Lecture 4 Muscles

Question 1

What are the 5 fiber arrangements of muscles?

Answer 1

Straight
Fusiform (tapered at either end)
Unipennate
Bipennate
Multipennate

Question 2

What is an agonist?

Answer 2

Mover when its contraction contributes to movement

Ex) biceps

Question 3

Antagonist

Answer 3

Opposes movement

Ex) triceps antagonist of bicep

Question 4

Stabilizer or fixator

Answer 4

Stabilizes the bone segment on which another bone moves

Question 5

Neutralizer/synergistic

Answer 5

Nullifies 1 or more actions of another m.

Pronator teres nullifies supination

Question 6

Active insufficiency?

Answer 6

Decreased ability to produce/maintain active tension

-agonists

Question 7

Passive insufficiency?

Answer 7

Inactive antagonist m has insufficient length to force to complete full ROM

Question 8

Muscle organization

Answer 8

Myofilament (myosin & actin) 
Myofibril (chain of sarcomeres) 
Myofiber (bundle of myofibrils)
Fascicle (bundle of myofibers)
Muscle (# of fascicles)

Question 9

CT organization within muscles

Answer 9

Endomysium - surrounds each m. Fiber
Perimysium - surrounds each fascicle
Epimysium - surrounds each muscle

Question 10

Motor unit

Answer 10

A motor neuron & all the myofibrils it innervates — All or None contraction

Question 11

Characteristic of Slow fibers

Answer 11

Red, dark 
Fatigue resistant 
Contact slowly
Rely on OP 
High # of mitochondria 
High [myoglobin] 
Low [ATPase]

Ex) running long distance

Question 12

Characteristics of Fast Twitch

Answer 12

White, light 
Fatigue easily 
Contract rapidly 
Rely on glycolysis 
Low # mitochondria 
Low [myoglobin]
High [ATPase]

Ex) sprints

Question 13

Muscle contraction

Answer 13

Isometric - length of m doesn’t change (force does)
Isotonic - force stays the same, length changes
Shorter - concentric
Longer - eccentric

Question 14

What is the 4th type of muscle?

Answer 14

Branchiometric
Assoc with pharyngeal arches
Innervated by cranial nerves
Transition b/w smooth m & striated