SKELETAL SYTSEM

Question 1

What is the name of the anterior cavity of the scapula?

Answer 1

Subscapular fossa

Question 2

Which part of the scapula articulates with the humerus?

Answer 2

Glenoid cavity

Question 3

_______ is where the membrane passes and attaches the fibula to the tibia.

Answer 3

Interosseous border

Question 4

The number of cervical vertebrae is?

Answer 4

7

Question 5

To which part of the sternum does the sternoclavicular joint attach?

Answer 5

Manubrium

Question 6

Name and classify the tissues that make the largest contribution to the skeleton.

Answer 6

Bones

• osteoblasts and osteoclasts
• chemical composition of bone matric
• organic matrix, e.g collagen
• inorganic salts, e.g Ca and P
• bone marrow, periosteum and endosteum, neurovasulature

Cartilage

• hyalin
• fibrous
• elastic

Question 7

Describe the changes in the proportion of cartilage and bone contribution from embryo to old age.

Answer 7

At the embryonic stages of development, the skeleton mainly consists of hyaline cartilage and at the 8th week the cartilage starts to ossify and the majority of the skeleton becomes bone. Babies have more cartilage than bone, whereas adults have more bones than they do cartilage.

Question 8

List the 5 functions of the skeletal system.

Answer 8

1. Main supporting tissue of the body
2. Protection of vital organs
3. Mechanical basis for movement
4. Storage of salts
5. Contain blood-producing cells

Question 9

Classify bones according to macroscopic structures and give examples of each.

Answer 9

• Compact bone: dense bone that forms the outer shell
  of all bones
• mainly solid matter and little spaces between bone
  tissue
  e.g the periosteum
• Spongy bone: consists of spicules of bone enclosing
  cavities containing blood-forming
  cells
• little solid matter and a lot of spaces
  between bone tissue
  e.g inside the bone

Question 10

Explain how the architecture of compact and spongy bone varies with function.

Answer 10

• Compact bone provides strength for weight-bearing- it mostly occurs near the middle of the shaft
• Spongy bones reduce the density of the bone and allow the bone to compress under stress. It mostly occurs in areas that are not heavily stressed or areas that experience stress from many directions

Question 11

Classify bones according to the 5 shapes and give examples of each.

Answer 11

1. Long bones: tubular, e,g humerus and femur
2. Short bones: cuboidal, only found in the tarsals, e.g bones of the wrist and ankle
3. Flat bones: two compact bone plates separated by spongy bones, e.g skull
4. Irregular bones: bones with various shapes, e.g bones of the face
5. Sesamoid bones: round/oval bones that develop in the tendons

Question 12

Classify bones according to development and give examples of each.

Answer 12

• Intramembranous ossification
  Example: clavicles, flat bones, mandible
• Endochondral ossification
  Example: all bones except those mentioned above

Question 13

Compare the development of intramembranous and endochondral bone.

Answer 13

In intramembranous ossification, mesenchymal models are formed directly from the mesenchyme

In endochondral ossification, cartilage models are formed from the mesenchyme and the bones replace all the cartilage

Question 14

Identify the 6 major parts of a typical long bone.

Answer 14

1. Epiphysis
2. Diaphysis
3. Medullary cavity
4. Articular cartilage
5. Periosteum
6. Endosteum

Question 15

List, explain, and give examples of the most common bone markings.

Answer 15

• Depressions and openings
• Projections or processes
• Articulation facets

Question 16

Discuss endochondral ossification.

Answer 16

• The mesenchymal cells form a cartilaginous bone model
• The cartilage calcifies and the periosteal capillaries supply its interior
• Capillaries + bone forming cells = periosteal bud
• Capillaries initiate the primary ossification centre
• Diasphysis is formed
• Secondary ossification centres form epiphysis
• Flared part near epiphysis = metaphysis
• During growth, epiphysial plates intervene between the diaphysis and epiphysis to allow growth
• Epiphysial lines are formed by fusing of diaphysis and epiphysis

Short bones only undergo the primary ossification centre.

Question 17

Discuss fracture healing.

Answer 17

• Reduction of fratcture
• Collagen producing fibroblasts form a collar of callus to hold the bone together
• Callus calcifies
• Callus is reabsorbed and replaced by bone matrix

Question 18

Discuss resorption.

Answer 18

• Bone may be absorbed
• Atrophy
• Hypertrophy

Question 19

Discuss response to bone stress.

Answer 19

• Bones remodel in relationship to stressed placed on them.

Question 20

Name the 3 types of cartilage, their structure, functions and give examples of each.

Answer 20

1. Hyaline
   Moderate amount of collagen fibers, e.g articular surfaces of bones
2. Fibrous cartilage
   Substantial amount of collagen fibers, e.g intervertebral discs
3. Elastic
   Contains collagen fibers and a large number of elastic fibers, e.g external ear

Question 21

List the primary subdivisions of the appendicular skeleton.

Answer 21

Upper extremity:
Shoulder girdle, arm, forearm

Lower extremity:
Pelvic girdle, thigh, leg, ankle, and foot

Question 22

List the primary subdivisions of the axial skeleton.

Answer 22

Skull, vertebral column, sacrum, ribs, sternum, cranium, mandible, facial skeleton, calvaria