Back Muscle Actions + Innervations

Question 1

upper trapezius innervation

Answer 1

spinal accessory nerve (cranial nerve XI)

Question 2

upper trapezius action

Answer 2

elevation and upward rotation of scapula

Question 3

middle trapezius innervation

Answer 3

spinal accessory nerve (cranial nerve XI)

Question 4

middle trapezius action

Answer 4

retraction of scapula

Question 5

lower trapezius innervation

Answer 5

spinal accessory nerve (cranial nerve XI)

Question 6

lower trapezius action

Answer 6

depression, retraction, and upward rotation of scapula

Question 7

latissimus dorsi innervation

Answer 7

thoracodorsal nerve (C6-C8)

Question 8

latissimus dorsi action

Answer 8

shoulder extension, adduction, and internal rotation
depression of scapula

Question 9

levator scapulae innervation

Answer 9

dorsal scapular nerve (C4-C5)

Question 10

levator scapulae action

Answer 10

elevation of scapula

Question 11

rhomboid major innervation

Answer 11

dorsal scapular nerve (C4-C5)

Question 12

rhomboid major action

Answer 12

elevation, retraction, and downward rotation of scapula

Question 13

rhomboid minor innervation

Answer 13

dorsal scapular nerve (C4-C5)

Question 14

rhomboid minor innervation

Answer 14

elevation, retraction, and downward rotation of scapula

Question 15

serratus posterior superior innervation

Answer 15

intercostal nerve
ventral rami

Question 16

serratus posterior superior action

Answer 16

elevates upper ribs for inspiration

Question 17

serratus posterior inferior innervation

Answer 17

intercostal nerve
ventral rami

Question 18

serratus posterior inferior action

Answer 18

depresses lower ribs for expiration

Question 19

splenius capitis innervation

Answer 19

dorsal rami of cervical spinal nerves (C2-C3)

Question 20

splenius capitis action

Answer 20

neck + head extension
ipsilateral sidebend + rotation of the neck

Question 21

splenius cervicis innervation

Answer 21

dorsal rami of spinal nerves

Question 22

splenius cervicis action

Answer 22

neck extension
ipsilateral sidebend + rotation of the neck

Question 23

iliocostalis (lumborum, thoracis, and cervicis) innervation

Answer 23

dorsal rami of spinal nerves

Question 24

iliocostalis (lumborum, thoracis, and cervicis) action

Answer 24

back extension
ipsilateral back sidebend + rotation
lumborum and thoracis: depression of rib cage for expiration

Question 25

longissimus (thoracis, cervicis, and capitis) innervation

Answer 25

dorsal rami of spinal nerves

Question 26

longissimus (thoracis, cervicis, and capitis) action

Answer 26

back extension ipsilateral SB + rotation cervicis + capitis: neck and head extension, ipsilateral rotation of neck and head thoracis: depression of rib cage for expiration

Question 27

spinalis (thoracis, cervicis, and capitis) innervation

Answer 27

dorsal rami of spinal nerves

Question 28

spinalis (thoracis, cervicis, and capitis) action

Answer 28

back extension ipsilateral SB + rotation

Question 29

multifidi innervation

Answer 29

dorsal rami of spinal nerves

Question 30

multifidi action

Answer 30

back extension ipsilateral back SB contralateral rotation

Question 31

semispinalis (thoracis, cervicis, and capitis) innervation

Answer 31

dorsal rami of spinal nerves

Question 32

semispinalis (thoracis, cervicis, and capitis) action

Answer 32

back extension ipsilateral back SB + contralateral rotation cervicis + capitis: head extension, ipsilateral head sidebend, contralateral head rotation

Question 33

rotator longus + rotator brevis innervation

Answer 33

dorsal rami of spinal nerves

Question 34

rotator longus + rotator brevis action

Answer 34

back extension ipsilateral sidebend contralateral rotation

Question 35

intertransversarii innervation

Answer 35

dorsal rami of spinal nerves

Question 36

intertransversarii action

Answer 36

back extension ipsilateral sidebend