402 PONS VAROLIL 



to the cerebellum. The corpora restiformia thus form the 

 line of connection between the spinal marrow, medulla 

 oblongata, and cerebellum. Mr. Solly calls these bodies 

 ganglia restiformia, or the ganglia of the pneumogastric 

 nerves. 



The Posterior pyramids are seen on the back part of the 

 cord on either side of the posterior fissure, in relation with 

 the fourth ventricle, and continuous partly with the resti- 

 form, and partly with the posterior olivary bodies. They 

 are found to commence as low down as the dorsal region, 

 and to ascend as high as the fourth ventricle. They are 

 viewed as commissural to the spinal cord and medulla ob- 

 longata. These posterior pyramids are also called auditory 

 ganglia. The medulla oblongata, thus composed, is justly 

 regarded as a most important ganglionic centre, or as Mr. 

 Solly thinks, of six ganglia, three on either side of the 

 fissure, i. e. the anterior, lateral, and posterior, in addition 

 to the columns for motion and sensation. 



Nerves of the Medulla Oblongata. Between the pyramids 

 and olivary are the ninth nerves, between the olivary and 

 the restiform bodies are the eighth pair. From the oli- 

 vary, by the side of the calamus scriptorius, are the audi- 

 tory. The fifth can be traced also into the olivary, and 

 the sixth are between the pyramids and pons. 



PONS VAROLII. 



The Pons Varolii, or tuber annulare, (Fig. 16,) so called 

 from its arched or bridge-like form and its discoverer, is 

 a white body, situated upon the top of the medulla ob- 

 longata, about the centre of the base of the brain, and 

 between the cerebrum and cerebellum. 



It rests upon the cuneiform process of the occipital bone 

 at its junction with the sphenoid, by its inferior and ante- 

 rior surface. Its superior and posterior surfaces are in rela- 

 tion with the tubercula quadrigemina, the fourth ventricle, 

 and the aqueduct of Sylvius. The crura cerebri are con- 

 nected to its upper extremity, the crura cerebelli to its sides, 

 and the medulla oblongata to its lower extremity. Its in- 



