Outer ear problems by bcs24005

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									                            THE HUMAN EAR




The human ear is divided into three parts:

The outer ear
• The visible part of the ear (the pinna), which consists of folds of skin
  and cartilage.
• The ear canal (meatus), which is approximately 2.5 cm long. The first
  part is cartilage and the latter two thirds is bone lined with skin.
• The ear drum (tympanic membrane), which is a thin layer of membrane,
  covered with skin. This separates the ear canal from the middle ear.

The middle ear which is a small air filled cavity containing the smallest
bones in the human body.
• The malleus (hammer)
• The incus (anvil)
• The stapes (stirrup)

The inner ear is a capsule of dense bone deep within the skull.
• The cochlea is shaped like a snail and the size of a pea. This contains
  the hearing nerves
• The semi circular canals which are concerned with balance
• The auditory nerve




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                    The passage of sound through the ear.



                          Sound waves
                                                   Sound waves        This moves the
Sound causes air       travel to the pinna
                                                   vibrate the       malleus, then the
  particles to            and down the
                                                    tympanic         incus and finally
    vibrate             external auditory
                                                    membrane            the stapes
                              canal




 The cochlear                                                          The stapes is
                                                 Vibrations in the
nerve sends the          This stimulates                             connected to the
                                                 fluid are changed
impulses to the         the fibres of the                            oval window which
                                                   into electrical
brain where it is        cochlear nerve                              then pushes in on
                                                      impulses
  interpreted                                                        the cochlear fluid




                            Conductive Hearing Loss

This is the result of problems occurring in the outer or middle ear. This
type of hearing loss generally affects children under the age of 8 or 9
years.

Outer ear problems
Blockages of the external ear canal are often caused by wax; this can be
removed with drops or a doctor may syringe the ear. Blockages may also
occur in children who have pushed beads or other foreign bodies into
their ears.

Rarely, babies are born with abnormalities of the outer ear – this may
affect the pinna but it can be corrected by plastic surgery. The ear canal
can also be underdeveloped and closed (atresia). If this affects both
ears, surgeons can insert a bone-anchored hearing aid.

Middle Ear Problems
The most common of these problems is acute otitis media (glue ear); it
is most likely to affect children aged between 2 and 5 years and may
follow a cold or flu. This condition occurs when the Eustachian tube
becomes blocked and air cannot get into the middle ear. The middle ear
fills up with fluid that becomes thick, like glue. The tympanic membrane

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cannot move and hearing is reduced. Many children will get better without
treatment, but if they continue to get glue ear an operation called a
myringotomy may be required. This is where a small slit is made in the
tympanic membrane and the fluid drained out. The surgeon may also
insert a small tube or grommet into the hole; this allows air to get into
the middle ear and lets fluid drain away. These grommets may fall out on
their own, but the surgeon can easily remove them. Other surgical
treatment for glue ear involves removing the adenoids at the back of the
nose as these may be blocking the Eustachian tube.

In severe cases of glue ear, pressure builds up behind the tympanic
membrane and this causes it to burst or perforate. If it does not heal
itself in a few days, the perforation can be repaired by an operation
called a myringoplasty. This is where a graft of skin is used to seal the
hole in the tympanic membrane.

Sometimes babies are born with damaged ossicles. They can be repaired
or replaced by an ossiculoplasy operation. Here, the damaged ossicles are
replaced with either artificial bones (plastic or ceramic) or small pieces
of bone taken from elsewhere in the body.




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