EXAM III The Back

Question 1

What are the components of the 3 layers of the hypaxial/superficial/extrinsic back muscles?

Answer 1

Layer I: (superficial to layer 2)

Trapezius

Latissimus Dorsi

Layer 2:

Rhomboid major/minor (major is inferior to minor)

Levator scapulae

Layer 3:

Serratus posterior superior - deep to rhomboids

Serratus posterior inferior

Question 2

What nerve innervates the trapezius muscle?

Answer 2

Spinal Accessory Nerve (motor)

CN XI

ONLY back muscle that is innervated by part of a CN; whereas the others come off the brachial plexus

Sensory = ventral rami

Question 3

What nerve innervates the rhomboids?

Answer 3

Dorsal Scapular Nerve

via roots, one of the first branches off of the brachial plexus

Question 4

What nerve innervates the latissimus dorsi?

Answer 4

Thoracodorsal

A long branch off of the posterior cord of the brachial plexus

Question 5

What is the action of the trapezius?

Answer 5

Elevates, depresses, retracts scapula

Rotates glenoid fossa superiorly during abduction of the arm (raising arm in front)

Question 6

What are the actions of the latissimus dorsi?

Answer 6

Raises torso towards arms when climbing (i.e. pullups)

Extends, Adducts, Medially rotates humerus

Question 7

What are the actions of the rhomboid muscles?

Answer 7

Retracts, Elevate, and Rotate Scapula

Fix scapula to thoracic wall

Question 8

What nerve innervates the levator scapulae muscle? (2)

Answer 8

Dorsal scapular nerve

Ventral rami of cervical spinal nerves

Question 9

What are the actions of the levator scapula muscle?

Answer 9

Elevates scapula

Downward rotation of scapula by tilting glenoid fossa inferiorly

Question 10

What are the segmental muscles of the back?

Answer 10

Interspinales

Intertransversari

Levator costarum

Question 11

What muscle lies beneath the rhomboid muscles?

Answer 11

Serratus posterior superior

Question 12

What are the actions of the serratus posterior superior?

Answer 12

Elevates ribs

Breathing muscles

Question 13

What nerve innervates the serratus posterior superior muscle?

Answer 13

Intercoastal nerves via ventral rami

Question 14

What nerve innervates the serratus posterior inferior muscle and what is its function?

Answer 14

Depresses the ribs

Intercostal nerves

Subcostal nerve (ventral rami)

Question 15

What are the 2 major groups of the epaxial back muscles?

Answer 15

Erector Spinae Group:

Spinalis

Logissimus

Iliocostalis

Transversospinalis Group:

Rotatores

Multifidus

Semispinalis

Question 16

Which section of the erector spinae muscle group has lumbar insertions?

Answer 16

Iliocostalis lumborum

Question 17

What back muscle lies deep to the splenius capitis?

Answer 17

Semispinalis capitis

Question 18

What nerves innervate the segmental back muscles? What is the one exception?

Answer 18

Dorsal rami of spinal nerves innervate all

Ventral rami innervate Intertransversari group

Question 19

What muscles lie superior to the suboccipital triangle muscles?

Answer 19

Splenius

Semispinalis

Question 20

What nerve innervates the suboccipital triangle muscles?

(motor and sensory)

Answer 20

Motor: Suboccipital nerve

Sensory: Greater Occipital nerve

Question 21

What are the functions of the suboccipital triangle muscles?

Answer 21

Mainly Postural muscles

Aid in extension and rotation at atlantoaxial joint

Question 22

What artery supplies the suboccipital triangle?

Answer 22

Vertebral artery

Question 23

What nerve supplies all of the epaxial muscles? Name one exception

Answer 23

Dorsal Rami of Spinal Nerves

Exception: Intertransversari is innervated by both dorsal and ventral rami

Question 24

What muscles does the transverse cervical artery supply?

Answer 24

Trapezius - superficial + deep branch

Levator scapula - deep branch

Rhomboids - deep branch

Question 25

What is the action of the splenius capitis and splenius cervicis muscles

Answer 25

Bilaterally - **elevate head and neck** Unilaterally - **flex neck, epsilateral rotation of the head**

Question 26

What are the breathing muscles of the back?

Answer 26

**Serratus posterior superior** **Serratus posterior inferior**

Question 27

Which muscles are apart of the erector spinae group?

Answer 27

**Iliocostalis (most lateral)** - contains a lumborum portion **Longissimus (middle)** **Spinalis (medial)** Superficial to Transversospinalis group

Question 28

Which muscles are apart of the transversospinalis group?

Answer 28

**Multifidus** **Rotatores** **Semispinalis Capitis** Deep to erector spinae group

Question 29

What are the actions of the Iliocostalis portion of the erector spinae group?

Answer 29

Bilaterally - **Extend vertebral column, head, and neck** Unilaterally - **Laterally flex vertebral column**

Question 30

What are the actions of the longissimus muscle of the erector spinae group? (capitis, cervicis, thoracis)

Answer 30

Capitis - **extend head** Cervicis - **extend and laterally bend the neck** Thoracis - **extend spine**

Question 31

What are the actions of the multifidus muscle?

Answer 31

**Stabilizes vertebrae during localized movements of vertebral column**

Question 32

What are the actions of the rotatores muscle of the transversospinalis group?

Answer 32

**Extend head** **Rotate cervical and thoracic contralaterally** Longus and brevis portion

Question 33

What are the actions of the semispinalis capitis muscle of the transversospinalis group?

Answer 33

**Extend head, cervical and thoracic** **Rotates head, cervical, thoracic contralaterally** **Bends neck laterally**

Question 34

What muscles are involved in elevating the scapula?

Answer 34

**Trapezius** **Levator scapulae** **Rhomboids**

Question 35

What muscles rotate scapula downwards?

Answer 35

**Levator scapulae** **Rhomboids major and minor**

Question 36

What muscles are involved in extending the head? (5)

Answer 36

**Splenius capitis and cervicis** **Iliocostalis cervicis region** **Longissimus capitis** **Rotatores** **Semispinalis capitis**

Question 37

What muscles are involved in extending the spine? (2)

Answer 37

**Longissiumus thoracis** **Spinalis**