Superficial Back

Question 1

What muscles connect the trunk to the upper extremity?

Answer 1

Latissimus dorsi, levator scapulae, pectoralis major, pectoralis minor, rhomboids, serratus anterior, subclavius, trapezius

Question 2

Name the actions and innervation (including common spinal cord segments) of the latissimus dorsi.

Answer 2

C6-C8
Attachments: from lower thoracic spinous processes, thoracolumbar fascia and iliac crest to the floor of the intertubercular sulcus of the humerus
Actions: adduction, extension, and medial rotation of humerus
Innervation: thoracodorsal nerve

Question 3

Name the actions and innervation (including common spinal cord segments) of the levator scapulae.

Answer 3

C4-C5
Attachments: from transverse processes of C1-C4 to the superior angle and superomedial border of the scapula
Actions: elevation and downward rotation of the scapula
Innervation: dorsal scapular nerve (sensory: direct branches of C3-C4)

Question 4

Name the actions and innervation (including common spinal cord segments) of the pectoralis major.

Answer 4

Clavicular head: C5-C6; Sternocostal head: C7-T1
Attachments: from clavicle, costal cartilages, sternum and aponeurosis of the external oblique to the lateral lip of the intertubercular sulcus of the humerus
Actions: humeral adduction, flexion and medial/internal rotation (sternocostal portion assists with extension of the flexed arm)
Innervation: medial and lateral pectoral nerves

Question 5

Name the actions and innervation (including common spinal cord segments) of the pectoralis minor.

Answer 5

C5-T1
Attachments: from outer surfaces of ribs 3-5 to the coracoid process
Actions: anterior tilt of scapula; assists with depression of the shoulder and forced inspiration
Innervation: medial and lateral pectoral nerves

Question 6

Name the actions and innervation (including common spinal cord segments) of the rhomboids.

Answer 6

C4-C5
Attachments: major - from spinous processes T2-T5; minor - from ligamentum nuclear & spinous processes C7-T1 to the medial border of the scapula
Actions: scapular retraction, elevation (upper) and downward rotation
Innervation: dorsal scapular nerve (sensory: direct branches of C3-C4)

Question 7

Name the actions and innervation (including common spinal cord segments) of the serratus anterior.

Answer 7

C5-C7
Attachments: from the outer surfaces and superior borders of upper 8-10 ribs to the costal surface of the medial border of the scapula
Actions: scapular protraction and upward rotation
Innervation: long thoracic nerve

Question 8

Name the actions and innervation (including common spinal cord segments) of the subclavius.

Answer 8

C5-C6
Attachments: from 1st rib and cartilage to the undersurface of the clavicle
Actions: depresses and stabilizes the clavicle
Innervation: subclavian nerve

Question 9

Name the actions and innervation (including common spinal cord segments) of the trapezius.

Answer 9

Accessory n. (CN XI) motor; C3-C4 sensory
Attachments: from the superior nuchal line, external occipital protuberance, ligamentum nuchae, and cervical and thoracic spinous processes to the clavicle, acromion, and scapular spine
Actions: scapular elevation (upper), depression (lower), retraction ( middle), and upward rotation (upper and lower)
Innervation: accessory nerve (CN XI: motor) and C3-C4 (sensory)

Question 10

What are the extrinsic back muscles?

Answer 10

Superficial: 
Levator scapulae
Trapezius
Rhomboids
Latissimus dorsi

Intermediate:
Serratus Posterior Superior
Serratus Posterior Inferior

Question 11

What are the intrinsic back muscles?

Answer 11

Superficial: splenius capitis and splenius cervicis
Intermediate: erector spinae —> spinalis, longissimus, iliocostalis
Deep: transverspinalis —> semispinalis, multifidus, and rotatores

Question 12

List the intermediate extrinsic back muscles.

Answer 12

Serratus posterior superior and serratus posterior inferior (innervated by anterior rami of spinal n. AKA intercostal n.)

Question 13

List the intrinsic back muscles.

Answer 13

Superficial: splenius capitis and splenius cervicis —> innervated by posterior rami of spinal n.
Intermediate: erector spinae (spinalis, longissimus, iliocostalis) —> innervated by posterior rami of spinal n.
Deep: transversospinalis (semispinalis, multifidus, rotatores) —> unnerved by posterior rami of spinal n.

Question 14

Locate areas of skin associated with a single spinal segment/nerve (dermatome).

Answer 14

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