spinal cord or brachial plexus?

I am age 49, male.  During the week of June 20 (this year) I rather foolishly hung from a bar and attempted to do chin-ups.  A few days afterwards my left thumb and forefinger felt numb (diminished touch,  but temp, texture, wet, air movement OK), as did the left front side of my neck.  Also, my left arm was clumsy, in that it tended to overshoot its intended target.  The neck numbness diminished quickly, but within two weeks my left hand had become nearly useless - profound numbness on both sides of my hand, numbness on the outside of my forearm to just below the elbow, fingers very difficult to move - not weak, but my forearm felt like it was coated with thick, sticky glue.  The muscles around my shoulder and base of neck tended to pull spontaneously, like my left ear was connected to my left shoulder.

MRI revealed a possible demyelinating lesion in my spinal cord at the C2 level.  A neurologist noted I had a brisk biceps reflex in my left arm.  Per the dermatome map, my hand/arm symptoms correlate very well with compromise to the C6, C7, C8 nerves.  Why would a C2 spinal cord lesion cause definite problems w/ areas served specifically by C6-8 and cause no other symptoms?  Could the brisk reflex be caused by trauma to the roots of the brachial plexus nerves?  Happily, after 7 weeks the symptoms have gotten much better w/ no intervention - I'm almost back to normal and feel fine in all other ways.  I don't expect a diagnosis, but your professional opinion would be greatly appreciated.  Thanks!

[CCF-Neuro-M.D.-PW]

All the nerves to the arm descend through the spinal cord before exiting at different levels of the spinal cord. The nerves to the C6,7 and 8 muscles must pass through the C2 level as they only branch out at a lower point than this. So a bruise, for instance from trauma (that may be the cause ni your case), can produce neurological symptoms at any point lower down. (C2 is higher than C6 etc). The brisk reflex would suggest that the clinical lesion was higher than C5/6, as a lesion directly at this level would cause an absent reflex

I wonder if there was a bony spur or something liek that at the C2 level, which predisposes to cord compromise with exessive movement or trauma?