820 



THE NERVOUS SYSTEM 



stance, the nucleus 0} the lateral lemniscus, in which many of its fibres are inter- 

 rupted. 



The upper and greater portion of the lateral lemniscus with its nucleus belongs 

 to the auditory apparatus, being connected with the nucleus of termination of the 

 cochlear nerve, chiefly of the opposite side. (See fig. 601 .) A large part of the fibres 

 of this portion terminate in the inferior quadrigeminate bodies. Many of these enter 

 at once the nucleus of the body of the same side, and disappear among its cells; others 

 cross the mid-line to the quadrigeminate body of the opposite side. In crossing, 

 some pass superficially and thus contribute to the stratum zonale, while others pass 

 either through the nucleus or below it and cross beneath the floor of the median 

 groove between the stratum zonale and the dorsal surface of the central grey sub- 

 stance, forming there an evident decussation with similar fibres crossing from the 

 opposite side. Most of the fibres arising from the cells of the nucleus of the quad- 

 rigeminate body either pass by way of the inferior brachium to the medial geniculate 



Fio. 612. DIAGRAM OF LONGITUDINAL SECTION OF NUCLEUS OF OCULOMOTOR NERVE. 



(After Edinger.) 



NUCLEUS OF POSTE- 

 RIOR co.v.vmi*rRE 



AND MED. LONG IT. 



FAHC. 



MEDIAL LONGITUDI- 

 NAL FASCICULUS 



MM. C1LIARIS (ra) 

 AND SPHINCTER 

 1R1DIS (b I 



LEV A TOR 

 PALL>EBRJE 



OBLiqUUS INFERIOR 



RECTUS SUPERIOR 

 RECTUS MEDIALIS 

 RECTUS INFERIOR 



SUPERIOR GROUP 

 (Nucleus of Edinger 

 and Westpltal) 



-INFERIOR GROUP 



body and the thalamus, or pass ventrally to terminate in the nucleus of origin of the 

 trochlear nerve. Another portion of the lateral lemniscus passes obliquely forwards 

 in company with the inferior brachium, and terminates in the medial geniculate 

 body. Thus the inferior quadrigeminate bodies with their brachia and the medial 

 geniculate bodies and a large portion of the lateral lemniscus are concerned with 

 the sense of hearing. 



Practically all the remainder of the lateral lemniscus terminates in the nucleus, 

 or stratum cinereum, of the superior quadrigeminate body of the same and opposite 

 sides. They approach the nucleus from below, and contribute to the well-marked 

 band of fibres coursing on the dorso-lateral margin of the central grey substance, 

 and known as the ' optic^acoustic reflex path' (fig. 611). 



The medial lemniscus arises in the medulla oblongata from the nuclei (of term- 

 ination) of the funiculus gracilis and funiculus cuneatus of the opposite side, and 

 likewise from the nuclei of termination of the sensory roots of the cranial nerves. It 



