Under this head will be described those muscles which arise on the
scapula and end on the arm; they may be divided into two groups—one
covering the dorsum, the other the venter of the scapula.
The =superficial fascia= of the shoulder and arm contains the panniculus
carnosus of this region, and may be considered to be continued on the
inner side of the limb by the subscapular fascia.
The =thoracic= or =scapulo-humeral portion= of the =panniculus= (M.
cutaneus scapulæ et humeri) arises by a thin aponeurosis from the
ligamentum nuchæ at the withers. The fleshy portion begins over the
upper part of the scapula and extends to the elbow. Its fibers have in
general a dorso-ventral direction. It is continuous behind with the
abdominal portion.
The =deep fascia= of the shoulder and arm (Fascia omobrachialis) is much
more developed and important. It is strong and tendinous, and is
intimately adherent to the muscles on the outer surface of the scapula,
between which it detaches =intermuscular septa=, which are attached to
the spine and borders of the scapula. The brachial portion is, for the
most part, only loosely attached to the underlying muscles, for which it
forms sheaths; it is attached to the humerus, especially to the lips of
the bicipital groove and the deltoid tuberosity. It blends distally with
the tendon of insertion of the biceps, and is continued by the
antibrachial fascia.