Topic 11: Muscular System

Question 1

Muscular System

Answer 1

— refers to skeletal muscle system
— primarily attached to bone
— produce movement by contracting – byproduct = heat

Question 2

Skeletal Muscle

Answer 2

cells called fibers

Question 3

fascicle

Answer 3

group fibers

Question 4

whole muscle

Answer 4

= group of fascicles

Question 5

List the CT component of skeletal muscle

Answer 5

1) Fascia

2) Tendons + Aponeuroses

Question 6

Fascia

Answer 6

= CT

Question 7

Epimysium

Answer 7

– surrounds entire muscle

Question 8

Perimysium

Answer 8

– surrounds fascicles

Question 9

Endomysium

Answer 9

– surrounds each muscle fiber

Question 10

Tendons + Aponeuroses

Answer 10

— extensions of epi-, peri-, + endomysium

— anchors to bone (periosteum), cartilage, skin, or fascia

Question 11

tendon

Answer 11

= rope-like
o e.g. Achilles tendon

connect muscle to bone

Question 12

aponeurosis

Answer 12

e. g. galea aponeurotica = epicranial aponeurosi

- sheet like

Question 13

Describe the structure of Skeletal Muscle Fiber

Answer 13

— large multinucleate cells
— parts:
1) Sarcolemma = cell membrane
2) Sarcoplasm = cytoplasm
3) Myofibrils (intracellular
4) T-tubules structures)
5) Sarcoplasmic Reticulum

Question 14

Myofibrils

Answer 14

— within each fibre there are several hundreds to thousands

— composed of sarcomeres:

Question 15

Describe the structure of sarcomeres

Answer 15

(composed of proteins):
o made of 2 types of myofilaments:
a) thin filaments:
thick filaments

Question 16

thin filaments

Answer 16

— composed of:
i. actin – functions in contraction

2
ii. tropomyosin + iii. troponin – regulate
contraction (regulatory proteins)

Question 17

thick filaments

Answer 17

— composed of:
i. myosin – functions in contraction
— attached to Z discs by titin
— has rod-like tail with 2 globular heads
o head extends toward actin and attaches to it
– forming a crossbridge

Question 18

A band

Answer 18

dark = length of thick filament – myosin + actin

with troponin + tropomysosin

Question 19

H zone

Answer 19

lighter band at center of A band – myosin only

Question 20

I band

Answer 20

— light = actin (with troponin + tropomyosin) + titin

Question 21

Z discs

Answer 21

(in center of I band)
— actin + titin attach
— connect sarcomeres: between 2 z-discs = 1 sarcomere

Question 22

M line

Answer 22

where myosin tails (thick myofilaments) attach to
each other (center of sarcomere

Question 23

T-tubules

Answer 23

— continuations of sarcolemma that extend deep into fiber (cell)
— directly encircle myofilaments of myofibrils at junction of A & I bands
(2/sarcomere)

Question 24

Sarcoplasmic Reticulum

Answer 24

— = smooth ER

— triad = 2 enlarged areas of SR (terminal cisternae) & T-tubule

Question 25

How do muscles produce movement?

Answer 25

1) Pulling on bones when they contract
2) Using group action
3) Lever systems

Question 26

origin

Answer 26

attachment of tendon to stationary bone

Question 27

insertion

Answer 27

attachment of tendon to movable bone

Question 28

agonist

Answer 28

major muscle producing the movement

Question 29

synergists

Answer 29

help the agonist action and prevent undesirable motions caused by the
agonist

Question 30

antagonist

Answer 30

produces opposite action of agonist (contraction inhibited when agonist
contracts)

Question 31

Lever systems

Answer 31

bone/muscle interaction at a joint
parts:
a) levers = bone
b) fulcrum = joint

Question 32

effort

Answer 32

contraction of agonist

Question 33

resistance

Answer 33

opposes movement

Answer 34

effort must be greater than resistance to get movement

Question 35

flexion of forearm

Answer 35

o agonist = biceps brachii
o antagonist = triceps brachii
o synergists = brachialis, brachioradialis
o lever = radius (insertion of agonist)
o fulcrum = elbow joint
o effort = muscle contraction
o resistance = weight of object plus forearm

Question 36

extension of forearm

Answer 36

o agonist = triceps brachii

o antagonist = biceps brachii

Question 37

Flexors

Answer 37

— decrease angle between 2 bones

— e.g. biceps brachii

Question 38

Extensors

Answer 38

— increase angle (back to anatomical position after flexion)

— e.g. triceps brachii

Question 39

Abductors

Answer 39

move limb away from midline

Question 40

Adductors

Answer 40

move limb toward midline

Question 41

Naming of skeletal muscles

Answer 41

1. action
2. shape
3. size
4. origin insertion
5. number of origins
6. shape of fibres
7. location