APPLIED ANATOMY. 



Clot in lower 

 portion 



Facial nerve 



Hemorrhage into the Pons Crossed Paralysis. Apoplexy may also occur 

 in other portions of the brain. It may occur in the pons (see Fig. 39)- This produces 



two different sets of symptoms, accord- 

 ing to its location, which is due to 

 the fatt that the fibres of the seventh 

 or facial nerve, in their passage from 

 the cortex to the face, decussate in the 

 Clot in pons, upper pons. If a small hemorrhage occurs 

 P rtlon into the upper portion of the pons, it 



will destroy the motor fibres to the 

 face and the extremities of the oppo- 

 site side. If, however, the hemor- 

 rhage is below the point of decussa- 

 tion, the side of the face on the side of 

 the lesion will be paralyzed and the 

 extremities of the opposite side, thus 

 producing what is known as crossed 

 paralysis, that is, a paralysis of the face 

 on one side and of the extremities on 

 the other. 



Cortical Apoplexy. Hemor- 

 rhages of the cortex are apt to be less 

 in extent and more localized on ac- 

 count of the smaller size of the ves- 

 sels affected. They either destroy or 

 irritate the brain at the site of injury, and produce, if they involve certain areas 

 of the brain, definite peripheral symptoms which serve to indicate the seat of lesion. 



THE CEREBRAL LOBES. 



Each cerebral hemisphere is composed of five lobes, called t\\& frontal, parietal, 

 occipital, temporosphenoidal, and central, or island of Reil. 



The frontal lobe comprises the anterior portion of the brain, as far back as the 

 fissure of Rolando or central sulcus, and as far toward the base as the fissure of Sylvius. 



arietal lobe 



Spinal nerves 



FIG. 39. Diagram illustrative of crossed paralysis. A 

 clot iti the upper portion of the pons causes paralysis of the 

 muscles of the face and extremities of the same side of the 

 body. A clot in the lower portion of the pons causes paraly- 

 sis of one side of the face and the extremities of the opposite 

 side of the body. 



Frontal lobe 



Occipital lobe 



Central lobe or insula 



\ Temporal lobe 



FIG. 40. Lobes of the brain. 



The parietal lobe extends from the fissure of Rolando (central sulcus) in front 

 to the parieto-occipital fissure behind. Below, it is limited anteriorly by the fissure 

 of Sylvius, while its posterior portion merges into the temporosphenoidal lobe. 



The occipital lobe extends posteriorly from a line joining the occipitoparietal 

 fissure above to the pre-occipital notch below. 



The temporosphenoidal lobe consists of that portion of the brain below the 

 fissure of Sylvius, as far back as the pre-occipital notch. It occupies the middle 

 fossa of the skull. 



