Erb's palsy

[TallScrubs]

I am having a little trouble understanding Erb's palsy and how it causes adduction, internal rotation, and waiter's tip deformity.

I do not understand how an injury to C-5/C-6 would cause the hand to flex; it makes sense in Klumke's palsy where the radial nerve is damaged and the extensors are lost.

anyone have insight?

Thanks- TS

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[Druggernaut]

I am having a little trouble understanding Erb's palsy and how it causes adduction, internal rotation, and waiter's tip deformity.

I do not understand how an injury to C-5/C-6 would cause the hand to flex; it makes sense in Klumke's palsy where the radial nerve is damaged and the extensors are lost.

anyone have insight?

Thanks- TS

The extensors of the wrist are innervated by the radial nerve. They come from spinal nerves C5, C6, C7, and C8. With the injury to the upper part of the brachial plexus, you lose some of the function of these muscles, and the wrist becomes flexed.

You lose supination since the supinator and biceps are innervated by these levels. Loss of abduction comes because the suprascapular and axillary nerves inntervate the supraspinatus and deltoid. Teres minor and infraspinatus are innervated by these same nerves, and cause lateral rotation, which explains the internal rotation that is seen.

Klumpke's palsy is ulnar. I think you might be getting tripped up on how the brachial plexus is laid out, and that's causing you to switch things around.

 

[TallScrubs]

The extensors of the wrist are innervated by the radial nerve. They come from spinal nerves C5, C6, C7, and C8. With the injury to the upper part of the brachial plexus, you lose some of the function of these muscles, and the wrist becomes flexed.

You lose supination since the supinator and biceps are innervated by these levels. Loss of abduction comes because the suprascapular and axillary nerves inntervate the supraspinatus and deltoid. Teres minor and infraspinatus are innervated by these same nerves, and cause lateral rotation, which explains the internal rotation that is seen.

Klumpke's palsy is ulnar. I think you might be getting tripped up on how the brachial plexus is laid out, and that's causing you to switch things around.

I know exactly what happened. We were told we did not have to know which spinal levels each terminal nerve came from; consequently, I did not associate the radial nerve with an upper BP injury.

Thank you for the explanation.

Edit: although we were told that we did not have to know the origins of the terminal nerves, a quick examination of the brachial plexus shows me how easy it is to understand them--now I feel like a turd.

 

[Morsetlis]

Wikipedia has a great figure near the bottom (color-coded) that allows you to visualize without memorizing numbers.