\Bran"chi*al\, a. (Anat.)
Of or pertaining to branchi[ae] or gills.

{Branchial arches}, the bony or cartilaginous arches which
   support the gills on each side of the throat of fishes and
   amphibians. See Illustration in Appendix.

{Branchial clefts}, the openings between the branchial arches
   through which water passes.