. Cunningham's Text-book of anatomy. Anatomy. 366 THE MUSCULAR SYSTEM. triangular flat tendon, beneath which a bursa is placed—-into a rough tuberosity at the base of the spine of the scapula (Fig. 328, p. 367). The fibres inserted into the clavicle, acromion, and the upper border of the spine of the scapula spread over the adjacent subcutaneous surfaces of these bones for a variable distance. The occipital portion of the muscle may be in the form of a separate slip, or may be entirely absent. The trapezius is superficial in its whole extent. Its upper lateral border forms the posterior limit
. Cunningham's Text-book of anatomy. Anatomy. 366 THE MUSCULAR SYSTEM. triangular flat tendon, beneath which a bursa is placed—-into a rough tuberosity at the base of the spine of the scapula (Fig. 328, p. 367). The fibres inserted into the clavicle, acromion, and the upper border of the spine of the scapula spread over the adjacent subcutaneous surfaces of these bones for a variable distance. The occipital portion of the muscle may be in the form of a separate slip, or may be entirely absent. The trapezius is superficial in its whole extent. Its upper lateral border forms the posterior limit of the posterior triangle of the neck. The inferior lateral border, passing over the upper edge of the latissimus dorsi and the vertebral margin of the scapula, forms a boundary of the so-called triangle of auscultation, completed below by the latissimus dorsi, and laterally by the vertebral margin of the scapula. This space is partly filled up by the rhomboideus major. The muscle overlaps the latissimus dorsi, and covers the levator scapulae, rhomboidei, and the deeper axial muscles of the back, along with the ascending and the descending branch of the transverse artery of the neck, the accessory nerve, and muscular branches from the cervical plexus. Nerve-Supply.—The trapezius lias a double nerve-supply: (1) from the terminal fibres of the accessory nerve, and (2) from the cervical plexus (C. 3. and 4.). These nerves communicate with the accessory nerve both in the posterior triangle of the neck and beneath the trapezius. Action.—The main action of the trapezius is to draw the scapula backwards and upwards. The upper fibres of the muscle elevate the shoulder-girdle, while the lower fibres, pulling on the base of the spine of the scapula, depress the vertebral margin ; the two movements result in a rotation of the scapula, by which the glenoid cavity is tilted upwards, as in the movement of raising the arm above the head in a forward direction. M. Latissimus Dorsi.—The
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