Muscles of pectoral region

Question 1

Pectoralis major

Answer 1

Origin:

• Medial half od clavical
• Anterior surface of sternum
• First seven costal cartilages
• Aponeurosis of external oblique

Insertion:

• Lateral lip of intertubercular sulcus of humerus (Grays)

OR

• Crest of the greater tubercle (Thieme)

Innervation:

• Medial and lateral pectoral nerves

Function:

• Adduction
• Medial rotation
• Flexion of the humerus at the shoulder joint

Question 2

Pectoralis minor

Answer 2

Origin:

• Anterior surfaces of the third, fourth and fifth ribs
• Deep fascia overlaying the related intercostal spaces

Insertion:

• Coracoid process of scapula

Innervation:

• Medial pectoral nerves

Function:

• Depresses tip of shoulder
• Protracts scapula

Question 3

Subclavius

Answer 3

Origin:

• Rib 1 at junction between rib and costal cartilage

Insertion:

• Groove on inferior surface of middle third of clavicle

Innervation:

• Nerve to subclavis

Function:

• Pulls clavicle medially to stabilize sternoclavicular joints
• Depresses tip of shoulder