140 



BIOLOGICAL PHYSICS 



shelving downwards from front to back, and^ each 

 possessing, at its lowest floor level, a system of exits, 

 into which gravitate all the residual materials from? the 



FIG. 56. INTERNAL BASE OF THE SKULL. (A. T.) i. 



i, anterior fossa and roof of the orbit, as formed by the frontal bone ; between 2 and 3, 

 the foramen caecum, crista galli and cribriform plate of ethmoid ; 3, ethmoidal 

 spine of the sphenoid ; 4, lesser wing of sphenoid terminating posteriorly in the 

 anterior clinoid process, inside which is the optic foramen ; 5, placed in the 

 pituitary fossa, behind the olivary eminence and transverse groove of the optic 

 commissure ; 6, dorsum sellae, terminating in the posterior clinoid processes ; 7, 

 foramen rotundum, in front of which, but not seen in the figure, is the sphenoidal 

 fissure ; 8, foramen ovale ; 9, foramen spinosum ; 10, on the petrous bone, near 

 its apex, and to the inside of the hollow occupied by the Gasserian ganglion ; in 

 front of this is the foramen lacerum ; n, in front of the eminence of the superior 

 semicircular canal, and behind the hiatus Fallopii ; 12, upper border of the 

 petrous, marked by the superior petrosal groove ; 13, the posterior surface of 

 the petrous to the inside, the internal auditory meatus, behind, the scale of bone 

 covering the aqueduct of the vestibule ; 14, basilar groove ; 15, anterior cpndylar 

 foramen ; 16, jugular foramen ; 17, groove of the lateral sinus ; 18, internal 

 occipital protuberance, and running down from it the internal occipital crest ; 

 between 17 and 18, the upper part of the groove of the lateral sinus, between 17 

 and 16, the lower part ; 19, cerebellar fossa. 



ventricular cavities and inter-meningeal spaces, through 

 which they percolate, or are driven into, textures without the 

 skull, directly continuous with them, for ultimate disposal. 

 The cribriform foramina of the ethmoid bone, the early 



