Muscles of the Shoulder Region

Question 1

Extrinsic muscles

Answer 1

Originate from torso, attach to the bones of the shoulder

Two layers - superficial and deep

Question 2

Superficial extrinsic muscles

Answer 2

Trapezius

Latissimus dorsi

Question 3

Deep extrinsic muscles

Answer 3

Levator scapulae
Rhomboid major
Rhomboid minor

Question 4

Trapezius

Answer 4

Origin - skull, ligamentum nuchae and spinous processes C7-T12
Attachments - clavicle, acromion and scapula spine
Innervation - accessory nerve (C3 and C4)
Action - elevate scapula and rotate it during abduction, retract scapula, pull scapula inferiorly

Question 5

Latissimus dorsi

Answer 5

Origin - spinous processes T6-T12, iliac crest, thoracolumbar fascia and inferior 3 ribs
Attachment - intertubercular sulcus of humerus
Innervation - thoracodorsal nerve
Actions - extends, adducts and medially rotates the upper limb

Question 6

Levator scapulae

Answer 6

Origin - transverse processes of the C1-C4 vertebrae
Attachment - medial border of scapula
Innervation - dorsal scapula nerve
Actions - elevates the scapula

Question 7

Rhomboid major

Answer 7

Origin - spinous processes of T2-T5 vertebrae
Attachment - medial border of scapula, between scapula spine and inferior angle
Innervation - dorsal scapula nerve
Actions - retracts and rotates scapula

Question 8

Rhomboid minor

Answer 8

Origin - spinous process of C7-T1 vertebrae
Attachment - medial border of scapula at spine of scapula level
Innervation - dorsal scapula nerve
Actions - retracts and rotates scapula

Question 9

Testing the accessory nerve

Answer 9

Most common cause of damage - iatrogenic (due to medical procedure)
Trapezius function can be tested by asking patient to shrug shoulders
Other clinical features - muscle wasting, partial paralysis of sternocleidomastoid and an asymmetrical neckline