Muscle Systems

Question 1

Skeletal muscles are ….?

Answer 1

multinucleate, striated, and covered by endomysium

Question 2

Muscle fascicles are …?

Answer 2

bundles of muscle fibers which are covered by perimysium

Question 3

The muscle trunk is …?

Answer 3

a bundle of fascicles and is covered by epimysium and fascia

Question 4

The connective tissue of muscles is …?

Answer 4

bound firmly to the connective tissue of the tendon.

-which connects to the periosteum and the bone matrix

Question 5

A muscle fiber is …?

Answer 5

a single cell consisting of sarcolemma, sarcoplasm, several nuclei, and myofibrils

Question 6

Myofibrils are …?

Answer 6

bundles of thick and thin filaments which are covered by sarcoplasmic reticulum

Question 7

What are organized into sarcomeres?

Answer 7

Thick and thin filaments

Question 8

Thin filaments are composed of …?

Answer 8

actin, tropomyosin, and troponin

Question 9

Thick filaments are composed of …?

Answer 9

myosin

Question 10

Events of a Muscle Contraction

1st Action

Answer 10

The action potential in the motor neuron reaches the axon termini, which release acetylcholine [ACh].

Question 11

Events of a Muscle Contraction

2nd Action

Answer 11

ACh diffuses across the cleft of the neuromuscular junction, inducing an action potential, which spreads over the sarcolemma and down the T tubules.

Question 12

Events of a Muscle Contraction

3rd Action

Answer 12

The action potential reaches the sarcoplasmic reticulum, causing the SR to release Ca++.

Question 13

Events of a Muscle Contraction

4th Action

Answer 13

Ca++ binds to troponin, troponin-tropomyosin moves, exposing myosin-binding sites on actin.

Question 14

Events of a Muscle Contraction

5th Action

Answer 14

Myosin head attaches to actin [=crossbridge formation]; myosin head changes shape, thick and thin filaments slide past each other.

Question 15

Events of a Muscle Contraction

6th Action

Answer 15

Z-discs are drawn toward each other; sarcomeres shorten; muscle fiber shortens; muscle shortens.

Question 16

Events of a Muscle Contraction

7th Action

Answer 16

Myosin head binds fresh ATP and releases from actin.

Question 17

Events of a Muscle Contraction

8`th Action

Answer 17

As long as ATP and Ca++ are present, the cycle continues.

Question 18

The less moveable part of the muscle

Answer 18

origin

Question 19

The more moveable part of the muslce

Answer 19

insertion

Question 20

What do synergists do?

Answer 20

function together to produce movement

Question 21

What do antagonists do?

Answer 21

oppose or reverse the action of another muscle

Question 22

What do prime movers do?

Answer 22

responsible for movement

Question 23

Head moving muscles cause …?

Answer 23

flexion, extension, rotation, abduction, and adduction of the head

Question 24

Facial muscles originate on…
insert on…
and cause movement of the…

Answer 24

skull bones or fascia
skin
facial skin, lips, and eyelids

Question 25

What opens the jaw

What closes the jaw

Answer 25

gravity

3 muscles

Question 26

Most respiratory movement is caused by ?

Answer 26

the diaphragm

Question 27

Other than the diaphragm, what muscles aid in respiration?

Answer 27

muscles attached to the ribs

Question 28

Abdominal wall muscles do what?

Answer 28

hold and protect abdominal organs and cause abduction, rotation, and flexion of the vertebral column.

Question 29

Muscles which attach the humerus to the scapula or the trunk cause …?

Answer 29

flexion, extension, abduction, adduction, rotation, or circumduction of the arm.

Question 30

Anterior pelvic muscles cause …?

Answer 30

flexion of the thigh.

Question 31

Muscles of the buttocks …?

Answer 31

extend, abduct, and rotate the thigh.

Question 32

The thigh can be divided into 3 compartments:
medial, anterior, posterior
What do they do?

Answer 32

medial compartment muscles adduct the thigh
anterior compartment muscles flex the thigh
posterior compartment muscles extend the thigh.

Question 33

The leg muscles can be divided into 3 compartments
medial, anterior, posterior
What do they do?

Answer 33

anterior compartment muscles dorsiflex, invert, or evert the foot
lateral compartment muscles plantar flex and evert the foot
posterior compartment flex the leg, plantar flex and evert the foot, and flex the toes.