Midlateral Approach to Flexor Sheaths

Midlateral line of the finger marked as a dotted line on the side of the digit, with the planned skin incision drawn in relation to it
Midlateral line of the finger marked as a dotted line on the side of the digit, with the planned skin incision drawn in relation to it. Image from Cho H, Ono S, Chung KC. Management of Scar Contractures of the Hand-Our Therapeutic Strategy and Challenges. J Clin Med. 2024, 13(5), 1516. CC BY 4.0.
Gray’s Anatomy illustration of the digital nerves
Superficial nerves of the palm. The digital nerves run along each side of the finger, palmar to the midlateral line used in this approach. Image by Henry Vandyke Carter, Gray’s Anatomy (1918), Wikimedia Commons, public domain.

Position

  • Supine
  • Arm board

Landmarks

  • Proximal interphalangeal crease
  • Distal interphalangeal crease
  • Junction between volar smooth skin & dorsal wrinkled skin
    • (which is more dorsal)

Incision

  • Direct dorsolateral longitudinal incision
  • Stay on the more dorsal side (junction of smooth & wrinkled skin)

Internervous Plane

  • None

Superficial Dissection

  • Incise subcutaneous fat in line with skin incision
  • Dangers
    • Neurovascular bundle is in the volar flap
      • Volar branch of digital nerve & artery
    • Dorsal branch of digital nerve

Deep Dissection

  • To get to tendons
    • Incise fibrous flexor sheath longitudinally

Dangers

  • Palmar digital nerve
  • Volar digital artery

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.