Ring Finger Flexor Tendon Sheath Bursa

bursa vaginae tendinum flexorum digiti anularis

The ring finger flexor tendon sheath is the synovial sleeve around the superficialis and profundus tendons of the ring finger, from about the A1 pulley to the end of the finger. It lets the tendons glide under the pulleys. It is usually separate from the ulnar bursa at the wrist, but a connection is present in some hands.

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 separate from the ulnar bursa, though connections occur in a minority of hands.

Clinical Relevance

Clinical Notes

Ring finger flexor tenosynovitis may be mistaken for a ring avulsion injury due to the ring finger's vulnerability to clothing and machinery. The ring finger sheath's occasional communication with the ulnar bursa means spread to the wrist and hypothenar space is possible in advanced infections. Horseshoe abscess (ulnar bursa to radial bursa) typically involves the small finger and thumb rather than the ring finger.

Pathology

Common Injuries & Conditions

Ring Finger Flexor Tenosynovitis

Suppurative infection of the ring finger sheath that may rarely communicate with the ulnar bursa, requiring careful assessment of wrist extension during examination to exclude proximal spread.

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