanded ends of long bone;
spongy bone filled with red
bone marrow
hematopoiesis,
form synovial joints with other
long bones
Periosteum
dense fibrous CT that
surrounds outer surface of
bone; inner layer is
osteogenic layer composed
of osteoblasts & osteoclasts;
A nutrient foramen serves as
passageway for nutrient
artery to penetrate bone.
protection,
attachment site for muscles,
bone remodeling
Endosteum
inner lining of medullary
cavity with osteogenic layer
lining,
bone remodeling
Articular cartilage
covers epiphysis
shock absorber,
forms synovial joint
Nutrient
Foramen/Perforating Canal
Perforating canal allowing
blood vessels to enter and
leave bone
Nourishment
Epiphyseal Line
at junction of epiphysis and
diaphysis
remnant of epiphyseal (growth)
plate
7-25
UNIT 2 - CHAPTER 7: SKELETAL SYSTEM
CHAPTER 7: THE SKELETAL SYSTEM
SAMPLE OF BONE SUMMARY TABLES
NAME of bone:
SCIENTIFIC
SCAPULA
COMMON
SHOULDER BLADE
AXIAL OR
APPENDICULAR
SKELETON?
APPENDICULAR
AXIAL
APPENDICULAR
CLASSIFICATION
BY SHAPE
FLAT
FLAT
LONG
HOW MANY IN
SKELETON?
2
2
56
SPECIAL
FEATURES OR
MARKINGS
ACROMION
ARTICULATES
WITH CLAVICLE,
GLENOID FOSSA
ARTICULATES
WITH HEAD OF
HUMERUS,
CORACOID
PROCESS SERVES
AS ORIGIN FOR
BICEPS BRACHII,
TRIANGULAR
POSTERIOR SPINE
EXT. ACOUSTIC.
MEATUS FOR EAR
CANAL, MASTOID &
STYLOID
PROCESSES SERVE
AS ATTACHMENT
FOR NECK
MUSCLES,
ZYGOMATIC
PROCESS
ARTICULATES WITH
TEMPORAL
PROCESS OF
ZYGOMATIC TO
FORM ARCH
ARTICULATION
SEE ABOVE
SEE ABOVE
WITH ONE ANOTHER
TO FORM FINGERS
SPECIAL
FUNCTIONS
ATTACHMENT SITE
OF UPPER LIMBS,
HEMATOPOIESIS
PROVIDES INLET
FOR SOUND WAVES,
PROTECTION OF
SKULL
MANIPULATION
TEMPORAL
PHALANX
DIGIT (FINGER)
7-26