THE BRAIN 



707 



The red nuclei are so called on account of the colour they present 

 to the naked eye on section of the mid-brain. They are situated 

 centrally, just on either side of the middle line. The nuclei form 

 intimate connection with the fibres of the superior cerebellar peduncles, 

 and with fibres from the optic thalamus and cerebral cortex. Its 

 cells give origin to the rubro-spinal tract (Monakow's bundle, or the 

 prepyramidal tract). The fibres of this tract almost immediately 



iSt,V\: 



"'^imi? 



.. ^.-f/l.F.p. 



n 

 *y 



I'j". 432. SECTION ACROSS MID-BKAIN, THROUGH THK ANTEKIOK CORPORA QUAPRI- 

 CI-.MINA. PHOTOGRAPH MAGNIFIED ABOUT 3J DIAMETERS. (E. A. Schafjr, 

 from "Quain's Anatomy.") 



*>/.. Aqueluct of Sylvius; c.p., posterior commissure; gl.pi., ]>ineal gland ; c.q.a., an- 

 terior corpus (juadrige:ninum; c.g.tn., internal geniculato body; c.g.l., lateral 

 geniculatc body; tr.opt., oj)tic tract; p.p., pes; p.l.b., posterior longitudinal 

 bundle; ft., upjer fille';; r.n., rei nucleus; n.III., nucleus of third nerve; ///., 

 issuing fibre; of third nerve; I. p.p., locus pcrfora its posticus. 



cross, forming what is known as Forel's decussation. and pass down 

 through the pons and medulla to occupy a position in the cord just 

 anterior (prepyramidal) to the crossed pyramidal tract. Eventually, 

 they terminate around the cells of the anterior horn. From cells 

 in the roof of the mid-brain arise the fibres of the tecto-spinal tract, 

 which cross the mid-line forming the fountain decussation of Meynert, 

 and then pass into the anterior longitudinal bundle. 



