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Retired NBME 20 Answers

nbme20/Block 1/Question#10 (reveal difficulty score)
A 77-year-old woman has been having ...
C7-T1 foraminal stenosis ๐Ÿ” / ๐Ÿ“บ / ๐ŸŒณ / ๐Ÿ“–
tags: msk

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 +6  upvote downvote
submitted by โˆ—hayayah(1212)
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Little finger = ulnar nerve.

C8-T1 are the roots of the ulnar nerve, which is a branch of the medial cord. The ulnar nerve is not found in the carpal tunnel (the medial nerve is).

Ulnar n. damage can lead to loss of wrist flexion and adduction, flexion of medial fingers, abduction and adduction of fingers (interossei), actions of medial 2 lumbrical muscles. Loss of sensation over medial 1 1/2 fingers, including hypothenar eminence.

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sugaplum  Also to add: since it is a bilateral sx it is more likely to be coming from the spinal cord then from equal compression of ulnar nerve (in guyons canal) on both sides. unless she is a cyclist +33
thefoggymist  shouldn't the other nerves of the same roots be affected? +1
thefoggymist  shouldn't the other nerves of the same roots be affected? +
charcot_bouchard  Not really. In klumpeke paralysis ulnar nerve s/s dominates (Almost same cause) +
topgunber  is this related to RA? Where there is cervical subluxation or am I going nuts +
athenathefirst  @topgunber There is join subluxation in RA, but A says subluxation of the lunate meaning dislocation of the lunate. Subluxation of the lunate can cause acute carpal tunnel syndrome which you don't see the symptoms for in this question (numbness/paresthesia on the distrbution of median nerve, thenar atrophy w/o loss of sensation). The question specifically mentions the "litttle fingers" indicating it's an ulnar nerve problem. +
athenathefirst  @topgunber also says intrinsic muscle indicating the interossei (DAP/PAD muscles) which abduct and adduct the digits and innervated by the ulnar nerve. +
athenathefirst  DAB/PAD +



 +1  upvote downvote
submitted by โˆ—hauyuehlin(2)
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Thoracic outlet syndrome:

  1. Atrophy of intrinsic hand muscles.
  2. Lower trunk compression -> affect C8/T1 -> Loss of sensation of 4th/5th digit (C8 dermatome).
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