The pectoral fascia is a thin lamina, covering the surface of the pectoralis major, and sending numerous prolongations between its fasciculi: it is attached, in the middle line, to the front of the sternum; above, to the clavicle; laterally and below it is continuous with the fascia of the shoulder, axilla, and thorax. 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.