A New Surface Landmark for Thumb Digital Nerve Bifurcation: A Cadaveric Study

Area of Science:

• Anatomy
• Surgical Anatomy
• Hand Surgery

Background:

• The radial and ulnar thumb digital nerves are crucial for hand sensation and dexterity.
• Accurate identification of nerve bifurcation is vital for surgical precision and patient safety.

Purpose of the Study:

• To validate a surface landmark for the bifurcation of the thumb radial digital nerve (RDN) and ulnar digital nerve (UDN).
• To assess the consistency of this landmark in cadaveric dissections.

Main Methods:

• Dissection of 24 fresh-frozen cadaveric specimens.
• A specific hand and finger positioning was used to identify the bifurcation point.
• A U-shaped incision was made, and measurements were taken from its edges to the bifurcation point.

Main Results:

• The bifurcation point was consistently located within the U of the incision in 92% of specimens.
• Variations in branching patterns, including the index RDN, were observed in a significant number of cases.
• Most bifurcation points were found at the ulnar and proximal edge of the U-shaped incision.

Conclusions:

• The U-shaped incision serves as a reliable surface landmark for the thumb RDN and UDN bifurcation.
• Observed variations underscore the necessity of careful clinical evaluation for penetrating injuries to the thenar eminence.
• This landmark can help prevent iatrogenic injuries and identify critical structures during palm trauma.