Viewing a single comment thread. View all comments

TheEastStudentCenter t1_jdudvkj wrote

When a body part is compressed, the pressure on the sensory nerves that carry information about touch, temperature, and pain can cause temporary disruption of their function. This disruption can lead to paresthesia, which is an abnormal sensation like tingling, numbness, or burning. In more severe cases, the compression can cause anesthesia, which is a complete loss of sensation in the affected area.

On the other hand, motor neurons that control voluntary movement are less affected by compression because they are less sensitive to pressure. These neurons are located deeper in the body and are more protected by other tissues like muscle and bone. Additionally, motor neurons do not rely on sensory information to generate movement. Instead, they receive signals from the brain and spinal cord that instruct them to contract or relax muscles.

Therefore, even if the sensory neurons are temporarily affected by compression, the motor neurons can still receive signals from the brain and spinal cord and initiate voluntary movements. However, if the compression is severe or prolonged, it can eventually affect the motor neurons as well, leading to paralysis or weakness.


manatrall t1_jduvwll wrote

This is just a long way of rephrasing the observations in the OP.

The real question is 'why are motor neurons less sensitive to pressure?'


RobleViejo t1_jdvas5s wrote

Evolution. The monkes who couldnt move their legs after sleeping on it got eaten.

Most likely this distinction between nerves happened first in Amphibians or Reptiles and goes way back to the first land vertebrates who actually had to deal with the weight of their own bodies.

If Fish dont have this distinction then my guess is right


malefiz123 t1_jdvgwxk wrote

> These neurons are located deeper in the body and are more protected by other tissues like muscle and bone

Motor and sensory neurons are within the exact same nerves. Your answer doesn't make sense


TheEastStudentCenter t1_jdvjgs2 wrote

They are not. Motor neurons are actors and end at skeletal muscle. Sensory neurons can be as close as the skin, making it more superficial and vulnerable to sensation.


malefiz123 t1_jdvmoi7 wrote

Paresthesia due to compression is happening because nerves are compressed, not because of the sensory neurons in the skin. Thats the reason your feet are tingeling when you compress your upper legs by sitting on the toilet but you don't get paresthesia in your handy by carrying something heavy


Xeronami t1_jdvonma wrote

This isn’t accurate. Motor and sensory nerves share a similar pathway. For example, look at the ulnar nerve (your funny bone). It splits at various points to give rise to partial sensation to your hand and partial to intrinsic musculature of your hand as well as some muscles of your forearm. This is just one example, but most spinal nerves have both sensory and motor function.


Hola3008 OP t1_jdxcnl4 wrote

Can I get a source on this information?