[TA] synovial tendon sheaths that allow movement of tendons across the anterior aspect of the tarsal bones, deep to the extensor retinacula; included are the tendinous sheaths (vagina tendinis musculi...) of: (1) the tibialis anterior (muscle) [TA] (...tibialis anterioris [TA]), (2) the extensor hallucis longus (muscle) [TA] (...extensoris hallucis longi [TA]), and (3) the extensor digitorum longus (muscle) [TA] (...extensoris digitorum longi [TA]). SYN: vaginae tendinum tarsales anteriores [TA].