Pectoral

Pectoral is an adjective used to describe structures associated with the chest or anterior thorax. In humans it can refer to the pectoral region of the chest, the pectoral girdle that anchors the upper limb, and the muscles collectively known as the pectoral muscles. In other animals it can describe pectoral fins or the analogous flight-related muscles in birds.

In human anatomy, the pectoral region lies on the anterior chest wall. The major muscles are the pectoralis major and the pectoralis minor. Pectoralis major has clavicular and sternocostal heads; its origins include the medial half of the clavicle and the sternum plus costal cartilages 1–6, respectively, and it inserts on the lateral lip of the bicipital groove of the humerus. It is innervated by the medial and lateral pectoral nerves and functions to flex, adduct, and medially rotate the humerus; it also aids in deep inspiration when the arm is fixed. Pectoralis minor originates from ribs 3–5 and inserts on the coracoid process of the scapula; it is innervated by the medial pectoral nerve and stabilizes the scapula by drawing it anteriorly and inferiorly against the thoracic wall.

The pectoral girdle consists of the clavicles and scapulae and connects the upper limbs to the trunk. It includes joints such as the sternoclavicular and acromioclavicular joints and enables shoulder movement through scapulothoracic articulation, which coordinates with arm motion.

In other animals, pectoral structures include pectoral fins in fishes, supported by the pectoral girdle and radial elements, used for steering and stabilization. In birds, the pectoralis major powers the wing’s downstroke, while the supracoracoideus assists the upstroke.