UE dermatome

[Azmany]

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I am having trouble reconciling the different dermatomes for UE. One show responsibility at the spinal level, but the other shows via each branch of the brachial plexus, but I dont see how they match up?

http://www.netterimages.com/image/4674.htm

http://www.google.com/imgres?um=1&h...tbnw=169&start=88&ndsp=11&ved=1t:429,r:4,s:88

thanks in advance

 

[Isoprop]

Well you can kind of make sense out of it. I mean musculocutaneous has higher spinal nerve levels than ulnar. But dermatomes/nerve fields are so imprecise that it differs slightly from various sources. Plus, things get messy because of limb rotation during embryology and nerve mixing from the brachial plexus.

My advice is to just memorize them.

 

[loveoforganic]

I am having trouble reconciling the different dermatomes for UE. One show responsibility at the spinal level, but the other shows via each branch of the brachial plexus, but I dont see how they match up?

http://www.netterimages.com/image/4674.htm

http://www.google.com/imgres?um=1&hl=en&safe=off&sa=N&biw=1024&bih=499&tbm=isch&tbnid=WiZ6rmg12fmQRM:&imgrefurl=http://www.pitt.edu/~regional/Interscalene/interscalene_brachial_plexus_blo.htm&docid=5bAmQlJWfRntvM&imgurl=http://www.pitt.edu/~regional/Interscalene/Dermatome.jpg&w=720&h=540&ei=fI-wTr7TE6LniALom6kb&zoom=1&iact=hc&vpx=592&vpy=181&dur=577&hovh=127&hovw=169&tx=94&ty=71&sig=104703825995090328061&page=9&tbnh=127&tbnw=169&start=88&ndsp=11&ved=1t:429,r:4,s:88

thanks in advance

Just to be clear - you're aware peripheral nerve fields correspond to named nerves and dermatomes correspond to spinal cord segments, right? If you are, is there a specific segment combo in the two that's confusing?

 

[topwise]

The answer is that they don't "match up" in any way that is intuitive without knowing the brachial plexus. Some peripheral nerves, such as the ulnar nerve (C8-T1) or the musculocutaneous nerve (C5-C6), have most of their innervation from two nerve roots, but the other peripheral nerves have more diffuse contribution from C5-T1.

You can make sense of it, but you have to know the brachial plexus really well. It's important to have this understanding if you're localizing a nerve injury to a peripheral branch, the plexus, or a nerve root.