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Welcome to 2 minute neuroscience, where I explain neuroscience topics in 2 minutes or
less.
In this installment I will discuss the trigeminal nerve.
The trigeminal nerve is the main sensory nerve of the head.
It carries information about touch, pain, temperature, and proprioception, or the awareness
of the position of muscles and joints.
It also controls the muscles involved with chewing, as well as the tensor tympani, a
small muscle in the middle ear that helps to dampen the sound of loud noises, and the
tensor veli palatini, a muscle that both helps prevent food from entering the nasopharynx
during swallowing and opens a small tube called the eustachian tube, which connects the upper
throat with the middle ear.
This helps to equalize pressure between the middle ear and outside air.
The trigeminal nerve has three divisions, the ophthalmic, maxillary, and mandibular divisions,
which supply three different regions of the head and face as seen in the image.
The ophthalmic and maxillary divisions carry sensory information, while the mandibular
division has sensory and motor components.
There are three sensory nuclei and a motor nucleus associated with the trigeminal nerve.
They form a column of cells that reaches from the midbrain of the brainstem to the upper
spinal cord.
The main sensory nucleus receives information from the head about touch and proprioception.
The spinal trigeminal nucleus receives information about pain and temperature sensations.
The mesencephalic nucleus receives proprioceptive information from the jaw and teeth to prevent
damage while biting and chewing.
The motor nucleus controls the muscles of chewing and other muscles mentioned earlier.
Damage to the trigeminal nerve or its associated nuclei can cause varying levels of abnormal
sensation.
The patient may experience decreased sensation, increased pain, and/or weakening of the muscles
of chewing.
Trigeminal nerve damage can also lead to a condition called trigeminal neuralgia, in
which patients experience short but intense bouts of facial pain.