1. Reflect the skin covering the sternomastoid muscle, and make a
longitudinal incision of the muscle so as to expose the carotid artery.
Lying along the artery find the combined trunk of the sympathetic and
vagus nerves. Follow the vagus (p. 378) first craniad; transect the
muscles as necessity arises, and find its ganglion nodosum and at the
same time locate the superior cervical ganglion of the sympathetic nerve
(p. 404, and Fig. 156). Then find the hypoglossal nerve (Fig. 156, _b_),
passing outside of the carotid artery to the tongue, and the accessory
(Fig. 156, _c_), passing to the trapezius. Cut and reflect the digastric
muscle and find the small glossopharyngeal nerve (Fig. 156, _a_),
passing to the surface of the bulla and then beneath the carotid artery.
2. Follow the vagus (p. 378) caudad to its termination. To do this it
is necessary to remove one side of the thorax, as in dissecting the
blood-vessels. Do not injure the nerves of the axilla, nor the phrenic
or sympathetic nerves. For the vagus in the thorax, compare Fig. 157.
Find the branches of the nerve; in dissecting them, pull on them to make
them tense. They are then more easily visible. To dissect the abdominal
portion of the vagus, open the abdominal cavity, and compare Fig. 164
(p. 407).
3. Dissect the sympathetic (p. 404), following it and its branches to
the pelvic region (Figs. 156, 157, and 164).