title: The Cup of Diogenes: a fixed anatomical landmark for carpal tunnel surgery.
abstract: OBJECTIVE
  Carpal tunnel syndrome is a common entrapment neuropathy. When conservative management fails to relieve symptoms, carpal tunnel surgery is indicated. The surgical exposure for this procedure is commonly based on variable anatomic landmarks. The purpose of this study was to describe a fixed, easily referenced anatomical landmark for the distal extension of the transverse carpal ligament, the "Cup of Diogenes."
  
  
  METHODS
  Topographical landmarks including Kaplan cardinal line, palmaris tendon, and distal palmer crease were marked on six fresh frozen cadaveric wrist and hand specimens. The apex of the Cup of Diogenes is determined to be the confluence of the thenar and hypothenar musculature of the palm. Wrists were dissected and the distance between these landmarks and the superficial palmar arch, median nerve, transverse carpal ligament, and ulnar nerve were measured.
  
  
  RESULTS
  In all specimens, the ulnar nerve was ulnar to this the apex of the Cup of Diogenes, while the median nerve was radial. The apex was proximal in all specimens to the superficial palmar arch. The apex marked the distal extent of the transverse carpal ligament in all specimens.
  
  
  CONCLUSIONS
  Based on our results, we feel the apex of the Cup of Diogenes is a consistent, fixed anatomical marker for the distal extent of the transverse carpal ligament, marking a safe zone in the palm for surgical planning of incisions.
  
  
  METHODS
  Level V - Therapeutic.
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, 200 First St. SW, Rochester, MN 55905 USA.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Houdek
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, 200 First St. SW, Rochester, MN 55905 USA.
authors.forename: Eric R
authors.initials: ER
authors.lastname: Wagner
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, 200 First St. SW, Rochester, MN 55905 USA.
authors.forename: Alexander Y
authors.initials: AY
authors.lastname: Shin
keywords: Carpal tunnel; Carpal tunnel release; Kaplan cardinal line