Upper limb
Common flexor tendon sheath (Ulnar bursa)
Vagina communis tendinum musculorum flexorum
- Origin
- Large synovial sheath beginning approximately 2-3 cm proximal to the flexor retinaculum in the distal forearm
- Insertion
- Traverses the carpal tunnel enclosing all 8 tendons of FDS and FDP, expands into the midpalm, and continues uninterrupted to the distal phalanx of the fifth digit
- Function
- Provides comprehensive synovial lubrication preventing friction among crowded flexor tendons in the carpal canal
- Innervation
- Sensory branches of the median nerve
- Movement & chain
- Accommodates large-amplitude tendon excursions during fist formation
- Palpation
- Palpable in volar wrist crease as fullness/swelling in synovial inflammation
- Clinical
- Horseshoe abscess (infectious tenosynovitis spreading between the ulnar bursa and radial bursa of the thumb across Parona's space); acute infectious flexor tenosynovitis meeting Kanavel's 4 cardinal signs
- Segmental innervation
- C7–T1 roots
- In clinical practice
- Surgical emergency requiring immediate operative irrigation and debridement to prevent flexor tendon necrosis and permanent claw deformity
- Region in the model
- Upper limb