CEREBELLUM, PONS, AND MEDULLA. 241 



cerebellum, and they have been rewarded by obtaining results of 

 a positive character. The newer anatomical nomenclature is 

 illustrated in Fig. 105, which gives a schematic representation of 

 the arrangement of the lobules of the cerebellum of the dog, ac- 

 cording to Bolk. Adopting this schema, van Rynberk reports 

 that excision of the lobulus simplex is followed by movements of 

 the head (head nystagmus), which indicate an abnormal innerva- 

 tion of the neck muscles. Injury on one side of the crus primum 

 of the ansiform lobule is followed by abnormal movements of the 

 forefoot of the same side, while similar injuries to the crus se- 

 cundum result in abnormal movements locahzed to the hind foot. 

 Extirpation of a lobulus paramedianus causes roUing movements 



Fig. 105. — Schema of dog's cerebellum to show Bolk's nomenclature for the lobes and 

 sulci. Dorsal view : La, lobus anterior (this lobe is separated from the larger posterior lobe 

 by the deep primary fissure, Spr) ; Ls, lobulus simplex ; Lans, lobulus ansiformis ; Lp, 

 lobulus paramedianus ; Lmp, lobulus medianus posterior ; Fv, formatis vermicularis (pars 

 tonsillaris) ; C, crus primum ; C^, crus secundum ; Spr, sulcus primarius ; Sp, sulcus 

 paramedianus ; Si, sulcus intercruralis. — (After van Rynberk.) 



round the long axis of the body or bending of the body to one side 

 (pleurothotonus). These experimental results have been confirmed 

 in part by observations on clinical cases in which an asynergy of 

 a definite character in the movements of the arms or legs has been 

 related to lesions of definite portions of the cerebellar hemisphere 

 of the same side, while the muscles of the head, neck, and trunk 

 are affected by lesions occurring in the vermis.* 



The Medulla Oblongata. — In the medulla oblongata we must 

 recognize a region of special physiological importance in that it 

 is the seat of certain centers which control the activity of the 

 circulatory and respiratory organs. If the medulla is severed 

 from the portion of the brain lying anterior to it the animal con- 

 tinues to live for a considerable period. The respiratory move- 



* Bardny, "Wiener Klin. Wochenschrift," December 26, 1912. See also 

 Gordon, "Trans. American Neurological Association," 1919. 

 16 



