PRACTICAL DIRECTIONS. 467 
the branch of this nerve which runs to the inferior oblique muscle, 
and on it the ciliary ganglion; find the branches to the ciliary gan- 
glion from the ophthalmic nerve and follow them (p. 371). Follow 
also the short ciliary nerves (p. 370) to the eyeball. 
11. Trace the third nerve (p. 369) to its foramen of exit and find 
its branches. Where it passes between the superior and lateral recti, 
find the ophthalmic nerve (p. 370) by its side and trace its branches, 
12. Find the fourth nerve (p. 370), passing outside of the lateral 
rectus at its origin and entering the superior oblique. 
13. Follow the third, fourth, fifth, and sixth nerves into the skull 
by chipping away the bone and removing the dura. Note the semi- 
lunar or Gasserian ganglion (p. 370, and Fig. 138, 4) and the origin 
of the fifth nerves from it, and the relation of the ventral root of the 
fifth nerve to the mandibular nerve, 
2. SprnaL NERVES. 
The spinal nerves may be dissected on the same side used for 
dissecting the cranial nerves. (If an undissected specimen is used, 
remove the skin from the side of the neck, and cut the sternomastoid, 
sternohyoid, and sternothyroid muscles, as directed for the vagus and 
sympathetic.) 
Cervical Nerves (p. 383).—The ventral rami of the cervical nerves 
are to be sought as they pass out between the bundles of the 
scalenus, or between the scalenus and longus capitis, in the neck. 
This region has already been uncovered in dissecting the vagus and 
sympathetic (Fig. 156). Dissect first the second cervical (p. 385). 
Find its ventral ramus as it emerges between the levator scapulz 
ventralis and cleidomastoid (Fig. 158, 2), and follow its branches, — 
the auricularis magnus (5) and cutaneus colli (6), Find its dorsal 
ramus, the great occipital nerve (p. 384), by reflecting the clavo- 
trapezius muscle; the nerve will be found emerging from the under- 
lying muscles close to the craniomedial angle of the clavotrapezius, 
near its origin. Trace the nerve in both directions. 
The ventral ramus of the first cervical (p. 385) will be found 
emerging from beneath the wing of the atlas, a little distance craniad of 
the second (Fig. 156, 7). Trace it. To find its short dorsal ramus, 
the suboccipital nerve (p. 384), it is necessary to dissect apart the 
muscles on the dorsal side of the atlas till the nerve is found passing 
from the atlantal foramen. 
Dissect the third, fourth, and fifth nerves (p. 385, and Fig. 158). 
Brachial Plexus (p. 386, and Figs. 159 and 160).—The brachial 
plexus has been partly uncovered in dissecting the vagus and sympa- 
thetic. (If a new specimen or the opposite side is used, reflect the 
skin from the ventral surface of the thorax and arm, and cut the 
‘pectoral muscles, thus uncovering the vessels and nerves of the 
axilla.) Reflect the skin from the ventral surface of the unner arm. 
