The Biceps Reflex

Nikolaj FS

Im curious about this reflex.

What does it affect?

#1 - Does it causes the hand to open/close - if yes, why?
#2 - Does will it flex either the tricep or the bicep?

I've noted by pressing the the latereal cutaneous nerve with a thumb, which is close to the biceps brachii tendon the sameside leg buckles, the back bends forward along with the head.

Can anyone explain this phenomen? Is it due to the crossed extensor reflex or something else? Reestablishing balance?

Hope you can help.

DanP

http://www.ncbi.nlm.nih.gov/bookshel...=cm&part=A2361

Moonbear

If pressing on your arm causes your knees to buckle, go see a doctor.

The biceps tendon is more toward the medial side of the arm, not the lateral side, so should have nothing to do with the lateral cutaneous nerve of the forearm. As the name of the reflex implies, it causes contraction of the biceps brachii muscle. You're testing integrity of the C5 spinal nerve with that reflex.

The triceps reflex is separate and tests primarily C7 spinal nerve integrity.

Nikolaj FS

So you say that by inflicting pain into the nervous system, you should not be able to buckle the legs?

Moonbear

I would say by inflicting mild pain in the arm, you should not be buckling your legs (we've all bumped our ulnar nerve..."the funny bone" and our knees don't buckle from it).

If you were managing to inflict great amounts of pain upon yourself and didn't quit before getting to that point, I think you should consider consulting a psychiatrist.

Nikolaj FS

http://www.youtube.com/watch?v=EzRNF...m=PL&index=102

Can you help me explain this effect then? I want you to look at his left leg.

Moonbear

Bad acting.

Nikolaj FS

No acting - i get the same effect on 9 out of 10 people, even on my self. Any reflexes could explain this effect, or just auto balancing the body ?

Moonbear

Seriously, there is no connection in what you're describing in the arm to what you're describing in the leg. It could have something to do with simply the position they put the person in in the first place, pulling them slightly off balance with the initial set up, so one more tug on the arm causes them to lose their balance and correct. That light little tap on the arm is just distraction.