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Lab 9 (ƒ 10) - Cranial Nerve Nuclei and Brain Stem Circulation

Cranial Nerve XII-Hypoglossal Nerve

Before proceeding with this exercise, familiarize yourself with the planes of section and the directional terms used in the study of the central nervous system (see figure on right.) Keep in mind that certain terms were developed to describe the nervous system of quadrupeds and may have a slightly different meaning when applied to bipeds. For example, the ventral surface of the quadruped spinal cord is comparable to the anterior surface of the biped. In the following descriptions, the terms are applied to a standing human. The terms rostral and anterior refer to a direction towards the face/nose. The terms caudal and posterior refer to a direction towards the buttocks/tail. The terms inferior and superior generally refer to spatial relationships in a vertical direction. A coronal section is parallel to the vertical plane and a mid coronal section would divide the head into anterior and posterior halves. The sagittal section is also parallel to the vertical plane, but a mid sagittal section would divide the head into right and left halves. The horizontal section is parallel to the horizontal plane and a mid horizontal section would divide the head into superior and inferior halves. Transverse or cross sections of the spinal cord of humans are taken in a plane perpendicular to the vertical, i.e., in the horizontal plane of the head.