Radial Nerve uh-oh’s

Evenin’ kids…

But first, a little reminder about our friend, the most radial of nerves. She starts out from the posterior cord of the brachial plexus, grooves along down the arm via the radial sulcus around the humerus, pops out through the lateral intermuscular septum jumping from posterior compartment to anterior, slides down the radial tunnel in the elbow anterior to the lateral epicondyle,  then dives on into the posterior compartment of the forearm, soon splitting into a superficial (cutaneous) branch and a deep (muscular) branch which becomes the posterior interosseous nerve. Along the way she does her business supplying triceps brachii, all 12 posterior compartment muscles of the forearm, cutaneous supply to the posterior arm and dorsum of the hand.

Now everything might seem all fine and dandy, but sometimes life can be cruel to our friend the radial nerve. That’s when bad things start to happen. Things like wrist drop, caused by weakness to complete paralysis of the wrist extensor muscles.  The provocatively titled provocative test (resistive extension of middle finger)  might cause pain over the radial tunnel. Proximally, triceps troubles can cause weakness of elbow extension, as well as visible atrophy of the triceps himself. Finally cutaneous miscommunications can cause radiating neuropathic pain along the back of the arm, and paresthesia and hypesthesia in the radial dorsum of the hand can make the hand seem like a bit of a stranger…

The causes of such dramas are many. Up in the proximal arm crutch palsy and saturday night palsy, or a more dramatic stab to the chest can cause radial nerve trauma. A brutal midshaft humeral fracture can get all up in the radial nerve’s personal space around the radial groove, and repetitive elbow movements or elbow trauma can cause  radial tunnel (compression) syndrome. Down around the wrist a tight watch or bondage handcuffs and other fun stuff can impinge on the radial nerve. Finally and substantially less obviously lead poisoning can mess around with radial nerve transmission, causing wrist drop and such.

With all of these fun situations, the symptoms can be matched to the cause by ascertaining the level at which radial dysfunction is arising, for example a crutch palsy will affect triceps down, a wrist compression will affect wrist down.

fun fun fun fun fun.

Nalin

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~ by pcl4 on September 4, 2008.

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