Pectoralis Major Anatomy and Function

This tutorial covers the anatomy of the pectoralis major muscle, a large fan-shaped muscle in the chest. It details the muscle's two heads, the clavicular and sternocostal, their origins, insertions, and actions. The tutorial explains how the muscle flexes, extends, adducts, and rotates the humerus. It also covers the nerve supply from the brachial plexus and the blood supply from the thoracoacromial artery. The video concludes with a recommendation to explore the Anatomy Learning app for further study.

What is the shape of the pectoralis major muscle?

• Triangular

• Rectangular

• Fan-shaped

• Circular

Where does the clavicular head of the pectoralis major originate?

• Costal cartilages of ribs 7 to 12

• Lateral border of the scapula

• Posterior surface of the sternum

• Antero-medial half of the clavicle

Which structure does the tendon of the pectoralis major insert into?

• Acromion process of the scapula

• Greater tubercle of the humerus

• Lateral lip of the bicipital groove

• Medial epicondyle of the humerus

What is the function of the posterior lamina of the pectoralis major tendon?

• Receives fibers from the clavicular head

• Receives deeper fibers from the costal cartilages

• Attaches to the sternum

• Connects to the scapula

What action does the clavicular head of the pectoralis major perform?

• Lateral rotation of the humerus

• Abduction of the humerus

• Flexion of the humerus

• Extension of the humerus

What is the primary action when both heads of the pectoralis major work together?

• Abduction of the humerus

• Adduction of the humerus

• Lateral rotation of the humerus

• Extension of the humerus

Which head of the pectoralis major is responsible for flexing the humerus?

• Neither head

• Both heads equally

• Clavicular head

• Sterno-costal head

What is the role of the sterno-costal head when the arm is in a flexed position?

• Performs further flexion

• Performs extension back to anatomical position

• Performs abduction

• Performs lateral rotation

Which nerve originates from the medial cord of the brachial plexus to innervate the pectoralis major?

• Medial pectoral nerve

• Lateral pectoral nerve

• Axillary nerve

• Radial nerve

Which artery provides the main blood supply to the pectoralis major?

• Radial artery

• Subclavian artery

• Brachial artery

• Thoracoacromial artery