Types of Muscles & Contraction

Question 1

Smooth Muscle

Answer 1

These muscles form the walls of the hollow viscera (stomach, bladder and various systems of tubes like those found in the circulatory & respiratory systems and the reproductive organs) The contraction of these muscles is unvoluntary

Question 2

Cardiac Muscle

Answer 2

This muscle displays structural and functional ressemblances to both skeletal and smooth muscles. The most characteristic feature of the fibers of the cardiac muscle are that they give off branches and are connected and are connected in such a manner that they can function as a single unit for contraction

Question 3

Skeletal Muscles

Answer 3

Composed of thread-like fibers displaying alternating dark & light bands (striations). The fibers are innervated by cranial or spinal nerves and are under volontary control. This type of muscles contains both pain endings and proprioceptors. Two of its principle movement are body movement and maintenance of posture.

Question 4

Structure of Skeletal Muscle

Answer 4

The muscle ms make up approximatively 40 to 45% of the adult bodyweight. The volontary muscular system includes appr. 434 muscles, but only 75 pairs are involved in general posture and movement.

Question 5

Tonic Muscles

Answer 5

Slow twitch (Type I, red) Slow twitch fibers are more efficient in maintaining isometric activity & sustained contractions. Postural muscles tend toward overuse and eventual shortening. Stabilizers tend to be tonic.

Question 6

Phasic Muscles

Answer 6

Fast twitch (Type II, white) Fast Twich fibers can produce more force but fatigue more easily. Movers tend to be phasic

Question 7

Agonist

Answer 7

Principle muscle in movement

Question 8

Antagonist

Answer 8

Opposite muscle in action to the agonist

Question 9

Synergist

Answer 9

A muscle or muscles that act to neutralize an undesired action.

Question 10

Co-contraction

Answer 10

Contraction of tha agonist and antagonist at the same time to produce a stable joint or balanced movement.

Question 11

Motor Unit

Answer 11

A motor neuron and the muscle fibers it innervates. A motor unit contracts according to the “All or nothing” principle, meaning it will either contract or not at all.

Question 12

Isometric Contraction

Answer 12

Contraction of a muscle in a static position. There is no change of length of the muscle or the angle of the joint. Isometric contractions are typically used by the stabilizers.

Question 13

Isotonic (Dynamic) Contraction

Answer 13

Contraction of a muscle through the full ROM or part of ROM againt a resitance force. Isotonic contractions are typically used by the movers and can be divides into two specific types : concentric & eccentric.

Question 14

Concentric Contraction

Answer 14

Shortening contraction. The muscles shortens during the contraction and the angle of the joint/s will decrease.

Question 15

Eccentric Contraction

Answer 15

Lenghtening contraction. The muscle lengthens during the contraction and the angle of the joint/s will increase.

Question 16

Isokinetic Contraction

Answer 16

Contraction of a muscle through all part of the ROM with the resistance automatically adjusting to the degree of force exerted against it. (ex : breastroke in swimming)