Muscles Of The Shoulder Girdle

Question 1

Origin: Medial half of clavicle, sternum, and cartilage of ribs 1-7
Insertion: The lateral lip of the bicycle groove of the humerus
Action: Adducts, medially rotates, flexes and extends the arm at the glenohumeral joint

Answer 1

Pectoralis major

Question 2

Origin: ribs 3, 4 and 5
Insertion: Medial surface of the coracoid process of the scapula
Actions: Protracts, depresses and downwardly rotates the scapula at the scapulocostal joint
Reverse Action: Elevates the ribs 3-5 at the sternocostal and costospinal joints

Answer 2

Pectoralis minor

Question 3

Origin: Junction of the first rib and it’s costal cartilage
Insertion: Middle half of the inferior surface of the clavicle
Standard action: depressed the clavicle at the sternoclavicular joint
Reverse action: Elevates the first rib at the sternocostal and costospinal joints

Answer 3

Subclavius

Question 4

Origin: anterolateral aspect of ribs 1-9
Insertion: Anterior surface of medial border of the scapula
Action: Protracts and upwardly rotates the scapula at the scapulocostal joints

Answer 4

Serratus anterior