Quain's elements of anatomy . fig. 315, n XI) arisespartly in the lower part of the medulla oblongata from the con-tinuation downwards of the vagus nucleus, partly along the wholeextent of the cervical portion of the spinal cord—from the intermedio-lateral tract and adjacent part of the anterior cornu below (fig. 316),but from the reticular formation and base of the posterior cornu is the former (medullary) part which joins the vagus and isdistributed along with that nerve (vagal portion) ; the latter part(spinal portion) which originates fiom the cervical cord is accessory tothe cerv
Quain's elements of anatomy . fig. 315, n XI) arisespartly in the lower part of the medulla oblongata from the con-tinuation downwards of the vagus nucleus, partly along the wholeextent of the cervical portion of the spinal cord—from the intermedio-lateral tract and adjacent part of the anterior cornu below (fig. 316),but from the reticular formation and base of the posterior cornu is the former (medullary) part which joins the vagus and isdistributed along with that nerve (vagal portion) ; the latter part(spinal portion) which originates fiom the cervical cord is accessory tothe cervical nerves and supplies the sterno-mastoid and trapeziusmuscles. The part of the vagus nucleus from which the accessory takes Fig. 316.—Sectiojt of upper end op spinal cord Fig. 316. AT THE JUNCTION WITH THE MEDULLA OBLONGATA. (After Lockhart Clarke.) /, anterior ; fp, posterior fissure ; p, end of decussa-tion of pyramids; Cla, CTp, anterior and posterior rootsof first cervical nerve ; XI, root of sxnnal origin is placed immediately behind and tothe side of the central canal (fig. 267, n XI),where this remains closed, in a situationcorresponding to the base of the posteriorcornu of the spinal cord ; but where thecentral canal opens out at the point of the calamus scriptorius, the nucleus lies just at the side of the median sulcusof the fourth ventricle. The root-fibres of the vagal portion have acourse through the substance of the medulla like those of the vagus, andin every way this part of the spinal accessory resembles a separated partof the vagus. It receives a few fibres fiom the solitary bundle. Thener^^e emerges as a long series of roots the upper of which are attachedto the side of the medulla in a line with the posterior roots of the spinalnerves below, and the roots of the vagus above ; while the lower emergefrom the lateral column of the spinal cord, which they traverse in theirpassage fiom the gxey matter. Twelfth or hypoglossal nerve. The nuc
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