Middle ear

Middle ear consists of cavities and channels connected with each other: the tympanic cavity, auditory (Evstafieva) pipe, progress in antrum, antrum and mastoid cells (Fig.). The boundary between the outer and middle ear is ear drum (see).

the structure of the organ of hearing The structure of the organ of hearing (section along the right ear): 1 - the auricle; 2 and 7 of the temporal bone;
3 - hammer;
4 - the anvil;
5 - the stapes;
6 - the semicircular canals;
8 - the auditory nerve;
9 - snail;
10 - hearing (Evstafieva) pipe;
11 - tympanic cavity;
12 - eardrum;
13 - the ear canal.

Drum cavity is the pyramid of the temporal bone. Its volume is about 1 cm3. The outer wall of the tympanic cavity formed an ear-drum and bone, which is the continuation of the walls of the ear (see the Outer ear). Medial) wall is mostly formed by a capsule ear labyrinth (see the Inner ear). It has a Cape (promontorium), formed the main whorl snail, and two Windows: one of them, oval (vestibule), closed with a pasture plate (base) stirrup; the other, round (snails), closed secondary tympanic membrane (diaphragm round window). The back wall of the borders of the mastoid process. In its upper section is a move in antrum. The front wall in the bottom part borders on the internal carotid artery. Above the plot is located drum mouth hearing (Evstafieva) pipe. Upper wall borders with the middle cranial fossa. The lower wall borders with onion jugular vein. When abnormalities of onion can go into the lumen of the tympanic cavity, which is very dangerous when paracentesis (see) eardrum. In the tympanic cavity, there are three ear bones - hammer, the handle of which is connected to the tympanic membrane (see)and the head (joint) with the body anvils; in the anvil, in addition to her body, distinguish between short and long legs; the latter is connected with the head of the stirrup. In the stirrup, in addition to the head and neck, there are two legs front and back, and a pasture plate (ground).
In the tympanic cavity, there are three sections: upper (Attica, epitympanum, nadbramna space), medium (mettimano) and lower (hypothenemus).
In the tympanic cavity, there are two muscles - stremennaya and his eardrum. These muscles play a big role in the accommodation of conductive and the protection of the inner ear from acoustic trauma. Sound vibrations through the ear canal are transferred to the ear drum and further along the chain auditory ossicles (hammer, anvil and stirrup) in the inner ear. This is their strengthening as the difference between the surfaces of the drum membranes and the lower plate of the stirrup, and the lever-action auditory ossicles.
Hearing (Evstafieva) tube channel with a length of about 3,5 cm, informing the tympanic cavity to the nasopharynx. It consists of two parts - bone (drum) and webbed cartilage (nasopharyngeal). Tube lined with multi ciliary epithelium. Pipe revealed mainly in swallowing movements. This is necessary for ventilation of the middle ear and pressure it to the outside.
In the mastoid process has antrum (cave) is the largest, the cell constant, soamsawali to the tympanic cavity through progress in antrum (aditus ad antrum), as well as other cells of the Appendix (if developed). Upper wall of antrum borders with the middle cranial fossa, medial - back (sigmoid sinus). It is of great importance in the spread of infection of the middle ear cavity of the skull (otogenny purulent meningitis, arachnoiditis, abscess of the brain, the cerebellum, thrombosis sigmoid sinus, sepsis).

wall tympanic cavity
Fig. 1. The lateral wall of the tympanic cavity. Fig. 2. The medial wall of the tympanic cavity. Fig. 3. Cutting head held along the axis of the auditory tube (the lower part of the section): 1 - ostium tympanicum tubae audltivae; 2 - tegmen tympani; 3 - membrana tympani; 4 - manubrium mallei; 5 - recessus epitympanicus; 6-caput mallei; 7-incus; 8 - cellulae mastoldeae; 9 - chorda tympani; 10 - n. facialis; 11 - a. carotis int.; 12 - canalis caroticus; 13 - tuba auditiva (pars ossea); 14 - prominentia canalis semicircularis lat.; 15 - prominentia canalis facialis; 16 - a. petrosus major; 17 - m. tensor tympani; 18 - promontorium; 19 - plexus tympanicus; 20 - stapes; 21 - fossula fenestrae cochleae; 22 - eminentia pyramidalis; 23 - sinus sigmoides; 24 - cavum tympani; 25 - the entrance to the meatus acustlcus ext.; 26 - auricula; 27 - meatus acustlcus ext.; 28 - a. et v. temporales superficiales; 29 - glandula parotis; 30 - subtalar temporomandibularis; 31 - ostium pharyngeum tubae auditivae; 32 - pharynx; 33 - cartilago tubae auditivae; 34 pars cartilaginea tubae auditivae; 35 - n. mandibularis; 36 - a. meningea media; 37 - m. pterygoideus lat.; 38 - in. temporalis.
cutting head along the axis of the auditory tube

Pathology of the middle ear - see Aerootite, Eustachitis, Mastoiditis, Ear, Otosclerosis.