Relations of the Meatus.—
Relations of the Meatus.—In front of the osseous part is the condyle of the mandible, which however, is frequently separated from the cartilaginous part by a portion of the parotid gland. The movements of the jaw influence to some extent the lumen of this latter portion. Behind the osseous part are the mastoid air cells, separated from the meatus by a thin layer of bone.
The arteries supplying the meatus are branches from the posterior auricular, internal maxillary, and temporal.
The nerves are chiefly derived from the auriculotemporal branch of the mandibular nerve and the auricular branch of the vagus.
Tympanic cavity positioned in thickness of temporal pyramid and has the following walls:
- tegmentalwall (superior);
- jugularwall (inferior);
- labyrinthicwall (medial), where found 2 windows: vestibular (oval) window and cochlear (round) window. Vestibular window is closed by base stapes. Round window is tightened by secondary tympanic membrane;
- mastoidwall (posterior). On it located stapedius muscle. Superiorly posterior wall continues into mastoid cave, the mastoid cells open in it;
- carotid wall(anterior), a tympanic foramen of auditory tube and muscle-tensor of tympanic membrane are found here;
- membranouswall (lateral) is formed tympanic membrane. Epitympanic recess contains a head of malleus and body of the incus.
The middle ear or tympanic cavity is an irregular, laterally compressed space within the temporal bone. It is filled with air, which is conveyed to it from the nasal part of the pharynx through the auditory tube. It contains a chain of movable bones, which connect its lateral to its medial wall, and serve to convey the vibrations communicated to the tympanic membrane across the cavity to the internal earПоділитися цим: