Common flexor tendon sheath

Looks like

A long lubricated sleeve (ulnar bursa) around the finger flexor tendons, from above the wrist through the carpal tunnel into the palm, joining the little finger's sheath.

What it does

Lets the eight finger flexor tendons glide smoothly under the wrist ligament.

Keeping it well

Its swelling adds to carpal tunnel syndrome. Infection can spread from the little finger into the palm and needs urgent surgery.

Related conditions

• Carpal tunnel syndrome
• De Quervain's tenosynovitis
• Dupuytren's contracture & trigger finger
• Ganglion cyst
• Gout
• Haemophilia & bleeding disorders
• Juvenile idiopathic arthritis
• Lyme disease
• Marfan syndrome & connective tissue disorders
• Osteoarthritis
• Pseudogout (calcium pyrophosphate disease)
• Psoriatic arthritis
• Raynaud's phenomenon
• Repetitive strain & overuse injury
• Rheumatic fever & rheumatic heart disease
• Rheumatoid arthritis
• Systemic lupus erythematosus
• Temporomandibular joint disorder