What Are the Effects and Causes of the Biceps Reflex?

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Discussion Overview

The discussion centers on the biceps reflex, exploring its effects and causes, particularly in relation to the hand's movement and the response of the legs. Participants examine the reflex's implications for muscle contraction and balance, as well as anecdotal observations of related phenomena.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions whether the biceps reflex causes the hand to open or close and whether it flexes the triceps or biceps.
  • Another participant notes an observation where pressing the lateral cutaneous nerve leads to the buckling of the leg and asks if this is related to the crossed extensor reflex.
  • Some participants assert that pressing on the arm should not cause the knees to buckle, suggesting that the biceps tendon is located medially and not related to the lateral cutaneous nerve.
  • There is a suggestion that if mild pain in the arm leads to leg buckling, it may indicate a need for medical consultation.
  • One participant shares a video link and requests an explanation of the observed effect, specifically regarding the left leg's response.
  • Another participant claims to observe the same effect in most individuals, questioning whether it relates to reflexes or body balancing mechanisms.
  • Some participants argue that the described arm and leg responses are not connected and suggest that the initial positioning may contribute to balance issues.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between the biceps reflex and leg movement, with some asserting a lack of connection while others propose potential explanations involving reflexes or balance. The discussion remains unresolved regarding the mechanisms at play.

Contextual Notes

Participants reference specific anatomical locations and reflexes, but there are limitations in the assumptions made about the connections between the arm and leg responses. The discussion also includes anecdotal evidence that may not be universally applicable.

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