82 OSTEOLOGY [Parr II. 
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polished elevated area of the orbital fossa, the posterior rounded edge of which forms its anterior margin, 
which is seven lines long; its base is four lines and one-third ; for a line above it, the surface is, as it were, 
scooped out. 
A smooth tract, corresponding to the post-orbital vascular flexus, and leading to the foramen rotundo- 
ovale, occupies the remainder of the floor of the temporal fossa: it terminates below, at the convex pro- 
jection of the tympanic tube, which runs horizontally outwards and backwards; its anterior wall is formed 
by a curved plate, which, after covering the inferior efferent pneumatic cells and the Hustachian tube, is 
attached to the outer margin of the sphenoid lozenge and basilar protuberance; behind which, it presents 
a deep triangular incision, bounded below by the thin, inferiorly concave edge ; formed by its junction, at an 
acute angle, with the inner wall. Its orifice is in a line with the post-temporal process ; the edge is deeply 
concave, the lower angle being prolonged into a sharp, slightly incurved styloid process. The tympanic 
convexity subsides internally towards the digital fossa, which is the deepest part of the lateral facet, con- 
taining in front the optic foramen, and behind, the subdivisions of the foramen lacerum anterius, perforating 
the thinnest part of the cranial parietes. The foramen for the transmission of the oculomotor and abducens 
nerves, occurs immediately behind the lower moiety of the optic foramen ; it is longitudinally oval, one line 
and a half long, and one line high; it is directed obliquely upwards, and divided internally into three aper- 
tures by delicate osseous threads: the posterior one is the orifice of a canal, four lines and a half long, 
which lodges the sixth nerve; the two anterior give passage to the divisions of the third pair, and run into 
a vertical groove separated by a ridge from that which is continued upwards from the posterior orifice, both 
terminate on a level with the upper margin of the foramen opticum ; at the apex of the anterior is situated the 
minute orifice of a canal, two lines long, for the transmission of the patheticus nerve ; itis capable of admitting 
afine bristle ; a groove passes forwards and upwards from it. At the lower angle, between the optic foramen 
and that for the third nerve, is the aperture of a very slender canal, opening internally into the sed/a turcica, 
and probably conducting outwards, a twig from the ento-carotid artery. Above the tympanic convexity, 
and three lines and a half from the posterior border of the foramen opticum, is the rounded, sharp-edged 
aperture, one line in diameter, for the transmission of the ophthalmic branch of the trigeminal nerve; a 
groove, concave downwards, leads forwards across the patheticus foramen, and apparently enters the optic 
outlet, behind the supra-orbital furrow. The vertically oval orifice, foramen rotundo-ovale, giving passage 
to the second and third divisions of the fifth pair, occurs midway between it and the margin of the osseous 
tympanic aperture ; it is one line and a half high, and one wide; an osseous thread separates from its base 
anteriorly, a minute foramen. 
The digital fossa is separated by a slight ridge from a concavity on the side of the most constricted 
part of the sphenoid, beneath the foramen opticum; this depression is produced by the great trunk of the 
internal maxillary vein, it slopes inwards below, and is separated from its fellow by the narrow, sharp-edged 
gutter on the inferior surface, leading to the common orifice of the Eustachian tubes; its superior border is 
convex upwards ; in the posterior triangular tract between it, and the edge of the digital fossa, are two 
foramina; the anterior and upper is the smallest, and longitudinally oval; the posterior and larger has the 
same shape, but its greatest diameter is at right angles to that of the former. A narrow band, one line in 
breadth, separates them, and presents two capillary apertures above, but supports below the minute, thin 
and flexible upwardly-curved style, representing the articular peduncle for the pterygoid ; which does not exist 
on the right side. These foramina transmit communicating branches from the internal maxillary artery to the 
ento-carotid, with their accompanying venous sinuses; the canals to which they lead pass backwards in the 
septum between the Hustachian tube and the efferent pneumatic cells, and open into the carotid canal as it 
curves inwards to unite with its fellow. 
