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The clavipectoral fascia is a sheet of soft tissue found in the chest. Shaped like a triangle, it separates the pectoralis major, the large superficial muscle of the chest, from the muscles layered beneath it. Also known as the coracoclavicular fascia, this tissue layer extends from the subclavius muscle just beneath the collarbone down to the inside border of the pectoralis minor muscle, and from the top rib bone just to the side of the breastbone across to the coracoid process, a projection of the shoulder blade situated at the top front aspect of the shoulder. The clavipectoral fascia is penetrated by numerous vessels, including the lymph vessels that lead to nodes in the axilla or armpit, the lateral pectoral nerve, the cephalic vein, and the thoracoacromial artery and vein.
In the anterior wall of the human thorax, a region also referred to as the chest, are several layers of tissue covering the front of the ribcage. These tissues are bordered by the sternum or breastbone in the middle of the chest, the clavicle or collarbone crossing the top of the chest, the coracoid process of the scapula on the top of the shoulder, and the axilla on the lateral aspect of the chest. Deep to the skin and fat forming the outermost layers of the chest tissue is the pectoralis major muscle, whose fibers originate along the length of the side of the breastbone and come together to attach to the front of the upper humerus bone in the arm. Like many of the body’s muscles, the pectoralis major is enclosed by a thin sheath of tissue known as fascia.
Immediately beneath the fascia covering the deep or innermost surface of the pectoralis major is the clavipectoral fascia. Above, it originates on the inferior aspect or underside of the clavicle bone, specifically on a narrow depression called the subclavian groove. This is where the subclavius muscle attaches to the bone, a thin muscle that runs parallel to the clavicle and horizontally crosses the upper chest. The clavipectoral fascia arises from the edges of the groove in two layers that cover the front and back sides of this muscle.
Below the subclavius, the two layers of the clavipectoral fascia come together to form a single sheet of tissue. This sheet extends from the fascia arising from the near border of the sternum in the space between the first and second ribs as well as from the top rib itself. It then crosses the space below the subclavius muscle and attaches to the pectoralis minor, dividing again into two layers that enclose this muscle. The pectoralis major is a strap-like muscle that crosses the chest obliquely from the coracoid process of the shoulder to the front of the ribcage. It forms the diagonal border that gives the clavipectoral fascia its triangular shape.
The top outside corner of the fascia, after following the lower border of the collarbone toward the shoulder, attaches to the coracoid process as well. This is the rounded bony protrusion of the upper scapula that projects forward over the top of the shoulder. At this upper corner of the chest where the subclavius meets the pectoralis minor, the clavipectoral fascia covers and gives protection to the vessels that extend from the thorax into the axillary region or armpit: the thoracoacromial blood vessels, the lymph vessels, the cephalic vein, and the lateral pectoral nerve.