180 CLINICAL APPLIED ANATOMY. 



The auditory centre lies in the posterior part of the upper 

 temporo-sphenoidal convolution and the angular and supra- 

 marginal visual centres are adjacent. Hence alexia, agraphia 

 and word-deafness may accompany extensive or acute temporo- 

 sphenoidal abscesses of the left side. The deafness which 

 accompanies these abscesses and usually also the occasional 

 complete facial paralysis are accounted for by the lesion in 

 the ear on the side of the abscess. Barely, cortical deafness 

 occurs in the opposite ear, but frequently this ear is also 

 diseased. 



Temporo-sphenoidal abscesses have a great tendency to rup- 

 ture into the ventricles of the brain and naturally break into 

 the descending cornu of the lateral ventricle since this traverses 

 the lobe in which they lie. 



The third cranial nerve on the same side as the abscess 

 often shows signs of weakness in the form of ptosis or paralysis 

 of the muscles of the globe or inactive pupil. The nerve 

 lies in the front part of the tentorium cerebelli, and is possibly 

 subject to pressure from the swollen temporo-sphenoidal lobe, 

 for the uncus of this lobe is often deeply grooved by the 

 edge of the tentorium. 



The knowledge of the localisation of cerebellar functions is 

 scanty, so the application of anatomical facts is difficult. 

 Cerebellar abscesses are subtentorial, and may produce pressure 

 symptoms in the posterior fossa, such as occipital headache 

 radiating down the neck, and distension of the ventricles of 

 the brain. 



From the dentate nucleus of the cerebellum fibres stream out 

 to the superior peduncle and so reach the opposite cerebral hemi- 

 sphere. Interference with these fibres is supposed to produce a 

 particular type of paralysis which consists in considerable 

 brachial monoplegia on the side of lesion, coupled with 

 this may be some weakness of the lower extremities. This 

 paralysis is explained by the assumption that the cerebellar 

 hemisphere normally augments the action of the cerebral 

 hemisphere of the opposite side. Since the cerebellar abscess 



