Sunday, August 3, 2014

Why do we feel temperature with the back of our hand and why not the front?

The answer to this question goes back to Anatomy.

The front of our hand is innervated by the Median and Ulnar nerves which come from the lateral and medial cords of the brachial plexus.
However, the back of the hand is innervated mostly by the Radial nerve which comes from the posterior cord of the brachial plexus. The posterior cord carries the maximum number of nerve roots, that is, C5, C6, C7, C8 & T1.

The radial nerve provides cutaneous sensory innervation to most of the back of the hand so I guess it's better to check temperature with a nerve with maximum representative nerve roots. I assume if one or two roots are not working properly, say C8 & T1, the other roots from the same nerve will compensate for it.

Yes, there are other theories like the palmar skin is thicker than the skin on the dorsal aspect of the hand, but that's not the real reason we check the temperature with the back of the hand because temperature is sensed by nerves and nerve endings aren't dependent upon the thickness of the skin.

Note: Thermoreceptors are free nerve endings. In the mammalian peripheral nervous system, warmth receptors are thought to be unmyelinated C-fibres (low conduction velocity), while those responding to cold have both C-fibers and thinly myelinated A delta fibers (faster conduction velocity).

Source: My surgery professor told this to us. I could not find any other source on the internet confirming this information. I thought I'll share it with you.. Lemme know if I am wrong though!

That's all!
Happy friendship day :D
-IkaN

For the sake of completion, I thought I'd add about all the nerves involved:

The median nerve is formed from contributions from the lateral and medial cords of the brachial plexus, originating from ventral roots of C5, C6 & C7 (lateral cord) and C8 & T1 (medial cord).

The ulnar nerve originates from the C8 & T1 nerve roots (and occasionally carries C7 fibres) which form part of the medial cord of the brachial plexus.

The radial nerve originates from the posterior cord of the brachial plexus, carrying fibers from the ventral roots of spinal nerves C5, C6, C7, C8 & T1.

6 comments:

  1. Nice info dude:-)

    ReplyDelete
  2. you are a medicangel....friend , in this post both median and radial nerves seems to have the same roots event though from different cords... and same number of roots too...isn't it ironic ? please be kind enough to clarify my doubt

    ReplyDelete
    Replies
    1. Thank you, sweet friend :)

      Yes, they do have the exact same roots but the AREA INNERVATED is different. Radial nerve covers the WHOLE of the back of the hand and median innervates only a part of the palmar aspect.

      Delete
  3. if you have perpheral neuropathy why do you not feel cold on the back of your hand

    ReplyDelete
  4. Who says medical is boring!!
    Learning such concepts is real fun
    And ty for that.

    ReplyDelete

This is express yourself space. Where you type create something beautiful! <3
Wondering what do I write? Well..
Tell us something you know better. You are a brilliant mind. Yes, you are! ^__^
Ask about something you don't understand @_@?
Compliment... Say something nice! =D
Be a good critic and correct us if something went wrong :|
Go ahead. Comment all you like here! (:

Related Posts Plugin for WordPress, Blogger...