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Midpalmar Space

spatium mediopalmare

The midpalmar space is the ulnar potential space in the deep palm, bounded medially by the hypothenar septum, laterally by the oblique septum running to the middle finger metacarpal, anteriorly by the flexor tendons to the middle, ring, and little fingers, and posteriorly by the fascia over the interosseous muscles. The ulnar bursa (common flexor sheath) is adjacent to this space and may communicate in flexor sheath infections.

Region: Hand & Wrist

Clinical Relevance

Clinical Notes

Midpalmar space infections are the most common deep palmar space infections, arising from penetrating wounds, flexor tendon sheath rupture, or extension from web space infections. The characteristic clinical features are loss of the normal concavity of the palm, tenderness on direct palpation between the metacarpals, and pain with passive extension of the middle or ring finger. Surgical drainage requires a longitudinal palmar incision between the ring and middle finger metacarpals to avoid damage to the digital vessels and nerves.

Pathology

Common Injuries & Conditions

Midpalmar Space Abscess from Flexor Sheath Rupture

Untreated flexor tenosynovitis with sheath rupture allows pus to decompress into the midpalmar space, producing palm fullness, loss of the normal palmar concavity, and pain with middle or ring finger passive extension; urgent drainage of both the flexor sheath and the midpalmar space prevents tendon necrosis.