362 



ANATOMY OF THE RABBIT 



ta - 



(b) The rhomboid fossa (fossa rhomboldea) is the shallow 

 depression enclosed by the thick lateral and anterior walls 

 and floor of the ventricle. The middle line shows a narrow 

 depression, the median fissure (sulcus medianus fossae 

 rhomboideae) , on either side of which the floor is raised into 

 a low ridge, described as the medial eminence (eminentia 

 medialis). The posterior end of the fossa forms with the 

 enclosing wall the some- 

 what triangular figure des- 

 cribed as the calamus scrip- 

 torius. 



(c) The lateral supports of the 

 cerebellum, now represent- 

 ed by their cut ends, are \ 

 formed by fibre-bands con- ^^'^ 

 necting the cerebellum with 

 adjacent portions of the fc- 

 brain. In each there are 

 three main bands or ped- s 

 uncles, though these cannot 

 usually be distinguished in 

 the cut surfaces. A middle 

 peduncle, thebrachium pon- 

 tis, represents the direct 

 continuation of the pons in- 

 to the cerebellum, bringing 

 impulses to the latter from the cerebral cortex. An ante- 

 rior band, the brachium conjunctivum, contains chiefly 

 (not exclusively) fibres leading out of the cerebellum and 

 running into the floor of the midbrain. A third band, the 

 inferior cerebellar peduncle or restiform body (corpus 

 restiforme) , comes from behind as a thick ridge continuous 

 with the dorsal part of the lateral funiculus of the spinal 

 cord. It forms the lateral wall of the more caudal portion of 

 the rhomboid fossa. Before turning dorsad into the cere- 

 bellum it passes under a rounded elevation, the acoustic 

 tubercle, where part of the auditory nerve ends. The 

 restiform body conveys impulses from various centres in 



Fig. 122. The rhombencephalon. Dorsal 

 view, after removal of the cerebellum; 

 be, brachium conjunctivum; bp, brachium 

 pontis; cl, clava; cli, inferior colliculus 

 (mesencephalon); cr, restiform body; em, 

 medial eminence; fc, fasciculus cuneatus; 

 fg, fasciculus gracilis; fm, median fissure 

 of the rhomboid fossa; smp, dorsal me- 

 dian sulcus of the medulla; sip, dorso- 

 lateral sulcus; ta, acoustic tubercle; vma, 

 anterior medullary velum. 



