Task: Class Definition Understanding (ontology: Sciences/Biology)

Which of the following definitions best describes 'hypoglossal nucleus'?

A. Nucleus forming a longitudinal cell column in the medulla, close beneath the floor of the 4th ventricle, containing motor neurons that innervate the muscles of the tongue (Brodal, Neurological Anatomy, 3rd ed., 1981, pg 453).
B. The raphe obscurus projects to the cerebellar lobes VI and VII and to crus II along with the nucleus raphe pontis . This so called obscure nucleus has also been implicated in the modulation of the hypoglossal nerve. It has been observed that the ablation of this nucleus causes a change in the firing pattern in the XII nerve . In addition, the raphe obscurus mediates expiration via the inhibitory effect of serotonin and depresses periodic synaptic potentials . It has also been shown that this nucleus stimulates gastrointestinal motor function; microinjections of 5-HT into the n.r. obscurus increase gastric movement . [WP,unvetted].
C. The the concept is the largest nucleus situated in the olivary body, part of the medulla oblongata.
D. TO DO: see DOI: 10.1002/cne.902660403 for next steps in defining different octaval nerve nuclei.

Answer: Nucleus forming a longitudinal cell column in the medulla, close beneath the floor of the 4th ventricle, containing motor neurons that innervate the muscles of the tongue (Brodal, Neurological Anatomy, 3rd ed., 1981, pg 453).