Dorsal Digital Expansion

• Dorsal Digital Expansion:

  • associated with the tendon on extensor digitorum
  • base lies proximally over the metacarpophalangeal joint
  • the sides warp around the phalanx
  • the apex points distally
  • at the distal end of the proximal phalanx the tendon of extensor digitorum splits into 3
  • central portion inserts into base of middle phalanx
  • outer portions reunite at base of distal phalanx
  • also reinforced on either sides by lumbricals and interosseous muscles - allows flexing the metacarpophalangeal joint whilst extending the interphalangeal joint