tendinous sheath of extensor pollicis longus muscle

tendinous sheath of ex·ten·sor pol·li·cis lon·gus mus·cle

[TA] the dorsal carpal synovial tendon sheath surrounding the extensor pollicis longus tendon in its passage deep to the extensor retinaculum. Synonym(s): vagina tendinis musculi extensoris pollicis longi [TA]