Large pectoralis muscle

Large pectoralis muscle , m. Pectoralis major, paired, wide, located most superficially in the antero-thoracic parts of the thorax.

Upper-lateral margin, the muscle approaches the anterior margin of the deltoid muscle, forming with it the deltoid-thoracic furrow, and at the edge of the clavicle - the subclavian fossa, fossa іnfraclavicularis. The lower margin of the large pectoral muscle is sometimes clearly delineated through the skin. The muscle begins on the inner side of the clavicle - the clavicular part, pars clavicularis, from the anterior surface of the sternum and the cartilages of the II-VII ribs - the sternocostal portion, the pars sternocostalis, and from the anterior wall of the rectus abdominal vagina - the abdominal part, pars abdominalis (mild) .

Heading laterally and upward, the bundles of the large pectoral muscle converge so that the bunches of the lower part of the muscle lie behind the bundles of the upper part, as a result of which the muscle is considerably thickened at this point. This narrowed but thickened part of the muscle goes over to the humerus, forming the anterior wall of the axillary fossa, fossa axillaris, and then to the tendon, attached to the crest of the large tubercle of the humerus, the lower tufts higher, and the upper ones lower.

Function: leads and rotates the shoulder inward, with the horizontal position of the hand leads it to the sagittal position, and with the upper limb strengthened by its sternum-rib part the muscle promotes the expansion of the thorax in the act of breathing.

Innervation: nn. Pectorales medialis and lateralis (CV-ThI).

Blood supply: aa. Thoracoacromialis, thoracica lateralis, thoracica superior, rr. Intercostales anteriores.