Muscles of the Back

Question 1

Back Muscles

Latissimus Dorsi - Origin

Answer 1

O: spinous processes of T7 - L5, sacrum, iliac crest

Question 1

Back Muscles

Latissimus Dorsi - Insertion

Answer 1

I: intertubercular groove of humerus

Question 2

Back Muscles

Latissimus Dorsi - Innervation

Answer 2

N: Thoracodorsal nerve (C6 to C8) (Ventral Ramus)

Question 3

Back Muscles

Latissimus Dorsi - Action

Answer 3

Fx: Extends, adducts, and medially rotates the humerus

Question 4

Back Muscles

Levator Scapulae - Origin

Answer 4

O: transverse processes of C1 to C4

Question 5

Back Muscles

Levator Scapulae - Insertion

Answer 5

I: superior angle of the scapula

Question 6

Back Muscles

Levator Scapulae - Innervation

Answer 6

N: dorsal scapular nerve (Ventral Ramus)

Question 7

Back Muscles

Levator Scapulae - Action

Answer 7

Fx: elevates scapula

Question 8

Back Muscles

Rhomboid Major and Minor - Origin

Answer 8

O: spinous process of lower cervical and upper thoracic vertebrae

Question 9

Back Muscles

Rhomboid Major and Minor - Insertion

Answer 9

I: medial border of scapula (major - inferior and minor - superior to spine)

Question 10

Back Muscles

Rhomboid Major and Minor - Innervation

Answer 10

N: dorsal scapular nerve (Ventral Ramus)

Question 11

Back Muscles

Rhomboid Major and Minor - Action

Answer 11

Fx: retracts and medially rotates the scapula

Question 12

Back Muscles

Splenius Capitis & Cervicis - Origin

Answer 12

O: ligamentum nuchae, spinous processes C7 and upper thoracic vertebrae

Question 13

Back Muscles

Splenius Capitis & Cervicis - Insertion

Answer 13

I: Capitis - mastoid process and superior nuchal line, Cervicis - transverse processes of upper cervical vertebrae

Question 14

Back Muscles

Splenius Capitis & Cervicis - Innervation

Answer 14

N: Dorsal Rami of Spinal Nerves

Question 15

Back Muscles

Splenius Capitis & Cervicis - Action

Answer 15

Fx: bilaterally - extend the head and neck, unilaterally - rotate head to one side

Question 16

Back Muscles

Erector Spinae - Origin

Answer 16

O: sacrum, iliac crest, ribs, spinous and transverse processes of vertebrae

Question 17

Back Muscles

Erector Spinae - Insertion

Answer 17

I: spinous and transverse processes of vertebrae, ribs, skull

Question 18

Back Muscles

Erector Spinae - Innervation

Answer 18

N: Dorsal rami of spinal nerves

Question 19

Back Muscles

Erector Spinae - Action

Answer 19

Fx: bilaterally - extend the head and trunk, unilaterally - bend the trunk laterally (also controls flexion against gravity)

Question 20

Back Muscles

Semispinalis Capitis - Origin

Answer 20

O: Transverse processes of lower cervical and upper thoracic vertebrae

Question 21

Back Muscles

Semispinalis Capitis - Insertion

Answer 21

I: occipital bone near nuchal lines

Question 22

Back Muscles

Semispinalis Capitis - Innervation

Answer 22

N: dorsal rami of spinal nerves

Question 23

Back Muscles

Semispinalis Capitis - Action

Answer 23

Fx: bilaterally - extend the head and neck, unilaterally - rotate the head to one side

Question 24

# Back Muscles Trapezius - Origin

Answer 24

O: superior nuchal ine, external occipital protuberance, ligamentum nuchae, spinous process of C7 to T12

Question 25

# Back Muscles Trapezius - Insertion

Answer 25

I: lateral one-third of clavicle, acromion, spine of scapula

Question 26

# Back Muscles Trapezius - Innervation

Answer 26

N: Motor - accessory nerve CN XI

Question 27

# Back Muscles Trapezius - Action

Answer 27

Fx: superior fibers elevate and laterally rotate scapula, middle fibers retract scapula, inferior fibers depress and laterally rotate scapula