Regulation of Movement

Question 1

Joints

Answer 1

The region where two or more bones a􀄴ach is referred to as a joint. Each
joint is classified according to its structure and degree of mobility. There
are three classifications of joints: cartilaginous, fibrous, and synovial
(McCance and Huether, 2017). Fibrous joints fit closely together and are
fixed, permi􀄴ing li􀄴le if any movement, such as the syndesmosis between
the tibia and fibula (Fig. 38.1A). Cartilaginous joints have li􀄴le movement
but are elastic and use cartilage to unite separate bony surfaces, such as the
synchondrosis that a􀄴aches the ribs to the costal cartilage. When bone
growth is complete, the joints ossify (see Fig. 38.1B). Synovial joints, or
true joints, such as the hinge type at the elbow, are freely movable and the
most mobile, numerous, and anatomically complex body joints (see Fig.
38.2AB).

Question 2

Ligaments, Tendons, and Cartilage

Answer 2

Ligaments are white, shiny, flexible bands of dense fibrous tissue that bind joints and connect bones and cartilage and are elastic.

Tendons are white, glistening fibrous bands of tissue. Tendons connect muscle to bone and are
strong, flexible, and inelastic.The Achilles tendon is the thickest and strongest tendon in the body.

Cartilage is nonvascular (without blood vessels) supporting connective tissue located chiefly in the
joints and thorax, trachea, larynx, nose, and ear. It has the flexibility of a firm, plastic material. Because of its gristlelike nature, cartilage sustains weight and serves as a shock absorber between articulating bones.
Permanent cartilage is unossified (not hardened), except in advanced age and diseases such as osteoarthritis, which impairs mobility.

Question 3

Skeletal muscle

Answer 3

2 types of muscle contractions, isotonic and isometric. An
isotonic is mobilizing, causing body to move.
isometric contraction is stabilizing, causing
the body to hold a stable position. Isotonic contractions
have two varieties, concentric and eccentric. In concentric tension increased muscle contraction causes muscle shortening, resulting in
movement. Eccentric tension causes lengthening of a muscle to control the speed
and direction of movement.
Isometric contraction causes increase in muscle tension or muscle work but no shortening or active movement of the muscle (e.g.,instructing a patient to tighten and relax a muscle group, as in quadriceps
set exercises or pelvic floor exercises). Voluntary movement is a combination of isotonic and isometric contractions.

Prime mover - Muscle that directly performs a specific movement. Brachialis is a prime mover when flexing the
elbow.
Antagonist - Muscle that directly when contracting opposes prime mover or
agonist. Relaxes while prime mover contracts. Provides
precision and control during contraction of prime mover.
The triceps brachii is an
extensor that relaxes
when brachialis
contracts.
Synergists - Muscle that contracts at same time as prime mover. Facilitates
prime mover actions to produce more effective movement.
The deltoid contracts
when brachialis contracts
Fixators - Muscles that stabilize joints; act as type of synergist. Serve to
maintain posture and balance.
The deltoid maintains
balance of arm when
brachialis contracts.

Question 4

Proprioception

Answer 4

Proprioception is a muscle sense that makes us aware of the position of the body and its parts, including body movement, orientation in space, and muscle stretch. For example, if you close your eyes and bend your elbow, you will know where your hand and lower arm are even if you cannot see them. Stretch receptors associated with muscles, joint capsules, and tendons are classified as proprioceptors. The nervous system regulates posture, which requires coordination of proprioception and balance. As a person carries out ADLs, proprioceptors monitor muscle activity and body position. For example, the proprioceptors on the soles of the feet contribute to correct posture
while standing or walking. In standing, pressure is continuous on the bottom of the feet. The proprioceptors monitor the pressure, communicating this information through the nervous system to the antigravity muscles.

Question 5

Balance and Alignment

Answer 5

Body balance occurs when a person is properly aligned with a relatively low center of gravity balanced over a wide, stable base of support. In the case of standing, a vertical line falls from the center of gravity through the base of support (Fig. 38.6). Adequate balance is necessary to stand, walk, turn, lift, or perform ADLs. Proper posture enhances body balance. The term “posture” means maintaining optimal body position or alignment that favors function. It requires the least muscular work to maintain, and places the least strain on muscles, ligaments, and bones. Nurses maintain patient alignment when positioning patients and when turning or moving them (see Chapter 39). The nervous system controls balance specifically through the inner ear, the cerebellum, and through vision.

Question 6

To achieve balance and alignment

follow these steps:

Answer 6

• Widen your base of support by separating the feet to a comfortable
distance.
• Bring the center of gravity closer to your base of support to
increase balance.
• Bend your knees and flex the hips until squa􀄴ing, and maintain
proper back alignment to keep the trunk erect.