Macalister — 0)1 Ligamentmn PtcrygO'Spinosum, 205 



tated (fig. 9 x). This is often tlie case in tlie ligamentum accessorium 

 also (fig. 10 x), but here complete ossification and obliteration of the 

 suture at the point of junction is much commoner, so that the arch 

 becomes simple, solid (fig. 13). 



A form of spurious arcuation may be produced by the elongation 

 and convergence of the two ecto-ptcrygoid teeth, -which may loop 

 towards each other in an arched form, and may even touch, leaving 

 thus a round hole in the external pterygoid plate (figs. 2, 4 w). This 

 when present transmits an anomalous branch of the internal maxillary 

 artery. 



The whole trunk of the internal maxillary, in a not uncommon 

 anomalous coui'se under the external pterygoid muscle, either pierces 

 below, or through, or under the ligament of Civinini, so that when 

 this band is ossified, it is not uncommon to find the whole truuk of 

 the aii;ery passing through the loops of the bony bridge. ■ Such an 

 arrangement is the exact repetition of the course of the artery in 

 Eodents and many other mammalian orders ; indeed this seems the only 

 assignable use for the ligament, to protect the artery from the pressure 

 of the pterygoid muscles. In Henle-Krause's Handbuch der Gefass- 

 lelire des Menschen, p. 243, Professor Krause describes the anomalous 

 internal maxillary as trasversing sometimes a hole in the lamina 

 lateralis processi pterygoidi ossis sphenoidei (external pterygoid plate), 

 and speaks of this being analogous to the condition in the rabbit. The 

 hole referred to is the arch of the ligament ; for the trunk internal 

 maxillary artery never passes through any hole in the outer pterygoid 

 plate proper. 



In a Mandingo skull, the spina angularis is double, half formed of 

 the squamosal element of the anterior lip of the glenoid cavity, and 

 half of the sphenoid, the spheno-squamosal suture crossing the summit 

 of the process, and this coexists with a foramen spinosum in the spheno- 

 petrosal suture. In another skull the tooth on the pterygoid plate is a 

 tooth on the outside, not on the hinder margin of the plate. 



