EAR AND ITS DISEASES

Categories: Diseases of The Eye and Ear

The external ear is called auricle or pinna. It is an oval funnel-shaped

organ. The canal leading in to the membrane (drum) is called the external

auditory meatus. It extends inward about one and one-quarter inches and

terminates in a membrane.



Membrane Tympani (drum) which separates the external ear from the tympanic

cavity. To examine the drum, you must pull the ear backward and outward to

make the cana straight.



Membrane Tympani (the drum) Membrane This is situated at the inner end

of the canal and separates it from the tympanum or middle ear. It is

placed like the membrane in the telephone. It is pearly gray in color.

This membrane not only serves as a protection to the delicate structures

within the tympanum, but also receives the sound vibrations from without

and transmits them to the ossicular (bony) chain of the middle ear.



The Tympanum or Middle Ear. This cavity just beyond the drum, which forms

the greater part of its outer wall, is an irregular cavity, compressed

from without inward and situated in the petrous bone. The mastoid cells

lie behind. It is filled with air and communicates with the nose-pharynx

(naso-pharynx) by the eustachian tube. The upper portion of this cavity,

the attic, lies immediately below the middle lobe of the brain, separated

from it by a thin layer of bone, which forms the roof of the cavity. This

cavity is separated from the internal ear.






The Eustachian tube. This is the channel through which the middle ear

communicates with the pharynx. With an opening in the anterior of the

middle ear, a bony canal passes from this point, inward, forward, and

downward through the petrous bone, when it merges into a cartilaginous

canal, which terminates in a funnel-shaped protuberance, with a slit-like

orifice, located in the nose pharynx. This is the eustachian tube. It is

lined with mucous membrane like the throat. The air goes up from the

throat, through this canal to the middle ear. The mucous membrane of the

middle ear is continuous with that of the nose-pharynx through the

eustachian tube. So you can readily understand how easy it is for an

inflammation of the throat to extend to the middle ear through the

eustachian tube.



The posterior wall which has the greatest height, reveals in its upper

portion a passage (antrum) through which the vault of the tympanum (attic)

communicates with the cells of the mastoid process, situated posteriorly.

From this description you see how near to each other these parts are

placed and when one becomes diseased the disease can extend to the other

part or parts. The brain is separated from some of these cavities by a

very thin shell of bone, and the disease can soon affect the brain through

infection or breaking through the thin structures that separates the

parts.



Diseases of the middle ear and the mastoid are always to be considered

serious, and should be very closely watched. A child with a running ear is

in danger, for it may at any time become closed up and serious.