Apologize for making "another" benediction vs. claw topic...

[thawunandonly]

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I've read through old posts and topics and have seen pictures. But most people make 2x2 tables and call it a day. I may or may not be confusing myself but I actually have 8 scenarios (proximal vs. distal, extend vs. make a fist, median vs. ulnar) and was wondering if I'm thinking about it right. Now maybe only 4 of these situations are relevant, and I don't want to confuse anyone who already has it down but for my understanding...please entertain me. 🙂

To keep it short I will just call one configuration "Pope" (2&3 fingers up, 4&5 down) and "Claw" (2&3 down, 4&5 up), even though there is a slight variation, since lumbricals are all you really need to know. (Really hope I haven't lost you already >_>)

Proximal median, make fist -> Pope
Proximal median, extend fingers -> ?

Distal median, make fist -> OK
Distal median, extend fingers -> Claw

Proximal ulnar, make fist -> Claw
Proximal ulnar, extend fingers -> ?

Distal ulnar, make fist -> OK
Distal ulnar, extend fingers -> Pope

Okay so here are the actual questions.

1. Obviously, what belongs in the 2 ? slots... in proximal lesions, aren't the use of the lumbricals lost too? In which case, they'd be the same as the distal lesion...

2. I read that to differentiate proximal median vs. distal median is to check for sensation to the palm. Because that nerve does not pass through the carpal tunnel, a proximal lesion (usually through the carpal tunnel) would leave sensation intact. Is it possible to differentiate proximal and distal ulnar in a special way?

3. Side note, I guess. Is ape hand just "part" of Pope hand in a proximal median nerve lesion? Regardless of making a fist or extending fingers or at rest?


................Apologize for the mind**** if that wasn't clear. 😀

 

[Myxedema]

I've seen the term "clawing" used only for ulnar n. injuries in reference books. Pope's hand is caused by the loss of finger flexors in the forearm component, whereas clawing is caused by the loss of lumbricals 4 and 5 in the hand. If we separate it based on nerve:

Median n.
- Proximal injury (example: supracondylar fracture of humerus): Unable to flex the fingers at radial side --> Pope's hand (+), weakness at wrist flexion and pronation; ape hand (+), loss of opposition of thumb (bottle sign), weakness of lumbricals I and II (hyperextension at MCP, flexion at IPs), sensory deficit at radial side of palm and 3 and 1/2 fingers extending to volar surface.
- Distal injury (example: carpal tunnel syndrome): Pope's hand (-), no weakness at wrist flexion and pronation; the rest is the same

Ulnar n.
- Proximal injury (example: fracture at medial epicondyle): [Forearm] Weakness at wrist flexion (minor), weakness at flexion of fingers of ulnar side; [Hand] hypothenar atrophy, loss of adduction of all digits, loss of abduction of all digits except thumb, loss of lumbricals III and IV (hyperextension at MCP, flexion at IPs) --> creates "claw hand", sensory deficit at ulnar side of palm and 1 and 1/2 fingers.
- Distal injury (example: laceration of wrist): Same as proximal, except forearm component will be spared. So claw hand, loss of intrinsic muscles of hand, sensory deficit

 

[sharklasers]

What about median claw?

I don't understand how an injury to the median nerve can prevent you from flexing them (popes hand) and extending them (median claw).

Thanks!!

 

[Myxedema]

What about median claw?

I don't understand how an injury to the median nerve can prevent you from flexing them (popes hand) and extending them (median claw).

Thanks!!

According to the reference books, there is no such thing as a "median claw". You may ask, if loss of lumbricals III and IV in ulnar n. palsies create the "ulnar claw", then why doesn't loss of lumbricals I and II in median n. palsies create "median claw"? I found no explanation given in reference books, so this lead me to believe it is more of a preference or historical nomenclature issue.

To sum it up:
- Claw hand: Loss of lumbricals III and IV (ulnar n.)
- Pope's hand (aka. hand of benediction): Loss of flexors in forearm compartment (median n.)

For those who wish to have more information: http://www.dartmouth.edu/~humananatomy/part_2/chapter_11.html

 

[sharklasers]

First Aid 2013, on page 383 has ulnar claw, median claw and "popes blessing"

You are right in that it is the loss of the lumbricals that first aid says causes median claw. So I guess lumbricals function to extend the mcp and flex the pip/dip?

How come if you have loss of forearm flexors, you can still flex digits 4 and 5? flexor carpi ulnaris?

 

[Myxedema]

First Aid 2013, on page 383 has ulnar claw, median claw and "popes blessing"

You are right in that it is the loss of the lumbricals that first aid says causes median claw. So I guess lumbricals function to extend the mcp and flex the pip/dip?

How come if you have loss of forearm flexors, you can still flex digits 4 and 5? flexor carpi ulnaris?

I think First Aid mentions them to clarify the underlying reason of clawing, which is the loss of lumbrical muscles. What the First Aid does not mention is the cause of Pope's blessing: It is the loss of flexor muscles in the anterior compartment of the arm (flexor digitorum profundus and superficialis). Except for the medial part of profundus, they're innervated by the median nerve. So, a person with a proximal median n. deficiency would not be able to flex his finger at PIP joints (superficialis), and DIP joints except 4th and 5th (profundus). This will be seen clearly when the patient is asked to make a fist, since making a fist requires flexing both PIP and DIP joints.

Just to make it sure, I've went and checked Moore's Clinically Oriented Anatomy and it does not mention clawing when it talks about the loss of lumbricals I and II in median n. injuries. (3rd Edition, p. 575). It does, however, mention clawing in ulnar n. injuries (p. 577)