Index Finger Flexor Tendon Sheath Bursa

bursa vaginae tendinum flexorum digiti indicis

The index finger flexor tendon sheath is the synovial sleeve that wraps the superficialis and profundus tendons from about the A1 pulley in the palm to the end of the finger. It lets the tendons glide under the fibrous pulleys. It is usually closed off from the wrist bursae, so an infection stays within the finger.

Anatomical Data

Boundaries & Contents

Location	Palm side of the finger, from about the metacarpal neck (A1 pulley) to just beyond the distal interphalangeal joint
Boundaries	Fibrous digital sheath with annular (A1-A5) and cruciform (C1-C3) pulleys (outer layer) Palmar plates of the finger joints and the phalanges (floor) Closed proximal pouch near the metacarpal neck Distal end just beyond the distal interphalangeal joint
Contents	Flexor digitorum superficialis tendon Flexor digitorum profundus tendon Vincula carrying blood vessels to the tendons

Biomechanics

Function & Actions

Lets the two flexor tendons glide smoothly under the pulleys. It is usually closed off from the palm, so infection stays in the finger (Kanavel signs).

Clinical Relevance

Clinical Notes

Suppurative tenosynovitis of the index finger flexor sheath is identified by Kanavel's four cardinal signs: fusiform swelling, tenderness along the sheath, semi-flexed posture, and pain on passive extension. The isolated nature of the index sheath means infection remains confined to the finger unless it communicates with the radial bursa at the wrist. Surgical decompression via open or closed tendon sheath irrigation is required for established tenosynovitis.

Pathology

Common Injuries & Conditions

Index Finger Flexor Tenosynovitis

Suppurative infection of the index finger flexor sheath producing Kanavel's signs, requiring urgent surgical drainage to prevent tendon necrosis and permanent stiffness.

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