<P> The anterior communicating artery connects the two anterior cerebral arteries across the commencement of the longitudinal fissure . Sometimes this vessel is wanting , the two arteries joining together to form a single trunk , which afterward divides ; or it may be wholly , or partially , divided into two . Its length averages about 4 mm , but varies greatly . It gives off some of the anteromedial ganglionic vessels , but these are principally derived from the anterior cerebral artery . </P>
where is the anterior communicating artery in the brain
connects the two anterior cerebral arteries across the commencement of the longitudinal fissure