Definition: the carpal tunnel is a tunnel formed by the bony gutter formed by the carpal bones and flexor retinaculum.
Attachment of the flexor retinaculum:
medially: to the pisiform and hook of the hamate
laterally: to the scaphoid and the trapezium
floor of the tunnel is formed by carpal bones.
proximal: scaphoid, lunate, triquetrium and pisiform
distal: trapezium, trapezoid, capitate and hamate.
These are arranged from lateral to medial.
1. Median nerve
2. Tendon of flexor carpi radialis  lying most laterally.
3. Tendon of flexor longus covered with its own synovial sheath
4. The four tendons of flexor digitorum superficialis arranged in two vertical rows.
5. The four tendons of the flexor digitorum profundus arranged in a horizontal row in the common synovial sheath.
Clinical correlates:
Carpal tunnel syndrome: in this syndrome the median nerve can be compressed especially by long continued swelling in the synovial sheath. Symptoms are wasting and weakness of the thenar muscles, loss of power of opposition of the thumb and anaesthesia over 3½ digits of the radial side of the hand.
Treatment: this is by partial or complete division of the flexor reticunalum. The operation is called “carpal tunnel release.”