Anterior Shoulder Muscles

Question 1

Pectoralis major

Answer 1

O: medial half of clavicle; sternum; superior seven costal cartilages; aponeurosis of external abdominal oblique
I: intertubercle groove of humerus
I: lateral (c5-c7) and medial pectoral nerves (c8-t1)
A: flexes, adducts, and medially rotates arm at the shoulder; extension of flexed arm

Question 2

Pectoralis minor

Answer 2

O: 3rd-5th ribs
I: coracoid process of scapula
I: medial pectoral nerve (c8-t1)
A: depresses scapula and stabilizes it

Question 3

Serratus anterior

Answer 3

O: lateral surface of upper eight ribs
I: inferior surface of clavicle
I: nerve to subclavius (c5-c6)
A: protracts and rotates scapula upward and pulls it anteriorly toward thoracic wall

Question 4

Subclavius

Answer 4

O: junction of 1st rib and costal cartilage
I: interior surface of clavicle
I: nerve to subclavius (c5-c6)
A: depress clavicle

Question 5

Deltoid

Answer 5

O: lateral 3rd of clavicle, acromion and spine of scapula
I: deltoid tuberosity of humerus
I: axillary nerve (c5-c6)
A: Anterior part- flexes and medially rotates arm at shoulder
Middle part- abducts arm at shoulder
Posterior part- extends and laterally rotates arm at shoulder