Fig. 1
From: Morphological relationships between external auditory canal and vital structures of tympanic cavity
Morphological evaluation of the tympanic sinus, vertical portion of the facial nerve, and jugular bulb. A shows the posterior (a) and outer (b) distance of the tympanic sinus compared with straight lines drawn horizontal to the basal turn of the cochlea and touching the posterior portion of the facial nerve. Another straight line drawn perpendicular to the first line touches the interior of the facial nerve using slice where growth of the tympanic sinus cavity can be typically confirmed. B shows the posterior distance from the line of the posterior wall of the external auditory canal to the vertical portion of the facial nerve (c), and the lateral distance from the tympanic membrane line to the vertical portion of the facial nerve (d) using slices at a height midway between the tympanic umbo and the lower edge of the bony tympanic ring. C shows the shortest distance (e) from the tympanic membrane to the jugular bulb at the height of the lower edge of the tympanic ring (C-â‘ ). The height of the jugular bulb (f) was measured from the number of slices from the bottom of the jugular bulb(C-â‘ ) to the apex of the jugular bulb(C-â‘¢), multiplied by the slice width