—The principal reason for attack upon this nerve is spasmodic torticollis, or wryneck. It is exposed through an incision along the anterior border of the sternocleidomastoid muscle, extending two inches downward from the ear. The nerve is found a little above the level of the hyoid bone; or, again, it may be found by an incision along the outer border of the muscle, opposite its centre, just above which it will be detected ([Fig. 405]).
The Deep Posterior Cervical Plexus.
—When operation upon the spinal accessory has failed to relieve long-standing and serious spasmodic torticollis, Keen has suggested to divide the first, second, and third cervical nerves. The operation is difficult and not always successful; still it is worth trying. A transverse incision is made below the level of the lobe of the ear, the trapezius being divided and dissected up until the great occipital nerve is found. It is followed after the necessary division of the complexus until its origin from the posterior division is reached. The suboccipital or first cervical nerve, which lies in the triangle close to the occiput that is formed by the two oblique muscles and the posterior rectus, is excised. The exterior branch of the posterior division is found lower down, and should be divided close to the bifurcation of the main nerve ([Fig. 406]).
Fig. 405
Exposure of the spinal accessory nerve alone: a, digastric; b, jugular veins; c, sternomastoid muscle; d, spinal accessory. (Marion.)
Fig. 406
Incisions through which the various nerves in the neck may be sought: a, facial; b, facial and hypoglossal; c, facial and sp. acces.; d, spinal accessory; e, cervical plexus; f, brachial plexus. (Marion.)