EXE 408: FINAL EXAM

fall 2025

206

the human adult skeleton has _____ bones

270

babies are usually born with around _____ bones that fuse together as they grow

axial skeleton

skull, thoracic cage, vertebral column/spine

appendicular skeleton

upper and lower extremities, including shoulder and pelvis

clavicle

1 and 3

scapula

2 and 4

humerus

5

ulna

6

radius

7

carpus

8

metacarpals

9

phalanges

10

pelvic girdle

11

femur

12

patella

13

fibula

14

tibia

15

tarsus

16

calcaneus

17

metatarsal

18

phalanges

19

long bone

examples: femur, tibia, radius

function: levers to transmit longitudinal force

short bone

examples: carpal, tarsal

function: levers to transmit longitudinal force

flat bone

examples: sternum, ribs, skull, iliac crest

function: protection, points of attachment for ligaments

irregular bones

examples: vertebrae

function: providing protection, support, attachment points for muscles, and contributing to blood cell production and mineral storage

sesamoid bones

examples: patella

function: improved lever

osteoblast

form new bones

osteoclast

resorb old bone

ruffled border allows osteoclast to secrete calcium as consequence of killing of bones

osteocyte

mature bone cell

support, protection, system levers to allow motion

3 important mechanical functions of bones

mineral component (calcium carbonate, calcium phosphate)

60-70% of weight of bone

water

25-30% of weight of bone

mineral component

what contributes to stiffness and compressive strength in bone?

collagen

what contributes to flexibility and tensile strength (ability to resist tension) in bone?

cortical bone

compact mineralized bone with low porosity; found in the shafts of long bones

trabecular (cancellous) bone

less compact bone with high porosity; found in the ends of long bones and the vertebrae

epiphyseal plates/epiphyses

growth centers where new bone cells are produced until the epiphysis closes during late adolescence or early adulthood

Epiphysis

develop from secondary ossification centers

found at the ends of long bones

protected by layer of articular cartilage

Metaphysis

meta: after

wide portions of long bones

Diaphysis

between (dia) two epiphyses

develop from primary ossification centers

hollow structure surrounding the medullary cavity

Medullar cavity

used for fat storage site

not in flat bone

periosteum

outer layer of the bone

periosteum is well supplied with blood vessels and nerves

hypertrophy

just like muscle, bones respond to certain kinds of training

Wolff’s law

the densities, and to a lesser extent, the sizes and shapes of bones are determined by the magnitude and direction of the acting forces

what diminishes bone density?

lack of weight bearing exercise

spending time in water

bed rest

traveling in space outside of the earth’s gravitational field

osteopenia

pre-stage to osteoporosis

osteoporosis

disorder involving decreased bone mass and strength with pain and one or more fractures resulting from daily activity

osteoporosis

collapse in a wedge shape

cannot straighten up

often associated with aging, especially women

osteoblast < osteoclast

cortical bone: thinner, less dense

trabecular bone: less trabeculae, thinner, most vulnerable

true

dynamic loading during exercise has been shown to affect bone size and strength more than muscle mass

weight bearing exercise

since the larger the forces the skeletal system sustains, the greater the osteoblast response

type 1: postmenopausal

osteoporosis affects about 40% of women after age 50

type 2: age-associated

osteoporosis affects most women and men after age 70

female athlete triad

osteoporosis, disordered eating, amenorrhea (loss of menstrual cycle)

transverse bone fracture

linear bone fracture

oblique, nondisplaced bone fracture

oblique, displaced bone fracture

spiral bone fracture

greenstick bone fracture

comminuted bone fracture

stress fracture

• relatively low load but repeated load

• increase training duration or intensity

• no time for bone remodeling

• abrupt change in running surface

synarthroses

immovable

sutures

dense fibrous tissue binds the bones together

amphiarthroses

slightly movable

symphyses: a place where two bones are closely joined

hyaline cartilage disc separating the bones of the pubic symphysis

diarthroses or synovial

freely movable

articular (hyaline) cartilage

a protective layer of dense white connective tissue covering the articulating bone surfaces

articular (joint) capsule

a double-layered membrane that surrounds the joint

synovial fluid

clear, slightly yellow liquid that provides lubrication inside the articular capsule

bursae

small capsules filled with synovial fluid that cushion the structures they separate

Collateral ligaments

a

articular (joint) capsule

b

blood vessels

c

nerves

d

synovial membrane

e

articular (hyaline) cartilage - no blood vessels or nerves

f

bursae

g

problems of not having blood vessels in articular cartilage

• Articular cartilage is squish material

• Compressed: water flows out

• Unloaded: absorb the water again.

• Through loading and unloading - the water that once flows out brings nutrition and oxygens and be absorbed to the cartilage.

Main Structure of Articular Cartilage

1. Cells – Chondrocytes (<10% volume)

2. Fibers – Collagen (10-30% of weight, % increase with age)

3. Proteoglycan (3-10%)

4. Water (60-90%)

Diarthroses/Synovial

• gliding

• hinge

• pivot

• condyloid

• saddle

• ball and socket

• translations and rotations possible of synovial joint

saddle joint

gliding joint

condyloid joint