Page 56 - Human anatomy COMPLETELY DONE1

complex shape of the auricle, thanks to which the sound from different directions is
distorted somewhat differently.
The auricle directs sound vibrations of the air into the external auditory canal.
The cartilage of the external auditory canal is a continuation of the auricle, then
the cartilage tissue passes into the bone. The passage is a slightly curved channel about
3 cm long, at the end of which the eardrum separates the outer ear from the tympanic
cavity of the middle ear.
Middle ear (figure 36).
The main part of the middle ear is the tympanic cavity with a volume of about 1
cm3. The cavity is located in the temporal bone.
The smallest bones of the human body are located here: a hammer, an anvil and
a stirrup.
The handle of the hammer fuses with the eardrum, its head is movably attached
to the anvil, which is movably connected with the stirrup by another part. The stirrup is
fused with a wide base with the membrane of an oval window leading to the inner ear.

Figure 36. Middle ear anatomy

The sound wave causes the column of air filling the external auditory canal to
oscillate. These vibrations are captured by the tympanic membrane and transmitted
through a hammer, anvil and stirrup to an oval window covered with an elastic
membrane. Thus, the auditory ossicles are a chain that transmits vibrations.
The frequency of vibrations of the eardrum is greater, the higher the sound. An
increase in the magnitude of the vibrations of the eardrum is associated with an increase
in the strength of sound.
When passing through the system of sound bones, sound vibrations are amplified
tenfold and transmitted to the fluid filling the cavities of the inner ear.

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