The Muscular System: Key Terms

Question 1

actin

Answer 1

one of the two contractile proteins in muscle cells; the other is myosin

Question 2

agonist

Answer 2

the muscle that carries out a given movement; prime mover

Question 3

antagonist

Answer 3

the muscle that opposes an agonist; it must relax when the agonist contracts

Question 4

cardiac muscle

Answer 4

involuntary muscle that makes up the heart wall

Question 5

fascia

Answer 5

the fibrous sheath of connective tissue that covers a muscle; called deep fascia to differentiate it from the superficial fascia that underlies the skin

Question 6

fascicle

Answer 6

a small bundle, as of muscle or nerve fibers

Question 7

insertion

Answer 7

in a given movement, the point where a muscle attaches to a moving part of the skeleton

Question 8

muscle

Answer 8

and organ that produces movement by contracting; also the tissue that composes such organs

Question 9

myosin

Answer 9

one of the two contractile proteins in muscle cells; the other is actin

Question 10

neuromuscular junction (NMJ)

Answer 10

the point of contact, or synapse, between a branch of a motor neuron and a muscle cell

Question 11

origin

Answer 11

in a given movement, the point where a muscle is attached to a stable part of the skeleton

Question 12

skeletal muscle

Answer 12

voluntary muscle that moves the skeleton and maintains posture

Question 13

smooth muscle

Answer 13

involuntary muscle that makes of the wall of hollow organs, vessels, and ducts; visceral muscle

Question 14

synergist

Answer 14

a muscle that assists an agonist to produce a given movement

Question 15

tendon

Answer 15

a fibrous band of connective tissue that attaches a muscle to a bone

Question 16

tonus

Answer 16

a state of steady, partial muscle contraction that maintains firmness; muscle tone

Question 17

acetylcholine (ACh)

Answer 17

a neurotransmitter that stimulates contraction of skeletal muscles

Question 18

ALS

Answer 18

amyotrophic lateral sclerosis: a disease caused by motor neuron degeneration resulting in muscular weakness and atrophy; Lou Gehrig disease

Question 19

chronic fatigue syndrome (CFS)

Answer 19

a disease of unknown cause that involves persistent fatigue, along with muscle and joint pain and other sx; may be virally induced

Question 20

dermatomyositis

Answer 20

a disease of unknown origin involving muscular inflammation as well as dermatitis and skin rashes

Question 21

fibromyalgia syndrome (FMS)

Answer 21

a disorder associated with widespread muscular aches and stiffness and having no known cause

Question 22

muscular dystrophy

Answer 22

a group of hereditary muscular disorders marked by progressive weakness and muscular atrophy

Question 23

myasthenia gravis (MG)

Answer 23

a disease characterized by progressive muscular weakness; an autoimmune disease affecting the neuromuscular junction

Question 24

polymyositis

Answer 24

a disease of unknown cause involving muscular inflammation and weakness

Question 25

repetitive strain injury (RSI)

Answer 25

tissue damage caused by repeated motion, usually overuse of the arm or hand in occupational activities such as writing, typing, painting, or using hand tools; aka repetitive motion injury, cumulative trauma injury, overuse syndrome

Question 26

sprain

Answer 26

injury to a ligament caused by abnormal or excessive force at a joint, but without bone dislocation or fracture

Question 27

strain

Answer 27

trauma to a muscle because of overuse or excessive stretch; if severe, may involve muscular tearing, bleeding, separation of a muscle from its tendon, or tendon separation from a bone

Question 28

tendinitis

Answer 28

inflammation of a tendon, usually caused by injury or overuse; the shoulder, elbow, and hip are common sites; tendonitis

Question 29

tenosynovitis

Answer 29

inflammation of a tendon and its sheath

Question 30

CK

Answer 30

creatine kinase: an enzyme found in muscle tissue; the serum CK level increases in cases of muscle damage; creatine phosphokinase

Question 31

EMG

Answer 31

electromyography: study of electrical activity of muscles during contraction