Introduction Indications decompression of median nerve flexor tendon synovectomy carpal tunnel tumor excision carpal tunnel nerve and tendon repair drainage of sepsis tracking up from the mid-palmar space ORIF of fxs and dislocations of distal radius and carpus especially volar lip intra-articular fxs Preparation Anesthesia local (most common) regional Position patient supine on table supinate operative arm and place on armboard with palm facing up Tourniquet exsanguinate arm Internervous Plane Distal no internervous plane no muscles are transected APB and palmaris brevis fibers that cross the midline can occassionally be dissected true anatomic dissection major nerves identified, dissected out and preserved plane of dissection between median nerve and FCR Approach Incision landmark thenar crease make incision just ulnar to the thenar crease in hand and ulnar to palmaris longus in wrist begin 4cm distal to flexion crease make ulnar curve so you dont cross perpendicular to flexion crease also helps protect palmar cutaneous branch end 3 cm proximal to flexion crease Superficial dissection incise skin flaps incise fat section fibers of superficial palmar fascia in line with incision retract curved flaps medially to expose insertion of PL into flexor retinaculum retract PL tendon toward ulna to expose median nerve between PL and FCR pass a blunt object between median nerve and flexor retinaculum. incise entire length of retinaculum/transverse carpal ligament on ulnar side of nerve Deep dissection identify motor branch of median nerve (anterolateral side of median nerve as it emerges from carpal tunnel) if require access to volar aspect of wrist joint mobilize median nerve and retract radially (so you dont stretch motor branch) mobilize and retract flexor tendons incise base of carpal tunnel longitudinally Extension Indications to further expose median nerve Proximal extend incision up middle of arm incise deep fascia between PL and FCR retract PL (ulnarly) and FCR (radially) to expose FDS median nerve adheres to deep surface of FDS Dangers Palmar cutaneous branch of median nerve arises 5 cm proximal to wrist joint runs ulnar to FCR before crossing flexor retinaculum greatest threat when you do not curve your incision ulnar Motor branch of median nerve significant anatomic variation risk to nerve minimized if incision through retinaculum made ulnar to median nerve Superficial palmar arch crosses palm at level of distal end of outstretched thumb in danger if flexor retinaculum blindly cut (can go too far distally) avoid injury if retinaculum cut under direct observation for its entire length