10-2. Principle Muscles and their Actions

Question 1

frontalis

Answer 1

draws scalp forward, raises eyebrows, wrinkles forehead

Question 2

occiptalis

Answer 2

draws scalp backward

Question 3

orbicularis oculi

Answer 3

closes the eye (blinking, squinting)

Question 4

orbicularis oris

Answer 4

moves the lips (kiss)

Question 5

masseter

Answer 5

elevates the mandible, closes the jaw (chew)

Question 6

temporalis

Answer 6

elevates the mandible, maintains position of jaw at rest

Question 7

sternocleidomastoid

Answer 7

contraction of one rotates face from side to side; contraction of both causes head flexion

Question 8

rectus abdominus

Answer 8

compresses abdomen to aid in defecation, urination, childbirth, and forceful exhalation (“sit ups” muscle)

Question 9

external oblique

Answer 9

contraction of both compresses abdomen; contraction of one bends the body laterally

Question 10

pectoralis major

Answer 10

prime mover of arm flexion, also adducts and rotates arm medially. Used to climb, throw and push

Question 11

latissimus dorsi

Answer 11

prime mover of arm extension, also adducts and rotates arm. Used to strike a blow, hammer, swim, or row

Question 12

What is an example of a pair of antagonists in the trunk?

Answer 12

pectoralis major and latissimus dorsi

Question 13

biceps brachii

Answer 13

flexes elbow joint and supinates forearm

Question 14

triceps brachii

Answer 14

extends forearm at elbow

Question 15

What is an example of a pair of antagonists in the arm>

Answer 15

biceps brachii and triceps brachii

Question 16

gluteus maximus

Answer 16

extends the thigh (as in climbing stairs), also rotates thigh laterally

Question 17

tensor fasciae latae

Answer 17

flexes and abducts thigh

Question 18

quadriceps femoris

Answer 18

powerful knee extensor used in climbing, running and jumping

Question 19

What muscles make up quadriceps femoris?

Answer 19

rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius

Question 20

hamstrings

Answer 20

flex knee and extend thigh

Question 21

What muscles make up the hamstrings?

Answer 21

biceps femoris, semitendinosus, semimembranosus

Question 22

tibialis anterior

Answer 22

prime mover of dorsiflexion

Question 23

gastricnemius

Answer 23

plantar flexes foot

Question 24

sartorius

Answer 24

flexes thigh and rotates it laterally (cross your legs)

Question 25

What are some examples of antagonists in the leg?

Answer 25

quadriceps femoris and hamstrings

tibialis anterior and gastricnemius

Question 26

Achilles tendon

Answer 26

thick, very apparent tendon that attaches the gastricnemius muscle to the calcaneius