Anatomy of the trigeminal nerve (CN V)

When it comes to the trigeminal nerve, or CN V, tri means three, so right off the bat, you can tell that the trigeminal nerve has three major branches: the ophthalmic nerve, or V1, the maxillary nerve, or V2, and the mandibular nerve, or V3.

The ophthalmic and the maxillary nerves only have sensory functions, while the mandibular nerve has both sensory and motor functions.

So, the trigeminal nerve is in charge of sensation for the face, mouth, nasal cavity and dura mater of the cranial cavity, and also of motor functions like biting and chewing.

In addition to motor and sensory fibers, postganglionic parasympathetic fibers join many of the branches of the trigeminal nerve to reach their final destination; so the branches of the trigeminal nerve serve as a pathway for parasympathetic innervation.

Now, the trigeminal nerve emerges from the lateral aspect of the pons by a large sensory root and a small motor root.

The large sensory root mainly consists of cell bodies of the pseudounipolar neurons that make up the sensory trigeminal ganglion, which sits within a dural recess lateral to the cavernous sinus, called the trigeminal cave.

When the ophthalmic, maxillary, and sensory component of the mandibular nerves detect a signal from their sensory nerve endings, the pseudounipolar neurons that make up these nerves transmit their signal through the trigeminal ganglion as first order neurons in the pathway, to synapse in the different trigeminal nuclei located along the brainstem.

The cell bodies of these pseudounipolar nerves are located in the trigeminal ganglion, similar to how the dorsal root ganglions hold the cell bodies for the sensory pseudounipolar neurons of the body.