[TA] of a pair of branches, the branch passing to the left side of the body, to the left member of a bilateral pair of structures, or to the left portion of an unpaired structure; the other member of the pair being a right branch. Terminologia Anatomica lists left branches of 1) atrioventricular bundle (crus sinistrum fasciculus atrioventricularis [TA]); 2) hepatic artery (proper), (ramus sinister arteriae hepaticae proprii [TA]); 3) portal vein (ramus sinister venae portae hepatis [TA]). SYN: ramus sinister [TA].