Naming Skeletal Muscles

Question 1

How are muscles named? (7)

Answer 1

1. Direction of muscle fibers
2. Relative size of the muscle (maximus, minimus, longus)
3. Location of the muscle
4. Number of origins (triceps, biceps, quadriceps)
5. Location of the muscle’s origin and insertion
6. Shape of the muscle
7. Action of the muscle

Question 2

What are skeletal muscles composed of and what feature does this allow? (2)

Answer 2

1. Fascicles

2. Produces muscles with different structures and functional properties

Question 3

How are circular fascicles arranged?

Answer 3

In concentric rings

Question 4

How are convergent fascicles arranged?

Answer 4

Converging towards a single insertion tendon; fan-shaped or triangle-shaped

Question 5

How is the parallel fascicle arranged?

Answer 5

Parallel to a long axis and trap-like

Question 6

What is the modification of the parallel fascicle called and how is it arranged?

Answer 6

1. Fusiform

2. Spindle-shaped muscle with an expanded belly

Question 7

How is “pennate” described?

Answer 7

Feather-like pattern

Question 8

List the 3 pennate categories and briefly describe each. (3)

Answer 8

1. Unipennate = only inserts into one side of the tendon
2. Bipennate = inserts into the opposite sides of the tendon
3. Multipennate = muscles insert from several side

Question 9

List 4 important facial muscles for facial expression and briefly describe then. (4)

Answer 9

1. Frontalis → allows you to raise your eyebrows and wrinkle your forehead
2. Orbicularis oculi → allows closing, blinking, and squinting
3. Orbicularis oris → the kissing muscle
4. Buccinator → used to blow whistle

Question 10

List 3 important facial muscles for the chewing motion and briefly describe them. (3)

Answer 10

1. Zygomaticus → corner of the mouth to the cheekbone → smiling
2. Masseter → muscle closes the jaw by elevating the mandible
3. Temporalis → fan-shaped muscle overlaying the temporal bone and acts as a synergist in masseter in closing jaw

Question 11

List 2 important neck muscles and briefly describe them. (2)

Answer 11

1. Platysma → Produces the downward sag of the mouth (frown)

2. Stenocleidomastoid → 2-headed muscle which arises from the sternum and the clavicle

Question 12

List 3 important truck muscles and briefly describe them. (3)

Answer 12

1. Pectoralis major → fan-shaped covering upper part of the chest
2. Intercoastal muscles - found between the ribs
   (Raising the rib cage → removes CO2 from the lungs)
3. Abdomen girdle → contains the rectis abdominis, external and internal obliques, and transverse abdominos

Question 13

Define: muscular dystrophy

Answer 13

Group of inherited muscle-destroying diseases that affect specific muscle groups

Question 14

State and briefly describe one COMMON form of muscular dystrophy. (4)

Answer 14

1. Duchenne’s muscular dystrophy
2. Expressed almost exclusively in boys
3. Diagnosed between the ages of 2-7
4. Diseased muscle fibers lack protein (dystrophin) which helps maintain the sarcolemma

Question 15

State and briefly describe one RARE form of muscular dystrophy. (4)

Answer 15

1. Myasthenia gravis - rare autoimmune disease that can affect muscles during adulthood
2. Characterized by drooping upper eyelids, difficulty swallowing and talking, and general muscle weakness
3. Involves a shortage of acetylcholine receptors at neuromuscular junctions
4. Death usually occurs when respiratory muscles can no longer function → respiratory failure