Muscle function

Question 1

Teres major

Answer 1

adducts and medially rotates arm

Question 2

Latissimus dorsi

Answer 2

extends, adducts, and medially rotates humerus at shoulder

Question 3

Levator scapulae

Answer 3

elevates scapula medially, inferiorly rotates glenoid cavity

acts to draw the scapula medially upward while moving the inferior angle of the scapula medially and to incline the neck to the same side

Question 4

Rhomboids

Answer 4

fix scapula to thoracic wall; retract and rotate scapula to depress glenoid cavity (drop shoulder)

Question 5

Sternocleidomastoid

Answer 5

Unilaterally acts to tilt the head to the same side and rotate the head to the opposite side.

Bilaterally acts to extend the head and to aid in respiration when the head is fixed

Question 6

Trapezius

Answer 6

Abducts humerus

• descending part of the trapezius acts to draw the scapula obliquely upward, to rotate the glenoid cavity superiorly, to tilt the head to the same side, and to rotate the head to the opposite side.
• transverse part of the trapezius acts to draw the scapula medially (adducts it).
• ascending part of the trapezius acts to draw the scapula medially downward

Question 7

Splenius capitis and cervicis

Answer 7

bilaterally to extend the cervical spine and head.

unilaterally to flex and rotate the head to the same side

Question 8

Scalene muscles

Answer 8

With the ribs mobile, the anterior, middle and posterior scalenes act to elevate the upper ribs during forced respiration.

With the ribs fixed, the anterior scalene unilaterally acts to bend the cervical spine to the same side and rotate the head to the opposite side; bilaterally acts to flex the neck anteriorly.

The middle and posterior scalenes act unilaterally to bend the cervical spine ipsilaterally.

Combined, the scalene muscles are powerful lateral flexors of the neck

Question 9

Omohyoid

Answer 9

acts to depress the hyoid and to draw the larynx and hyoid bone down for phonation and swallowing

Question 10

Triceps

Answer 10

• long head is the least active of the three, and aids primarily in extending the arm.
• medial head is the workhorse of forearm extension (actually deep to lateral head).
• lateral head is typically the strongest generator of force, but functions primarily against active resistance (not during passive motions)

Question 11

Deltoid

Answer 11

abducts arm, anterior fibers flex and medial rotate, posterior fibers extend and lateral rotate

Question 12

Erector spinae

Answer 12

lateral extension of spine

Question 13

Infraspinatus

Answer 13

laterally rotates arm and stabilizes shoulder joint

Question 14

Latissimus dorsi

Answer 14

extends, adducts, and medially rotates arm

Question 15

Serratus posterior inferior

Answer 15

depresses ribs

Question 16

Serratus posterior superior

Answer 16

elevates ribs

Question 17

O. Capitis inferior

Answer 17

Rotates atlas to turn face to same side

Question 18

O. Capitis superior

Answer 18

Extends and bends head laterally

Question 19

R. C. posterior major

Answer 19

Extends and rotates head to same side

Question 20

R. C. posterior minor

Answer 20

Extends head

Question 21

Rhomboid major

Answer 21

Fixes scapula to thoracic wall and retracts and rotates

Question 22

Rhomboid minor

Answer 22

Fixes scapula to thoracic wall and retracts and rotates

Question 23

Semispinalis

Answer 23

Extends head, neck, and thorax, and rotates to opposite side

Question 24

Flexor carpi radialis

Answer 24

Flexes and abducts hand at wrist

Question 25

Flexor carpi ulnaris

Answer 25

Flexes and adducts hand at wrist

Question 26

Flexor digitorum profundus

Answer 26

Flexes distal phalanges of medial four digits, assists with flexion of hand at wrist

Question 27

Flexor digitorum superficialis

Answer 27

Flexes middle and proximal phalanges of medial four digits, flexes hand at wrist

Question 28

Flexor pollicis longus

Answer 28

Flexes phalanges of thumb

Question 29

Palmaris longus

Answer 29

Flexes hand at wrist and tenses palmar aponeurosis

Question 30

Pronator quadratus

Answer 30

Pronates forearm

Question 31

Pronator teres

Answer 31

Pronates forearm and assists with elbow flexion

Question 32

Anconeus

Answer 32

Assists triceps in extending elbow, abducts ulna in pronation

Question 33

Biceps brachii

Answer 33

Flexes and supinates forearm at elbow

Question 34

Brachialis

Answer 34

Flexes forearm at elbow

Question 35

Coracobrachialis

Answer 35

Flexes and adducts arm at shoulder

Question 36

Triceps brachii

Answer 36

Extends forearm at elbow; long head stabilizes head of abducted humerus and extends and adducts arm at shoulder

Question 37

Abductor digiti minimi

Answer 37

Abducts little finger

Question 38

Abductor pollicis brevis

Answer 38

Abducts thumb

Question 39

Adductor pollicis

Answer 39

Adducts thumb

Question 40

Dorsal interosseous

Answer 40

Abduct digits from axial line of hand (3rd digit); flex digits at metacarpophalangeal joint and extend interphalangeal joints

Question 41

Flexor digiti minimi brevis

Answer 41

Flexes proximal phalanx of little finger

Question 42

Flexor pollicis brevis

Answer 42

flexes proximal phalanx of thumb

Question 43

Lumbrical, first and second

Answer 43

Extend digits at interphalangeal joints, flex metacarpophalangeal joints

Question 44

Lumbrical, third and fourth

Answer 44

Extend digits at interphalangeal joints, flex metacarpophalangeal joints

Question 45

Opponens digiti minimi

Answer 45

Draws 5th metacarpal anteriorly and rotates it to face thumb

Question 46

Opponens pollicis

Answer 46

Draws 1st metacarpal forward and rotates it medially

Question 47

Palmar interosseous

Answer 47

Adducts digits toward axial line of hand (3rd digit); flexes digits at metacarpophalngeal joint and extends interphalangeal joints

Question 48

Palmaris brevis

Answer 48

deepens hollow of hand, assists grip

Question 49

Pec major

Answer 49

Flexes and adducts arm, rotates medially

Question 50

Pec minor

Answer 50

Lowers lateral angle of scapula and protracts scapula

Question 51

Abductor pollicis longus

Answer 51

Abducts and extends thumb at carpometacarpal joint

Question 52

Brachioradialis

Answer 52

Weak flexion of forearm when forearm is midpronated

Question 53

Extensor carpi radialis brevis

Answer 53

Extends and abducts hand at wrist

Question 54

Extensor carpi radialis longus

Answer 54

Extends and abducts hand at wrist

Question 55

Extensor carpi ulnaris

Answer 55

Extends and abducts hand at wrist

Question 56

Extensor digiti minimi

Answer 56

Extends 5th digit

Question 57

Extensor digitorum

Answer 57

Extends medial four digits, assists in wrist extension

Question 58

Extensor indicis

Answer 58

Extends 2nd digit and helps extend hand at wrist

Question 59

Extensor pollicis brevis

Answer 59

Extends proximal phalanx of thumb at carpometacarpal joint

Question 60

Extensor pollicis longus

Answer 60

Extends distal phalanx of thumb at interphalangeal and metacarpophalngeal joints

Question 61

Supinator

Answer 61

Supinates forearm

Question 62

Teres minor

Answer 62

Laterally rotates arm