Skeletal Muscle

Question 1

What are the functions of skeletal muscle (4)

Answer 1

Posture,
movement,
Heat generation,
Joint stability

Question 2

What are the functions of circular muscles and what is the structure

Answer 2

Act as sphincters to adjust opening,

Arranged as concentric fibres

Question 3

Two examples of circular muscles

Answer 3

Orbicularis Otis

Orbicularis Occuli

Question 4

What are the 3 categories of parallel muscles

Answer 4

Strap,
Fusiform,
Fan shaped

Question 5

Example of fusiform muscle (wider and cylindrical in middle)

Answer 5

Biceps Brachii

Question 6

Example of strap muscle (snapped like belt)

Answer 6

Sartorius

Question 7

Example of fan shaped muscle (converge at one end, wide at other)

Answer 7

Pectoralis Major

Question 8

What are the 3 categories of Pennate muscles

Answer 8

Unipennate,
Bipennate,
Multipennate

Question 9

Example of unipennate muscle (all fascicles on same side of tendon)

Answer 9

Extensor digitorum longus (in calf)

Question 10

Example of bipennate muscle (fascicles on both sides of central tendon)

Answer 10

Rectus Femoris

Question 11

Example of multipennate muscle (central tendon branches)

Answer 11

Deltoid

Question 12

What are the limbs divided into

Answer 12

Compartments delineated by fascia

Question 13

Trauma in one compartment can cause what

Answer 13

Higher pressure on nerves and vessels and thus compartment syndrome

Question 14

How many compartments does the lower limb have

Answer 14

4:
Anterior,
Lateral,
Superficial Posterior,
Deep posterior

Question 15

How can compartment syndrome be treated

Answer 15

Fasciotomy (sub-sequentially covered by skin graft)

Question 16

What are the roles muscle can have during movement

Answer 16

Agonist (prime movers),
Antagonist,
Synergists (assist prime movers),
Neutralisers (prevents unwanted actions that agonist could perform),
Fixators (holds body part in place)

Question 17

What are the types of Contraction

Answer 17

1) isotonic (variable muscle length)
a) concentric
b) eccentric
2) Isometric (variable tension)

Question 18

What is Rigor Mortis

Answer 18

With lack of ATP, myosin heads can’t detach from actin binding sites

Question 19

What does a lower amount of fibres per motor unit mean

Answer 19

Fine control (eg movement of the eye)

Question 20

What does a higher ratio of muscle fibres to motor unit mean

Answer 20

A powerful muscle (eg gastrocnemius has average of 1934 fibres per motor unit)

Question 21

What are the 3 main types of skeletal muscle fibres

Answer 21

Slow type I,
Fast Type IIA,
Fast Type IIX

Question 22

What is the basis of the muscle fibre types

Answer 22

Myosin heavy chain (MHC) expression

Question 23

What is the differences between Type I/IIA muscle fibres and Type IIX

Answer 23

Type IIX is:
Anaerobic Glycolysis,
Few mitochondria,
Low level of myoglobin,
Poorer capillary supply

Question 24

What is hypotonia

Answer 24

Lack of skeletal muscle tone

Question 25

Examples of conditions that result in hypotonia

Answer 25

Muscular dystrophies,
Spinal muscular atrophy
Charcot-Marie-tooth disease