Anatomy Muscles 450-475

Front 1

Teres Minor innervation

Back 1

Axillary nerve

Front 2

Supraspinatus origin and insertion

Back 2

origin: Supraspinous fossa of scapula; insertion: Superior part of greater tubercle of humerus

Front 3

Infraspinatus action

Back 3

Helps to hold head of humerus in glenoid cavity; rotates humerus laterally

Front 4

Infraspinatus innervation

Back 4

Suprascapular nerve

Front 5

Subscapularis origin and insertion

Back 5

origin: Subscapular fossa of scapula; insertion: Lesser tubercle of humerus

Front 6

Supraspinatus action

Back 6

Stabilizes shoulder joint; helps to prevent downward dislocation of humerus, as when carrying a heavy suitcase; assists in abduction

Front 7

Supraspinatus innervation

Back 7

Suprascapular nerve

Front 8

Deltoid origin and insertion

Back 8

origin: Embraces insertion of the trapezius; lateral third of clavicle; acromion and spine of scapula; insertion: Deltoid tuberosity of humerus

Front 9

Subscapularis action

Back 9

Chief medial rotator of humerus; assisted by pectoralis major; helps to hold head of humerus in glenoid cavity, thereby stabilizing shoulder joint

Front 10

Subscapularis innervation

Back 10

Subscapular nerves (C5-C7)

Front 11

Latissimus Dorsi origin and insertion

Back 11

origin: Indirect attachment via lumbodorsal fascia into spines of lower six thoracic vertebrae, lower 3 to 4 ribs, and iliac crest; also from scapula’s inferior angle; insertion: Spirals around teres major to insert in floor of intertubercular groove of humerus

Front 12

Deltoid action

Back 12

Prime mover of arm abduction when all its fibers contract simultaneously; antagonist of pectoralis major and latissimus dorsi, which adduct the arm; if only anterior fibers are active, can act powerfully in flexion and medial rotation of humerus, therefore synergist of pectoralis major; if only posterior fibers are active, effects extension and lateral rotation of arm; active during rhythmic arm swinging movements during walking

Front 13

Deltoid innervation

Back 13

Axillary nerve (C5, C6)

Front 14

Pectoralis major origin and insertion

Back 14

Origin: Clavicle, sternum, cartilage of ribs 1-6, and aponeurosis of external oblique muscle; Fibers converge to insert by a short tendon into greater tubercle of humerus

Front 15

Latissimus Dorsi action

Back 15

Prime mover of arm extension; powerful arm adductor; medially rotates arm at shoulder; depresses scapula; because of its power in these movements, it plays an important role in bringing the arm down in a power stroke, as in striking a blow, hammering, swimming, and rowing

Front 16

Latissimus Dorsi innervation

Back 16

Thoracodorsal nerve

Front 17

Pectoralis Major action

Back 17

Prime mover of arm flexion; rotates arm medially; adducts arm against resistance; with scapula (and arm) fixed, pulls rib cage upward, thus can help in climbing, throwing, pushing and in forced inspiration