[TA] synovial tendon sheaths enabling tendon movement across the posterior aspect of the wrist deep to the extensor retinaculum; they are the following six tendinous sheaths (vaginae tendinum... [TA]): (1) of abductor longus and extensor pollicis brevis (muscles) [TA] (...musculorum abductoris longi et extensoris pollicis brevis [TA]); (2) of extensors carpi radiales (muscles) [TA] (...musculi extensorum carpi radialium [TA]); (3) of extensor pollicis longus (muscle) [TA] (...musculi extensoris pollicis longi [TA]); (4) of extensor digitorum and extensor indicis (muscles) [TA] (...musculorum extensoris digitorum et extensoris indicis [TA]); (5) of extensor digiti minimi (muscle) (...musculi extensoris digiti minimi [TA]); and (6) of extensor carpi ulnaris (muscle) [TA] (...musculi extensoris carpi ulnaris [TA]). SYN: vaginae tendinum carpales dorsales [TA].