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Chapter 4
Textbook
The Skeletal System
Chapter-Opening Question
It is important for astronauts to exercise in space because
without exercise, they would experience rapid loss of bone
mass and strength due to time spent outside the earth’s
gravitational field.
Lesson 4.1 Bone as a Living Tissue
Before You Read
Do all bones have the same internal structure?
No; cortical bone, which makes up the outer surfaces
of all bones and the long bones of the limbs, is dense
with a relatively high mineral content. It has relatively high
strength, low flexibility, and low shock-absorbing ability. By
contrast, trabecular bone, which is found in the interior of
the vertebrae, femoral neck, and wrist and ankle bones,
is porous with a relatively low mineral content. It has low
strength but more flexibility and shock-absorbing ability.
When and why do bones stop growing?
Bones grow in diameter throughout most of life,
but longitudinal growth stops during or shortly after
adolescence, when the epiphyseal plate dissolves.
What practices can make bones stronger or weaker?
Physical activity, especially dynamic activities such as
running and jumping, makes bones stronger. A sedentary
lifestyle and reduced forces such as gravity makes bones
weaker.
Check Your Understanding, page 111
1. support, protection, movement, storage, and blood
cell formation
2. to act as a storehouse for fat in the body and to aid in
blood cell formation
Check Your Understanding, page 113
1. 60% to 70%
2. a protein that provides bone’s flexibility
3. on the outer layer of a bone and in the long bones of
the arms and legs
4. in the interior of bones and in the bones of the spinal
column
5. long, short, flat, and irregular
Check Your Understanding, page 117
1. The periosteum is a fibrous connective tissue that
surrounds and protects the diaphysis, contains blood
and lymph vessels, and is involved in bone growth,
repair, and nutrition.
2. The endosteum lines the medullary cavity; it is inside
the periosteum.
3. articular cartilage
4. Osteoblasts build new bone tissue; osteoclasts
resorb or eliminate weakened or damaged bone
tissue.
5. As we age, there is a progressive loss of collagen,
the substance that provides elasticity in the body.
Without collagen and the elasticity it provides, adults
become more vulnerable to bone fractures.
Check Your Understanding, page 119
1. Hypertrophy occurs when bones are subjected
to strong force, such as in those who are more
physically active, those who are heavier, and those
who perform dynamic activities that involve landing
impacts.
2. Atrophy is caused by a reduction of forces such
as gravity. It is common among elite swimmers,
astronauts, and bedridden people.
Caption Questions
Figure 4.1: Trabecular bone is spongy and flexible; cortical
bone is stiff and generally stronger.
Figure 4.5: Spongy trabecular bone and Haversian canals
are both tube-like structures inside bone that, to some,
might resemble subway tunnels.
Figure 4.6: during or shortly after adolescence
Figure 4.7: the circumference
Figure 4.8: in his dominant upper arm
Taking It Further, page 118
1. Regular physical activity has been shown to aid
in bone remodeling and hypertrophy. In addition,
repetition of physical activity and the amount of force
involved in impacts contribute to remodeling and
hypertrophy.
2. Answers will vary.
Know and Understand
1. The skeletal system provides support for the trunk
and limbs; protection for the delicate internal organs;
movement (walking, running, jumping, etc.); storage
for minerals that the body needs; and blood cell
formation.
2. Cortical bone is dense and stiff, whereas trabecular
bone is spongy and porous.
3. The diaphysis is the shaft of the long bone, and the
epiphysis is the bulbous ending. The periosteum
surrounds the exterior of the diaphysis, and the
endosteum lines the medullary cavity inside the
diaphysis.
Analyze and Apply
4. Osteoblasts and osteoclasts both serve important,
complementary functions during bone growth.
Osteoblasts create bone tissue, and osteoclasts
clean up old bone tissue.
5. Damage to the epiphyseal plate could affect the
ability of the child’s long bones to grow in length.
In the Lab
6. Answers will vary. Examples include the arms and legs
(long bones), the wrists and ankles (short bones), the
1
bones of the skull (flat bones), and the bones of the
spinal column and hip girdle (irregular bones).
Lesson 4.2 The Axial Skeleton
Before You Read
Why is the skull composed of multiple bones?
to allow for movement, and change in size and shape
in response to force
Why is the spine curved instead of straight?
to protect the spinal cord, support the weight of the
trunk, and allow flexibility in multiple directions
Check Your Understanding, page 123
1. the axis and the appendages
2. the skull, spinal column, and thoracic cage
3. Sutures hold the bones of the skull together. These
joints permit a very small amount of movement,
which gives compliance and elasticity to the skull.
4. The fontanels enable compression of the skull during
birth, and brain growth during late pregnancy and
early infancy.
5. frontal bone (forehead), parietal bones (top and
sides of the skull—2), temporal bones (surrounding
the ears—2), occipital bones (base and lower back
portion of the skull), ethmoid bones (part of the nasal
septum), and sphenoid bone (located centrally within
the skull)
6. maxillary (upper jaw—2), palatine (posterior of
the hard palate—2), zygomatic (cheekbones—2),
lacrimal (connecting to the orbits—2), nasal (bridge
of the nose—2), vomer (bony nasal septum), concha
(sides of the nasal cavity—2), and mandible (lower jaw
bone)
Check Your Understanding, page 127
1. cervical, thoracic, lumbar, sacrum, and coccyx
2. When the body is in an upright position, the vertebrae
farther down the spine (the lumbar region) support
more weight than the vertebrae near the top of the
spine (the cervical region); therefore, the vertebrae in
the lumbar region are larger.
3. Intervertebral disks serve as shock absorbers and
allow the spine to bend.
Check Your Understanding, page 128
1. the ribs, sternum, and thoracic vertebrae
2. the manubrium, the body of the sternum, and the
xiphoid process
3. twelve pairs
4. eight ribs
Figure 4.16: False ribs do not attach to the sternum.
Know and Understand
1. The axial skeleton provides stability to the core of
the body. It includes the skull, spinal column, and
thoracic cage.
2. cranial bones and facial bones
3. Sutures and fontanels are features of the skull that
allow movement, however small.
4. cervical region (7), thoracic region (12), lumbar
region (5), sacrum (5), and coccyx (4)
5. the vertebral body, vertebral arch, transverse
process, spinous process, and superior and inferior
articular processes
6. the mandible
Analyze and Apply
7. Their fontanels, or soft spots, on the baby’s skull
have not yet closed, so the baby’s brains are not
fully protected; also, babies cannot support their
own head weight, making them vulnerable to cranial
injury.
8. All three are conditions of abnormal spinal curvature,
but each involves a different region of the spine.
Lordosis is an exaggeration of the lumbar curve,
kyphosis is an accentuation of the thoracic curve,
and scoliosis is any lateral deviation of the spine.
9. Because intervertebral discs are made of
fibrocartilage, a pliant substance, they are able to
provide cushioning between vertebral bodies and
allow for bending.
10. True ribs attach directly to the sternum, false ribs
attach to the cartilage of the seventh rib rather than
the sternum, and floating ribs don’t attach to the
sternum at all.
11. The thoracic and sacral curves are the primary spinal
curves, and the lumbar and cervical curves are the
secondary spinal curves. The primary curves are
present at birth; the secondary curves develop after
the baby begins to raise the head, sit, and stand.
In the Lab
12. Axial skeleton models will vary, but all major bones,
as shown in the text, should be labeled.
Lesson 4.3 The Appendicular
Skeleton
Before You Read
Figure 4.10: Twenty-two bones make up the skull, and they
are held together by sutures.
Why are there two bones in the forearm?
One bone (the radius) articulates with the wrist on
the thumb side. The other (the ulna) articulates with the
humerus at the humeroulnar joint (elbow), and it attaches
to the wrist on the “little finger” side. This framework allows
the forearm and hand to freely rotate.
Figure 4.11: The sacrum is made up of five bones, and the
coccyx is made up of four bones. These bones differ from
those of the other three regions of the vertebral column
because they contain vertebrae that are fused together.
What are the best and worst design features of the hip joint?
The hip joint is stable because the femur fits snugly
into the acetabulum of the hip, but the neck of the femur is
vulnerable to hip fractures.
Figure 4.13: superior and inferior articular processes
Check Your Understanding, page 134
Caption Questions
Figure 4.15: genetic or congenital abnormalities, or habitual
subjection of the spine to asymmetrical forces
Introduction to Anatomy and Physiology
1. the shoulder complex, arms, wrists, hands, pelvic
girdle, legs, ankles, and feet
Chapter 4 Answer Key
2
2. the left and right clavicles, left and right scapula, and
glenohumeral joint
3. the radius
4. 27
Check Your Understanding, page 137
1.
2.
3.
4.
the coxal bones (hip bones) and the sacrum
the ilium, ischium, and pubis
the femur
The toes increase the surface area of the foot during
weight-bearing activities, thereby increasing body
stability.
Caption Questions
Figure 4.21: the radius
Figure 4.23: Similarities: The phalanges of both the hand
and the foot are divided into distal, middle, and proximal
phalanxes and are followed by a set of bones with the
prefix meta-.
Differences: The metatarsals of the foot each have three
parts, and the metacarpals of the hand are just one piece.
Also, sections of the phalanges in the foot are longer than
sections in the phalanges of the hand.
Figure 4.24: The pelvic bones of a female are wider, allowing for classification.
Figure 4.25: The neck of the femur is the part of the femur
most vulnerable to fracture.
Figure 4.29: The arches of the foot compress during the
weight-bearing phase of our gait, and then act as springs,
rebounding to their original shape during the propulsive
phase of the gait.
Know and Understand
1. The bones of the pectoral girdle, the clavicle and
the scapula, serve as sites of attachment to many
muscles, as well as to the acromioclavicular and
sternoclavicular joints, which enable motion of the
arms at the shoulders in so many different directions.
2. the ulna
3. to allow for pregnancy and childbirth
4. the tibia
Analyze and Apply
5. The bones of the pectoral girdle attach to many
muscles and joints, allowing for movement. The
pelvic girdle does not have these attachments.
6. The framework made up of the radius, which
articulates with the wrist on the thumb side, and
the ulna, which articulates with the humerus at the
humeroulnar joint and attaches to the wrist on the
“little finger” side, is what allows the forearm and
hand to freely rotate.
7. Metatarsals and phalanges increase the area of
the foot during weight-bearing activities (such as
walking), thus increasing body stability. Without this
stability, you would not be able to walk properly.
In the Lab
8. Appendicular skeleton models will vary, but all major
bones, as shown in the text, should be labeled.
Introduction to Anatomy and Physiology
Lesson 4.4 Joints
Before You Read
Why do some joints permit little to no movement?
These joints provide stability and protection against
injury.
How do joints avoid damage from frictional wear over time?
cushioning from bursae, synovial fluid secreted by
tendon sheaths, and articular fibrocartilage
Caption Questions
Figure 4.31: ball-and-socket joints
Know and Understand
1. “Bones articulate together” means that they come
together at the joint.
2. sutures (skull) and syndesmoses (coracoacromial
joint or distal tibiofibular joints)
3. synchondroses (sternocostal joints or epiphyseal
plates) and symphyses (vertebral joints or pubic
symphysis)
4. gliding (intercarpal), hinge (interphalangeal), pivot
(atlantoaxial), condyloid (radiocarpal), saddle
(carpometacarpal), and the ball-and-socket (hip)
Analyze and Apply
5. Cartilage cushions joints, reduces friction and wear,
and absorbs shock at the joint.
6. Joints that provide little to no movement are
important because they provide stability and
protection for vital organs.
7. The joints are no longer being properly lubricated
and protected, making movement more difficult and
increasing the likelihood of injury.
In the Lab
8. Pictures and illustrations will vary, but the joints
should be properly labeled.
Lesson 4.5 Common Injuries and
Disorders of the Skeletal System
Before You Read
What is the female athlete triad and why is it potentially
deadly?
The female athlete triad is a condition that involves
a combination of disordered eating, amenorrhea, and
osteoporosis. It is potentially deadly because of the
combined health consequences caused by these individual
conditions.
What is osteoarthritis and how might it possibly be prevented?
Osteoarthritis is a degenerative disease of the
articular cartilage. Possible prevention includes regular
physical activity.
Check Your Understanding, page 143
1. In a simple fracture, the bone ends remain within the
surrounding soft tissues. In a compound fracture,
one or both bone ends protrude from the skin. A
comminuted fracture is a splintered bone. In an
avulsion, the tendon or ligament pulls away from its
Chapter 4 Answer Key
3
attachment to a bone. A spiral fracture is caused
by forceful bending and twisting movements. A
greenstick fracture is an incomplete fracture. Stress
fractures are tiny, painful cracks in bone that result
from overuse.
2. Osteochondrosis is a condition in which the area
around the tibia attachment site becomes irritated or
swollen. It is thought to be caused by overuse injuries
before the area has finished growing.
3. These injuries can result in premature closure of the
epiphyseal junction and termination of bone growth.
Check Your Understanding, page 146
1. Osteoporosis results in fractures, whereas
osteopenia does not. Osteopenia often progresses to
osteoporosis.
2. ligaments, tendons, and other connective tissues
3. falls or forceful collisions
4. Causes of bursitis include overuse of a joint that
results in inflammation of one or more of the bursae.
Symptoms include pain and sometimes swelling.
Caption Questions
Figure 4.33: women over 60 years of age and men over 70
years of age
Figure 4.34: She could engage in physical activity and
avoid harmful lifestyle factors such as excessive weight
loss and smoking.
patient, students may work in pairs, with their partner
acting in the role of the patient.
Chapter Assessments
Lesson 4.1 Bone as Living Tissue
1. support, protection, movement, storage, blood cell
formation
2. B
3. C
4. long, short, flat, irregular
5. diaphysis; epiphyses
6. B
7. C
8. Descriptions and illustrations will vary. Students
may compare Haversian canals to a subway system,
lacunae to buildings, lamellae to highways, and
canaliculi to streets.
Lesson 4.2 The Axial Skeleton
9.
10.
11.
12.
13.
14.
15.
Figure 4.37: Answers will vary; radiographers typically have
a bachelor’s degree that includes training in radiography.
Taking It Further, page 145
1. Students’ list content will vary.
Know and Understand
1. An avulsion is a fracture caused by a tendon or
ligament detaching from a bone, taking a small chip
of bone with it.
2. during adolescence
3. painful fractures
4. the ankle
5. In a person with rheumatoid arthritis, the body’s
immune system attacks the joint tissue, resulting in
limited joint movement.
Lesson 4.3 The Appendicular Skeleton
16.
17.
18.
19.
20.
21.
22.
23.
24.
Analyze and Apply
6. Bone responds to stress-related injury by remodeling.
Osteoclasts resorb the damaged tissue, and then
osteoblasts deposit new bone at the site. When
overuse occurs, the remodeling process cannot
“keep up” to sufficiently repair the damage. As a
result, further damage occurs.
7. because females participating in certain sports are
subject to pressure (both external and internal) to
achieve and maintain an idealized physique
8. Students should suggest a modified diet, a calcium
supplement, and continued physical activity.
In the Lab
9. Treatment plans and presentations will vary. As an
alternative to having students share their treatment
plans with the class, as though the class were the
Introduction to Anatomy and Physiology
D
A
C
D
A
D
To promote disc health, a person should avoid
sedentary activities because remaining motionless
curtails the pumping action that brings in nutrients.
Avoid excessive computer time because it requires
you to remain inactive for a long time, and avoid
excessive television watching because that is also
done in a sedentary, inactive position.
C
C
D
C
D
clavicle; scapula
27
ilium, ischium, pubis
The pelvis of the skeleton will indicate whether it is a
male or female; a female skeleton has a much wider
pelvis than a male skeleton.
Lesson 4.4 Joints
25.
26.
27.
28.
29.
30.
A
D
synarthroses
Bursae
Tendons; ligaments
Although ball-and-socket joints allow a wide range of
movement in all directions, they would not promote
body stability or protect the internal organs very well.
Lesson 4.5 Common Injuries and Disorders of
the Skeletal System
31. B
32. C
33. C
Chapter 4 Answer Key
4
34.
35.
36.
37.
Stress
apophysis
Rheumatoid arthritis
The boy has greater bone density because he is
young, but the father’s bones are more brittle from
age.
Building Skills and Connecting
Concepts, page 47
Analyzing & Evaluating Data
38. about 3% to 6%
39. 25.5 pounds
40. 10 to 20 pounds
Communicating about Anatomy and
Physiology
41. Report content will vary. Encourage students to
share their reports in a brief (10-minute) PowerPoint ®
presentation.
42. Stories will vary and should include as many creative
references to the bones as possible.
Lab Investigations
43. Project results will vary.
Workbook
Lesson 4.1: Learning the Key Terms
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
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19.
20.
G
P
J
B
M
N
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F
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K
T
L
A
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Q
R
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O
H
Lesson 4.1: Study Questions
1. support, protection, movement, storage, blood cell
formation (hematopoiesis)
2. minerals, notably phosphorous and calcium, and
bone marrow
3. yellow stores fat; red is key in blood cell formation
4. Bones are composed 60%–70% of minerals, mostly
calcium carbonate and calcium phosphate, with the
remaining 30%–40% composed of collagen.
Introduction to Anatomy and Physiology
5. Children’s bones have more collagen and water than
adult bones.
6. Cortical bone is stiffer due to its higher mineral
content, so it is generally stronger than trabecular
bone. Trabecular bone is more flexible than cortical
bone.
7. Answers may vary. Long: humerus, ulna, radius,
femur, tibia, fibula
Short: wrists or ankles
Flat: the scapula and bones of the skull
Irregular: the spinal column and hip girdle
8. The periosteum surrounds and protects the diaphysis.
It is involved in bone growth, repair, and nutrition.
9. A bone has a system of passageways which are like
tiny tunnels; they are laid out both lengthwise and
in concentric circles, crisscrossing like a subway
system. Blood vessels and nerves travel through
these tiny tunnels.
10. Ossification is the process of bone formation that
begins before birth and has two phases. In the first, a
bone matrix shell covers the hyaline cartilage through
the activity of osteoblasts. Next, osteoclasts resorb
the enclosed hyaline cartilage, creating a medullary
cavity within the bony superstructure.
11. At the end of a person’s growth period, the plates
dissolve and the bone on either side of the plate
fuses, effectively ending the longitudinal growth of
the bone.
12. loss of collagen
13. Women have smaller bones than men, so there is
less bone mass to lose.
14. They involve landing impacts, which cause motion of
fluid within the bone matrix and triggers osteoblasts
to build bone.
15. about 15%
16. The buoyancy of the water counteracts gravity
and reduces stress on the bones. Swimming does
not involve impact forces, so swimmers may need
extra activities such as weight training and running
to provide those impact forces, and thus maintain
normal bone density.
17. Hypertrophy is the building and strengthening of
bones, while atrophy is weakening of bones through
the loss of bone mineral density and strength.
18. Because of the weightless and gravity-less
environment in space, bone loss is so rapid that it
prevents long-term space missions.
Lesson 4.1: Anatomical Structure of a
Long Bone
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
E
H
C
K
J
G
F
D
B
I
A
Chapter 4 Answer Key
5
Lesson 4.2: Learning the Key Terms
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
Intervertebral discs
vertebra
axial skeleton
lumbar region
Sutures
skull
thoracic region
cervical region
cranium
Maxillary bones
axis
thoracic cage
fontanel
atlas
mandible
sternum
coccyx
sacrum
Facial bones
Lesson 4.2: Study Questions
1. 22 bones into two groups named cranial and facial
bones
2. to provide stability to the core of the body
3. While other skull bones are joined by sutures, the
mandible is attached to the skull by a movable joint.
4. Answers may vary. Babies’ skulls account for about
1/4 of body height, while adults’ account for about
1/8; a baby’s skull is not completely bone, unlike an
adult’s, but have soft spots called fontanels.
5. Frontal bone: forms the forehead; parietal bones:
form the majority of the top and sides of the skull;
temporal bones: surround the ears; occipital bone:
forms the base and lower back portions of the skull;
ethmoid bone: forms part of the nasal septum;
sphenoid bone: centrally located within the skull
6. 2
7. 33
8. atlas and axis; The atlas is specialized to provide the
connection between the occipital bone of the skull
and the spinal column. The axis is also specialized,
with an upward projection called the odontoid
process, on which the atlas rotates.
8. Answers may vary. vertebral body, vertebral arch,
vertebral foramen, transverse process, spinous
process, superior articular process, and interior
articular process
10. Thoracic and sacral curves are known as primary
spinal curves because they are present at birth.
Lumbar and cervical curves are referred to as
secondary spinal curves because they develop after
the baby begins to raise the head, sit, and stand.
11. Exaggeration of the lumbar curve is termed lordosis;
accentuation of the thoracic curve is called kyphosis,
and any lateral deviation of the spine is known as
scoliosis.
12. Aging reduces the water retention capability of
intervertebral discs. Water between the discs causes
them to expand, which slightly increases a person’s
Introduction to Anatomy and Physiology
height. Without this water, a person appears to be
losing height, or gradually “shrinking.”
13. the thoracic cage
14. at the lower end of the sternum
15. True ribs: attach directly to the sternum
False ribs: attached to cartilage of seventh rib, rather
than directly to sternum
Floating ribs: not attached to bone or cartilage in the
front of the body
Lesson 4.2: Bones of the Skull
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
front bone
parietal bone
sphenoid bone
zygomatic bone
mastoid process
maxillary bone
mandible
nasal bone
temporal bone
lacrimal bone
vomer
Lesson 4.2: Vertebrae Identification
1.
2.
3.
4.
5.
6.
cervical, lateral
lumbar, superior
thoracic, superior
lumbar, lateral
cervical, superior
thoracic, lateral
Lesson 4.3: Learning the Key Terms
1.
2.
3.
4.
5.
6.
7.
8.
9.
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11.
12.
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J
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Lesson 4.3: Study Questions
1. The appendicular skeleton deals with appendages
and is built for motion, while the axial skeleton’s
function is to provide stability for the core of the body.
2. right and left clavicles, or collarbones; right and left
scapula, or shoulder blades. They act as attachment
Chapter 4 Answer Key
6
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
sites for numerous muscles that allow arm motion at
the shoulders in many directions.
the point where the sternum meets the clavicle;
shrugging the shoulders, raising the arms, and
swimming
the region between each scapula and the underlying
tissues
instability; the shoulder is one of the human body’s
most frequently dislocated joints
the humerus connects shoulder to arm; the
radius rotates around the ulna; the ulna is a major
contributor to elbow flexibility
the elbow
to provide a base for the bones of the hand
called the opposable thumb, both species’ hands
have such thumbs, giving them the ability to freely
rotate the thumb and to stretch it across the palm of
the hand
Two coxal bones (hip bones), the sacrum, and the
coccyx make up the pelvic girdle. The pelvic girdle
shelters and protects the reproductive organs,
bladder, and segments of the large intestine.
the ischium
The female pelvis is wider than the male pelvis to
enable pregnancy and childbirth.
bones: femur, tibia, fibula, patella;
joints: iliofemoral (hip) joint, tibiofemoral (knee)
joint, patellofemoral joint, and proximal and distal
tibiofibular joints
the fibula
the femur, the upper leg or thigh bone
The tibia and fibula are connected along their lengths
by an interosseous membrane, as are the radius and
ulna.
The toes increase weight-bearing area of foot, which
provides stability.
The arches compress during weight-bearing
moments in gait and then act as springs when
they return to their original shape during propulsive
(push-off) part of the gait.
Lesson 4.4: Learning the Key Terms
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
amphiarthrosis
tendon sheaths
articular fibrocartilage
syndesmosis
ligaments
hinge joint
synchondrosis
saddle joint
condyloid joint
ball-and-socket joint
synarthrosis
synovial joint
symphysis
bursae
gliding joint
tendons
pivot joint
diarthrosis
Introduction to Anatomy and Physiology
Lesson 4.4: Study Questions
1. Answers may vary. Joints can be classified based on
the joint complexity, the number of axes present, joint
structure, and joint function.
2. joint function
3. immovable joints (synarthroses), the slightly movable
joints (amphiarthroses), and the freely movable joints
(diarthroses)
4. to absorb shock but permit little or no movement of
the articulating bones
5. Synchondroses meaning “held by cartilage,”
are joints in which the articulating bones are
held together by a thin layer of hyaline cartilage.
Symphyses are joints in which thin plates of hyaline
cartilage separate a disc of fibrocartilage from the
bones.
6. amphiarthroses
7. Answers may vary. sternocostal joints (between the
sternum and the ribs); the epiphyseal plates (growth
plates)
8. Diarthroses each feature a joint surrounded by an
articular capsule lined with a synovial membrane that
secretes a lubricant called synovial fluid.
9. Answers may vary. At gliding joints the articulating
bone surfaces are nearly flat, and the only movement
permitted is gliding.
In hinge joints one articulating bone surface is convex
(curved outward), and the other is concave (curved
inward). Strong ligaments restrict movement to a
planar, hinge-like motion, similar to the hinge on a
door.
Pivot joints permit rotation around only one axis.
(Think about moving around your stationary pivot
foot in basketball).
At condyloid joints one articulating bone surface is an
oval, convex shape, and the other is a reciprocally
shaped concave surface. Flexion, extension,
abduction, adduction, and circumduction are
permitted.
Saddle joints are so named because their articulating
bone surfaces are both shaped like the seat of a
riding saddle. Movement capability is the same as
that of the condyloid joint but with greater range of
movement allowed.
Ball-and-socket joints are the most freely movable
joints in the body. In these joints, the surfaces of
the articulating bones are reciprocally convex and
concave, with one bone end shaped like a “ball”
and the other like a “socket.”
10. pivot joint
11. gliding joints
12. saddle joint
13. Bursae are small capsules lined with synovial
membranes and filled with synovial fluid that cushion
the structures they separate. Most bursae separate
tendons from bone, reducing the friction on the
tendons during motion of the joints.
14. Tendons connect muscles to bones while ligaments
connect bones to other bones.
Chapter 4 Answer Key
7
15. collagen and elastic fibers
16. They help to distribute force evenly and absorb shock
at the joint.
Lesson 4.4: Identifying Movable
Joints
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
D
E
G
C
J
A
I
H
F
L
B
K
Lesson 4.5: Learning the Key Terms
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
G
C
N
B
F
J
M
E
L
I
O
A
H
D
K
Lesson 4.5: Study Questions
1. Answers may vary. size, direction, and duration of the
injurious force, the health and maturity of the bone
2. A simple fracture is when the bone ends remain
within the surrounding soft tissues; a compound
fracture occurs when one or both bone ends protrude
from the skin.
3. An avulsion occurs when the tendon or ligament pulls
away from the bone, taking a small bone chip with it
4. an incomplete fracture, one that bends or twists but
not completely breaks; more common in children
than adults because children’s bones are more
flexible than adults’
5. repeated overuse that doesn’t allow for the bone that
has been slightly injured to heal
6. those to the epiphyseal plate (growth plate), articular
cartilage, and the apophysis
7. Acute injuries and injuries caused by overuse
can harm the growth plate, potentially resulting in
premature closure of the epiphyseal junction and
termination of bone growth.
8. an epiphyseal injury in which the area of the
upper tibia around the quadriceps attachment site
becomes irritated, swollen, and painful from overuse;
common in adolescents who play soccer, basketball,
Introduction to Anatomy and Physiology
9.
10.
11.
12.
13.
14.
15.
16.
volleyball, and gymnastics because they often
overuse this area before it has finished growing
osteopenia
crushed-vertebrae type injuries resulting from picking
up a load; can reduce body height and accentuate a
kyphotic curve in the thoracic region of the spine
Answers may vary. weight-bearing exercise such as
running, jumping, and walking; dairy consumption
during the teenage years to obtain adequate amounts
of calcium and vitamin D; avoiding tobacco products
The female athlete triad is a condition involving
a combination of disordered eating, a lack of
menstruation (called amenorrhea), and osteoporosis.
because the ankle is a major weight-bearing joint and
there is less ligament support on the lateral side of
the ankle than on the medial side
A sprain involves overstretching or tearing of
ligaments or tendons, while a dislocation is an
outright displacement of an articulating bone from its
socket.
the inflammation of the bursae, which provide
cushioning of moving tissues around a joint;
symptoms include pain and sometimes swelling
Rheumatoid arthritis is an autoimmune disorder
caused by the body’s own immune system attacking
healthy joint tissues, and it results in extremely
limited joint motion and, in extreme cases, complete
fusing of the articulating bones.
Chapter 4: The Human Skeleton
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
skull
costal cartilages
thoracic cage
ribs
pelvis
coccyx
frontal bone
parietal bone
occipital bone
maxillary bone
mandible
clavicle
scapula
sternum
humerus
vertebral column
ulna
radius
hip bone
sacrum
carpal bones
metacarpal bones
phalanges
femur
patella
fibula
tibia
tarsals
metatarsals
phalanges
pectoral girdle
Chapter 4 Answer Key
8
Chapter 4: Skeletal System Statistics
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
206
15
22
8
14
33
7
12
5
5
4
24 (12 pairs)
14 (7 pairs)
6 (3 pairs)
4 (2 pairs)
126
27
8
5
14
2
5
3
6
Chapter 4 Lab Investigation: Know
Your Bones
1. A. 3
B. 2
2. 5
3. A. Answers may vary; most students will be able to
distinguish some of the carpal bones
B. intercarpal (gliding)
4. A. radius
B. ulna
5. A. radius
B. ulna
6. A. humeroulnar (hinge)
B. styloid process
7. no
8. A. sternum, or manubrium
B. acromion
9. Students should be able to feel this notch.
10. A. Of the 24 ribs, students will feel different
numbers.
B. Most students will say they cannot feel their
floating ribs.
C. Students should be able to feel the xiphoid
process.
11. A. tibiofemoral joint, or synovial joint
B. yes
C. femur, tibia, fibula
12. A. yes
B. yes
13. A. yes
B. Students should be able to feel some of their
tarsals.
C. 5
D. 2
Introduction to Anatomy and Physiology
E.
14. A.
B.
C.
D.
15. A.
B.
C.
D.
E.
F.
3
lower back of the skull
2
forehead
around the ears
yes
orbits
2
yes
upper jaw
yes
Conclusions
Bones of the Appendicular Skeleton: phalanges, tibia,
humerus, patella, radius, calcaneus, metacarpals,
ulna, tarsals, clavicle
Bones of the Axial Skeleton: sacrum, rib bones,
temporal bones, frontal bone, cranium, occipital
bones, zygomatic bones, xiphoid process
Chapter 4 Practice Test
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
35.
36.
osteoblast
atrophy
sternum
sprains
compound
F
F
T
T
F
B
B
A
A
B
I
F
D
E
B
H
A
G
J
C
J
E
A
C
G
B
I
F
H
D
The axial skeleton is the central, stabilizing portion
of the skeletal system. It is composed of the skull,
spinal column, and thoracic cage. The appendicular
skeleton consists of the bones of the body’s
appendages, or the legs and arms.
Chapter 4 Answer Key
9
37. The atlas is specialized to provide the connection
between the occipital bone of the skull and the spinal
column. The axis is also specialized, with an upward
projection called the odontoid process, on which the
atlas rotates.
Introduction to Anatomy and Physiology
Chapter 4 Answer Key
10