The Anterior Cerebral Artery passes forwards between the first and second cerebral nerves, to reach the great longitudinal fissure; it then ascends with the corresponding artery of the opposite side between the anterior lobes of the brain, and in front of the anterior part of the corpus callosum, along the upper surface of which it runs, and then descends behind it so as nearly to circumscribe this commissure. The branches from its concavity are small, and distributed to the corpus callosum; those from its convexity are more considerable, and supply the internal surface of the hemispheres. The anterior arteries of the cerebrum are united by one or two transverse branches which complete the circle of Willis in front; these are called the anterior communicating branches: when there is but one,it is a large vessel; if more than one, they are proportionably small: on the anterior communicating branch or branches the ganglion of Ribes is situated.