[Neuroscience] Re: Are the dorsal roots parts of the somatic nervous system?

r norman via neur-sci%40net.bio.net (by r_s_norman from comcast.net)
Sat Jul 18 12:18:53 EST 2009


On Sat, 18 Jul 2009 09:52:08 -0700 (PDT), GreenXenon
<glucegen1x from gmail.com> wrote:

>On Jul 18, 8:32 am, r norman <r_s_nor... from comcast.net> wrote:
>
>> Does a single sensory
>> neuron entering the dorsal root suddenly become "non-somatic" the
>> instant it plunges into the spinal cord?
>
>
>That's another question I find interesting. Sadly, I don't know.
>
>
>> However, to answer your question, the facial and trigeminal cranial
>> nerves are generally considered to be somatic sensory without
>> autonomic sensory function and the special sensory cranial nerves:
>> vision, olfaction, audition and balance, taste might be considered
>> sort of somatic.  Of course these are not spinal roots.
>
>
>Sorry. I forgot to specify my question.
>
>Are there any purely-somatic *tactile* afferent nerve roots in the
>human body?
>
>Tactile = pertaining to sensory phenomenon other than vision, smell,
>hearing, taste, or balance. IOW, 'tactile' pertains to senses of
>touch, tickle, pain, temperature, pressure, itch, movement and pretty
>much any physical sensory entity.
>
>All afferent nerves in the arms, legs, feet, hands, abdomen, chest,
>back and neck are "tactile" nerves. In the head and face are both
>tactile and non-tactile afferent nerves.
>
>Another question is, are there any nerve "roots" outside of the head,
>face, and spine?

The central nervous system consists of the brain and spinal cord so
the only connection to the periphery is through the cranial nerves to
the brain and the dorsal/ventral roots to the spinal cord.

There are more senses than the ones you list.  There are chemical
sensors detecting a variety of things.  There are mechanoreceptors
that don't serve "touch" but are part of the proprioceptive system
monitoring position of the body, force on the tendons, distension of
the gut and other body organs and membranes.  Generally sensors
connected with digestion, defecation, micturation (urination), and the
cardiovascular system are considered autonomic.    As I said, these
autonomic receptors are scattered around the body and I don't know
whether they are restricted to particular spinal roots or are all over
the place.


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