Friends, Romans, countrymen, lend me your auricles!
Now hear this! The term ear shares as much of a connection in sound, as in spelling. Here is how ear appears in various languages from around the world: auris, aus, eyra, eare, are, orr, ore, ora, to name a few! Sound familiar? The term ear may originate from ancient words meant to imply a “sense of perception.” The ear is divided into three sections. The external, middle, and inner ear.
In anatomy and physiology, our sense of “hearing” is referred to as the sense of audition. To hear a lecture, one might go to an auditorium, which means “a place where something is heard.” The term pinna is synonymous with auricle, and refers to the main structure of the external ear. The proper term for our earlobe is the lobule, which refers to a “small rounded projection.” While pinna means “winged or feather,” auricle means “little ear” or “of the ear.”
The self-service here is excellent!
As I’m not including graphics thus far in this blog, bringing up an image of the external ear that includes labeled landmarks is a quick web search away. Once you’ve found the image, here is a list of interesting landmarks and their etymologies.
The helix means “to spiral, twist or roll,” and was chosen as the helix appears to take a convoluted path from the head to the outer edge of the ear. The cavum conchae consists of cavum meaning a “cavity or cave,” and conchae, which means “shell.” The cymba conchae consists of cymba, which means “cup or boat shaped,” and obviously, conchae. These two landmarks are divided by the crus, which means “a leg-like part, a body part consisting of elongated masses that resemble legs.”
That really gets my tragus!
The tragus is a skin covered cartilaginous projection in front of the opening to the “external ear canal.” The external ear canal is also referred to as the external acoustic meatus, or the external auditory meatus. The term meatus means "a passage, or an opening."
Tragus means "goat." This whimsical term was selected because it was observed that as men age, little tufts of hair poke out from behind the tragus, and this was reminiscent of the beard of a goat! Tragus is directly related to tragedy. Tragedy means "goat song, or song of the goat." Actors in ancient plays often dressed in goat skins and portrayed satyrs, which were woodland deities. Many of these performances included songs, hence, "song of the goat." The antitragus is a composite of “anti,” which in this case means “opposite,” and the aforementioned tragus. Therefore, the antitragus is located opposite the tragus.
Well, I’ll be a monkey’s uncle!
The auricular tubercle of Darwin is a small projection on the inside edge of the helix. It also goes by the names Darwin’s tubercle, Darwin’s bump, and Darwin’s point. This anatomical landmark is generally prominent during an early stage of fetal development and is present in the fully developed ear in only an extremely small amount of the population. Charles Darwin, author of The Descent of Man, and On The Origin of Species, lends his name to this landmark.
Sculptor and poet Thomas Woolner produced a staggering number of works, two of which included a bronze cast medallion in 1869, and a marble bust in 1870 of Charles Darwin. Thomas Woolner also created a sculpture of Puck, who is described as a fairy, elf, imp, or sprite, and appears as a character in William Shakespeare’s “A Midsummer Night’s Dream.” Puck was a mischievous prankster who sported rather prominent and pointed ears. Woolner and Darwin were discussing this sculpture of Puck when Woolner mentioned the similarity between this tubercle-like feature of Puck’s ear, and this same feature during human fetal development. Darwin agreed. Darwin believed this tubercle to be a vestigial remnant of human evolution and although it usually appears in texts as Darwin’s tubercle, Darwin himself initially named it the Woolnerian Tip, giving credit to Woolner’s observation.
Anyone care for a chocolate tuber?
A tubercle is a “small lump, swelling, nodule, bump or hump.” Tubercle or tuberosity, often refers to a projection or protuberance on the surface of a bone. Tubercle also appears in the condition known as tuberculosis due to the characteristic appearance of small bumps or tubercles that were present when this disease especially affected the lungs. The characteristic appearance of the fascinating, fungal fruiting body of an underground “mushroom” we know as the truffle derives its name from “tuber” as well. During the early 20th century, the word truffle was applied to the heavenly chocolate confection due to the external texture and appearance of these delightful treats. Bon Appetit!
I think I’m having a tympanic attack!
Somebody call a musician!
The tympanic membrane, also known as the eardrum, isolates the external ear from the middle ear. Tympanic refers to its shape being reminiscent of the drumskin of a tympani drum. Tympani is said to derive from a word meaning “to strike.” Membrane comes originally from a word meaning “parchment, a skin, a member of the body.” In anatomy it generally refers to a “covering or barrier” surrounding a structure.
If I had a malleus, I’d hammer in morning!
The middle ear is the chamber containing the ossicles, or “tiny bones.” The bone attached directly to the tympanic membrane is the malleus, which means “mallet or hammer.” The malleus articulates with the incus, which means “anvil.” The incus articulates with the stapes, which means “stirrup.” Incidentally, the stapes is the smallest bone in the human body. The vibration of sound waves striking the tympanic membrane causes the movement of the ossicles, in turn affecting the pitch, which refers to the perceived quality of high to low tones. The faster the vibration, the higher the perceived pitch. Slower vibrations result in a perception of a lower tone.
The ossicles also regulate amplitude, or “loudness.” The stapedius muscle contracts to minimize excessive movement of the stapes, thereby dampening the amplitude of sound waves. The tensor tympani muscle also assists in dampening the amplitude of sound waves by pulling the malleus medially, thereby tensing and minimizing excessive movement of the tympanic membrane. The stapedius is the smallest skeletal muscle in the human body.
The other point of interest regarding the middle ear is the Eustachian tube. This term is an eponym honoring Bartolomeo Eustachio, an Italian anatomist who first described its structure. It connects the middle ear chamber or cavity, to the nasopharynx and serves to equalize atmospheric pressure on each side of the tympanic membrane. A more current term for Eustachian tube is the auditory tube. Nasopharynx literally means “nose throat,” and refers to the area of the soft palate of the throat that lies behind the nose.
Are we there yet?
The final destination regarding the ear is the true structural marvel called the inner ear! It houses not only our organ of hearing, the organ of Corti, it’s home to the awe inspiring vestibular apparatus, an organ that regulates our “sense of equilibrium, interprets head movement, head position relative to gravity, and stabilization of vision during head movement, to name only a few of its responsibilities. The organ of Corti, is another example of an eponym being associated with an anatomical structure, and belongs in this case to Alfonso Giacomo Gaspare Corti. The organ of Corti is located in the part of the inner ear called the cochlea. The term cochlea means “snail shell,” and was given to this structure because of its shape.
You are here!
Proprioception means awareness of “one’s own self,” providing a sense of body position in space and the relative position of individual body parts in space. For example, I can sense that an elbow or knee is bent or straight without the aid of vision. Proprioceptors are present in skeletal muscles, tendons, ligaments, joints. Subcutaneous pressure receptors in the soles of the feet also subserve balance by relaying information to the nervous system regarding the surface terrain one is standing upon. This initiates the contraction of appropriate muscles to maintain one’s balance. Subcutaneous means “below or under the skin.”
The vestibular apparatus consists of five structures that include the three semicircular canals and two otolithic structures known as the utricle, which means “water vessel or leather bottle,” and the saccule, which means “little bag.” Otolithic refers to the otoliths, which are chiefly composed of calcium carbonate crystals that are a constituent of limestone. Calcium actually means "limestone." Otolith literally means “ear stone.” So if you’ve ever been accused of having “rocks” in your head, you’re not alone. We all do! Another term is otoconia, which means “ear dust.” The otoliths reside upon a gelatinous layer called the otolithic membrane.
That being said, and moving forward. Literally!
The utricle and saccule primarily indicate linear acceleration such as forward, backward, upward, downward, and sideward movement and various combinations of these directions. The sensory hair cells of the utricle and the saccule are contained within the macula, or the plural, maculae. Macula means a "small spot." The otoliths provide mass to this system, and as the solid skull moves in space the “weight” of the otoliths upon the gelatinous otolithic membrane provides inertia causing a lag that bends or shears the embedded sensory hair cells triggering a series of electrical and chemical events that ultimately inform the brain of the direction of head movement.
The utricle and saccule produce a similar electrical and chemical chain of events during head tilts, informing the brain of the position of the head relative to gravity. These organs are often referred to as the “gravitational receptors.” The semicircular canals primarily inform the brain of angular acceleration, for example during turning of the head.
Inertia is related to inert, and Latin iners which means “unskilled, without art, idleness, laziness!” This was the classical meaning until a titan of mathematics and astronomy during the 17th century named Johannes Kepler used inertia as a technical term in the field of physics.
We have a vestibular apparatus within each of the two temporal bones. This provides a total of ten sense organs within our skull dedicated to the maintenance of balance! The calcium carbonate crystals forming the otoliths are so incredibly small that their size is measured and defined in microns. To appreciate the relative size of a structure one micron in diameter, have a go at this. Placed side by side, it would require 25,400 microns to equal the width of one inch! A micron is also called a micrometer. I suggest reading more about how these fascinating structures operate. It will be time well spent as the amazing anatomy and physiology of our vestibular system borders on the realm of the nearly miraculous!
Now that’s a load of bull!
Many centuries ago, the vestibular apparatus was known simply as the labyrinth. In anatomy, vestibular means “pertaining to a vestibule,” in this case a chamber that leads to an entrance to another chamber. Housed within the petrous portion of the temporal bone, it was described by the terms, the bony labyrinth, and the membranous labyrinth. Petrous means “rock,” and in this sense refers to the hard “rock-like” area of the temporal bone. A common related term containing petrous is petroleum, which means “rock oil.”
The term labyrinth was given to this structure as it reminded the anatomists of the famous Labyrinth of Greek Mythology that held the ferocious Minotaur. The Minotaur is usually depicted as having the head of a bull and the body of a man. Minotaur translates as the “bull of Minos.” Theseus, the revered hero of Athens, would ultimately slay the Minotaur with the aid of a sword and ball of thread, provided by King Minos' daughter Ariadne. The name Theseus is said to derive from a word meaning “settler, orderer, to place or set.” The name Ariadne means “very pure.”
Talk about following a thread!
The ball of thread provided a means for Theseus to find his way out of the convoluted maze once the dastardly deed of slaying the Minotaur was done. Following the shrieks spewing forth from the Minotaur, Theseus unraveled the thread as he crept down twisting corridors toward his intended target. He would simply follow the thread back to the entrance to the labyrinth.
A “ball of thread” such as the one provided by Ariadne was called a clew. This is the derivation of the modern day word clue which describes anything that might provide a path or direction leading toward the solution of a mystery or unresolved problem. Incredible! N'est-ce pas?
Until next time….