Muscles of Shoulder/Trunk

Question 1

PECTORALIS MAJOR

Answer 1

O: sternum, costal cartilages of ribs 1-7, medial 1/3 of clavicle, and aponeurosis of EAO
I: lateral lip of bicipital groove of the humerus
N: medial and lateral pectoral nerves
K:
1) Extension of the arm @ shoulder
2) Flexion of the arm " "
3) Adduction
4) Medial rotation
5) Abduction
6) Horizontal flexion/adduction

Question 2

PECTORALIS MINOR

Answer 2

O: ribs 3-5
I: coracoid process
N: medial and lateral pectoral nerves
K:
1) Downwardly rotates scapula
2) Protracts scapula
3) Depresses the scapula
4) Elevates ribs 3-5

Question 3

SERRATUS ANTERIOR

Answer 3

O: ribs 1-9 anterolaterally
I: medial border of scapula inferior to the root of spine & inferior angle
N: long thoracic nerve (C5, C6, C7)
K:
1) Protraction of the scapula
2) Upward rotation of the scapula

Question 4

LATISSIMUS DORSI

Answer 4

O: SP’s of T7-L5, posterior sacrum, posterior superior iliac crest, ribs 9-12 via the thoracolumbar fascia
I: floor of the bicipital groove of the humerus
N: thoracordorsal nerve
K:
1) Adduction of the arm at the shoulder joint
2) Extension “ “
3) Medial rotation “ “
4) Anteriorly tilts the pelvis