Just hear me out, Future K12 IA Doctors! It was only a matter of time before we got to the sense organs who happen to be so into themselves and their own emotional state that they even have the nerve to refer to themselves as the ‘special senses.’ Hey, no problem. An over-emphasis on one’s own self-importance is so 21st century. Having said that, the Central Nervous System did send a shiver up this author’s spine just to let it be known that, while it doesn’t refer to itself as ‘special,’ it would like to remind readers that its important too. Poom!
So who are these special snowflake senses that everyone gives credit to for making life worth living. In short, they are the eye, the ear, the nose, and the taste buds. And, true, it would be hard to enjoy that manicotti I love so much if not for visually tasting food with my eyeballs’ rods and cones before I actually suck it down over the gustatory cells and their companion chemoreceptors. The ability to see that food, coupled with the follow-up taste, is a close tie on any given day as to which precious MarySue sense system I favor on a regular basis.
Having said all that, I’d have to say the system I’d miss the most should I lose it would be hearing. And for this reason, folks, I’m going to give you a play by play on how the ear works from the outer shell (pinna) all the way through cranial nerve 8. Cranial nerve 8, in my own imagination, is the subway to a night club that plays the music (cough, cough, voices) in my head all night. So without further ado…let’s talk hearing.
It all starts with the journey of a delicate sound wave having bounced from some surface only to be funneled into the outer ear also known as the shell. As these sound waves tumble down the ear canal they then bounce on the tympanic membrane like a karate kid on a trampoline. These waves set the tympanic membrane vibrating which in turn set the three smallest bones in the human body in motion.
These bones were lovingly dubbed a long, long time ago by some scientist with long hair and no social life as the incus, malleus, and stapes.
Author’s note: After much research, it has been determined that the malleus intends no malice against sound waves or anything else that might pass through its environment. Having said that, a large buildup of ear wax in the ear canal can inhibit the function of these three bones, but these three bones (the malleus in particular) wishes to be absolved from any allegations suggesting they are responsible for causing cranky ear also called an ‘earache.’ When asked for a statement, the triumvirate of hearing boldly stated that “The vestibulocochlear nerve is responsible for the sense of hearing and it is also pertinent to balance, to the body position sense. Problems with the vestibulocochlear nerve may result in deafness, tinnitus (ringing or noise in the ears), dizziness, vertigo and vomiting (MedicineNet). In short, don’t blame us for your bad hair day!” Sadly, for these bones who obviously feel constantly shaken (but not stirred), it was noted that these three bones do play an important role in balance as well, and patients who experience vertigo on a regular basis may be referred to a physical therapist to remediate their symptoms.
The journey from here grows more complicated as the mechanical energy created by the tympanic membranes vibrations changes into electrical energy as it passes through the cochlea. The energy is then transferred through the organ of corti to the brain via cranial nerve 8.
Not specific enough for you, you say? Well, let’s get more detailed then! On with the show!
Act 1: The Shell Meets Wave
External Ear – When you think of the external ear, what do you think of? The flexible, slightly squishy thing hanging off your head? Well…err, you wouldn’t be wrong. But like that blonde girl in a horror movie we’re expected to sympathize with, there’s more to the external ear than something to put sparkly precious (or fake) metals in. The external ear is made up of two main parts -- the Auricle and the External Auditory Canal. The auricle is that fleshy bit hanging off your head that we talked about, while the external auditory canal (can I just call it EAC? No? Okay) is the tube in between the outer ear and the tympanic membrane. The external ear is in charge of making ear wax which, speaking from experience, is a pain in the butt if you have too much of it and an infection on top of all of that. So…yeah.
Act 2: Lights, Camera, Tympani!
Middle Ear – Like magic, in between the external ear and the inner ear, we have the middle ear. The middle ear is like a Chihuahua; tiny with an overcompensating attitude. Regardless, it houses the smallest bones in the human body, the ossicles. While we remain in suspense of what these bones do (I’m sure we’ll find out soon…) let’s name them. These bones are called the malleus, the incus, and the stapes. The malleus is attached to the tympanic membrane and the incus. The incus is attached to the stapes, which is pushed up against the membrane of the oval window. The oval window is in between the middle ear and the inner ear. All of this leads up to the fact that the middle ear is a pansy and lets itself be pushed around by the eardrum and soundwaves. When said soundwaves hit the eardrum, it vibrates and the middle ear amps up the volume of that sound. All of this causes moving for the ossicles, the stapes in particular playing an important role. When the stapes is shaken against the oval window, it causes the fluid in the inner ear to move.
Act 3: A Journey to the Center of Your Mind
Inner Ear –
The inner ear has three different spaces that reside in the temporal bone (could you say the inner ear is…spacy? Heh…) This makes up the ‘bony labyrinth.’ Of course none of this would be interesting unless it was overly complicated with big words that I need to double check the spelling for, and that’s why we have perilymph. Perilymph is the fluid that is in the labyrinth. The labyrinth itself is divided into three different sections: the vestibule, the semi-circular canals, and the cochlea. Along with these parts is the membranous labyrinth, which is inside the bony labyrinth. The membranous labyrinth is filled with another kind of liquid called endolymph.
Right…now, don’t go blaming your ear every time you get dizzy, but there are parts of the inner ear that actually help or hinder when it comes to balance. They are called mechanoreceptors, and they’re located in the semicircular canals and the vestibule. Each canal has its own ampulla, which has a receptor called a crista ampullaris. The crista ampullaris generates a nerve impulse when you move your head. The crista ampullares have cells with threadlike extensions in endolymph. These hairs move when your head moves because the fluid they are suspended in, the endolymph, moves with the head.
Finally, we have the organ of Corti. The organ of Corti lies in the cochlea, and is surrounded by endolymph. The hair cells in the organ of Corti, when bent by movement of endolymph, generate nerve impulses.
A REAL PAIN IN THE…
What is it?
Earaches can be caused by any number of things. Speaking from experience as someone who has had them on a number of occasions, all of which I was scolded for later by my mother who doesn’t appreciate that I put my head under the water in the bathtub, these things hurt a lot. From allergies or a simple cold to too much freaking ear wax, the possibilities are endless when it comes to what’s causing problems in your middle ear. According to healthline.com, “Ear infections occur when one of your Eustachian tubes becomes swollen or blocked and fluid builds up in your middle ear.” Healthline also gave us a lovely list of what could potentially be causing your ear-pain (like man pain in a bad TV show, but not.)
allergies
colds
sinus infections
excess mucus
tobacco smoking
infected or swollen adenoids (tissue near your tonsils that trap harmful bacteria and viruses)
Symptoms?
The symptoms of an ear infection are what you would expect. A good way to tell if you have an ear infection is if you have pain in the ear. At this point, walk up to your mother and say, “I have pain in my ear.” Then she’ll probably put off going to the doctor in hopes that yet another ear infection won’t really be an ear infection. Her hope will probably be that it’ll just turn out that you’ve pretty much been in a constant state of having your headphones on so now you’re paying the price.
Of course, most ear infections happen because of fluid buildup in the ear. So, while your mother is lecturing you on cleaning habits, you realize you can’t hear her. Nothing new really, you tend to tune her out anyways. Still, it’s a little concerning and so you interrupt her, and suddenly an expression of concern crosses her features. Along with that hearing loss, you describe it as feeling like you’re on an airplane and your ears don’t appreciate it one bit.
Let’s not even get into pus-like, potentially bloody drainage out of the ear.
So, eventually she gives in and huzzah! You’ve got a one-way ticket to the clinic! And when you get to the clinic, blah, blah, blah. You see a doctor and that doctor…
Diagnosis?
Mayoclinic.org says that, “An instrument called a pneumatic otoscope is often the only specialized tool a doctor needs to make a diagnosis of an ear infection. This instrument enables the doctor to look in the ear and judge how much fluid may be behind the eardrum. With the pneumatic otoscope, the doctor gently puffs air against the eardrum. Normally, this puff of air would cause the eardrum to move. If the middle ear is filled with fluid, your doctor will observe little to no movement of the eardrum.”
Sometimes, however, a doctor may take a sample of whatever fluid (pus, etc.) is built up in your ear. Gross. They slap that mess…sorry, I meant fluid, on a slide and shove it under a microscope. There, they find out what kind of bacteria is causing the infection. After that, they can decide what kind of antibiotic to give you, which leads you…
Treatment?
You could always leave it alone. In truth, most ear infections clear up on their own if you don’t mess with them. Naturally, there are always complications to doing something like that, but we all know that antibiotics taste terrible.
Totally worth it.
Nah. At least, not as far as I’m concerned.
Let me summarize the treatment very quickly for you as we’re already approaching 2000 words on the body’s most special senses.
If you have an ear ache, you need to go to the doctor. If it’s an ear infection, a quick exam of the Tympanic membrane will tell your doctor what they need to do. It could be as simple as flushing the ear with water, or it could be prescribing antibiotics. Regardless, the human hearing mechanism is so precious and important that it’s not something even I want to joke about.
Sources:
"Cranial Nerve VIII." MedicineNet. N.p., n.d. Web. 25 Feb. 2016.
"Ear Infections." Healthline. N.p., n.d. Web. 25 Feb. 2016.
"Ear Infections-Cause." WebMD. WebMD, n.d. Web. 25 Feb. 2016.
"Ear Infections | Causes & Risk Factors." Ear Infections. N.p., n.d. Web. 25 Feb. 2016.
"Ear Infection (middle Ear)." Tests and Diagnosis. N.p., n.d. Web. 25 Feb. 2016.
"Ear Infection (middle Ear)." Treatments and Drugs. N.p., n.d. Web. 25 Feb. 2016.
Image Credits:
(outer ear)
http://www.riversideonline.com/source/images/slideshow/hdg22_outerear.jpg
(middle ear) https://www.google.com/search?q=middle+ear+image&tbm=isch&imgil=Jgy0MYePPx8rrM%253A%253B1S2dsTRDwY-8UM%253Bhttp%25253A%25252F%25252Fwww.skybrary.aero%25252Findex.php%25252FMiddle_Ear_and_Sinus_Problems&source=iu&pf=m&fir=Jgy0MYePPx8rrM%253A%252C1S2dsTRDwY-8UM%252C_&usg=__CM4ihMKzmX9Nc3r5KrTLr6TNiBw%3D&biw=1366&bih=643&ved=0ahUKEwjentbJ0PrKAhXMbj4KHWhsDegQyjcINA&ei=4jfCVt6lBczd-QHo2LXADg#imgrc=Jgy0MYePPx8rrM%3A
(inner ear)
https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcR9P_FuDFg0YTwUS-twkGsVDtn-zMcDAjON9wyW_YdbKKX2xHwv
