Pectoralis Major and Minor

Pectoral muscles to men are like breast to women. For women, their pectoral muscles are hidden by their breast. For some men, the bigger and firmer the better and helps to boost ego. However, it is to more important what it is for. For a start, it consist of 2 parts .The major and minor. We are going to talk about the shape, origin, insertion and the functions of it.

Shape

Pectoralis Major: It is a thick, fan shaped muscle, located in the anterior (towards the front) of the body and its form the bulk of the chest muscles.

Pectoralis Minor: It is a thin, triangular muscle that is hidden underneath the pectoralis major muscle.

Origin

Pectoralis major: Medial third of the clavicle, anterior (front) aspect of the sternum, upper 6 costal cartilages and the aponeurosis of the external obliques

Pectoralis minor: It arises from the upper margins and outer surfaces of the third, fourth, and fifth ribs, near their cartilages and from the aponeuroses covering the intercostalis.

Insertion

Pectoralis major: Lateral (away from the midline of the body) lip of the bicipital groove (sternal fibers, more proximally (nearer to the midline of the body), clavicular fibers insert more distally (further from the trunk of the body)

Pectoralis minor: The fibers pass superior (towards the head of the body) and lateral (away from the midline of the body) and converge to form a flat tendon which is inserted into the medial (closer to the midline) border and upper surface of the coracoid process (hook like structure) of the scapulae

Function

Pectoralis Major: It has actions which are primarily responsible for movement of the shoulder joint. The 1st action is flexion of the humerus (upper arm), as in lifting a child. Secondly, it adducts the humerus (supper arm), as when flapping the arms. Thirdly, it rotates the humerus medially (internally), as occurs when arm-wrestling.

Pectoralis Minor: It depresses the shoulder, drawing the scapula inferior (retraction of the scapulae), towards the thoracic region ( middle back).

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