(_a_) The olfactory nerve, arising from the anterior end of the
olfactory lobes, supplying the olfactory capsule.
(_b_) The optic nerve, arising from the ventral surface of the brain
below the optic lobes, supplying the retina of the eye.
(_c_) The trigeminal nerve, arising just behind the optic nerve,
giving rise to the following branches:--
(_i_) The ophthalmic nerve, which passes over the muscles of the
eye and supplies the skin in the region of the olfactory
capsule.
(_ii_) The maxillary nerve, which runs forward under the
eyeball, and supplies the skin covering the upper jaw.
(_iii_) The mandibular nerve, which is at first continuous with
the maxillary, and then bends round the inner surface of the
upper jaw to extend along the outer surface of the mandible.
(_d_) The glossopharyngeal and the vagus (or pneumogastric) nerves,
leaving the skull together, immediately behind the auditory capsule.
The glossopharyngeal passes along in front of the hypoglossal nerve
and proceeds along the base of the tongue. The vagus, after giving
off branches to the dorsal muscles, reaches the walls of the pharynx
and run obliquely backwards to supply the pharynx, heart, lungs and
stomach.
[Illustration: FIG. 18.--Brain. Cranial Nerves, Spinal Nerves, and
Sympathetic Nervous System of Xenopus and Rana.]
Make a complete sketch showing the brain and the above-mentioned
cranial nerves.
* * * * *
Transcriber's Notes:
Every effort has been made to replicate this text as faithfully as
possible, including inconsistencies in formatting.
Italic text is denoted by _underscores_ and bold text by =equal
signs=.
Both "exoccipitals" and "ex-occipitals" occur in original text, left as
printed.