ANATOMY IX A NUTSHELL. 



363 



anterior surface is convex from side to side and slightly convex from above 

 downward. Its superior border is longer than the lower border and Is convex, 

 while the lower border Is almost straight. In the median line on the anterior 

 surface there is a groove for the basilar artery. Its posterior surface is concave 

 and forms the upper part of the floor of the fourth ventricle. A 

 coronal section will divide it into an anterior or inferior portion and a posterior 

 or superior portion. The posterior part is called tegmentum. The anterior 

 part consists of three main divisions (1) superficial transverse fibres which pass 

 from the middle peduncles of the cerebrum and give the pons its name., (2) 

 deep transverse fibres which decussate in the pons connecting one side of the 

 cerebellum with the opposite side of the cerebrum. (3) is longitudinal fibres which 

 intermingle with the deep transverse fibres and pass through the medulla into 



PLATE CLXXXIH. 



Location of Centers of the Brain. 



the crust a or pes of the crus. The tegmental portion of the pons, or posteior 

 part, has four main parts. Anteriorly (1) the fillet. (2) formatio reticularis, 

 (3) posterior longitudinal bundle-, and (4) superior olivary nucleus. 



A hemorrhage in the pons, if it is above the decussation of the seventh nerve 

 will cause paralysis of the opposite side of the face and opposite side of the body 

 but if it is below the decussation of the seventh nerve it will cause paralysis of 

 the same side of the face and opposite side of the body, producing what is known 

 as crossed hemisphlegia. The sixth nerve, seventh nerve, and par' of the 

 eighth nerve have their deep origin in this part of the pons. The crus cerebri 

 or the peduncles of the cerebrum pass upward and outward from the upper 

 margin of the pons into the substance of the cerebrum. They are about three- 

 fourths of an inch long. A cononal section will divide this into an anterior or 

 inferior and a posterior or tegmental portion. The anterior is called crusta 



