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Branch of spinal cord in skull.

The medullary substance that lies within the cranium upon the basilary process of the occipital bone. The anterior surface which rests in the basilary groove, is impressed by the basilary artery. At the upper extremity, and on its posterior surface are the Tubercula quadrigemina. At the same extremity, the medulla gives rise to two prolongations, the peduncles of the brain, separated from each other by the mammillary eminences, and becoming lost in the optic thalami. The lower extremity is called the tail or Rachid'ian bulb, Bulbe rachidien, and is continuous with the medulla spinalis. It is to this part only that some anatomists apply the name Medulla oblongata. From the posterior angles two other prolongation arise, called Peduncles of the cerebellum. The medulla oblongata has several eminences and it has a longitudinal fissure before, and another behind, called the anterior and posterior median fissures. The vesicular neurine in the centre of the medulla is the nervous centre of respiration and deglutition: hence it has been called centrum vitale.

The organ of brain directly continuous with spinal cord.

That portion of the encephalon which rests in the basilar groove, being limited above by the lower borders of the pons and continuous at the lower edge of the foramen magnum with the spinal cord. It is covered in posteriorly by the cerebellar hemispheres. As originally used, the term included also the pons Varolii and crura cerebri.