Ch.5: The Skeletal System Flashcards
1
Q
What are the parts of the skeletal system?
A
- Bones (skeleton)
- Joints
- Cartilages
- Ligaments
2
Q
What are the two subdivisions of the skeleton?
A
- Axial skeleton
* Appendicular skeleton
3
Q
What are the functions of bones?
A
• Support the body
• Protect soft organs
*Skull and vertebrae protect brain and spinal cord
*Rib cage protects thoracic cavity organs
• Attached skeletal muscles allow movement
• Store minerals and fats
*Calcium and phosphorus
*Fat in the internal marrow cavity
• Blood cell formation (hematopoiesis)
4
Q
The adult skeleton has how many bones?
A
206
5
Q
What are the two basic types of osseous (bone) tissue?
A
• Compact bone *Dense, smooth, and homogeneous • Spongy bone *Small needlelike pieces of bone *Many open spaces
6
Q
Bones are classified on the basis of shape into which four groups?
A
- Long
- Flat
- Short
- Irregular
7
Q
What are the properties of long bones?
A
• Typically longer than they are wide
• Shaft with enlarged ends
• Contain mostly compact bone; spongy bone at ends
• All of the bones of the limbs (except wrist, ankle, and kneecap bones) are long bones
• Examples:
*Femur
*Humerus
8
Q
What are the properties of flat bones?
A
• Thin, flattened, and usually curved • Two thin layers of compact bone sandwich a layer of spongy bone between them • Examples: *Most bones of the skull *Ribs *Sternum
9
Q
What are the properties of short bones?
A
• Generally cube-shaped
• Contain mostly spongy bone with an outer layer of compact bone
• Sesamoid bones are a type of short bone that form within tendons (patella)
• Examples:
*Carpals (wrist bones)
*Tarsals (ankle bones)
10
Q
What are the properties of irregular bones?
A
• Irregular shape • Do not fit into other bone classification categories • Examples: *Vertebrae *Hip bones
11
Q
Concept Link 1
A
As we learn about the structure and organization of bones, remember the levels of structural organization (Figure 1.1, p. 3). Bones are organs, so they contain not only osseous tissue but also other connective tissues: fibrous tissue, cartilage, adipose tissue, and blood.
12
Q
What is the diaphysis (shaft) in the anatomy of a long bone?
A
- Makes up most of bone’s length
* Composed of compact bone
13
Q
What is the periosteum in the anatomy of a long bone?
A
- Outside covering of the diaphysis
- Fibrous connective tissue membrane
- Perforating (Sharpey’s) fibers secure periosteum to underlying bone
14
Q
What is the epiphysis (ends) in the anatomy of a long bone?
A
• Composed mostly of spongy bone enclosed by thin layer of compact bone
15
Q
What is the articular cartilage in the anatomy of a long bone?
A
- Covers the external surface of the epiphyses
- Made of hyaline cartilage
- Decreases friction at joint surfaces
16
Q
What is the epiphyseal line in the anatomy of a long bone?
A
- Remnant of the epiphyseal plate
* Seen in adult bones
17
Q
What is the epiphyseal plate in the anatomy of a long bone?
A
- Flat plate of hyaline cartilage seen in young, growing bone
- Causes lengthwise growth of a long bone
18
Q
What is the endosteum in the anatomy of a long bone?
A
- Lines the inner surface of the shaft
* Made of connective tissue
19
Q
What is the medullary cavity in the anatomy of a long bone?
A
- Cavity inside the shaft
- Contains yellow marrow (mostly fat) in adults
- Contains red marrow for blood cell formation in infants until age 6 or 7
20
Q
What are bone markings?
A
- Sites of attachments for muscles, tendons, and ligaments
* Passages for nerves and blood vessels
21
Q
What are the categories of bone markings?
A
• Projections or processes—grow out from the bone surface
*Terms often begin with “T”
• Depressions or cavities—indentations
*Terms often begin with “F”
22
Q
What is the microscopic anatomy of spongy bone?
A
- Composed of small, needlelike pieces of bone called trabeculae and open spaces
- Open spaces are filled by marrow, blood vessels, and nerves
23
Q
What is the microscopic anatomy of compact bone?
A
- Osteocytes
- Lacunae
- Lamellae
- Central (Haversian) canal
- Osteon (Haversian system)
- Canaliculi
- Perforating (Volkmann’s) canal
24
Q
What are osteocytes?
A
Mature bone cells situated in bone matrix
25
What are lacunae?
Cavities in bone matrix that house osteocytes
26
What are lamellae?
Concentric circles of lacunae situated around the central (Haversian) canal
27
What is a central (Haversian) canal?
* Opening in the center of an osteon (Haversian system)
* Runs lengthwise through bone
* Carries blood vessels and nerves
28
What is an osteon (Haversian system)?
* A unit of bone containing central canal and matrix rings
| * Structural and functional unit of compact bone
29
What are canaliculi?
* Tiny canals
* Radiate from the central canal to lacunae
* Form a transport system connecting all bone cells to a nutrient supply
30
What is a perforating (Volkmann’s) canal?
* Canal perpendicular to the central canal
| * Carries blood vessels and nerves
31
Bone is relatively lightweight and resists:
Tension and other forces
32
Organic parts (collagen fibers) of the bone make bone flexible and have great:
Tensile strength
33
Calcium salts deposited in the bone make bone hard to:
Resist compression
34
What is ossification?
* The process of bone formation
| * Occurs on hyaline cartilage models or fibrous membranes
35
What are the two major phases of ossification in long bones?
1. Osteoblasts (bone-forming cells) cover hyaline cartilage model with bone matrix
2. In a fetus, the enclosed cartilage is digested away, opening up a medullary cavity
36
By birth, most cartilage is converted to bone except for which two regions in a long bone?
1. Articular cartilages
2. Epiphyseal plates
• New cartilage is formed continuously on the external face of these two cartilages
• Old cartilage is broken down and replaced by bony matrix
37
What is appositional growth?
* Bones grow in width
* Osteoblasts in the periosteum add bone matrix to the outside of the diaphysis
* Osteoclasts in the endosteum remove bone from the inner surface of the diaphysis
* Bone growth is controlled by hormones, such as growth hormone and sex hormones
38
Bones are remodeled throughout life in response to which two factors?
1. Calcium ion level in the blood determines when bone matrix is to be broken down or formed
2. Pull of gravity and muscles on the skeleton determines where bone matrix is to be broken down or formed
39
What is involved in calcium ion regulation?
* Parathyroid hormone (PTH)
| * Hypercalcemia (high blood calcium levels) prompts calcium storage to bones by osteoblasts
40
What is the function of parathyroid hormone (PTH)?
* Released when calcium ion levels in blood are low
* Activates osteoclasts (bone-destroying cells)
* Osteoclasts break down bone and release calcium ions into the blood
41
What is a fracture?
A break in a bone
42
What are the types of bone fractures?
* Closed (simple) fracture
| * Open (compound) fracture
43
Closed (simple) fracture
A break that does not penetrate the skin
44
Open (compound) fracture
A broken bone that penetrates through the skin
45
How are bone fractures treated?
* Reduction and immobilization
| * Healing time is 6-8 weeks
46
What is a closed reduction?
Bones are manually coaxed into position by physician’s hands
47
What is an open reduction?
Bones are secured with pins or wires during surgery
48
The repair of bone fractures involves what four major events?
1. Hematoma (blood-filled swelling, or bruise) is formed
2. Fibrocartilage callus forms
• Cartilage matrix, bony matrix, collagen fibers splint the broken bone
3. Bony callus replaces the fibrocartilage callus
• Osteoblasts and osteoclasts migrate in
4. Bone remodeling occurs in response to mechanical stresses
49
What does the axial skeleton form?
Longitudinal axis of the body
50
The axial skeleton is divided into what three parts?
1. Skull
2. Vertebral column
3. Bony thorax
51
Concept Link 2
Recall the regional body terms you have already learned (look back at Figure 1.4, p. 12). Many of these terms can be associated with a bone name or group of bones. For example, the carpal region is the location of the carpals, or wrist bones.
52
What two sets of bone form the skull?
1. Cranium bones
| 2. Facial bones
53
What do cranium bones do?
Enclose the brain
54
What do facial bones do?
* Hold eyes in anterior position
| * Allow facial muscles to express feelings
55
What are the 8 cranial bones which protect the brain?
1. Frontal bone
2. Occipital bone
3. Ethmoid bone
4. Sphenoid bone
5&6. Parietal bones (pair)
7&8. Temporal bones (pair)
56
What are the 14 facial bones?
```
1&2. Maxillae (pair)
3&4. Palatine bones (pair)
5&6. Lacrimal bones (pair)
7&8. Zygomatic bones (pair)
9&10. Nasal bones (pair)
11. Vomer bone
12&13. Inferior nasal conchae (pair)
14. Mandible
```
57
What are the paranasal sinuses and what is their function?
• Hollow portions of bones surrounding the nasal cavity
• Functions of paranasal sinuses:
*Lighten the skull
*Amplify sounds made as we speak
58
What is the hyoid bone and what is its function?
* Closely related to mandible and temporal bones
* The only bone that does not articulate with another bone
* Serves as a movable base for the tongue
* Aids in swallowing and speech
59
What kind of support does the vertebral column provide?
Axial support
60
What are the 26 vertebral bones, which are separated by intervertebral discs?
* 7 cervical vertebrae are in the neck
* 12 thoracic vertebrae are in the chest region
* 5 lumbar vertebrae are associated with the lower back
* Sacrum (formed by fusion of 5 vertebrae)
* Coccyx (formed by fusion of 3–5 vertebrae)
61
What are primary curvatures?
* Spinal curvatures of the thoracic and sacral regions
* Present from birth
* Form a C-shaped curvature in newborns
62
What are secondary curvatures?
* Spinal curvatures of the cervical and lumbar regions
* Develop after birth
* Form an S-shaped curvature in adults
63
What are the parts of a typical vertebra?
```
• Body (centrum)
• Vertebral arch
*Pedicle
*Lamina
• Vertebral foramen
• Transverse processes
• Spinous process
• Superior and inferior articular processes
```
64
What is the function of the thoracic cage?
Bony thorax, or thoracic cage, protects organs of the thoracic cavity
65
What are the three parts of the thoracic cage?
1. Sternum
2. Ribs
• True ribs (pairs 1–7)
• False ribs (pairs 8–12)
• Floating ribs (pairs 11–12)
3. Thoracic vertebrae
66
The appendicular skeleton is composed of how many bones?
* 126 bones
* Limbs (appendages)
* Pectoral girdle
* Pelvic girdle
67
What are the two bones which compose the shoulder girdle (pectoral girdle? that attach the upper limb to the axial skeleton?
1. Clavicle
2. Scapula
• Light, poorly reinforced girdle
• Allows the upper limb a exceptional flexibility
68
What are the bones of the upper limbs?
* Humerus
* Ulna
* Radius
69
What is the humerus?
• Forms the arm
• Single bone
• Proximal end articulation
*Head articulates with the glenoid cavity of the scapula
• Distal end articulation
*Trochlea and capitulum articulate with the bones of the forearm
70
What two bones compose the forearm?
1. Ulna
| 2. Radius
71
What is the ulna?
• Medial bone in anatomical position
• Proximal end articulation
*Coronoid process and olecranon articulate with the humerus
72
What is the radius?
• Lateral bone in anatomical position
• Proximal end articulation
*Head articulates with the capitulum of the humerus
73
What bones are the hands composed of?
```
• Carpals—wrist bones
*8 bones arranged in two rows of 4 bones in each hand
• Metacarpals—palm bones
*5 per hand
• Phalanges—fingers and thumb
*14 phalanges in each hand
*In each finger, there are 3 bones
*In the thumb, there are only 2 bones
```
74
What are the bones of the pelvic girdle?
• Formed by two coxal (ossa coxae) bones
• Composed of three pairs of fused bones
1. Ilium
2. Ischium
3. Pubis
• Pelvic girdle = two coxal bones, sacrum
• Pelvis = two coxal bones, sacrum, coccyx
75
The total weight of the upper body rests on?
• The pelvis
76
Pelvis protects several organs, including:
* Reproductive organs
* Urinary bladder
* Part of the large intestine
77
What are the properties of the female pelvis?
* Inlet is larger and more circular
* Shallower, on the whole, and the bones are lighter and thinner
* Ilia flare more laterally
* Sacrum is shorter and less curved
* Ischial spines are shorter and farther apart; thus, the outlet is larger
* Pubic arch is more rounded because the angle of the pubic arch is greater
78
What is the femur?
• Thigh bone
• The heaviest, strongest bone in the body
• Proximal end articulation
*Head articulates with the acetabulum of the coxal (hip) bone
• Distal end articulation
*Lateral and medial condyles articulate with the tibia in the lower leg
79
The lower leg consists of which two bones?
1. Tibia
| 2. Fibula
80
What is the tibia?
• Shinbone; larger and medially oriented
• Proximal end articulation
*Medial and lateral condyles articulate with the femur to form the knee joint
• Distal end articulation
*Medial malleolus forms the inner part of the ankle
81
What is the fibula?
• Thin and sticklike; lateral to the tibia
• Has no role in forming the knee joint
• Distal end articulation
*Lateral malleolus forms the outer part of the ankle
82
What bones are the feet composed of?
• Tarsals—7 bones
*Two largest tarsals are the calcaneus (heel bone) and talus
• Metatarsals—5 bones form the sole of the foot
• Phalanges—14 bones form the toes
83
What are the arches of the feet?
* Bones of the foot are arranged to form three strong arches
* Two longitudinal
* One transverse
84
Joints are referred to as:
* Articulations
| * Occur where two or more bones meet
85
What are the functions of joints?
* Hold bones together securely
| * Allow for mobility
86
What are the ways in which joints are classified?
* Functionally
| * Structurally
87
What are functional joint classifications?
* Synarthroses
* Amphiarthroses
* Diarthroses
88
What are synarthroses?
Immovable joints
89
What are amphiarthroses?
Slightly movable joints
90
What are diarthroses?
Freely movable joints
91
What are structural joint classifications?
* Fibrous joints
* Cartilaginous joints
* Synovial joints
92
What are fibrous joints?
* Generally immovable
| * Bones are united by fibrous tissue
93
What are cartilaginous joints?
* Immovable or slightly movable
| * Bones are connected by fibrocartilage
94
What are synovial joints?
* Freely movable
* Articulating bones are separated by a joint cavity
* Synovial fluid is found in the joint cavity
95
Concept Link 3
To understand the structural classes of joints more clearly, recall the properties of tissues that form the joints. Fibrous connective tissue contains many collagen fibers for strength. The three types of cartilage (hyaline, fibrocartilage, elastic) provide structure with some degree of flexibility, and fibrocartilage also has the ability to absorb compressive shock (Chapter 3, p p. 94, 95). Synovial membranes contain areolar connective tissue and line the joint cavities of synovial joints (Chapter 4, p p. 110, 112).
96
What are the types of fibrous joints?
* Sutures
* Syndesmoses
* Gomphoses
97
What is a suture fibrous joint?
Immobile
98
What is a syndesmoses fibrous joint?
* Allow more movement than sutures but still immobile
| * Found on the distal ends of tibia and fibula
99
What is a gomphoses fibrous joint?
* Immobile
| * Found where the teeth meet the facial bones
100
What are the types of cartilaginous joints?
* Synchrondrosis
| * Symphysis
101
What are synchrondrosis cartilaginous joints?
* Immobile
| * Found in epiphyseal plates of growing long bones
102
What are symphysis cartilaginous joints?
* Slightly movable
| * Found in the pubic symphysis, intervertebral joints
103
What are the four distinguishing features of synovial joints?
1. Articular cartilage
2. Articular capsule
3. Joint cavity
4. Reinforcing ligaments
104
What are bursae in synovial joints?
* Flattened fibrous sacs
* Lined with synovial membranes
* Filled with synovial fluid
* Not actually part of the joint
105
What is a tendon sheath?
Elongated bursa that wraps around a tendon
106
What are the types of synovial joints based on shape?
* Plane joint
* Hinge joint
* Pivot joint
* Condylar joint
* Saddle joint
* Ball-and-socket joint
107
What are the developmental aspects of the skeleton from birth to adulthood?
* First “long bones” of a fetus are hyaline cartilage
* Earliest “flat bones” of the fetal skull are fibrous membranes
* As fetus grows, all bone models are converted to bone
108
What are the developmental aspects of the fetal skull?
Fontanels are fibrous membranes connecting the cranial bones
• Known as “soft spots”
• Allow skull compression during birth
• Allow the brain to grow during later pregnancy and infancy
• Usually ossify by 2 years of age
109
Growth of cranium after birth is related to:
* Brain growth
| * Increase in size of the facial skeleton follows tooth development and enlargement of the respiratory passageways
110
What is the size of the cranium in relationship to the body?
* 2 years old—skull is three-fourths the size of adult skull
* 8 or 9 years old—skull is near adult in size and proportion
* Between ages 6 and 11, the face grows out from the skull
111
What are the main skeletal changes from birth to adolescence?
• At birth, the head and trunk are proportionately much longer than the lower limbs
• During puberty:
*Female pelvis broadens
*Entire male skeleton becomes more robust
• By the end of adolescence, epiphyseal plates become fully ossified
112
What is osteoporosis?
• Bone-thinning disease afflicting:
*50 percent of women over age 65
*20 percent of men over age 70
• Disease makes bones fragile, and bones can easily fracture
• Vertebral collapse results in kyphosis (also known as “dowager’s hump”)
• Estrogen aids in health and normal density of a female skeleton
