|Henry Gray (18251861). Anatomy of the Human Body. 1918.|
in the interval between it and the Latissimus dorsi, where it closes in the axillary space and forms the axillary fascia; it divides at the lateral margin of the Latissimus dorsi into two layers, one of which passes in front of, and the other behind it; these proceed as far as the spinous processes of the thoracic vertebræ, to which they are attached. As the fascia leaves the lower edge of the Pectoralis major to cross the floor of the axilla it sends a layer upward under cover of the muscle; this lamina splits to envelop the Pectoralis minor, at the upper edge of which it is continuous with the coracoclavicular fascia. The hollow of the armpit, seen when the arm is abducted, is produced mainly by the traction of this fascia on the axillary floor, and hence the lamina is sometimes named the suspensory ligament of the axilla. At the lower part of the thoracic region the deep fascia is well-developed, and is continuous with the fibrous sheaths of the Recti abdominis.
FIG. 410 Superficial muscles of the chest and front of the arm. (See enlarged image)
| The Pectoralis major (Fig. 410) is a thick, fan-shaped muscle, situated at the upper and forepart of the chest. It arises from the anterior surface of the sternal half of the clavicle; from half the breadth of the anterior surface of the sternum, as low down as the attachment of the cartilage of the sixth or seventh rib; from the