The pectoralis major muscle is a superficial thorax muscle that takes on a quadrangular shape when the arm is hanging and a triangular shape when the arm is completely flexed. It can be divided into three parts: clavicular, sternocostal and abdominal
The clavicular part originates from the 2/3 medial of the anterior margin of the clavicle.
The sternocostal part originates from the anterior aspect of the sternum and from the first 6 costal cartilages.
The abdominal part from the anterior leaflet of the rectus abdominal muscle sheath.
The three bundles flatten out, move upwards and insert with a common tendon to the lateral lip of the bicipital groove of the humerus (also called crest of the large tuberosity or tubercle greater than the humerus). The abdominal part is the one that is inserted in the most proximal point of the humerus.
Adds and rotates the humerus inside, or raises the trunk if it takes a fixed point on the humerus. Participate with the clavicular bundle to flex about 0 to 50-60 ° of the arm (in synergy with the deltoid and coraco-brachial muscles).
The pectoralis major muscle also intervenes in forced inspiration, if the arm is fixed (as happens when an athlete at the end of a competition points his hands against his hips to recover the effort).
It is innervated by the anterior thoracic nerves of the brachial plexus (C5-C8 and T1)
The upper part is related to the mammary gland, covers the sternum, the intercostal muscles and the small pectoralis.
ORIGIN The clavicular part originates from the 2/3 medial of the anterior margin of the clavicle The sternocostal part originates from the anterior aspect of the sternum and from the first 6 costal cartilages The abdominal part from the anterior leaflet of the rectus abdominal muscle sheath |  |
| INSERTION With a single tendon on the lateral lip of the bicipital sulcus of the humerus (crest of the great anterior tuberosity of the humerus) | |
| ACTION Adduce and rotate the arm internally. taking the fixed point to the humerus, lift the trunk | |
| INNERVATION Anterior thoracic nerves of the brachial plexus (C5-C8 and T1) |
| Upper limb | Lower limb | Trunk | Abdomen | Articles |
