6-10) is delimited dorsally with the region of the frontal bone by the olfactory sulcus (Sulcus olfactorii) and the conspicuous medial orbitonasal
foramen (Foramen orbitonasal
aa auditory artery, aov anterior orbital vein, ba basilar artery, cava communicating artery with vertebral artery, hy hypophysis, in internal naris (choana), nv nasal vein, onv orbitonasal
vein, ov ophthalmic vein, va vertebral artery.
 reported the frequency of 19% of orbitonasal canon and 8.7% in no-oral canon.
In contrary to present findings, significant sex differences in relation to the frequency of the orbitonasal canon variant were found among Southern Chinese population .
The medial orbitonasal
foramen (Form, Figures 6-9) is larger in N.
(10) Ectethmoid foramina: The ectethmoid (= orbitonasal
) foramina were single, pinched, double, or in a few cases triple.
Sphenethmoid well ossified; anterior terminus lying well behind anterior margins of nasals; margins of orbitonasal
foramina bony; posterior border of bony sphenethmoid laterally and ventrally reaching level of anterior third of optic foramina, dorsomedially reaching area above foramen magnum; overlain by frontoparietals dorsally; bony anterodorsal and lateral surfaces exposed; cartilaginous ventral element without alae over parasphenoid alae and extending caudally horseshoe-shaped with its rounded apex reaching level between columellae.
The orbital region has seven pairs of foramina, two on dorsal position: one for the trochlear nerve and another for the oculomotor nerve; two on median position: one for the orbitonasal
channel and another for the optic nerve; and two in ventral position: one for the interorbital vein and another for the efferent artery.