. Cunningham's Text-book of anatomy. Anatomy. 556 THE NEKVOUS SYSTEM. in the medulla are the inferior olivary nucleus and the two accessory olivary nuclei. The nucleus olivaris inferior is the mass of gray substance which produces the swelling known as the olive, and constitutes a very striking object in trans- verse sections through this region. It presents the appearance of a thick wavy or undulating line of gray matter, folded on itself, so as to enclose a space filled with white matter. It is in reality a crumpled lamina arranged in a purse-like manner, with an open mouth or slit, which is
. Cunningham's Text-book of anatomy. Anatomy. 556 THE NEKVOUS SYSTEM. in the medulla are the inferior olivary nucleus and the two accessory olivary nuclei. The nucleus olivaris inferior is the mass of gray substance which produces the swelling known as the olive, and constitutes a very striking object in trans- verse sections through this region. It presents the appearance of a thick wavy or undulating line of gray matter, folded on itself, so as to enclose a space filled with white matter. It is in reality a crumpled lamina arranged in a purse-like manner, with an open mouth or slit, which is called the hilus (hilus nuclei olivaris), directed towards the median plane. The hilus does not reach either extremity, so that in transverse sections through either end of the nucleus the gray lamina is seen in the form of a completely closed capsule. Into and out of the open mouth of the olivary capsule streams a dense crowd of fibres. These constitute what is called the olivary peduncle. The accessory olivary nuclei are two band-like laminae of gray matter, which are respectively placed on the dorsal and medial aspects of the main nucleus. In transverse section each of these nuclei presents a rod-like appearance (Fig. 486). The medial accessory olivary nucleus (medialis) extends lower down in the medulla oblongata than the main nucleus, and it is much larger in its lower than its upper part. It begins immediately above the decussation of the pyramids, where it is seen lying on the lateral side of the cerebro-spinal fasciculus and the lemniscus medialis (Fig. 486). Higher up it lies across the mouth of the main nucleus and on the lateral side of the medial lemniscus. The dorsal accessory olivary nucleus is placed close to the dorsal aspect of the main nucleus. The two accessory nuclei fuse together before they finally disappear. The nerve-cells of the inferior olivary nucleus are small and round, and emit a large series of short radiating, complexly branched dendrites, so th
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