The three major branches of the trigeminal nerve—the ophthalmic nerve (V₁), the maxillary nerve (V₂) and the mandibular nerve (V₃)—converge on the trigeminal ganglion (also called the semilunar ganglion or gasserian ganglion), located within Meckel's cave and containing the cell bodies of incoming sensory-nerve fibers.
The trigeminal ganglion is analogous to the dorsal root ganglia of the spinal cord, which contain the cell bodies of incoming sensory fibers from the rest of the body.

From the trigeminal ganglion a single, large sensory root enters the brainstem at the level of the pons.
Immediately adjacent to the sensory root, a smaller motor root emerges from the pons at the same level.
Motor fibers pass through the trigeminal ganglion without synapsing on their way to peripheral muscles, but their cell bodies are located in the nucleus of the fifth nerve, deep within the pons.

The areas of cutaneous distribution (dermatomes) of the three sensory branches of the trigeminal nerve have sharp borders with relatively little overlap (unlike dermatomes in the rest of the body, which have considerable overlap).
The injection of a local anesthetic, such as lidocaine, results in the complete loss of sensation from well-defined areas of the face and mouth.
For example, teeth on one side of the jaw can be numbed by injecting the mandibular nerve.
Occasionally, injury or disease processes may affect two (or all three) branches of the trigeminal nerve; in these cases, the involved branches may be termed:
V1/V2 distribution – Referring to the ophthalmic and maxillary branches
V2/V3 distribution – Referring to the maxillary and mandibular branches
V1-V3 distribution – Referring to all three branches
Nerves on the left side of the jaw slightly outnumber the nerves on the right side of the jaw.
The three major branches of the trigeminal nerve—the ophthalmic nerve (V₁), the maxillary nerve (V₂) and the mandibular nerve (V₃)—converge on the trigeminal ganglion (also called the semilunar ganglion or gasserian ganglion), located within Meckel's cave and containing the cell bodies of incoming sensory-nerve fibers. The trigeminal ganglion is analogous to the dorsal root ganglia of the spinal cord, which contain the cell bodies of incoming sensory fibers from the rest of the body.
From the trigeminal ganglion a single, large sensory root enters the brainstem at the level of the pons. Immediately adjacent to the sensory root, a smaller motor root emerges from the pons at the same level. Motor fibers pass through the trigeminal ganglion without synapsing on their way to peripheral muscles, but their cell bodies are located in the nucleus of the fifth nerve, deep within the pons. 
The areas of cutaneous distribution (dermatomes) of the three sensory branches of the trigeminal nerve have sharp borders with relatively little overlap (unlike dermatomes in the rest of the body, which have considerable overlap). The injection of a local anesthetic, such as lidocaine, results in the complete loss of sensation from well-defined areas of the face and mouth. For example, teeth on one side of the jaw can be numbed by injecting the mandibular nerve. Occasionally, injury or disease processes may affect two (or all three) branches of the trigeminal nerve; in these cases, the involved branches may be termed:
V1/V2 distribution – Referring to the ophthalmic and maxillary branches
V2/V3 distribution – Referring to the maxillary and mandibular branches
V1-V3 distribution – Referring to all three branches
Nerves on the left side of the jaw slightly outnumber the nerves on the right side of the jaw.
Trigeminal nerve