Cut away a portion of the tympanic bulla and the base of the skull,
sufficient to follow these nerves in the jugular foramen, to the brain.
7. Locate the stylomastoid foramen and pick away overlying tissue until
the facial nerve is found emerging and then follow its branches to their
distribution (p. 375, and Fig. 155).
8. Expose the ventral surface of the pterygoid muscles just mediad of
the angle of the jaw. Divide and reflect them, and the mandibular
division of the fifth nerve (p. 373, and Fig. 154) will be found dorsad
of them and of the internal maxillary artery. The chorda tympani (p.
375) passes ventrad of the artery to join the lingual. Follow out (1)
the lingual branch (p. 375) (with the chorda tympani), and (2) the
inferior alveolar (p. 375) by cutting away the ventral border of the
mandible. Then cut the mandible near the canine tooth, and pull it to
one side, and follow out the muscular branches of the mandibular nerve.
9. Remove the mandible and find the maxillary nerve (p. 371) emerging
from the foramen rotundum. Follow its branches and find the
sphenopalatine ganglion (p. 372).
10. Remove the zygoma so as to expose the whole ventral aspect of the
orbit. Carefully pick away the fat in the orbit without injuring any
nerves, so as to expose the four recti muscles and the inferior oblique
(see p. 411, and Fig. 166). Find the abducens nerve (p. 375, and Fig.
154), entering the dorsal edge of the lateral rectus, and follow it
back. Look on the inner surface of the inferior rectus for the branch of
the third nerve (p. 369) which supplies it. Find the branch of this
nerve which runs to the inferior oblique muscle, and on it the ciliary
ganglion; find the branches to the ciliary ganglion 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 semilunar or
Gasserian ganglion (p. 370, and Fig. 138, _k_) and the origin of the
fifth nerves from it, and the relation of the ventral root of the fifth
nerve to the mandibular nerve.