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What is the Nervus Trigeminus?

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  • Written By: Michael Humphrey
  • Edited By: J.T. Gale
  • Last Modified Date: 25 November 2016
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Nervus trigeminus is the nerve responsible for feeling sensations in the face and also controls the motions of biting and chewing. Also called the fifth cranial nerve, the Latin term nervus trigeminus literally translates as "three twins," because the nerve branches into three sections on both sides of the face. It extends from the lateral surface of the pons into the skull and splits into the ophthalmic nerve, the maxillary nerve, and the mandibular nerve.

Four of nervus trigeminus’ six branches only act as sensory nerves. The ophthalmic nerves provide sensation to the upper part of the face. Ophthalmic nerves supply several parts of the eye as well as part of the nasal cavity and the skin of the nose, eyelids, eyebrows, and forehead. Maxillary nerves supply sensations to the middle part of the face, including parts of the nasal cavity, the sinuses, the upper lip, and mouth.

The mandibular nerves are the largest of nervus trigeminus’ nerves and the only to cause motion. They extend down the jaw bone and control feeling in the lower jaw, the lower lip, and the lower gum. Also, they control some of the muscle activity in the lower jaw, which allows the face to bite, chew, and perform part of the motion for swallowing. The nerves for motor control are the smallest of the nervus trigeminus.

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It is clear from its physiology that the most important role of the nervus trigeminus is that of sensation. The sensory nerves that make it up find their root in the largest cranial nerve, which extends down to the second cervical level of the spinal cord. On the other hand, the motor control nerve finds its root in the masticator motor nucleus, serving one specific purpose. The sensitivity of nervus trigeminus allows the face to feel subtle sensations, but also allows for one of the most painful conditions known to humankind, called trigeminal neuralgia.

Trigeminal neuralgia occurs when the nervus trigeminus becomes inflamed. Sharp pain that lasts seconds, and sometimes minutes, extends from the eye to the lower part of the face, usually on one side. Simple actions such as chewing or shaving can trigger the excruciating pain.

Generally, trigeminal neuralgia is most common among older adults, although cases have been noted in patients of all ages. The cause of this pain is often difficult to find. Brain swelling is one of the primary suspects, which causes a vein or artery to touch the nerve in the brain. Doctors try to mitigate the pain with medication and sometimes even surgery.

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Perdido
Post 4

The nervus trigeminus must be incredibly powerful. It supplies feeling to some of the most sensitive parts of the face, so it must have a lot of nerve endings.

When I touch the area around my eyes or my eyeball itself, I am always very careful. It is really easy to cause pain here by tugging or poking.

Also, my nose and mouth are tender areas. The inside of my nose is especially sensitive, so I have to be careful when blowing it often or trimming my nose hair, because any wrong move can send a shock wave of pain through my head.

wavy58
Post 3

@cloudel – The nerve affected by Bell's palsy is the nervus facialis. I also got Bell's palsy a few days after dental surgery, and you can bet I called my dentist up to question him.

He told me that the nerve he deadened was the fifth cranial nerve, and the one damaged by Bell's palsy is the seventh cranial nerve. He said that there' s no way it could be related, because the nervus facialis was just not affected by the novocaine that he gave me.

I admit that it does seem fishy, and even though he made a good point, I'm not sure I believe that the two things had nothing to do with each other. It just seems too coincidental, you know?

cloudel
Post 2

@StarJo – I know what you mean. I hate being numb!

I have a question. Are the nerves that get deadened when a dentist gives you novocaine the same ones that you lose power over when you get Bell's palsy? My aunt went in for dental work, and the next morning, she woke up with half her face paralyzed.

Her mouth and eye drooped on one side, and she thought she had experienced a stroke. She was glad when her doctor explained the condition to her and told her it would go away on its own. I'm just thinking this has got to be related to what the dentist did the day before.

StarJo
Post 1

The nervus mandibularis must be what loses feeling when my dentist gives me a shot to deaden my gums before drilling on my cavities. I lose all feeling in my lower face, and usually, my lips are affected, too.

I tried drinking something right after my dental appointment when I was a kid, and the liquid fell right out of my mouth onto the ground. I didn't have the ability to control my lips, so I couldn't hold it in!

I remember being hungry and upset that I couldn't eat anything until the feeling came back. Numbness is one of the worst sensations to me, because even though you don't feel pain, you feel a weird tingling and stuffiness in the area that is just uncomfortable.

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