CHAPTER VI. 



THE GROSS RELATIONS OF NERVES, SPINAL CORD, BRAIN AND OTHER GANGLIA. 



In speaking of the human brain stem, the term ( anterior ' means tipper 

 and ' posterior ' means lower. These terms are used in this way because 

 of the usual reference of the brain structures to the medullary tube from 

 which the cerebro-spinal system develops. The brain develops from the 

 anterior portion of this tube; the upper part of the brain stem (the fore- 

 brain) develops from the most anterior portion. Moreover, in the quad- 

 rupeds, in which the cerebro-spinal axis is horizontal, the ' anterior ' por- 

 tions are really anterior to the ' posterior '. 



Sulcus centralis (Roland)} 

 Salens praecentrilis 

 Sulcus frontalis 

 Sulcus frontalis infi 



Sulcus interparietals 



Fissura cerebri 

 lateralis (Sylvii) 



Ramus anterior 

 trurizon talis 

 Ramus ante 

 ■tscendens 



Ramus posterior' 

 Sulcus temporalis medius 



M 



 fr Sulci 



occipitales 

 laterales 

 leus occipitalis 

 transversa 



Sulcus temporalis supt. 



Fig. 65. Brain viewed from the left side, showing lateral surface of the left cere- 

 bral hemisphere. (Toldt, Anatomischer Atlas.) One-half normal size. 



The plane or section passing longitudinally through the body so as to 

 divide it accurately into right and left halves, which will be as symmetrical as 

 possible, is the medial plane. Any plane or section parallel to the medial 

 plane is a saggital plane. Any vertical plane through the body, cutting 

 the medial plane at right angles (»'. <?., giving a symmetrical outline of the 

 body), is a coronal or frontal plane. Planes at right angles to the 



