Slippery, sensual, sural nerve

It’s time to get on your nerves!
Reach down to the outside of your ankle. Put your thumbnail on the lateral malleollus and slide it down under the malleollus. Go down about a centimetre and there it is! – the slippery sensual sural nerve, one of the best examples of a forgotten nerve in the body. Give it a little flick, feel how its slips around, you may even rejoice in a little zing on the lateral aspect of your foot.

Develop a feeling for a forgotten nerve
I have had a soft spot for the nerve since 1980, after I saw a student with a swollen lateral ankle. He said it was always swollen after he donated a segment of the nerve for a research study! These days, ethics committees may have spared more people this insult, although the sural nerve is still seen as a ‘spare’ as it is the usual nerve of choice for a nerve graft.

Arising from variable combinations of peroneal and especially the tibial nerves, the nerve runs lateral to the Achilles tendon. Here, you can sometimes see it in its glory in the dorsiflexed foot – a little string usually as  thick as a match stick –seems to poke out in cyclists and very noticeable near the Achilles tendons of Dutch people.  I admit to looking at calves (human) to see if I can see it and maybe this is where the sensual bit comes in.  At the ankle it turns 90 degrees and then senses various inputs from the lateral aspect of the foot.

Kamerad-schnuerschuh and other syndromes
If you delve into the sural nerve literature, there are snippets of information about its involvement in Achilles tendon injuries, post vein stripping and ankle injuries. Mumenthaler (1991) reports Kamerad-Schnuershuh syndrome (terrifying diagnosis!) where the lacing of a style of army boots with knots laterally may lead to compression of the sural nerve.

But this is a forgotten nerve. We teach examination of this nerve on the NOI courses and from the thousands of sural nerves that our instructors have examined, the clinical findings include:

•    frequent involvement post ankle sprain
•    involvement in lateral ankle ‘impingements’ i.e. a bony impingement may be a misdiagnosis with the problem due to mid axon sural sparking instead.
•    Involvement in many disorders with persistent swelling around the lateral Achille’s tendon
•    I have noticed involvement in a person who had to hike many kilometers on the lateral aspect of the foot after a bad cut on the heel
•    Lateral heel pain (the sural nerve often branches to supplying the lateral heel
•    And a favourite from one of our Canadian teachers who reported the nerve involved in a dancer who was tying the knots of her ballet shoes on the nerve. Easy to understand and remedy, but only if this little nerve is remembered.

The 30 second sural nerve checkout

You can test it via palpating the nerve (try with the ankle in dorsiflexion and inversion as in the image) Most mid axon nerve problems are mechanosensitive and you may be able to put your finger right on the problem. The neurodynamic test is ankle dorsiflexion, eversion and the straight leg raise. Problems may respond well to using this as a mobilization technique. Other techniques are described in our DVD and manual.

So don’t forget this little, distal and rather unloved nerve.

Your turn
Your sural or other foot nerve stories could win a copy of the Neurodynamics Techniques DVD and Handbook this month. We are interested in problems where the nerve was involved and how you managed it.

Thanks for all your replies. We got stacks and have put them together so have a look at some interesting heuristics stories…

The Gold Medal prize of an Explain Pain book goes to Kieran of the United Kingdom.

“I often use analogies to help patients understand some of the rubbish that I am talking to them about regarding core stability etc.

One that seems to be of particular use is the ‘Olympics analogy’. I describe phasic muscles as your ‘Linford Christies’ (or now Usain Bolts) and your postural muscles as your ‘Paula Ratcliffes’. Obviously with Linford as a sprinter he works for short periods of time and then generally switches off. He gets all the praise and glory just like a well-defined set of quads or biceps should. Your ‘Paulas’ are marathon runners who pride themselves on their stamina, hence they work quietly in the background and generally don’t get as much praise as the big phasic ‘sprinters’. If a dysfunction exists (i.e. a dynamic stability issue), i often tell my patients that the brain is a great cheat and if the ‘marathon runners’ are struggling to do their job, it drafts in the ‘sprinters’. Asking Mr. Christie to run 26 miles is not going to work; hence the development of overactive, fatigued, complaining and ultimately uncomfortable phasic muscles may well develop.

For the younger guys, drum and bass seems to work! Postural muscles are the rolling baseline in the background; phasic muscles would be the snare dropping in now and then. When they are working well everything sounds lovely (to those who like drum and bass – i.e. me!!), however having a baseline that doesn’t know when to come in and a snare that seems to be playing too loudly and for far too long makes the whole thing sound like a real mess!

These normally raise a smile and generally seem to get people on board when potentially undertaking a core stability/ Pilates-type approach to treatment.”

Nice one Kieran!

Put your hands up for video hands
Recognise™ Online now has video hands which you can test out as a demo on the Recognise™ website or consider it an added feature to your already existing Recognise license.

We are really excited about Recognise™ Online because as we have done with video hands, images and features will be updated as often as new research qnd progress allows making them immediately accessible by all current license holders so nobody misses out on anything.


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