Muscle Actions

Question 1

Erector spinae

Answer 1

prime mover of back extension; each side consists of three columns (iliocostalis, longissimus, and spinalis muscles)

Question 2

trapezius

Answer 2

stabilizes, rises, and rotates scapula; middle fibers retract (adduct) scapula; superior fibers elevate scapula (shrugging); inferior fibers depress scapula and shoulder

Question 3

rhomboid major

Answer 3

retracts, elevates and rotates scapula

Question 4

rhomboid minor

Answer 4

retracts and elevates scapula

Question 5

pectoralis minor

Answer 5

abducts scapula, pulling it forward and downward; draws rib cage superiorly (raises ribs)

Question 6

pectoralis major

Answer 6

prime mover or arm flexion; rotates arm medially, adducts humerus; pulls arm across chest

Question 7

levator scapulae

Answer 7

elevates scapula; flexes neck laterally (to same side)

Question 8

serratus anterior

Answer 8

pulls scapula anteriorly and downward; abducts scapula

Question 9

teres major

Answer 9

posteromedially extends, medially rotates, and adducts humerus; synergist of latissimus dorsi

Question 10

latissimus dorsi

Answer 10

prime mover of arm extension; arm adductor; medially rotates humerus at shoulder

Question 11

deltoid

Answer 11

prime mover of arm abduction (at shoulder); extends and flexes arm

Question 12

brachialis

Answer 12

flexes elbow

Question 13

brachioradialis

Answer 13

flexes forearm at elbow

Question 14

rotator cuf

Answer 14

medially or laterally rotates arm at shoulder; supraspinatus assists abduction; stabilizes shoulder joint, helping to prevent downward dislocation of humerus

Question 15

rotator cuff consists of

Answer 15

supraspinatus, infraspinatus, teres minor, subscapularis

Question 16

biceps brachii

Answer 16

flexes elbow joint and supinates forearm and hand

Question 17

triceps brachii

Answer 17

extends forearm at elbow

Question 18

external oblique

Answer 18

tenses abdominal wall and compresses abdominal contents

Question 19

internal oblique

Answer 19

tenses abdominal wall and compresses abdominal contents

Question 20

hamstrings consists of

Answer 20

biceps femoris, semitendinosus, semimembranosus

Question 21

hamstrings

Answer 21

extends thigh and flexes knee; laterally or medially rotates leg, especially when knee is flexed

Question 22

transverse abdominis

Answer 22

compresses abdominal components

Question 23

rectus abdominis

Answer 23

flexes and rotates lumbar region of vertebral column; fixes and depresses ribs, stabilizes pelvis when walking, tenses abdominal wall, increases intra-abdominal pressure

Question 24

psoas major (iliopsoas)

Answer 24

flexes thigh; also affects lateral flexion of vertebral column; important postural muscle

Question 25

iliacus (iliopsoas)

Answer 25

prime mover for flexing thigh or for flexing trunk on thigh during a bow

Question 26

gluteus maximus

Answer 26

major extensor of thigh; generally inactive during standing and walking; laterally rotates and abducts thigh

Question 27

piriformis

Answer 27

abducts and rotates thigh laterally; stabilizes hip joint

Question 28

quadriceps consists of

Answer 28

vastus lateralis, medialis, and intermedius, rectus femoris

Question 29

quadriceps

Answer 29

extends and stabilizes knee

Question 30

gastrocnemius

Answer 30

plantar flexion of foot; flexes knee

Question 31

soleus

Answer 31

plantar flexion of foot