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Median nerve displacement through the carpal canal
R M Szabo1, B K Bay, N A Sharkey
1Department of Orthopaedics, University of California, Davis, School of Medicine.
The Journal of Hand Surgery
|November 1, 1994
Summary
Median nerve displacement occurs with wrist movement and flexor tendon contraction. Releasing the transverse carpal ligament (TCL) allows for significant median nerve motion during finger flexion.
Area of Science:
- Biomechanics
- Orthopedic Surgery
- Neuroanatomy
Background:
- The transverse carpal ligament (TCL) plays a crucial role in carpal tunnel syndrome.
- Understanding median nerve behavior relative to flexor tendons is vital for surgical outcomes.
- Wrist position significantly impacts carpal tunnel biomechanics.
Purpose of the Study:
- To quantify the direct relationship between wrist position and median nerve displacement.
- To assess median nerve and flexor tendon excursion during active flexion.
- To evaluate the effect of transverse carpal ligament (TCL) transection on nerve displacement.
Main Methods:
- Utilized fresh cadaveric specimens mounted in a custom apparatus for controlled wrist positioning.
- Measured tendon excursions and median nerve displacements using video camera marker tracking.
- Tested specimens at 0, 30, and 60 degrees of wrist extension, both pre- and post-TCL release.
Main Results:
- Flexor tendon excursion for full finger flexion averaged 3 cm.
- Median nerve displacement ranged from 0.9 to 1.4 cm (mean, 1 cm).
- A consistent linear relationship was observed between median nerve and flexor tendon excursion.
Conclusions:
- Active finger flexion induces significant median nerve displacement.
- Transverse carpal ligament (TCL) release enhances median nerve mobility within the carpal tunnel.
- Post-surgical, finger motion alone contributes to median nerve displacement, potentially altering nerve- गुंतt.