A transverse section of the olive (figure 36) shows that it is composed of an external white capsule, within which is a convoluted layer of grey matter surrounding a mass of white subtance. From its hilus, which is above and internal to the mass, fibres emerge which form a commissure between the opposite olivary bodies, and others are directed backward to the floor of the fourth ventricle to connect with the nuclei of the pnemnogastric and hypoglossal nerves. The upper part of the olive with the former, and the lower part with the latter (Van der Kolk). This body is supposed to be concerned with the co-ordination of the muscles of speech.
The restiform bodies, or inferior peduncles, connect the cerebellum with the medulla and spinal cord. They arise from the posterior and outer angles of the medulla upon the sides of the fourth ventricle, and arch upward and backward between the superior and middle peduncles of the cerebellum, to spread over the upper surface of the 'corpora dentata, in which they terminate. The upper border of the restiform body forms the posterior side of the restiform triangle. and
is in relation to the parts transmitted by the triangle, viz : the anterior root of the eighth nerve, the seventh and fifth nerves, and the posterior layer of the fillet. Its posterior border is in relation with the posterior root of the eighth nerve and the commissure of the ilocenlus. A transverse section through the restiform nucleus (figure 36) shows a body similar but larger than the nucleus of the olive, and that commissural fibres connect the opposite nuclei.
The restiform system of fibres of either side is derived : from the restiform nucleus at the side of the lower extremity of the fourth ventricle, from the clavate nucleus, the direct cerebellar tract of the cord, the arciform fibres of the an terior pyramid, the cerebellar fibres from the floor of the fourth ventricle derived from the raphe, and from the upper most fibres of the pens Varolii, which proceed from the raphe and floor of the fourth ventricle.