Fig. 7 LATERAL VIEW OF PARTS OF THE HEAD AT THE LEVEL OF THE TYMPANIC MEMBRANE
In this figure the same cavities are seen as in the preceding, besides other numerous structures. Above is the empty cranium. The eye socket (75) is also empty, its contents (52) remaining in the slab depicted in Fig. 6. In the maxillary sinus (18) a triangular opening, the hiatus (79), establishes communication with the nasal cavity. The oral cavity is filled by the tongue (106). The skeleton ofthe external auditory meatus (2) has become at this level almost entirely osseous. The far end of the meatus is shut off by the tympanic membrane or ear-drum (81) fitted into its ring at a slanting angle. The smooth and shiny membrane exhibits two light reflexes, a "cone of light" in its lower portion, and a point-like one above the first caused by the protruding lateral process of the malleus orhammer. The handle of the hammer is outlined through the thin, semi-transparent drum. Above the ear-drum two of the three auditory ossicles (84), hammer and anvil, are in part visible in the tympanum or cavity of the middle ear.