Ch. 1 - Skeletal system/types of bones/bone development/properties

Question 1

Axial skeleton

Answer 1

80 bones
- skull, spinal column, sternum, ribs, pelvis

Question 2

Appendicular skeleton

Answer 2

126 bones
- upper and lower extremities

Question 3

Long bones

Answer 3

long cylindrical shaft that contains the medullary cavity (containing bone marrow) with protruding ends
- femur, humerus, phalanges, metatarsals, metacarpals, tibia, fibula, radius, ulna

Question 4

Anatomy of a long bone

Answer 4

• Epiphyseal plate: growth plate, made of cartilage that becomes spongy bone once you stop growing, separates epiphysis and diaphysis
• Articular/hyaline cartilage: covers epiphysis to provide cushion and reduce friction, breaks down over time
• Endosteum: fibrous, surrounds medullary cavity
• Cortex: forms walls of diaphysis, hard and dense
• Medullary cavity: innermost cavity of bone, contains yellow marrow
• Periosteum: outermost layer of bone
• Epiphysis: cancellous/trabecular/spongy bone, used to connect bones and absorb force

Question 5

Short bones

Answer 5

small cube-shaped, proportionally large articular surface in order to articular with more than one bone
- carpals and tarsals

Question 6

Flat bones

Answer 6

usually having a curved surface and varying from thick to very thin, provide protection and muscle attachment
- ilium, ribs, sternum, clavicle, scapula

Question 7

Irregular bones

Answer 7

variety of purposes
- ischium, pubis, maxilla, ethmoid, ossicles, vertebrae

Question 8

Sesamoid

Answer 8

embedded w/n the tendon of a musculotendinous unit that provides protection and improve mechanical advantage
- patella, great toe, and thumb

Question 9

Endochondral bones

Answer 9

develop from hyaline cartilage, grow rapidly into structures similar to the bones they will eventually become

Question 10

Bones grow longitudinally as long as:

Answer 10

the growth plate is open, but will continue to grow in diameter

Question 11

Osteoblasts

Answer 11

new bone is formed by these

Question 12

Osteoclasts

Answer 12

cells that reabsorb old bone

Question 13

What builds new layers of bone?

Answer 13

periosteum

Question 14

Most outer bone is cortical, with cancellous bone underneath. Explain each.

Answer 14

• cortical: withstand more stress, low porosity
• cancellous: withstand greater strain before fracturing, spongy, high porosity

Question 15

Wolff’s Law

Answer 15

bone in a healthy individual will adapt to the loads under which it is placed; more load = stronger bone, less load = weaker bone