Section through the medulla at the level of the olives. The latter (Ol) are seen to be composed of a crinkled lamina of grey matter bent sharply on itself so as to produce a medially directed “hilum”. From the hilum emerge masses of olivo-cerebellar fibres which stream across the mid-line and then pass dorso-laterally to join the inferior cerebellar peduncle (Icp). Note the dorsal accessory (Da) and medial accessory (Ma) olives. The pyramid (P) is a conspicuous feature on either side of the antero-median fissure, and on its surface are some scattered islets of grey matter, the arcuate nuclei (Na). The medial fillet (Mf) is closely applied to the mid-line, and above, close to the floor of the 4th ventricle, is the medial longitudinal bundle (Md). Note the nucleus of the hypoglossal nerve (XII') and the rootlets of the nerve passing ventrally through the substance of the medulla (XII"). The fasciculus solitarius (Fs) in the lateral part of the floor of the fourth ventricle stands out conspicuously, and further lateral is the upper end of the cuneate nucleus (Nc). Note also the ventral spino-cerebellar tract (Scv) close to the lateral surface of the medulla dorsal to the olive (the dorsal spine-cerebellar tract has at this level become incorporated in the inferior cerebellar peduncle. Lastly, identify in the section the spinal nucleus of the 5th nerve (V) and its spinal tract (Sp.). 

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