tendinous sheath of ex·ten·sor car·pi ul·na·ris mus·cle[TA]
the dorsal carpal synovial tendon sheath surrounding the tendon of the extensor carpi ulnaris in its course deep to the extensor retinaculum.
peritenonAn obsolete term that formerly referred to peritendinous fibroconnective tissue.
peritenon(pĕr″ĭ-tē′nŏn) [″ + tenon, tendon]
The sheath of a tendon.
the connective tissue structures attached to and surrounding a tendon.