on one side, with its branches, _a_.
Vertical section of the cerebrum.
_b_. Section of the cerebellum, _c_.
Corpus callosum. _d_. Lower section
of medulla oblongata. Above
_d_, origin of the pneumogastric
nerve. 1. Pharyngeal branch. 2.
Superior laryngeal. 5. Branches
to the lungs. 4. Branches to the
liver. 6. Branches to the stomach.]

THE CRANIAL NERVES. From the brain, nerves are given off in pairs, which
succeed one another from in front backwards to the number of twelve. The
_first_ pair, the _olfactory_ nerves, are the nerves of the sense of
smell. The _second_ pair are the _optic_, or the nerves of the sense of
sight. The _third_ pair are called the _motores oculi_, the movers of
the eye, from the fact that they are distributed to all the muscles of
the eye with the exception of two. The _fourth_ pair and the _sixth_
pair each supply one of the muscles of the eye, on each side, the fourth
extending to the superior oblique muscle, and the sixth to the external
rectus muscle. The nerves of the _fifth_ pair are very large; they are
each composed of two bundles of filaments, one motor and the other
sensory, and have, besides, an additional resemblance to a spinal nerve
by having a ganglion on each of their sensory roots, and, from the fact
that they have three chief divisions, are often called the _trigeminal_,
or _trifacial_, nerves. They are nerves of special sense, of sensation,
and of motion. They are the sensitive nerves which supply the cranium
and face, the motor nerves of the muscles of mastication, the
_buccinator_ and the _masseter_, and their third branches, often called
the _gustatory_, are distributed to the front portion of the tongue, and