Brachial Plexus - Klumpkes Palsy Help

[coreytayloris]

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Hi all....Having some trouble understanding Klumpkes Palsy...

Klumpkes Palsy
C8 T1 injury - causes dennervation of all four lumbricals.
lumbricals are supplied by ulnar and median nerve....

typical C8 T1 injury presents as extended MCP joint and flexed PIP and DIP joints --> Klumpkes Palsy

So the extension of MCP makes sense - finger extensors (supplied by radial nerve) are obviously unopposed (because of lumbrical dennervation) thus MCP joints will be extended....

But then why do PIP and DIP joints flex? Flexor digitorum superficialis and Flexor digitorum profundus are both supplied by ulnar and median nerve so surely if these nerves are completely blown out there would be no clawing at all?!

Im not sure if ive explained that very well..... Basically why do the median and ulnar nerve supplying the lumbricals stop working but the medial and ulnar nerve supplying FDS and FDP continue to work allowing flexion of the PIP and DIP joints?

Any help much appreciated!
Thanks

 

[RySerr21]

its all about the loss of the lumbricals...the lumbricals flex the MCP joints and extend the DIP and PIP joints. So, when you lose the lumbricals, you get extension of the MCPs and flexion of the DIP/PIPs

 

[cowme]

Basically why do the median and ulnar nerve supplying the lumbricals stop working but the medial and ulnar nerve supplying FDS and FDP continue to work allowing flexion of the PIP and DIP joints?

Innervation in the upper extremity is supplied by C5-T1 nerve roots. The median nerve contains all of these nerve roots, whereas the ulnar nerve only contains C8 and T1 nerve roots.

So, obviously the ulnar nerve will be completely out of commission with Klumpkes. However, only the C8-T1 portion of the median nerve will be affected, while the more proximal C5, C6, C7 portions remain intact. Innervation tends to go proximal (C5) to distal (T1), so by losing C8 and T1 nerve roots, you will lose only distal hand muscles, while more proximal muscles innervation should remain intact.

 

[coreytayloris]

Innervation in the upper extremity is supplied by C5-T1 nerve roots. The median nerve contains all of these nerve roots, whereas the ulnar nerve only contains C8 and T1 nerve roots.

So, obviously the ulnar nerve will be completely out of commission with Klumpkes. However, only the C8-T1 portion of the median nerve will be affected, while the more proximal C5, C6, C7 portions remain intact. Innervation tends to go proximal (C5) to distal (T1), so by losing C8 and T1 nerve roots, you will lose only distal hand muscles, while more proximal muscles innervation should remain intact.

Thank you very much!!! 😀

 

[redsquareblack]

its all about the loss of the lumbricals...the lumbricals flex the MCP joints and extend the DIP and PIP joints. So, when you lose the lumbricals, you get extension of the MCPs and flexion of the DIP/PIPs

Nailed it.

 

[Shadowmoses]

Innervation in the upper extremity is supplied by C5-T1 nerve roots. The median nerve contains all of these nerve roots, whereas the ulnar nerve only contains C8 and T1 nerve roots.

So, obviously the ulnar nerve will be completely out of commission with Klumpkes. However, only the C8-T1 portion of the median nerve will be affected, while the more proximal C5, C6, C7 portions remain intact. Innervation tends to go proximal (C5) to distal (T1), so by losing C8 and T1 nerve roots, you will lose only distal hand muscles, while more proximal muscles innervation should remain intact.

While I see what you are saying, the problem I have is that KLM anatomy book says the the flexor dig. superficialis and flexor dig. profundus are innervated by C7,C8,T1 and C8,T1 nerves respectively (FDP when divided into medial and lateral parts still both use C8,T1 nerves).

I guess to your point the C7 nerve which innervates the flexor dig. superficialis picks up the slack (although it has to be severely weakened due to loss of C8 and T1) and flexes the proximal IP joints because the lumbricals are busted and cant extend the IP joint in order to oppose the flexion. This still doesnt explain what causes flexion of the distal IP joint because it sounds like to me the flexor dig. profundus should be completely out of commission due to being innervated by C8,T1 nerves only.

Please enlighten me, I'm still confused...or maybe I am looking too deeply at what KLM says that I am missing a bigger picture 🙁

 

[cowme]

While I see what you are saying, the problem I have is that KLM anatomy book says the the flexor dig. superficialis and flexor dig. profundus are innervated by C7,C8,T1 and C8,T1 nerves respectively (FDP when divided into medial and lateral parts still both use C8,T1 nerves).

I guess to your point the C7 nerve which innervates the flexor dig. superficialis picks up the slack (although it has to be severely weakened due to loss of C8 and T1) and flexes the proximal IP joints because the lumbricals are busted and cant extend the IP joint in order to oppose the flexion. This still doesnt explain what causes flexion of the distal IP joint because it sounds like to me the flexor dig. profundus should be completely out of commission due to being innervated by C8,T1 nerves only.

Please enlighten me, I'm still confused...or maybe I am looking too deeply at what KLM says that I am missing a bigger picture 🙁

Well, in this case you are losing both the extensor at the DIP (lumbricals) AND flexor at the DIP (FDP). The result is a partially flexed DIP joint.

 

[coreytayloris]

Well, in this case you are losing both the extensor at the DIP (lumbricals) AND flexor at the DIP (FDP). The result is a partially flexed DIP joint.

and that in essence would just be tonic flexion?

Because you'r flexors are naturally more stronger than you're extensors when both sets of muscles are dennervated?

 

[Dr McSexy]

Please enlighten me, I'm still confused...or maybe I am looking too deeply at what KLM says that I am missing a bigger picture 🙁

Probably, bigger picture has been hashed out by people above.

While you do need to know what segments contribute to the various nerves in the brachial plexus, knowing the which segments of those particular nerves contribute to the innervation of a particular muscle is less so important, imo. Aside from that distal musculature is more innervated by lower levels of the segments that contribute.

Aside from that, you should note that there is variability between texts about which particular segments contribute to the innervation of a specific muscle. Not to mention, there can be variability in which segments contribute to the brachial plexus itself.

I personally wouldn't get to hung up on these small details.

 

[Shadowmoses]

Thanks that clears things up!