Second half of Chapter 9

Question 1

Exercise and Articular Cartilage:

Answer 1

Exercise warms synovial fluid.Becomes less viscous, more easily absorbed by cartilage.Cartilage then swells and provides a more effective cushion. Warm-up period before vigorous exercise helps protect cartilage from undue wear and tear

Question 2

Exercise and Articular Cartilage continued

Answer 2

Repetitive compression of nonvascular cartilage during exercise squeezes fluid and metabolic waste out of the cartilage.When weight removed, cartilage absorbs synovial fluid like a sponge taking in oxygen and nutrients to the chondrocytes.Without exercise, cartilage deteriorates more rapidly from inadequate nutrition and waste removal.

Question 3

Joints and Lever Systems

Answer 3

Long bones act as levers to enhance the speed or power of limb movements.Lever—any elongated, rigid object that rotates around a fixed point called a fulcrum
Rotation occurs when an effort applied overcomes resistance (load) at some other point. Resistance arm and effort arm are described relative to fulcrum

Question 4

Mechanical Advantage Two kinds of advantage conferred by a lever:
Exerting more force

Answer 4

Exerting more force against a resisting object than the force applied to the lever. Moving a heavy object with help of crowbar

Question 5

Mechanical Advantage Two kinds of advantage conferred by a lever:Moving the resisting object farther or faster

Answer 5

Moving the resisting object farther or faster than the effort arm is moved.Movement of rowing a boat
A single lever cannot confer both advantages
As one increases, the other decreases

Question 6

Mechanical advantage (MA) of a lever

Answer 6

Mechanical advantage (MA) of a lever—the ratio of its output force to its input force

Question 7

Range of Motion

Answer 7

Range of motion (ROM)—the degrees through which a joint can move.ROM determined by:
Structure of the articular surfaces(Elbow).
Strength and tautness of ligaments and joint capsules(stretching, double jointed)
Action of the muscles and tendons(nervous system or muscle tone)

Question 8

Axes of Rotation

Answer 8

Axes of rotation:A moving bone has a relatively stationary axis of rotation that passes through the bone in a direction perpendicular to the plane of movement

Question 9

Flexion

Answer 9

Flexion—movement that decreases joint angle

Common in hinge joints

Question 10

Extension

Answer 10

Extension—movement that straightens a joint and returns a body part to the zero position

Question 11

Hyperextension

Answer 11

Hyperextension—extension of a joint beyond the zero position

Flexion and extension occur at nearly all diarthroses, hyperextension is limited to a few

Question 12

Abduction

Answer 12

Abduction—movement of a body part in the frontal plane away from the midline of the body

Question 13

Adduction

Answer 13

Adduction—movement in the frontal plane back toward the midline

Question 14

Elevation

Answer 14

Elevation—movement that raises a body part vertically in the frontal plane

Question 15

Depression

Answer 15

Depression—movement that lowers a body part in the same plane

Question 16

Protraction

Answer 16

Protraction—the anterior movement of a body part in the transverse (horizontal) plane

Question 17

Retraction

Answer 17

Retraction—posterior movement

Question 18

Supination

Answer 18

Supination—forearm movement that turns palm to face anteriorly or upward

Question 19

Pronantion

Answer 19

Pronation—forearm movement that turns palm to face either posteriorly or downward.

Question 20

Flexion

Answer 20

Flexion—forward-bending movements at the waist or neck

Question 21

Extension

Answer 21

Extension—straightens trunk or neck

Question 22

Hyperextension

Answer 22

Hyperextension—bending over backward

Question 23

Lateral flexion

Answer 23

Lateral flexion—tilting the head or trunk to the right or left at the midline

Question 24

Special Movements of Head and Trunk

Answer 24

Right and left rotation of trunk and head

Question 25

Temporomandibular joint (TMJ) syndrome

Answer 25

Temporomandibular joint (TMJ) syndrome
May affect as many as 75 million Americans
Signs and symptoms.Clicking sounds in the jaw, imitation of jaw movement
Pain radiating from jaw down the neck, shoulders, and back.Can cause moderate intermittent facial pain, or severe headaches, vertigo (dizziness), tinnitus (ringing in the ears)

Question 26

Knee Injuries and Arthroscopic Surgery

Answer 26

Highly vulnerable to rotational and horizontal stress.Most common injuries are to the menisci and anterior cruciate ligament (ACL).Heal slowly due to scanty blood flow

Question 27

Arthritis

Answer 27

Arthritis—a broad term for pain and inflammation of joints.Most common crippling disease in the United States

Question 28

Osteoarthritis (OA)

Answer 28

Osteoarthritis (OA)—most common form of arthritis

“Wear-and-tear arthritis”.Results from years of joint wear. Articular cartilage softens and degenerates