Quiz 2 Muscle Tissue and Muscular System

Question 1

Skeletal striated muscle

Answer 1

Voluntary somatic muscle that makes up the gross skeletal muscles that compose the muscular system, moving or stabilizing bones and other structures

Question 2

Cardiac striated muscle

Answer 2

Involuntary visceral muscle that forms most of the walls of the heart and adjacent parts of the great vessels, such as the aorta, and pumps blood

Question 3

Smooth muscle

Answer 3

(Unstriated muscle) is involuntary visceral muscle that forms part of the walls of most vessels and hollow organs (viscera), moving substances through them by coordinated sequential contractions (pulsations or peristaltic contractions).

Question 4

Flat muscles

Answer 4

Have parallel fibers often with an aponeurosis—for example, the external oblique. The sartorius is a muscle with parallel fibers.

Question 5

Pennate muscles

Answer 5

Feather like in the arrangement of their fascicles, and may be unipennate, bipennate, or multipennate—for example, extensor digitorum longus (unipennate), rectus femoris (bipen- nate), and deltoid (multipennate).

Question 6

Fusiform muscles

Answer 6

Spindle shaped with a round, thick belly (or bellies) and tapered ends—for example, biceps brachii.

Question 7

Convergent muscles

Answer 7

Arise from a broad area and converge to form a single tendon—for example, pectoralis major.

Question 8

Quadrate muscles

Answer 8

Four equal sides, for example, the rectus abdominis, between its
tendinous intersections.

Question 9

Circular or sphincteral muscles

Answer 9

Surround a body opening or orifice, constricting it when contracted—for example, orbicularis oculi (closes the eyelids).

Question 10

Multiheaded or multibellied muscles

Answer 10

Have more than one head of attachment or more than one contractile belly, respectively. Biceps muscles have two heads of attachment (e.g., biceps brachii), triceps muscles have three heads (e.g., triceps brachii), and the digastric and gastrocne- mius muscles have two bellies. (Those of the former are arranged in tandem; those of the latter lie parallel.)

Question 11

Origin

Answer 11

Usually the proximal end of the muscle, which remains fixed during muscular contraction

Question 12

Insertion

Answer 12

Usually the distal end of the muscle, which is movable.

Question 13

Reflexive Contraction

Answer 13

Not voluntarily controlled. Examples are the respiratory movements of the diaphragm, controlled most of the time by reflexes stimulated by the levels of oxygen and carbon dioxide in the blood (although we can willfully control it within limits), and the myotatic reflex, which results in movement after a muscle stretch produced by tapping a tendon with a reflex hammer.

Question 14

Tonic Contraction

Answer 14

Even when “relaxed,” the muscles of a conscious individual are almost always slightly contracted.

Question 15

Phasic Contraction

Answer 15

(1) isotonic contractions, in which the muscle changes length in relationship to the production of movement, and (2) isometric contrac- tions, in which muscle length remains the same—no movement occurs, but the force (muscle tension) is increased above tonic levels to resist gravity or other antagonistic force.

Question 16

Two types of isotonic contractions

Answer 16

(1) Concentric contrac- tion, in which movement occurs as a result of the muscle shortening—for example, when lifting a cup, pushing a door, or striking a blow.
(2) Eccentric contraction, in which a contracting muscle lengthens—that is, it undergoes a controlled and gradual relaxation while continually exerting a (diminishing) force, like playing out a rope.

Question 17

Prime mover

Answer 17

(Agonist) is the main muscle responsible for producing a specific movement of the body. It con- tracts concentrically to produce the desired movement, doing most of the work (expending most of the energy) required.

Question 18

Fixator

Answer 18

Steadies the proximal parts of a limb through isometric contraction while movements are occurring in distal parts.

Question 19

Synergist

Answer 19

Complements the action of a prime mover. It may directly assist a prime mover, providing a weaker or less mechanically advantaged component of the same movement, or it may assist indirectly, by serving as a fixator of an intervening joint when a prime mover passes over more than one joint

Question 20

Antagonist

Answer 20

A muscle that opposes the action of another muscle. Directly opposes the prime mover.

Question 21

Shunt muscle

Answer 21

A muscle’s pull is exerted along a line that parallels the axis of the bones to which it is attached.

Question 22

Spurt muscle

Answer 22

The more oblique a muscle’s line of pull is oriented to the bone it moves (i.e., the less parallel the line of pull is to the long axis of the bone, e.g., the biceps brachii when the elbow is flexed), the more capable it is of rapid and effective movement