LESSON XXXIII. 



THE MID-BRAIN AND INTER-BRAIN. 



1. Section through the anterior part of the 4>th 

 ventricle (man). The parts are the same as in 11, 

 Lesson xxxn. Note: 



The median fillet, an elongated mass of fibres 

 dorsally of the pons fibres. 



The lateral fillet (posterior mid-brain fillet), a 

 triangular mass of fibres, running obliquely dorsally, 

 at the lateral edge of the median fillet ; it has grey 

 substance on its surface and a little also amongst its 

 fibres. The sup. ce'r. ped. extending ventrally nearly 

 to the median fillet ; its ventral part is medial to the 

 lateral fillet. 



2. Section just behind the exit of the ^th nerve 

 (man). The parts are the same as in 1. The ventral 

 fibres of the sup. cer. ped. stretch to, or nearly to, the 

 middle line. The lateral fillet lies as an oval mass 

 over its outer surface with grey substance on both 

 sides of it. The post. long, bundle stretches laterally 

 nearly to the mid-brain root of the 5th n. 



