The hypoglossal nucleus is a cranial nerve nucleus, and it extends the length of the medulla, and being a motor nucleus, is close to the midline. In the open medulla, it is visible as what is known as the hypoglossal trigone, a raised area (medial to the vagal trigone) protruding slightly into the fourth ventricle.
In the closed medulla, the gracile and cuneate nuclei lie posteriorly, which means the nucleus is not as close to the back of the medulla as in the open medulla. It is, however, still close to the midline.
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