Extrinsic Back Muscles

Question 1

Match muscles with the layer they are in

Layer 1
Layer 2
Layer 3

Levator scapulae
Rhomboid major
Rhomboid minor
Trapezius
Serratus posterior inferior
Latissimus dorsi
Serratus posterior inferior

Answer 1

2 - Levator scapulae
2 - Rhomboid major
2 - Rhomboid minor
1 - Trapezius
3 - Serratus posterior inferior
1 - Latissimus dorsi
3 - Serratus posterior inferior

Question 2

Extrinsic back muscles are also considered?

a. Epaxial
b. Hypaxial
c. Apaxial
d. Deep

Answer 2

b. Hypaxial

Question 3

Extrinsic back muscles are innervated by which rami?

Answer 3

Ventral rami

Question 3

Deep back muscles typically do the following functions?

a. Move pectoral gurdle
b. Move upper limbs
c. Maintain posture
d. Rotation
e. Both A and B

Answer 3

e.

Question 5

Latissimus dorsi

Answer 5

Extends, adducts, & medially rotates humerus
Raises torso towards arms (pull-up)

Thoracodorsal nerve

Question 6

Levator scapulae

Answer 6

Elevates scapula
Tilts glenoid fossa inferiorly by rotating scapula

Dorsal scapular nerve
Cervical nerves (ventral rami)

Question 7

Rhomboid major

Answer 7

Retract, elevate, & rotate scapula downward
Fix scapula to thoracic wall

Dorsal scapular nerve

Question 8

Rhomboid minor

Answer 8

Retract, elevate, & rotate scapula downward
Fix scapula to thoracic wall

Dorsal scapular nerve

Question 9

Serratus posterior superior

Answer 9

Elevates ribs

T2-T5 Intercostal nerves (ventral rami)

Question 10

Serratus posterior inferior

Answer 10

Depresses ribs

Intercostal nerves (ventral rami)
Subcostal nerves (ventral rami)

Question 11

Trapezius

Answer 11

Elevates, depresses, & retracts scapula
Rotates glenoid fossa superiorly

CN IX - Accessory nerve —> Sensory
C3 & C4 (ventral rami) —> Motor