The ear provides humans with a remarkable range of hearing. It is divided up into three regions, the inner ear, the middle ear, and the outer ear. The outer and middle ear are responsible for hearing, while the inner ear regulates equilibrium, and balance.
The outer ear is
composed of the ear canal, the external auditory canal, and the pinna. The pinna is a
cartilage structure resting on opposite sides of the head. The purpose of the pinna is to
funnel sound waves into the external auditory chamber. The external auditory chamber is a
small, narrow chamber that is carved into the temporal bone of the skull. Within this
chamber are glands that regulate the secretion of cerium, commonly known as earwax. When
sound enters the external auditory chamber it is reflected to the tympanic membrane, known
as the eardrum, causing it to vibrate.
The middle
ear, also known as the tympanic cavity, is a small air filled cavity within the temporal
bone. It houses the auditory tube, which runs from the ear, to the throat. The auditory
tube regulates the pressure of the ear, and has adapted to accommodate any changes in the
pressure of the ear. The middle ear houses three of the smallest bones in the body, the
hammer, the anvil, and the stirrup. When the eardrum vibrates it transfers this vibration
to the hammer, the anvil, the stirrup, and finally presses against the oval window inside
the inner ear.
The inner ear
is also known as the osseous labyrinth. It may be divided into three regions, the cochlea,
the vestibule, and the semicircular canals. These regions are responsible for transforming
the vibrations to nerve impulses that can be sent to the brain. The inner ear holds the
perilymph. Inside of which is the membranous labyrinth. These structures contain a number
of sacs follow the shape of the bony labyrinth. These two structures are responsible for
equilibrium, or balance. In the sacs of the perilymph rest receptors known as maculae. The
maculae are responsible for balance. When the sacs of the ear are turned to a new
position, the maculae turn. When the maculae turn, the gel in the inner ear is pulled,
resulting in an impulse to the vestibular nerve, which notifies the brain of the change of
position
