Ear : Sense organ of hearing, which has three parts
Ear is the organ of special sense of hearing.
It is also responsible for equilibrium.
It is divided into three parts.
1. External Ear : Lying outside the skull.
2. Middle Ear : Lying inside the Skull.
3. Internal Ear
External ear consists of two parts
* Pinna – Funnel shaped organ made of fibroelastic cartilage. It is the organ of collection of sound waves.
* External auditory meatus : Small channel of about 3cm length. It is lined with skin and wax creating glands are contained in this part.
Hair and wax present in its outer part prevent dust particles. Its inner part is closed by thin membrane called tympanic membrane or ear drum.
This canel is the organ of conveyance of vibrations of sound to the tympanic membrane.
Middle Ear : It is small cavity in the temporal bone, internal to eardrum.
It contains
* Fenestra ovalis ( oval window ) and fenestra rotundum ( round window ). Round window is also called fenestra cochlease.
* Eustachian tube – which communicates with nasopharynx. It helps in equalisation of pressure on both sides of tympanic membrane.
* Auditus – Channel containing middle ear posteriorly with mastoid antrum of temporal bone.
* Auditory ossicles – Malleus, incus and stapes arranged across middle ear.
Internal Ear : It contains
* Body labyrinth – present in petrous portion of temporal bone.
* Membranous labyrinth – Lyeing with the bony labyrinth
