Muscles of Thorax, Shoulder Girdle, Upper Arms

Question 1

Trapezius (upper/middle/lower)

Answer 1

origin = occipital bone, spinous process of T1-T12
insertion = lateral clavicle, acromion, scapular spine of scapula
action = rotation, retraction, elevation, and depression of scapula; neck extension; shoulder stabilization
innervation = accessory nerve

Question 2

Levator scapulae

Answer 2

origin = transverse process C1-C4
insertion = medial border of scapula
action = elevates scapula
innervation = dorsal scapular nerve

Question 3

Rhomboids (major/minor)

Answer 3

origin = spinous process (minor = C7-T1, major = T2-5)
insertion = medial border of scapula
action = retracts scapula
innervation = dorsal scapular nerve

Question 4

Pectoralis minor

Answer 4

origin = ribs 3-5
insertion = coracoid process of scapula
action = elevates ribs; draws scapula down + medially
innervation = medial pectoral nerve

Question 5

Serratus anterior

Answer 5

origin = upper 8-9 ribs
insertion = medial border of scapula
action = retraction of scapula
innervation = long thoracic nerve

Question 6

Rotator Cuff Muscles (4)

Answer 6

1. Supraspinatus
2. Infraspinatus
3. Teres Minor
4. Subscapularis

(SITS)

Question 7

Deltoid (anterior/middle/posterior)

Answer 7

origin = clavicle and scapula
insertion = deltoid tuberosity of humerus
action = abduction of shoulder (away from body)
innervation = axillary nerve

Question 8

Pectoralis major

Answer 8

origin = ribs 2-6, body of sternum
insertion = greater tubercle of humerus
action = flexion, adduction, and medial rotation of shoulder
innervation = pectoral nerves

Question 9

Supraspinatus

Answer 9

rotator cuff muscle
origin = origin = supraspinatus fossa of scapula (above scapular spine)
insertion = greater tubercle of humerus
action = abduction at shoulder
innervation = suprascapular nerve

Question 10

Infraspinatus

Answer 10

rotator cuff muscle
origin = infraspinatus fossa of scapula (below scapular spine)
insertion = greater tubercle of humerus
action = lateral rotation at shoulder
innervation = suprascapular nerve

Question 11

Teres minor

Answer 11

rotator cuff muscle
origin = lateral border of scapula
insertion = greater tubercle of humerus
action = lateral rotation at shoulder
innervation = axillary nerve

Question 12

Teres major

Answer 12

NOT a rotator cuff muscle
origin = inferior angle of scapula
insertion = intertubercular groove of humerus
action = extension, adduction, medial rotation of shoulder
innervation = lower subscapular nerve

Question 13

Subscapularis

Answer 13

origin = subscapular fossa of scapula - inner surface of scapula
insertion = lesser tubercle of humerus
action = medial rotation at shoulder
innervation = subscapular nerves

Question 14

Latissimus dorsi

Answer 14

origin = spinous process of inferior thoracic + lumbar vert, ribs 8-12
insertion = intertubercular groove of humerus
action = extension, adduction, and medial rotation at shoulder
innervation = thoracodorsal nerve

Question 15

Coracobrachialis

Answer 15

origin = coracoid process of scapula
insertion = medial shaft of humerus
action = adduction and flexion at shoulder
innervation = musculocutaneous nerve