# Brains have zillions of nerves, yet you can root around in them w/o pain. What are "pain" nerves? **URL:** \ **Category:** Factual Questions\ **Created:** [February 17, 2013, 12:58am UTC](https://boards.straightdope.com/t/brains-have-zillions-of-nerves-yet-you-can-root-around-in-them-w-o-pain-what-are-pain-nerves/650562 "2013-02-17T00:58:22Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [February 17, 2013, 12:58am UTC](https://boards.straightdope.com/t/brains-have-zillions-of-nerves-yet-you-can-root-around-in-them-w-o-pain-what-are-pain-nerves/650562/1 "2013-02-17T00:58:22Z")
See subject. Autonomous I get, sort of: too much carbon dioxide, molecules–not nerves(?)–sense this, some organ or other signals chest to expand, pharynx to open (I think). There are many unique cell types in the body. Are there “different” synaptic structures? Our cornea doesn’t have nerves. You can look right through them. (Not a joke, just a novel–for me–observation [as it were].) What else doesn’t? ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [February 17, 2013, 1:11am UTC](https://boards.straightdope.com/t/brains-have-zillions-of-nerves-yet-you-can-root-around-in-them-w-o-pain-what-are-pain-nerves/650562/2 "2013-02-17T01:11:50Z")
[Nociceptors](http://en.wikipedia.org/wiki/Nociceptor). Not sure what synaptic differences you’d be looking for. If you’re mentioning the cornea, then you’d have to mention the lens and all the other structures, up to parts of the retina. BTW: “nerve” is kind of a vague term, but most commonly it refers to when the axons of many neurons bunch together, and usually implies the peripheral nervous system, i.e. not the brain (CNS usually contains “tract”). Your retina contains many neurons, but it isn’t until they leave the eye that the optic nerve is formed (misnamed, see above). ---
**Author:** ![orcenio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/orcenio/32/1036_2.png) [@orcenio](https://boards.straightdope.com/u/orcenio)\ **Post date:** [February 17, 2013, 2:04am UTC](https://boards.straightdope.com/t/brains-have-zillions-of-nerves-yet-you-can-root-around-in-them-w-o-pain-what-are-pain-nerves/650562/3 "2013-02-17T02:04:27Z")
Think this: Nociceptors = sensor = detects pain Nerve = wire = transmits signal Our body has many different types of sensors (sight, pressure, heat, taste, smell, etc) and all of them are connected by neurons that ultimately lead to the brain. And (generally) a bundle of these wires is called a nerve, and bundle of those are called a “tract” . ---
**Author:** ![doubleminus](https://avatars.discourse-cdn.com/v4/letter/d/5daacb/32.png) [@doubleminus](https://boards.straightdope.com/u/doubleminus)\ **Post date:** [February 17, 2013, 3:08am UTC](https://boards.straightdope.com/t/brains-have-zillions-of-nerves-yet-you-can-root-around-in-them-w-o-pain-what-are-pain-nerves/650562/4 "2013-02-17T03:08:18Z")
The cornea is highly innervated, perhaps more than any other organ. ---
**Author:** ![auntlohimein](https://avatars.discourse-cdn.com/v4/letter/a/74df32/32.png) [@auntlohimein](https://boards.straightdope.com/u/auntlohimein)\ **Post date:** [February 17, 2013, 3:52am UTC](https://boards.straightdope.com/t/brains-have-zillions-of-nerves-yet-you-can-root-around-in-them-w-o-pain-what-are-pain-nerves/650562/5 "2013-02-17T03:52:48Z")
-RN here- our brain does not have pain receptors, hence, a local of lidocaine to deaden nerves-pain receptors-in skin and MD’s can root around in your brain for stuff while u are awake and ask u questions about it to see that things are ok or say still working. SO have fun inside! ---
**Author:** ![AaronX](https://avatars.discourse-cdn.com/v4/letter/a/7bcc69/32.png) [@AaronX](https://boards.straightdope.com/u/AaronX)\ **Post date:** [February 17, 2013, 3:12pm UTC](https://boards.straightdope.com/t/brains-have-zillions-of-nerves-yet-you-can-root-around-in-them-w-o-pain-what-are-pain-nerves/650562/6 "2013-02-17T15:12:44Z")
The large intestine? ---
**Author:** ![Learjeff](https://avatars.discourse-cdn.com/v4/letter/l/94ad74/32.png) [@Learjeff](https://boards.straightdope.com/u/Learjeff)\ **Post date:** [February 18, 2013, 3:35pm UTC](https://boards.straightdope.com/t/brains-have-zillions-of-nerves-yet-you-can-root-around-in-them-w-o-pain-what-are-pain-nerves/650562/7 "2013-02-18T15:35:29Z")
A nociceptor different from cerebral neurons, but more importantly, they’re “wired” into a network of neurons whose purpose is to detect damage. The neurons in the brain are interconnected to, well, do all the stuff the cerebral cortex does, so stimulating or suppressing those nerves causes any nuber of apparent phenomena (such as stimulating memories, or suppressing normal functions.) My guess is that there are places in the brain (most likely medulla oblongata) where stimulation would cause pain, but the pain would be “felt” in various parts of the body: the brain itself wouldn’t seem to hurt. Imagine the security room in a big hotel. There’s a camera in the parking garage; the video display is always on a certain monitor. Substitute some signal (say, all black) in that camera at any point in the signal chain, and the security guys will say “Gee, I can’t see the garage”. The problem at first appears to be in the garage. Only with a diagnostic frame of mind would we consider the issue could be anywhere on the signal path; the intent of that monitor is to see the garage. Admittedly, a weak analogy, but I hope you get the point. ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [February 18, 2013, 4:07pm UTC](https://boards.straightdope.com/t/brains-have-zillions-of-nerves-yet-you-can-root-around-in-them-w-o-pain-what-are-pain-nerves/650562/8 "2013-02-18T16:07:59Z")
> [@auntlohimein](#): > > -RN here- our brain does not have pain receptors, hence, a local of lidocaine to deaden nerves-pain receptors-in skin and MD’s can root around in your brain for stuff while u are awake and ask u questions about it to see that things are ok or say still working. SO have fun inside! Please don’t take this as criticism, I’m just amused that you have time to type _lidocaine_ and _receptors_ but not _you_. ---
**Author:** ![Captain\_Amazing](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@Captain\_Amazing](https://boards.straightdope.com/u/Captain_Amazing)\ **Post date:** [February 18, 2013, 5:05pm UTC](https://boards.straightdope.com/t/brains-have-zillions-of-nerves-yet-you-can-root-around-in-them-w-o-pain-what-are-pain-nerves/650562/9 "2013-02-18T17:05:41Z")
> [@auntlohimein](#): > > -RN here- our brain does not have pain receptors. . . Because, really, what part of the body is it going to tell?