Clinical anatomy of the fourth ventricle foramina

Introduction The three foramina of the fourth ventricle of the human brain were first described during the 19th century. The primary purpose of this article was to review the anatomy of the foramina of the human fourth ventricle, as well as the main clinical conditions related to pathology of these neurosurgically important structures. The existing literature regarding the gross and neurosurgical anatomy of the foramina of the human fourth ventricle was reviewed with emphasis on the clinical disorders caused by several pathological conditions of these structures. Neuroanatomical comments on the location of these foramina are also provided. Discussion The fourth ventricle is connected through the foramen of Magendie with vallecula cerebelli and cisterna magna, and laterally through the foramina of Luschka with the cerebellopontine angles. The foramen of Magendie is probably the main path for the outflow of the cerebrospinal fluid from the ventricle. The Luschka foramina are found (at or) above the pontomedullary junction. The right Luschka foramen seems to be located slightly more superior and more posterior as compared to the left. Neuroendoscopy offers a detailed visualisation, particularly of the structures located in the inferior triangle of the fourth ventricle. The main pathological conditions affecting the foramina of the fourth ventricle are usually associated with hydrocephalus (responsible for clinical manifestations) and include occlusion, membrane obstruction, congenital imperforation, idiopathic stenosis, arachnoid adhesions and cystic dilation. Conclusion The foramina of the fourth ventricle, anatomically delicate and neurosurgically crucial apertures, have close relations with several important structures of the brainstem and cerebellum. Slight differences seem to exist between the two sides regarding the location of the Luschka foramen. Pathological conditions affecting the foramina of the fourth ventricle usually produce clinical manifestations due to obstruction of the cerebrospinal fluid normal flow. Microsurgical treatment of such rare but challenging lesions is nowadays feasible.