56 Bones of the Skull. 



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69. Right orbital cavity, orbita, from in front. 



Magnification 5:4. 



The orbita (orbital cavity} (see also Figs. 5558, 68, 71 and 72) lies on each side 

 in the upper part of the facial skull and, above, adjoins the cerebral skull. It opens in front 

 by a wide mouth, aditus orbitac, behind this widens suddenly in its lateral half and then 

 narrows gradually from before backward. Its shape, in front, is that of a four-sided, behind, 

 that of a three-sided, pyramid, since the medial and the inferior wall form in front an obtuse 

 angle with one another, while further back, they lie almost in one plane. The axes of the 

 two orbital cavities (from the middle of the anterior opening to the middle of the foramen 

 opticum) converge behind to the region above the sella turcica and are in addition inclined, 

 in front, somewhat downward. 



The opening of entrance, aditus orbitae, is more or less quadrangular with rounded 

 corners. The upper margin, margo supraorbilalis, is formed by the margo supraorbitalis and 

 processus zygomaticus oss. frontalis. the medial by the pars nasalis oss. frontalis and the pro- 

 cessus frontalis maxillae, the inferior, margo infraorbitalis , by the corpus maxillae and os 

 zygomaticum, the lateral by the os zygomaticum. 



