SOCIETY OF THE UNIVERSITY OF ABERDEEN. 97 



pierces the pyriformis muscle while the lower issues below the 

 muscle. 



(Signature of observer) MARGARET K. MOIR. 



Date of observation, February, 1908. 

 Sex, Female. 



Abnormality in arterial supply of orbit. 



In the right orbit the arterial blood supply consists of a small 

 branch from the internal carotid coming off in the usual situation of 

 the ophthalmic artery and entering the orbit by the optic foramen in 

 much the ordinary fashion ; the peculiarity being that it is very 

 small. This artery on coursing forwards towards the nasal side of 

 the orbital cavity is joined by an unusually large branch from the 

 middle meningeal artery entering by the sphenoidal fissure. The 

 point of junction is beneath the superior rectus muscle. 



On the left side no indication of an ophthalmic artery is found in 

 the usual position. Certainly no branch from the middle meningeal 

 exists as on .the opposite side. The apparent absence of the ophthalmic 

 artery may be due to various causes, but the injection of the other 

 eye is good and the fact that even in the right eye the artery is very 

 small tends to confirm the suspicion that no ophthalmic artery, or at 

 least a very tiny branch is present. 



Another peculiarity is that on the left side the infra-orbital artery 

 enters the infra-orbital canal by an aperture somewhat further 

 forwards than usual. The spheno-maxillary fissure is very small, and 

 there is a certain degree of compression of the bones in this region. 

 (Signature of observer) W. G. THOMSON. 



13 



