Extrinsic muscles of the shoulder

Question 1

Where are the extrinsic shoulder muscles?

Answer 1

Back of trunk

Question 2

What are the superficial muscles?

Answer 2

Trapezius

Latissimus dorsi

Question 3

What are the deep muscles?

Answer 3

Levator scapulae

Rhomboid major + minor

Question 4

Describe the origin, insertion, innervation of trapezius

Answer 4

Occipital protuberance of skull/nuchal ligament/spinous process C7-12
Clavicle/acromion/scapula spine
Spinal accessory nerve + proprioceptor fibres from C3-4

Question 5

Describe the actions of trapezius for the upper, middle + lower fibres

Answer 5

Upper = elevate scapula, rotate it in arm abduction (+90 degrees)
Middle = retraction
Lower = pull scapula inferiorly

Question 6

How do you test trapezius strength?

Answer 6

Patient shrug shoulders + you push them down

Question 7

Describe the origin, insertion, innervation + action of latissimus dorsi

Answer 7

Spinous process T6-12, iliac crest, thoracolumbar fascia, inferior 3 ribs
Intertubercular sulcus
Thoracodorsal nerve
Extends/adducts/medially rotates upper limb

Question 8

Describe the origin, insertion, innervation + action of levator scapulae

Answer 8

Transverse process C1-4
Medial scapula
Dorsal scapular nerve
Elevates scapula

Question 9

Describe the origin, insertion, innervation + action of rhomboid minor

Answer 9

(superior to rhomboid major)
Spinous process C7-T1
Medial scapula
Dorsal scapular nerve
Retracts scapula/rotates medial border (helps return to anatomical position after abduction above 90 degrees)

Question 10

Describe the origin, insertion, innervation + action of rhomboid major

Answer 10

Spinous process T2-5
Medial scapula
Dorsal scapular nerve
Same action as minor