The Recurrent Branch of the Anterior Cerebral Artery D. S. AHMED AND R. H. AHMED Department of Anatomy, University of Liverpool and Royal Southern Hospital, Liverpool, England ABSTRACT The recurrent branch of the anterior cerebral artery is of considerable applied importance. The extracerebral course of the vessel has been studied in dissection of 12 brains. Numerous variations in the course of the vessel were found and these have been presented. From the proximal part of the anterior cerebral artery numerous perforating branches arise, enter the fenestrations of the anterior perforated substance and contribute to the blood supply of the basal ganglia. Most of these vessels arise at right angles to the anterior cerebral trunk and pursue a somewhat tortuous but short course to the anterior perforated substance. They are usually fine vessels. An excep tion is the recurrent branch of the anterior cerebral artery. This arises from the anterior cerebral artery at the level of the anterior communicating artery. First described by Heubner (1874), it is unique among arteries in that after it doubles back on its parent anterior cerebral and follows this vessel and the middle cerebral artery for a variable distance before entering the brain. According to Critchley ('30) it branches into three main stems within the brain and supplies the anterior part of the caudate nucleus, the anterior third of the putamen, the tip of the outer segment of the globus pallidus and the anterior limb of the internal capsule. Critchley gave clinical and pathological evidence that occlusion of the recurrent artery results in hemiplcgia with brachial dominance. His work has been supported by other workers notably Webster et al. ('60). The course and relations of the vessel is thus of considerable importance to surgeons operating on aneurysms situated on the anterior half of the circle of Willis. Rather surprisingly, however, although the intracerebral distribution of the vessel has been studied in considerable detail, relatively little work has been done on its extracerebral course. This relative lack of knowledge prompted the present study. A N A T . REC!., 157: 699-700. The clinical implications have been reviewed by Ahmed ('65). MATERIAL AND METHOD Twelve human brains were dissected using simple instruments and the unaided eye. The recurrent arteries were dissected on both sides of the circle of Willis in each brain. RESULTS Variations in the course of the artery were found to be common. The most usual course (fig. 1 ) is as follows: The vessel arises from the anterior cerebral artery at the level of the anterior communicating artery and then passes backwards and laterally, closely bound by arachnoid strands to the superolateral aspect of the anterior cerebral trunk. After about 1 cm it is less closely applied to the Recurrentartery Posterior r Posterior artery Fig. 1 Diagram indicating the most usud course of the recurrent artery. The vessel has been shown on the right side only. 699 700 D. S. AHMED AND R. H. AHMED anterior cerebral artery, but still continues to run immediately above the vessel and then above the internal carotid bifurcation and the proximal part of the middle cerebral artery. It then enters the brain through the lateral end of the anterior perforated substance in a single stem or as two branches immediately above the middle cerebral bifurcation. The vessel is largely hidden until the anterior cerebral artery is displaced medially and supporting arachnoid strands between them are divided. The artery, especially in its distal part, tends to become slightly tortuous. The following variations in the course of the recurrent artery were found: 1. The origin of the vessel in one case, was formed by the union of two trunks arising in front of, and behind the anterior communicating artery respectively. 2. In one brain the artery arose from the mid-point of the proximal part of the anterior cerebral artery. 3. In three brains the vessel was represented by twin trunks running parallel and close to each other on one side of the circle of Willis whereas on the opposite side there was only one trunk. 4. In two cases, the vessel on one side of the circle of Willis was absent. 5. In six cases, the vessel on one side formed single or multiple loops and passed well lateral to the anterior cerebral artery between its point of origin and its point of entry into the brain. LITERATURE CITED Ahmed, R. H. 1965 C1I.M. Thesis: Anterior cerebral aneurysms. Liverpool. Critchley, M. 1930 The anterior cerebral artery and its syndromes. Brain, 53: 120-165. Heubner, 0. 1874 Die leutische Erkrankung der Hirnarterien. Leipzig: F. C. W. Vogel. Webster, J. E., E. S. Gurdjian, D. W. Lindner and W. G. Hardy 1960 Proximal occlusion of the anterior cerebral artery. Arch. Neurol., Chicago, 2: 19-26.