Boyer diss 2009 1046..

vestibuli. This groove’s point of origination in the posterior septum-formed fossula of
the fenestra cochleae is close to a foramen for an intrapetrous canal. The intrapetrous
canal leads medially to a foramen on the medial side of the promontorium where it
obtains the distinctive morphology relating to the tympanic canaliculus (Fig. 3.9: tca).
Another groove courses more ventromedially than g5 from near the anterolateral margin
of posterior septum (Fig. 3.9: g2). This second groove represents g2 (Fig. 2.40). It
approaches a septum that only is visible with HRxCT imagery. This septum is the most
anterior and lateral of those preserved on the specimen. It appears equivalent to the s1
(Fig. 2.40) and MacPhee’s (1981) anterior septum, which marks the course of the main
bundle of neurovasculature of the internal carotid plexus as the contents approach the
foramen lacerum to gain entrance to the endocranium. Another groove is present that is
medial to, but also vaguely parallel to the g2 groove (Fig. 3.9: g2). Traced anteriorly or
posteriorly, this groove can be seen to converge toward the g2 groove. Consequently, it
stems from the lateral aspect of the promontorium near the point where the internal
carotid plexus enters the tympanic cavity and then leads toward the anterior septum.
Thus, this more medially positioned groove also is likely to have transmitted to the
internal carotid plexus, especially considering the fact that the internal carotid plexus
frequently consists of two nerve bundles (MacPhee, 1981). Yet another groove crosses
the promontorium at a right angle to the two g2 grooves (Fig. 3.9: g3). This groove starts
from near to where the tympanic nerve groove ends on the lateral side of the
promontorium. Then the groove traverses to the medial side of the remnant of a second
bony ridge, or septum, that extends anteromedially from the promontorium (Fig. 3.9: s2 -
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