Trigeminal nerve

The trigeminal nerve is the fifth cranial nerve and its primary role is relaying sensory information from the face and head, although it does provide motor control to the muscles of mastication. It is both large and complicated and has multiple brainstem nuclei (sensory and motor) as well as many interconnections with other cranial nerves. It swaps parasympathetic fibres and taste fibres somewhat haphazardly, and divides into dozens of terminal branches.

Gross anatomy

Nuclei

There are three sensory and one motor nuclei. The sensory nuclei are arranged in a column which spans from the midbrain through the pons and medulla and into the upper cervical cord.

  1. mesencephalic nucleus: proprioceptive fibers for muscles of the face, orbit, mastication, and tongue
  2. main sensory nucleus: located in the upper pons, lateral to the motor nucleus is responsible for touch sensation for all three trigeminal divisions
  3. spinal nucleus: lower pons to upper cervical cord is responsible for pain and temperature; additionally it receives afferent fibers from the glossopharyngeal nerve and vagus nerve.

The motor nucleus is located in the upper pons and innervates the muscles of mastication as well as mylohyoid and tensor palati.

Intracranial component

The trigeminal nerve exits at the mid pons anteriorly, courses through the prepontine cistern (cisternal portion) to enter Meckel's cave (cavernous portion) where its fibers form the trigeminal (a.k.a. Gasserian or semilunar) ganglion. It then divides into three main branches:

Ophthalmic division (V1)

Courses anteriorly in the lateral wall of the cavernous sinus inferior to trochlear nerve. Just before entering the orbit, the tentorial nerve arises and ascends to supply a large portion of the falx and supratentorial dura. The ophthalmic division then divides into 3 terminal branches before each passes through the superior orbital fissure separately:

Maxillary division (V2)

Courses anteriorly in the lateral wall of the cavernous sinus inferior to trochlear nerve. Just before exiting the skull, the meningeal nerve arises and ascends to supply the anterior dura of the middle cranial fossa. It then passes through the foramen rotundum to exit skull and enters the superior aspect of the pterygopalatine fossa. It gives branches to pterygopalatine ganglion but also receives parasympathetic nerves from the ganglion via the greater petrosal nerve.  It then divides into the:

Mandibular division (V3)

Courses inferiorly through the foramen ovale to exit the skull. It hence does not course through the cavernous sinus. It gives motor supply to the muscles of mastication. It gives off muscular branches from the main trunk (before the division) to medial pterygoid, tensor tympani and tensor veli palatini a sensory meningeal branch. It then divides into anterior and posterior divisons:

Related pathology


Neuroanatomy
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Article Information

rID: 2207
Section: Anatomy
Synonyms or Alternate Spellings:
  • Trigeminal nerve (CN V)
  • Trigeminal nerve (V)
  • Nervus trigeminus

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    Figure 1: trigeminal nerve
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    Figure 2: CN V and CN VII connections
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    Figure 3: brainstem nuclei
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    Figure 4: cranial nerves
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    Figure 5: cranial nerves
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