- Discussion:
- transverse carpal ligament, is a heavy band of fibers which runs between
hamate &
pisiform medially to scaphoid and
trapezium laterally,
and forms fibrous sheath which contains carpal tunnel anteriorly within fibro-osseous tunnel;
- posteriorly, tunnel is bordered by carpal bones, and transports
median nerve & finger flexor tendons from forearm to hand;
- lies deep to
palmaris longus & is defined by 4 bony prominences;
- proximally, by
pisiform & tubercle of scaphoid;
- distally by hook of
hamate & tubercle of
trapezium;
- from hamate & pisiform medially to scaphoid & trapezium laterally;
- transverse carpal ligament, portion of volar carpal ligament, runs between these 4 prominences & forms fibrous sheath which contains
carpal tunnel anteriorly w/in fibro-osseous tunnel;
- posteriorly tunnel is bordered by carpal bones;
- Superficial Anatomy:
- palmaris longus passes in front of flexor retinaculum to become continuous with the palmar fascia (see
transverse carpal ligament);
-
palmar cutaneous branch of
median nerve, which innervates skin over base of thenar eminence, arises short distance prox to flexor retinaculum,
pierces deep fascia, & course superficial to the flexor retinaculum to reach the skin;
- palmar cutaneous nerve of ulnar nerve course superficial to transverse carpal ligament & is not involved in CTS;
- distal volar flexion crease crosses proximal end of scaphoid and
pisiform & marks proximal edge of TCL;
- Contents of Tunnel:
- tunnel transports
median nerve & finger flexor tendons (
FDS,
FDP , &
FPL);
-
motor branch of median nerve in hand arises under or just distal to flexor retinaculum, & winds around distal border of retinaculum to reach hypothenar muscles
and the lateral 2 lumbricals;
- numerous variations in the branching have been described;
- sensory branches innervate lateral three and 1/2 digits & palm of the hand;
- Guyon's Canal
-
ulnar nerve & artery do not pass thru tunnel but lie superficial to it in guyon's canal
-
pisiform is palpable & serves to mark entry, on its lateral aspect, of ulnar nerve and artery into the hand;
- Landmarks:
- distal volar flexion crease crosses proximal end of the scaphoid &
pisiform & identifies proximal edge of the transverse carpal ligament;
-
pisiform is palpable and just laterally will identify entry of
ulnar nerve and artery into hand;
- all thenar & hypothenar muscles, except the abductor minimi, originate partly from the transverse carpal ligament.
- Kaplan's Line:
- Kaplan oblique line (line drawn from apex of interdigital fold between thumb and index
finger, toward ulnar side of hand, parallel w/ proximal palmar crease, & passing
4-5 mm distal to
pisiform bone;
The transverse carpal ligament. An important component of the digital flexor pulley system.
Transverse carpal ligament reconstruction in surgery for carpal tunnel syndrome: a new technique.
Anatomy of the flexor retinaculum.
Prevalence of anatomic variations encountered in elective carpal tunnel release
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