Palmar carpal ligament

The palmar carpal ligament (also volar carpal ligament or Guyon's Tunnel) is a thickened portion of antebrachial fascia on anterior/palmar side of the wrist which - together with the flexor retinaculum of the hand - retains the tendons of most of the flexor muscles of the hand.

The PCL is not officially recognised in the Terminologia Anatomica. Confusingly, the PCL actually corresponds in location and structure to the extensor retinaculum of the hand (located on the opposite side of the wrist) with which the PCL is continuous as both are formations of the antebrachial fascia. Consequently, the flexor retinaculum is commonly referred to as the transverse carpal ligament to avoid confusion.

Relations
The palmar carpal ligament is superficial and proximal to the flexor retinaculum. The ulnar nerve and the ulnar artery run through the ulnar canal, which is deep to the palmar carpal ligament and superficial to the flexor retinaculum.