Muscle Actions

Question 1

sternocleidomastoid

Answer 1

acting together: flex cervical portion of vertebral column, flex head at atlanto-occipital joints
acting singly: laterally rotate and flex head to opposite side of contracting muscle
posterior fibers can assist in extension of head

Question 2

rectus abdominis

Answer 2

flexes vertebral column especially lumbar portion and compresses abdomen to aid in defecation, urination, force exhalation, and child birth

Question 3

external oblique

Answer 3

bilaterally: compress abdomen and flex vertebral column
unilaterally: laterally flex vertebral column, especially lumbar portion, and rotate vertebral column

Question 4

internal oblique

Answer 4

bilaterally: compress abdomen and flex vertebral column
unilaterally: laterally flex vertebral column, especially lumbar portion, and rotate vertebral column

Question 5

transversus abdominis

Answer 5

compresses abdomen

Question 6

diaphragm

Answer 6

contraction causes it to flatten and increase vertical dimensions of thoracic cavity resulting in inhalation
relaxation causes it to move superiorly and decrease vertical dimension of thoracic cavity resulting in exhalation

Question 7

external intercostals

Answer 7

contraction elevates ribs and increases anteroposterior and lateral dimensions of thoracic cavity resulting in inhalation
relaxation depresses ribs and decreases anteroposterior and lateral dimensions of thoracic cavity resulting in exhalation

Question 8

internal intercostals

Answer 8

contraction draws adjacent ribs together to further decrease anteroposterior and lateral dimensions of thoracic cavity during forced exhalation

Question 9

trapezius

Answer 9

elevate clavicle & head and adduct, rotate, elevate, and depress scapula
extends the head
superior fibers upward rotate scapula
middle fibers adduct scapula
inferior fibers depress and upward rotate scapula
superior and inferior fibers together rotate scapula upward
stabilizes scapula
superior fibers can help extend head

Question 10

rhomboideus major

Answer 10

elevates and adducts scapula and rotates it downward

stabilizes scapula

Question 11

pectoralis major

Answer 11

flex, medially rotate, and adduct humerus
as whole: adducts and mediall rotates arm at shoulder joint
calvicular head flexes arm
sternocostal head extends the flexed arm to side of trunk

Question 12

latissiums dorsi

Answer 12

extends, adducts, and medially rotates humerus
extends, adducts, and medially rotates arm at shoulder joint
draws arm inferiorly and posteriorly
RMA: elevates vertebral column and torso

Question 13

deltoid

Answer 13

abducts, flexes, extends, medially and laterally rotates humerus
lateral fibers abduct arm at shoulder joint
anterior fibers flex and medially rotate arm at shoulder joint
posterior fibers extend and laterally rotate at should joint

Question 14

supraspinatus

Answer 14

assists deltoid in abducting arm at shoulder joint

Question 15

teres major

Answer 15

extends arm at shoulder joint and assists in adduction and medial rotation of arm at shoulder joint

Question 16

teres minor

Answer 16

laterally rotates, extends, and adducts humerus

Question 17

biceps brachii

Answer 17

flexes forearm
supinates and pronates forearm
flexes arm

Question 18

brachialis

Answer 18

flexes forearm

Question 19

brachioradialis

Answer 19

flexes forearm

partially supinates and pronates forearm (to neutral position)

Question 20

triceps brachii

Answer 20

extends forearm at elbow joint

extends arm at shoulder joint

Question 21

rotator cuff

Answer 21

strengthen and stabilize shoulder joint

Question 22

palmaris longus

Answer 22

weakly flexes hand at wrist joint

Question 23

flexor digitorum superficialis

Answer 23

flexes middle phalanx of each finger

Question 24

flexor digitorum profundus

Answer 24

flexes distal phalanx of each finger

Question 25

flexor pollucis longus

Answer 25

flexes distal phalanx of thumb

Question 26

extensor carpi radialis longus

Answer 26

extends and abducts hand at wrist joint (radial deviation)

Question 27

extensor digitorum

Answer 27

extends phalanges of each finger

Question 28

extensor pollucis brevis

Answer 28

extends phalanges of thumb

Question 29

thenar

Answer 29

act on thumb

Question 30

hypothenar

Answer 30

act on little finger

Question 31

midpalmer

Answer 31

act on all fingers

Question 32

psoas major

Answer 32

``` flexes vertebra (flexes trunk on hip as in sitting up from supine position) flexes and laterally rotates femur ```

Question 33

gluteus maximus

Answer 33

extends, abducts, adducts, and laterally rotates femur

Question 34

gluteus medius

Answer 34

abducts and medially rotates femur

Question 35

tensor fasciae latae

Answer 35

flexes and abducts femur

Question 36

medial compartment (thigh)

Answer 36

adducts femur adductor longus, adductor magnus, adductor brevis, gracilis

Question 37

adductor longus

Answer 37

flexes, adducts, and laterally rotates femur | RMA: extends femur

Question 38

adductor brevis

Answer 38

flexes, adducts, and laterally rotates femur

Question 39

gracilis

Answer 39

adducts femur | flexes leg

Question 40

anterior compartment (thigh)

Answer 40

extends leg quadriceps femoris (rectus femoris, vastus lateralis, vastus medialis, vastus intermedias), sartorius

Question 41

quadriceps femoris

Answer 41

extends leg rectus femoris, vastus lateralis, vastus medialis, vastus intermedius

Question 42

rectus femoris

Answer 42

alone: flexes femur

Question 43

sartorius

Answer 43

flexes and medially rotates leg | flexes and laterally rotates femur

Question 44

posterior compartment (thigh)

Answer 44

extends femur and flexes leg biceps femoris, semitendinososis, semimembranosus

Question 45

biceps femoris

Answer 45

flexes and laterally rotates leg | extends femur

Question 46

semitendinosis

Answer 46

flexes and medially rotates leg | extends femur

Question 47

semimembranosus

Answer 47

flexes and medially rotates leg | extends femur

Question 48

posterior compartment (leg)

Answer 48

plantar flexion gastrocnemius, soleus, flexor hallucis longus, flexor digitorum longus

Question 49

gastrocnemius

Answer 49

plantar flexion and leg flexion

Question 50

soleus

Answer 50

plantar flexion

Question 51

flexor hallucis longus

Answer 51

plantar flexion | flexes distal and proximal phalanges of big toe

Question 52

flexor digitorum longus

Answer 52

plantar flexion | flexes phalanges of toes 2-5

Question 53

anterior compartment (leg)

Answer 53

dorsiflexion tibialis anterior, extensor digitorum longus, extensor hallucis longus

Question 54

tibialis anterior

Answer 54

``` dorsiflexion inverts (supinates) foot ```

Question 55

extensor digitorum longus

Answer 55

dorsiflexion | everts and extends phalanges of toes

Question 56

extensor hallucis longus

Answer 56

dorsiflexion | inverts and extends proximal phalanges

Question 57

flexor digitorum brevis

Answer 57

flexes toes 2-5 (lateral 4)

Question 58

flexor hallucis brevis

Answer 58

flexes big toe

Question 59

splenius

Answer 59

splenius capitis splenius cervicis extend head and laterally flex and rotate head

Question 60

erector spinae

Answer 60

iliocastilis -cervicis, thoracis, lumborum longissimus - capitis, cervicis, thoracis spinalis - capitis, cervicis, thoracis chief extensor of vertebral column important in controlling flexion, lateral flexion, and rotation of vertebral column and in maintaining lumbar curve

Question 61

transversospinales

Answer 61

semispinalis (capitis, cervicis, thoracis) - extend vertebral column and rotate head multifidus (C7-sacrum) - extends and laterally flexes vertebral column; important in maintaining lumbar curve rotatores (cervicis, thoracis, lumborum) - contribute little to vertebral movement but play important role in monitoring position of vertebral column and providing propioceptive feedback to stronger vertebral muscles