Electro-physiology and electro-therapeutics : showing the best methods for the medical uses of electricity / By Alfred C. Garratt.

The trapezius arises from the inner third of the occiput, and is attached to the last cervical and whole of the dorsal ver- tebras, also to the scapula, with clavicular attachment from occi- put to clavicle. It exercises action upon the shoulder in three directions; for its clavicular and occipital fibres draw the shoul- der upward ; its upper dorsal, cervical, and scapular fibres draw it backward, i. c, to the spine; its dorsal fibres draw it a little down- ward. If, then, the inferior portion of the trapezius be Fara- daized, the base of the scapula is drawn backward, and its inferior angle downward. If the middle portion be thus excited, the scapula is elevated, and its inferior angle is drawn farther from the spine. If the clavicular portion of this muscle be Farada- ized, then the head is drawn towards the side acted upon by the current, and besides, it is drawn slightly backward, so that the chin is turned a little towards the opposite side, and the clavicle is also elevated by it. The clavicular portion of the trapezius is exceedingly responsive by electric contractions, because it is animated by a double set of nerve fibrils, and that is, both from the spinal accessory and lrorn the cervical plexus. Therefore unusual care is required to proceed here with the currents in moderation and gentleness at first. If we apply the electric stimulus to the clavicular portions of both trapezius muscles, i. e., by directing one electrode to each at the same time, — the head is drawn directly backward. The latissimus dorsi arises from the spinous processes of the lower dorsal and of all the lumbar vertebras, also from the sa- crum, ilium, and four lower ribs, and is inserted into the bicipital grooves of the humerus. Hence the action of this great muscle tends to draw the shoulder back upon the spine, or the spine laterally toivards the shoulder. It passes over the inferior angle of the scapula, and by pressing upon it, steadies it. If it is Faradaized, it draws the arm downward and backward; the scapula is at the same time approximated to the spine, but not elevated. The trapezius and the latissimus dorsi form the first and outer layer of the muscles of the back. When the deltoid muscle is electrized, it abducts the humerus, but does not elevate it even in that direction above the horizontal