Anatomy and physiology of the ear
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Anatomy and physiology of the ear
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Our ears help us hear and balance ourselves in space, and they have three parts.
The first part is the outer ear which is the part you see and hang earrings on, called the pinna, as well as the ear canal.
The second part is the middle ear, which is a tiny chamber that houses even tinier ear bones—the malleus, incus, and stapes.
The third part is the inner ear, which contains the cochlea, a special structure that converts sound waves into electrical impulses for the brain, as well as the semicircular canals which help with balance.
Let’s start with the external ear. The pinna, also called the auricle, is made up of cartilage that gives our ears their various shapes and sizes, and it also has a fleshy bit at the bottom- called the ear lobe, or lobule.
The pinna directs sound waves towards the opening of the ear canal.
The ear canal, or the external acoustic meatus, is a short, curved tube that burrows through the temporal bone for about 1 inch - or 2 and a half centimeters - and ends at the tympanic membrane.
On the inside, the ear canal is covered by skin, along with hair follicles and ceruminous glands - which secrete cerumen, or the sticky, yellow-ish, earwax.
Cerumen helps prevents foreign objects or tiny insects from getting in and damaging the tympanic membrane. That’s a creepy thought.
The tympanic membrane is also called the eardrum, and it’s a thin, translucent membrane that separates the external ear from the middle ear. It’s shaped a bit like a cone, protruding slightly into the middle ear.
When sound waves reach the eardrum, it vibrates and transmits those vibrations to the tiny bones in the middle ear.
Sources
- "Medical Physiology" Elsevier (2016)
- "Physiology" Elsevier (2017)
- "Human Anatomy & Physiology" Pearson (2018)
- "Principles of Anatomy and Physiology" Wiley (2014)
- "An actin molecular treadmill and myosins maintain stereocilia functional architecture and self-renewal" Journal of Cell Biology (2004)
- "Extracellular current flow and the site of transduction by vertebrate hair cells" The Journal of Neuroscience (1982)