Muscles of the Scapular and Deltoid Regions

Question 1

subscapularis

Answer 1

origin: subscapular fossa
inertion: lesser tubercle of the humerus
innervation: upper and lower subscapular nerve
action: medial rotation of the arm

Question 2

supraspinatus

Answer 2

origin: supraspinous fossa
insertion: greater tubercle of the humerus (superior facet)
innervation: suprascapular N. (C5-C6)
action: abduction 0-15 degrees

Question 3

infraspinatus

Answer 3

origin: infraspinous fossa
insertion: greater tubercle of the humerus (middle facet)
innervation: suprascapular N. (C5-C6)
action: lateral rotation of the arm

Question 4

teres minor

Answer 4

origin: upper lateral border of the scapula
insertion: gerater tubercle of the humerus (inferior facet)
innervation: axillary n. (C5-C6)
action: lateral rotation of the arm

Question 5

teres major

Answer 5

origin: lower lateral border of the scapula
insertion: crest of the lesser tubercle of the humerus
innervation: lower subscapular n.
action: medial rotation, adduction and extension of the arm

Question 6

deltoid

Answer 6

origin: lateral margin of the scapular spine, acromion and clavicle (note that it mirrors the attachment of the trapezius
insertion: deltoid tuberosity of the humerus
innervation: axillary n. (C5-C6)
action: abduction 15-100 degrees, ant. fibers- med. rot. and flex. of the arm, post. fibers- lat. rot. and ext of the arm