372 SPECIAL ANATOMY. 



medulla oblongata, enclosing a canal in its interior, which passes 

 into the longitudinal sulcus of the sinus rhomb., in consequence 

 of which this fossa becomes covered with the gray substance 

 (stratum cinereum). In some places it is more particularly col- 

 lected together (alee cinerece and subst. ferruginosa). The ante- 

 rior crura of the gray substance of the medulla spinalis form the 

 (denticulated) nuclei of the olivary bodies (corpp. denticulata), 

 and are surrounded by white substance, the posterior, in like man- 

 ner, the nucleus of the corpora restiformia. The white fibres of 

 the spinal cord everywhere surround the gray substance in the 

 prolongations, form the pyramids and the so-called eminentice, 

 teretes of the sinus rhomb., and cross each other in several places 

 (Decussation). They then proceed into the pons, crura cerebri, 

 the cerebellum, and so forth. 



The pedunculi cerebelli, passing off from the cord-shaped bodies 

 of the med. oblong., form with their white mass the medullary 

 centre (meditullium album) of the cerebellum, which (except in 

 the vermis) encloses, as in the olivary body, a gray denticulated 

 nucleus, and divides externally into lobes, which are again over- 

 laid with gray substance, whereby arises the arbor meduttaris or 

 arbor mtc& (see before). The separate lobes and lobules are, as 

 also in the cerebrum, united together by means of arched fibres, 

 the so-called massa explementi which fill the intervals between 

 them. The pons consists of two transverse and two longitudinal 

 layers of fibres, between which the gray substance is deposited. 

 The pedunculi cerebelli superioris s. ad corpp. quadrigemina 

 pass away inwards under this (surrounded upon both sides by 

 the laqueus which passes into the corp. quadrigem.), and strengthen 

 the peduncles of the cerebrum. Hypophysis cerebri, and particu- 

 larly tuber cinereum and infundibulum, consist almost entirely 

 of gray substance, the nucleus of the medulla spinalis appearing 

 in view. The infundibulum has a hollow in it. The peduncles 

 of the cerebrum are continuations of the fibres from the medulla 

 oblongata (from the pyramids, funiculi siliqutz of Burdach) and 

 cerebellum. They consist of three fasciculi : basis, covering 

 (tegumentum), and cord (laqueus), which are separated by black 

 substance (which passes upon them into the three cerebral 

 ganglia). The inferior layer passes into the corpp. striata, the 

 superior or tegumentum into the optic thalami, the laquei into 

 the corp. quadrigem., the white mass of which they form. The 

 four tubercles have each four gray nuclei. The glandida pine- 

 alis attached to them has a granular structure like that of the 

 pituitaria, and consists of a grayish-red substance. The optic 



