ARTERIAL AND NEURAL RELATIONS AT THE POSTERIOR AND LATERAL ASPECTS OFTHE MEDULLO-SPINAL JUNCTION

The authors report the results of a series of 59 microdissections of t he region of the foramen magnum. These dissections were made under the strict conditions of a surgical approach using an operating microscop e. The major anatomic structures of the medullo-spinal junction are ar ranged mainly at its lateral aspect. The customary surgical approaches to the posterior cranial fossa give ready access to the cerebello and latero-medullary cisterns. The description of the neurovascular struc tures contained therein assumes a particular importance because of the relative frequency of lesions developing at this level. This study de als particularly with the vertebral a. (VA), the inferior posterior ce rebellar a. (IPCA), the cranial nn. IX (glossopharyngeal n.), X (vagus n.), XIc and XIs (cranial and spinal accessory n.) and XII (hypogloss al n.). The anatomy of this posterior and lateral region is characteri sed by the contrast between the relatively uniform course of the VA an d the variable course of the IPCA, a true guideline whose very irregul ar arrangement accounts for the diversity of its relations with the la st four cranial nn.