082 The Origin, Insertion, and Action of Pectoralis Major

This video by Leslie Samuel explores the pectoralis major muscle, detailing its structure, origins, insertion points, and actions. The muscle is divided into the clavicular and sternocostal portions, each with distinct origins. The insertion is at the humerus, specifically the crest of the greater tubercle. The video explains how the muscle's contraction leads to various arm movements, including flexion, extension, adduction, and medial rotation. The tutorial concludes with a review of these key points, emphasizing the muscle's role in arm movement.

What are the two main portions of the pectoralis major muscle?

• Clavicular and Sternocostal

• Sternocostal and Biceps

• Sternal and Trapezius

• Clavicular and Deltoid

Where does the clavicular head of the pectoralis major originate?

• Lateral half of the clavicle

• Medial half of the clavicle

• Entire clavicle

• Sternum

Which part of the body does the sternocostal head of the pectoralis major attach to?

• Medial half of the clavicle

• Lower 6 ribs

• Upper 6 costal cartilages

• Entire sternum

Where does the pectoralis major muscle insert?

• Lesser tubercle of the humerus

• Greater tubercle of the humerus

• Medial epicondyle of the humerus

• Olecranon of the ulna

What action is performed by the clavicular head of the pectoralis major?

• Flexion of the humerus

• Abduction of the humerus

• Lateral rotation of the humerus

• Extension of the humerus

What is the primary action of the entire pectoralis major muscle?

• Extension of the humerus

• Lateral rotation of the humerus

• Adduction of the humerus

• Abduction of the humerus

Which action is NOT performed by the pectoralis major?

• Medial rotation of the humerus

• Flexion of the humerus

• Extension of the humerus

• Pronation of the forearm