The Ear

The ear has three divisions:

External Ear

The external ear is made up of (Figure 1.1):

• The pinna
  
• The external auditory meatus (ear canal)
  
• Lateral portion of tympanic membrane (ear drum)

The outer (lateral) part of the external ear has a cartilaginous skeleton and the deep (medial) part has a bony skeleton: both are lined by skin. Skin overlying the lateral portion contains hair follicles and sebaceous and wax glands, which are all absent in the medial portion.

The tympanic membrane forms a boundary between the external and middle ears and is divided into the stiffer pars tensa below and the less rigid pars flaccida above (Figure 1.2).

Middle Ear

The middle ear is an air-filled space behind the tympanic membrane that contains the ossicles (bones of hearing): malleus, incus and stapes (Figures 1.1 and 1.3). The ossicles form the ossicular chain, which amplifies and transmits sound vibrations to the inner ear.

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