There are 5 Flexor and 9 Extensor Zones of the Hand. They are used to describe the location of a tendon injury, guide post-operative therapy and predict prognosis.
Flexor zone of hand
There are in total 5 flexor (volar) zones on the volar aspect of the hand1,2,3:
Zone 1: Distal to FDP Insertion
Zone 2: Proximal A2 Pulley to FDP Insertion
Zone 3: Carpal Tunnel to Proximal A2 Pulley
Zone 4: Carpal Tunnel
Zone 5: Proximal to Carpal Tunnel
T1: Distal to A2 Pulley
T2: A2 Pulley to A1 Pulley
T3: A1 Pulley to Carpal Tunnel
These flexor zones of the hand are illustrated below.
The location of flexor zones and their clinical significance are in the table below. For example:
Zone II injuries are often explored through a Bruner’s or mid-lateral incision.
Zone I finger replants often have better post-operative outcomes
Clinical significance
Zone 1 – fdp tendon ( Jersey finger)
Jersey finger” refers to a rupture of the flexor tendon, which is the tendon that bends the fingertip down. Its name comes from football athletes who have gripped the jersey of an opposing player who is trying to get away.
Zone 2- proximal A2 pulley to fdp insertion
( Finger pulley injury)
According to biomechanical testing, the amount of force on the A2 pulley is directly proportional to the external force at the fingertip,6 and also strongly influenced by the angle at the PIP joint (increased flexion = more force on pulley)
Zone 3 – Distal carpal tunnel to proximal A2 pulley (Hand pulley)
Any damage to a part of flexor tendon pulley system can affect the motor performance of the digits. The pulley system plays a crucial role in maintaining an angle of approach of the flexor tendons onto its insertion site and retinacular restrainer.
Flexor pulley system consists of the following:
Palmar Aponeurosis Pulley
5 Annular Pulleys
3 Cruciform pulleys.
Zone 4 -Carpal tunnel ( carpal tunnel syndrome)
Carpal tunnel syndrome is a common condition that causes numbness, tingling, and pain in the hand and forearm. The condition occurs when one of the major nerves to the hand — the median nerve — is squeezed or compressed as it travels through the wrist.
Zone 5 – proximal to carpal tunnel (carpal tunnel syndrome)
Management of carpal tunnel syndrome:(Physiotherapy treatment)
Physical therapists should give advice on modifications of activities and the workplace (ergonomic modifications)
Manual therapy techniques include mobilisation of :
Soft tissue
Carpal bone
Median nerve
Physiotherapy modalities (TENS and ultrasound) have little useful effects on hand sensory discomfort.