tendinous sheath of abductor pollicis longus

tendinous sheath of ab·duc·tor pol·li·cis lon·gus and ex·ten·sor pol·li·cis bre·vis mus·cles

[TA] the dorsal carpal synovial tendinous sheath lining the compartment of the extensor retinaculum that contains the abductor pollicis longus and extensor pollicis brevis tendons. Synonym(s): vagina tendinum musculorum abductoris longi et extensoris brevis pollicis [TA]