-Three in human ear.

There are...

- 3 parts of the human ear:-

1. External ear.
2. Middle ear.
3. Inner ear.

- 3 parts of the External ear:-

1. auricle (pinna).
2. external auditory meatus.
3. Tympanic membrane.

- 3 layers in tympanic membrane:-

1. Outter skin layer.
2. middle fibrous layer.
3. inner mucosal layer.

- 3 cranial nerves innervate the tympanic membrane:-

1. C.N. V (trigeminal).
2. C.N. IX(glossopharyngeal).
3. C.N. X (Vagus).

 -3 Parts of middle ear:-

1. Tympanic cavity.
2. Eustachian tube.
3. Mastoid air cells.

- 3 parts of the tympanic cavity:-

1. epi-tympanum.
2. meso-tympanum.
3. hypo-tympanum.

- 3 middle ear bones (auditory ossicles):-

1. malleus.
2. incus.
3. stapes.

- 3 parts of the malleus:-

1. Head.
2. lateral process.
3. handle.

- 3 parts of labyrinth:-

1. Bony cochlea.
2. 3 semicircular canals.
3. Vestibule.

- 3 semicircular canals :

1. Posterior.
2. lateral.
3. superior.

- 3 compartments of cavity of bony cochlea :-

1. scala vestibuli: Upper compartment.
2. scala media (cochlear duct):middle compartment.
3. scala tympani: lower compartment.

- 3 membranes in cochlear duct:-

1. vestibular.
2. Tectorial.
3. Basilar .

- 3 labyrnthine sensory end organs:-

1. Of cochlea..called organ of corti.
2. of s c c....called crista.
3. of utricle and saccule..called macula.

Enjoy it,,,,,
Dr Ibrahim...