Muscles of the Anterior Thorax and Shoulder

Question 1

Pectoralis Major

Answer 1

Origin: broadly along clavicle and sternum
Insertion: greater tubercle and upper part of humerus
Action: flexes and medially rotates arm

Question 2

Deltoid

Answer 2

Origin: lateral clavicle, acromion and spine of scapula
Insertion: deltoid tuberosity on lateral humerus
Action: abducts arm if entire muscle contracts; flexes and medially rotates arm if only anterior fibers contract; extends and laterally rotates arm if only posterior fibers contract

Question 3

Pectoralis Minor

Answer 3

Origin: ribs 3-5
Insertion: coracoid process of scapula
Action: depresses scapula and pulls scapula forward

Question 4

Serratus Anterior

Answer 4

Origin: ribs 1-8
Insertion: anterior/medial surface of scapula
Action: holds scapula to posterior thorax, raises shoulder by rotating scapula