Muscles of the Pectoral Girdle

Question 1

Pectoralis Major

Answer 1

O : Medial 1/2 of clavicle, sternum and cartilage of ribs 1-7
I : Lateral lip of the bicipital groove of the humerus
A :
1. Flexes the arm at the GH joint
2. Extends the arm at the GH joint
3. Medially rotate the arm at the GH joint
4. Adduct the arm at the GH joint

Question 1

Pectoralis Minor

Answer 1

O : Ribs 3-5
I : Medial surface of the coracoid process of the scapula
SMA :
1. Protracts the scapula at the scapulocostal joint
2. Depress the scapula at the scapulocostal joint
3. Downwardly rotates the scapula at the scapulocostal joint
RMA :
1. Elevates ribs 3- at the sternocostal and costospinal joint

Question 2

Subclavius

Answer 2

O : Junction of the 1st rib and its costal cartilage
I : Middle 1/2 of the inferior surface of the clavicle
SMA : Depress the clavicle at the sternoclavicular joint
RMA : Elevates the 1st rib at the sternocostal and costospinal joints

Question 3

Serratus Anterior

Answer 3

O : Anterolateral aspect of ribs 1-9
I : Anterior surface of medial border of the scapula
A :
1. Protracts the scapula at the scapulocostal joint
2. Upwardly rotates the scapula at the scapulocostal joint