Canal of Guyon

The canal of Guyon (or ulnar tunnel) is a small palmar tunnel at the ulnar side, located in between the flexor retinaculum (deep) and the superficial palmar ligament (superficial). It starts at the pisiform bone (ulnar side) and reaches till the hamulus of the hamate bone (radial side). It only contains the ulnar nerve, artery, and veins. Local squeezing of the ulnar nerve during this pathway may give rise to a specific motor and/or sensory neuritis. The three clinical types depend on the location of the squeezing of the nerve. Different pathologies may cause a local neuritis of the ulnar nerve.