42 Vessels of Brain 



from the ascending pharyngeal, through the anterior condylar 

 men. 



The veins, with the exception of the pair of middle meningeals, 

 which emerge by the foramen spinosum to join the internal maxillary 

 vein, end in the adjacent sinuses. 



The middle meningreal artery ascends for a short distance in the 

 substance of the anterior inferior angle of the parietal, so that fracture 

 of that part of the skull is apt to be followed by haemorrhage between 

 the bone and dura mater. For the most part, the vessel is wrapped in 

 the dura, so that a rent of the membrane tears the vessel also, in 

 which case bleeding is also external to the dura. The looseness of 

 the attachment of the membrane to the vault of the skull allows the 

 formation of an enormous blood-clot outside the dura, the brain being 

 thereby gradually compressed. The nature of the compression is 

 readily suspected : thus, it is over the motor area ; the symptoms do 

 not follow immediately on the accident, as they would if the compres- 

 sion were due to depression of bone : they come on gradually after a 

 few days, and there is no rise of temperature such as would be 

 associated with the compression due to suppuration. 



Being thus enclosed in bone and in the dura, there is little chance 

 of spontaneous cessation of bleeding when the artery is rent. The 

 haemorrhage being over the motor area, the progress of the clot can 

 be precisely noted. Trephining will be indicated, and on opening the 

 skull, if leakage from the vessel have not then ceased, there will be 

 little difficulty in finding and securing the torn vessel. >(Jacobson, 

 'Guy's Hospital Reports,' vol. xliii.) 



The arteries oi the brain are derived from the internal carotid and 

 the vertebral, the former giving off the anterior and middle cerebral. 



The anterior cerebral enters the front of the longitudinal fissure, 

 where it is joined with its fellow by the short anterior communicating 

 artery. It then winds on to the upper surface of the corpus cal- 

 losum, where it anastomoses with the posterior cerebral. It gives off 

 branches to the anterior perforated space (p. 53), to the anterior lobe, 

 and to the median surface of the hemisphere. 



The middle cerebral, ' the artery of cerebral haemorrhage,' supplies 

 the motor area (p. 48). Entering the Sylvian fissure, it gives branches 

 to the island of Reil, through the anterior perforated space, to the 

 corpus striatum, and to those parts of the frontal and parietal lobes 

 adjacent to the fissure of Rolando. Thus, when the main artery of 

 the left side (p. 49) is plugged, there is right hemiplegia and aphasia, 

 and when the right vessel is plugged there is left hemiplegia. \Ylu-n 

 a branch only is blocked the motor paralysis is partial, and, perhaps, 

 temporary, as the anastomotic branches of the pia mater may in due 

 time repair the lesion. The left middle cerebral is said to be more 

 often plugged than the right, because, it is argued, a vegetation 

 is more likely to pass with the blood-stream into it than into that of 



