Radial Nerve:From: www.wheelessoneline.com - See:
- Posterior Interosseous Nerve Syndrome :
- Radial Nerve Palsy Associated w/ Humeral Shaft Frx:
- Radial Nerve Block
- Tendon Transfers for Radial Nerve Palsy:
- Anatomy:
- three posterior divsions of brachial plexus form posterior cord: (C5 , C6 , C7, C8, T1)
- radial nerve (C5, C6, C7 , C8 , and T1 ) is largest of & most frequently injured branch of both the posterior cord (as well as the brachial plexus);
- in axilla, it gives off:
- posterior cutaneous nerve of arm;
- branch to long & medial heads of triceps;
- between axilla & spiral groove of humerus:
- it distributes a branch to the lateral head of the triceps;
- nerve may or may not travel in spiral groove and is often separated by the humerus by 1 to 5 cm of muscle;
- course of nerve through the intermuscular septum;
- nerve travels from deep to the lateral head of the triceps, piercing the intermuscular septum;
- after piercing lateral intermuscular septum, the nerve comes to lie between the brachialis and brachioradialis, and
goes on to pass in front of elbow:
- radial nerve emanates from the spiral groove approximately 10 cm proximal to the lateral epicondyle;
- branch to brachioradialis & ECRL ;
- nerve remains anterior relative to the humerus, and passes along the lateral column of the distal humerus;
- reference: One-third, two-thirds: relationship of the radial nerve to the lateral intermuscular septum in the arm.
- each of motor branches, arising from radial nerve & passing to lateral head of triceps, is accompanied closely by a branch of profunda brachi artery and vein;
- as noted by Gerwin et al (JBJS Am. 1996 Nov;78(11):1690-5.), the nerve crosses the posterior aspect of the humerus at 20-21 cm proximal to the
medial epicondyle and 14-15 cm proximal to the lateral epicondyle;
- posterior interosseous nerve :
- it divides in front of radial head, w/ deep branch (PIN) passing backward thru supinator (arcade of Froshe) to supply 9 muscles on extensor aspect of forearm;
- because of the numerous branches into which the deep radial nerve breaks up at the lower border of the supinator, surgical repair of the nerve here is difficult;
- remaining part PIN, runs downward parallel to posterior interosseous artery to supply all of deeper lying extensor muscles & ends as a twig to wrist joint;
- in this course, it passes superficial to long abductor & EPB of thumb, but its terminal branch to wrist joint passes deep to EPL & EIP;
- Sensory Branch:
- superficial branch of radial nerve passes into forearm deep to brachioradialis muscle;
- approx 8 cm from tip of radial styloid, nerve emerges from under tendon of BR between tendon of BR & tendon of ECRL;
- sensory branch passes downward emerging dorsally from beneath BR tendon about 5 cm proximal to radial styloid;
- it lies just deep to the superficial veins;
- distally, it provides sensation to dorsum of thumb, excluding subungual region which is supplied by branches of median;
- superficial branch innervates dorsal aspect of first web space & hand as far ulnarward as middle of ring finger & as far distally as proximal interphalangeal joint.
- references:
The radial sensory nerve . An anatomic study.
The superficial branch of the radial nerve: an anatomic study with surgical implications.
Transfer of sensory branches of radial nerve in hand surgery.
- Physcial Exam:
- signs of a radial nerve lesion include:
- inability to exten thumb, proximal phalanges, wrist or elbow;
- hand is pronated and the thumb adducted.
- termainal branches of superficial radial nerve are palpable in the anatomic snuff box where they cross EPL;
- paralysis of PIN will result in total loss of extension of fingers &, though rare occurrence, must be entertained in diff dx of extensor tendon rupture (w/ the R.A. pt):
- exam for brachial plexus injury:
- brachioradialis (C5-6)
- supinator (C5-C6)
- ECRB (C6-C7)
- triceps (C6-8)
- Radial Tunnel Compression Syndrome:
- compression of the radial nerve at the elbow can involve the PIN or the superficial branch;
- radial tunnel syndrome refers to the syndrome of forearm pain without muscular weakness;
- it is often misdiagnosed as resistant tennis elbow or PIN syndrome;
- unlike tennis elbow, there is tenderness about 4 cm distal to the lateral humeral epicondyle;
- sites of compression:
- fibrous bands anterior to the radial head at the entrance of radial tunnel;
- radial recurrent vessels;
- tendinous origin of ECRB
- tendinous proximal border of supinator (arcade of Frohse)
- this is the most common location of nerve compression in radial tunnel syndrome;
- distal edge of the supinator at exit;
- exam:
- look for tenderness over the radial tunnel;
- pain may be experienced when the long finger is extended against resistance;
- active supination from a pronated position (tightening supinator) along w/ wrist flexion (which tighens the ECRB) may reproduce the patient's symptoms;
- also consider differential injection of the deep radial nerve;
- treatment:
- as noted by Jebson and Engber et al 1997, about 2/3 patients with radial tunnel syndrome had good to excellent results, however, complete pain relief
and return to normal activities is not always predictable;
- treatment includes division of the fibrous edge of the supinator muscle (most common reason for impingement), and division of the medial border of the ECRB;
- reference:
- Radial nerve entrapment at the elbow: surgical anatomy.
- Radial tunnel syndrome caused by ganglion cyst: Treatment by arthroscopic cyst decompression
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