Pectoralis Muscle

**Semantic type:** Anatomical Structure

**Definition:** Muscles of the upper chest. The term may refer to one of two muscles, the pectoralis major and pectoralis minor. The former is a thick muscle in the anterior portion of the chest. Its action involves flexion, medial rotation, and adduction of the humerus. The latter is a thin muscle located beneath the pectoralis major. Its action involves lowering the scapula and raising the ribs.

**Synonyms:** - MUSCLE, PECTORALIS