Anatomy
Summary
The ear is anatomically organized into three main divisions: the outer ear, the middle ear, and the inner ear. The outer ear consists of the auricle (also known as the pinna) and the external auditory meatus (commonly referred to as the ear canal). The auricle helps capture and identify where sounds are coming from. Sound waves then travel along the external auditory meatus to the tympanic membrane. The tympanic membrane, or eardrum translates these sound waves into vibrations.
The middle ear, located within the temporal bone, contains tiny bones known as ossicles, namely the malleus, incus, and stapes. These ossicles carry vibrations from the eardrum to the inner ear via the oval window. The eustachian tube connects the middle ear to the nasopharynx, performing functions such as pressure equalization and secretion drainage. The chorda tympani, a branch of cranial nerve VII, also passes through the middle ear. The inner ear is composed of a bony and membranous labyrinth, housing the vestibular system (essential for balance) and the cochlea (for hearing). The cochlea contains the organ of Corti, the receptor organ that converts sound stimuli into electrical signals for the brain.
Lesson Outline
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FAQs
The primary components of the outer ear are the auricle (also known as the pinna) and the external auditory meatus, or ear canal. The auricle collects sound waves and directs them into the ear canal. The ear canal channels sound waves to the tympanic membrane (or eardrum).
The middle ear contains several important components, including the tympanic membrane, or eardrum, and the three tiny bones: the malleus, incus, and stapes. Incoming sounds vibrate the eardrum, which in turn moves the malleus. This sends a vibration through the incus and stapes, ultimately transferring the sound waves into the fluid of the inner ear at the oval window.
The inner ear consists of two important structures: the cochlea and the vestibular system. The cochlea is a spiral-shaped structure filled with fluid which converts the vibrations from the middle ear into electrical signals. These signals are then sent to the brain. The vestibular system, comprising three semicircular canals and the vestibule, is involved in balance and orientation in space.
The organ of Corti, located within the cochlea of the inner ear, is the main sensory organ of hearing. It is lined with hair cells that move in response to the fluid vibrations coming from the middle ear. When these hair cells move, they generate an electrical signal that is sent to the brain through the cochlear nerve. The brain interprets these signals as sound.
The eustachian tube connects the middle ear with the nasopharynx (the upper part of the throat behind the nose). This tube allows pressure equalization within the middle ear. It is also involved in secretion drainage.
