Finally! Took long enough! Outlander Anatomy Fun Facts tomorrow, July 28th!
The deeply grateful,
Outlander Anatomist
“If a Tree Falls – The Ear”
Summertime greetings to all Outlander anatomy students! Anatomy Lesson #24 covered the outer ear so today’s Anatomy Lesson #25 is the Ear – Part 2, or to be more exacting the middle and inner ears.
But first, what does a tree have to do with the ear? The title of this lesson derives from a 300 year old philosophical thought: “If a tree falls in a forest and no one is around to hear it, does it make a sound?” An 1884 issue of Scientific American correctly addressed this question. What do you think? Watch for the answer later on!
And to emphasize the importance of the ear in society, do you ken that the English language is replete with many idioms of all things ear? One website lists 120+ idioms including: a tin ear, all ears, music to the ears, up to the ears in, wet behind the ears, bend one’s ears, can’t make a silk purse out of a sow’s ear (who would try?), cute as a bugs ear (didn’t know bugs had ‘em), fall on deaf ears, in one ear and out the other, turn a deaf ear, and blow it out your ear (here’s to you, BJR!).
Now, onto the lesson. To review, in anatomy lesson #24 we learned that the human ear is divided into three ears: an outer (Photo A- green), a middle (Photo A- yellow) and an inner ear (Photo A- blue). That lesson dwelt almost exclusively on the outer ear. So, now we move to the middle and inner ears.
Photo A
Let’s begin with the middle ears. Each middle ear is housed inside a cavity within one of our two temporal bones. The human skull includes 22 bones two of which are os temporale (Latin meaning temporal bone). The temporal bone is weirdly shaped (Photo B – pink bone). From a side view, it comprises most of the skull around the external acoustic meatus or EAM (Anatomy Lesson #24). The temporal bone also includes the zygomatic arch, part of the cheek bone (Anatomy Lesson # 8) and the gothic-looking styloid process marked by the black arrow (Anatomy Lesson #12). Let’s add a new part of the temporal bone which is pertinent to today’s lesson, the rounded mastoid process.
Try this: Place your fingers behind the pinna of one ear and move downward until you feel a rounded mound of bone; this is your mastoid process. It typically lies just below the level of the EAM or ear hole as Claire called it (ha ha). Its outer layer is compact bone, but inside it is riddled with air-filled spaces. Well done folks!
Photo B
A different image of the skull helps us appreciate the location of the middle ear. With the top of the skull and brain removed, Photo C shows the cranial base. The right side of the image shows the tortuous shape of the bony floor upon which the brain rests. Nerves and blood vessels pass through the many holes in the skull bones. The left side of the image is color coded so once again, the temporal bone is pink. See the bright green area? This is the location of the middle ear – it lies inside the petrous (Latin meaning stone-like) part of the temporal bone, one of the densest bones of the human body.
Photo C
The middle ear is small but it contains a large number of components including tympanic cavity, inner leaflet of tympanic membrane, three bones, the opening of a throat tube, a posterior “attic door,” two wee windows, two tiny muscles, a nerve and a nerve plexus. Wow! That’s quite a list for such a small space! Let’s examine the components.
The tympanic cavity is an air-filled chamber (Photo D, yellow dashed line) inside the petrous temporal bone; its shape is so difficult to describe that many anatomists compare it to a small room with four walls, a roof and floor. So let’s do that: the roof and floor are petrous temporal bone. The outer (lateral) wall is the tympanic membrane. The inner (medial) wall will be discussed shortly. The back wall has an “attic door” leading to the mastoid air cells (see below). The front wall receives the opening of the throat tube or pharyngotympanic or Eustachian tube (photo D) that extends between the back of the throat and the tympanic cavity.
Please understand this: normally, air pressure between the tympanic cavity and the EAM is equal. However, as we climb in altitude, air pressure becomes lower in the EAM than in the tympanic cavity which pushes the tympanic membrane outward causing discomfort, even pain. As we descend in altitude, air pressure is higher in the EAM than in the tympanic cavity which pushes the tympanic membrane inward, again causing pain. Air pressure equalizes on each side of the tympanic membrane when we open the Eustachian tubes: with altitude, air escapes from the tympanic cavity and with descent, air enters the tympanic cavity. Got it? Chewing and swallowing activates a pair of itsy, bitsy, teeny weeny, tensor veli palatini muscles that open the Eustachian tubes to equalize the air pressure. I won’t show an image of these wee muscles because it will clutter the lesson. Just know that they work well unless the Eustachian tubes are congested.
Photo D
Remember the “attic door” in the back wall of the tympanic cavity? It has a longish Latin name, the aditus ad antrum, but the short of it is that the passageway leads to air cells which riddle the mastoid process (Photo E). These little spaces are thought to reduce the mass of the skull bones and provide physical protection.
Photo E
The middle ear bones bring us back to the anatomical rule of three! Three ossicles meaning tiny bones are the smallest bones of the human body. How small are they? Well, all three easily fit on a U.S. dime with plenty of wiggle room (Photo F)! There are three ossicles per middle ear and they are not included in the count of 22 skull bones.
Photo F
The ossicles form a tortuous bridge spanning the tympanic cavity from outer to inner walls (Photo G). Each ossicle resembles the object for which it is named: the malleus (Latin meaning hammer) has a handle firmly attached to the inner leaflet of the tympanic membrane and a head that articulates (forms a joint with) the incus. The incus (Latin meaning anvil) articulates with the stapes (Latin meaning stirrup) and the stapes inserts into the oval window, an opening in the inner wall of the tympanic cavity. Although tiny, the joints or articulations between the ossicles are moveable.
Please understand this: imagination is sometimes required to relate the Latin names to their corresponding anatomical objects. However, ancient anatomists used objects found in nature to name the body parts. The names such as stapes or malleus seem quaint but I actually prefer them to the current naming trend which often includes meaningless words containing lots of “cs”, “xs” and “zs.”
Photo G
The inner wall of the tympanic membrane bears two holes piercing the temporal bone. One hole, the oval window, is plugged by the stapes (Photo H); the other hole or round window is closed by a membrane (Photo H – black arrow). The inner wall has several other features too, but these are beyond the scope of this lesson
Photo H
Let’s stop for a short Clinical Correlation: The oral cavity and throat contain oodles of bacteria (Rupert and Angus consider germs in this hilarious video: Angus and Rupert Go Through The Stones). All is well unless they follow the Eustachian tube into the tympanic cavity where they can set up housekeeping to our detriment. Otitis media (Latin meaning inflammation of middle ear) is a rather common condition which typically includes bacterial (or viral) infections of the middle ear. Over 30 million doctor visits per year in the U.S. are due to otitis media. Symptoms include: pain, pulling at the pinna, irritability, sleeplessness, crying, etc. A trip to the doctor and an otoscope exam is in order (Photo I).
Photo I
Anatomy Lesson #24, showed the photo of a normal tympanic membrane (Photo J – left). But, with otitis media, the tympanic membrane is red, bulging because there is fluid in the middle ear and it hurts (Photo J – right)! Proper treatment is imperative.
Photo J
Unresolved otitis media can lead to mastoiditis (Latin meaning inflammation of mastoid bone). Now, dinna confuse mastoiditis with mastitis which is inflammation of the breast. Och, we are discussing ears, not mammary glands!
Here’s how mastoiditis works: recall that little attic door in the back wall of the middle ear that leads to the mastoid air cells (photo E)? Well, that door is a perfect conduit for bacteria to make their way from the middle ear into the mastoid air cells causing serious health complications in children and adults. Photo K (left side) shows bacterial invasion of the mastoid air cells and its presentation at the body surface (Photo K – right side). Signs include fever, redness, swelling, and tenderness behind the pinna which is pushed outward and forward.
Photo K
A picture is worth a thousand words, so this photo shows a case of mastoiditis (photo L – left mastoid process). Ouch, that hurts!
Photo L
Now back to anatomy. The inner ear is the last and by far the most complex of the three “ears”. At first blush it resembles a mutant squid or snail. It contains both bony and membranous elements. Bony parts include cochlea, vestibule and three (yes, three!) semicircular canals (Photo M- tan structures) filled with fluid (perilymph). Membranous elements (Photo M – blue structures) are suspended within the bony parts; these are the cochlear duct, utricle, saccule and three semicircular ducts; these are surrounded by perilymph and are filled with endolymph. Only the cochlear duct is involved in hearing, the utricle, saccule and semicircular ducts are necessary for balance and equilibrium.
Photo M
The cochlea and its cochlear duct spiral 2.5 times much like a snail shell. Within each cochlear duct lies the organ of Corti, a strip of 15,000-18,000 specialized “hair” cells arranged in rows like soldiers. “Bristles” project from the surfaces of the “hair” cells although these are unlike the hairs of skin. When examined by scanning electron microscopy (Anatomy Lesson #6), the bristles resemble the pipes of an organ (Photo N – cat hair cells). The bristles are covered by a gelatinous membrane (not shown in Photo N). The organ of Corti is also our organ of hearing.
Photo N
The following is a simplified version of how we hear, as the full vocabulary and structural and functional details would fill yet another anatomy lesson. Sound waves travelling through the air are gathered by the pinna and EAM; they strike the drum-like surface of the tympanic membrane pushing it inward with a thrust equal to the intensity of the sound. Ergo, loud noises push the eardrum inward more than soft sounds. The tympanic membrane vibrations are transferred through malleus, incus and stapes. With each vibration the stapes pushes inward at the oval window creating corresponding shockwaves through perilymph and endolymph of the cochlear duct (Photo O – black arrows). Movements of the fluids rub the bristles of the hair cells against the gelatinous membrane creating an excitation which is transfer to nerve cells forming the cochlear nerve (Photo O). The cochlear nerve joins with the vestibular nerve (see below) to form Cranial Nerve VIII (vestibulocochlear nerve). Impulses of each Cranial Nerve VIII follow auditory pathways into the brain. Hair cells near the base of the cochlea detect high-pitched sounds, such as ringing of a cell phone; those closer to the apex detect lower-pitched sounds, such as barking of a large dog.
Photo O
Electrical signals carried by the cochlear nerve make their way to the primary auditory cortex of the brain (Photo P – pink zone) where electrical signals are converted into “sounds” that we learn to recognize and understand.
In summary, outer, middle and inner ears work together to transfer sound waves through air (outer ear), solid (middle ear) and liquid (inner ear) where the good, good, good, good vibrations are converted into electrical signals that make their way to the brain for interpretation of sound. Go Beach boys!
Photo P
Do you recall this lesson began with “If a tree falls in a forest and no one is around to hear it, does it make a sound?” Take a moment to think of the answer and then read on.
The answer to this philosophical riddle is that if a tree falls in the forest it creates sound waves but a receptor must be present to convert those sound waves into sound. If any creature is present with an organ than can perceive and interpret sound waves, then the falling tree does make a sound otherwise it only makes sound waves. Make sense? Good!
Now, every anatomy lesson must tie into all things Outlander and hearing is no exception. So next is a jolly good quote from Outlander book when Claire tells Jamie she is from a waaay different time zone (Starz episode 111, The Devil’s Mark). Well, Jamie knew there was something unique about this braw and bonny lassie!
“Do you know when I was born?” I asked, looking up. I knew my hair was wild and my eyes staring, and I didn’t care. “On the twentieth of October, in the Year of Our Lord nineteen hundred and eighteen. Do you hear me?” I demanded, for he was blinking at me unmoving, as though paying no attention to a word I said.
“I said nineteen eighteen! Nearly two hundred years from now! Do you hear?” I was shouting now, and he nodded slowly. “I hear,” he said softly.
Hmmm, Jamie is thinking: I ken now why the Sassynach didna take to my leather belt spankin’! It also ‘splains her twitchy-witchy “know how.”
Now we must move on to how the inner ear provides balance and equilibrium. Our ability to balance is independent of outer ear, middle ear and cochlear parts of the inner ear but it is dependent on function of the three semicircular ducts (Photo Q – bone removed). The semicircular ducts contain endolymph and each bears an ampulla, a swelling at one end (Photo Q – red arrows). Each ampulla contains a patch of “hair cells” similar to those of the organ of Corti. Once again, the bristles are covered with a gelatinous membrane.
Anterior and posterior semicircular ducts are oriented vertically at right angles to each other. The lateral semicircular duct is slightly off the horizontal plane. Orientation of the ducts cause each duct to be stimulated by angular rotation of the head in a given plane.
Photo Q
Turning your head from left to right sides (as in no) moves endolymph in the lateral semicircular duct. Nodding your head (as in yes) moves endolymph in the anterior semicircular duct. Moving your head to touch one shoulder or as in doing a cartwheel moves endolymph in the posterior semicircular duct. In aviation terms, the semicircular ducts are oriented such that they detect pitch, roll and yaw.
Here is how the semicircular ducts work: As the head moves in angular rotation, endolymph moves in the opposite direction bending the gelatinous membrane (cupula) and exciting the hair cells (Photo R). The hair cells transfer the signal to nerve cells of the vestibular nerve (part of Cranial Nerve VIII). The signal is carried to the brain which interprets it as angular motion of the head. The information can be used to activate various muscles to adjust the head and/or body positions.
Photo R
The final anatomical elements of the inner ear are utricle (Latin meaning leather bag) and saccule (Latin meaning money bag – Dougal is into this one!) located between the semicircular duct and cochlear duct. These elements are also filled with endolymph (Photo S) and are designed to detect changes in linear acceleration or linear deceleration.
Photo S
Utricle and saccule each contain a patch of hair cells with surface bristles (Photo T – bullfrog hair cell) covered by a gelatinous membrane (absent in Photo T). The hair cells of the utricle are oriented horizontally and those of the saccule are vertically oriented.
Photo T
Seated atop the gelatinous membrane are wee otoliths (ear stones or ear rocks) made of calcium carbonate (Photo U); these add weight to the gelatinous membrane thus enhancing our sense of gravitational pull.
Photo U
The utricle and saccule work this way: As our head undergoes linear acceleration or linear deceleration (forward, backward, upward, downward), endolymph, the gelatinous membrane and otoconia move in the opposite direction (Photo V). This bends bristles of the hair cells causing them to activate nerve cells of the vestibular nerve of Cranial Nerve VIII. The electrical impulses are carried to the brain. The utricle detects horizontal changes and the saccule detects vertical changes in linear movements of the head. This information arrives at the brain which then determines if and how much the head is tilted and if the body needs to be reoriented in space.
Photo V
This brings us to the end of today’s important lesson but we must tie balance and equilibrium into Outlander. Here are a couple of great quotes from Outlander book. The book quote and the Starz images (Starz, episode 108, Both Sides Now) don’t quite match because the book scenarios weren’t filmed. Nevertheless, it is fun and you will get the idea. The first scene takes place as Frank and Claire descend from Craigh na Dun after watching the Druid’s dance. Frank, the soon-to-be Oxford professor, is so absorbed in thought he doesn’t watch where he plants his feet!
“He dropped into one of his scholarly trances … The trance was broken only when he stumbled unexpectedly over an obstacle near the bottom of the hill. He flung his arms out with a startled cry as his feet went out from under him and he rolled untidily down the last few feet of the path, fetching up in a clump of cow parsley… “Are you all right?” … “I think so.” He passed a hand dazedly over his brow, smoothing back the dark hair. “What did I trip over?” “This.” I held up a sardine tin…”
Compare and contrast Frank’s stumble-tumble with Jamie’s sure footedness (Outlander book). In this scene, it is nighttime and Jamie unerringly hauls Claire through the night:
“Jamie kept a tight hold on my arm, hauling me upright when I stumbled over rocks and plants. He himself walked as though the stubbled heath were a paved road in broad daylight. He has cat blood, I reflected sourly, no doubt that was how he managed to sneak up on me in the darkness.”
Yes, Jamie has grace, balance, and equilibrium (Starz episode 104, The Gathering). Nothing will trip-flip this kilt! Hang on tight, Claire! Snort!
You may have seen this arabesque in the teaser but let’s appreciate it anyway. Jamie throws water on burning hay, a fire set by a Watch weasle! Our highlander fireman even makes tossing water a thing of beauty. Balance and equilibrium on one foot; 17th century ballet!
At last, the time has come to report the results of Lesson #24 and the Pinna Poll! Six images of pinnae from the Starz cast (episodes #103, #109, #115, #116) were shown and votes tallied. All the ear flaps are fabulous!
Not sure if you are surprised, but the winner is:…………..drum roll………………..Jamie! Congratulations Big Red! And it was an honest count, too; no stuffing of the ballot box! Jamie garnered 38% of the votes while the remaining five pinnae were in almost a dead heat with a slight edge by bad boy BJR!
Great comments were shared by many readers including these: exquisite, lovely, charming, manly, rugged, beautiful, elfin-like, fawn-like, nibble-worthy, snuggle-worthy, elegant, awesome, symmetrical, balanced, proportionate and yum! Let’s thank our six wonderful characters and all of you for playing the Pinna Poll!
That’s it for the ear. Complex and elegant! Oh, and a word to the wise: keep music turned down a notch or two. Over the years, hair cells of the organ of Corti become damaged by excessive noise. For years, the damage has been considered irreversible although a recent study shows some promise using a gene-activating drug regime. Stay tuned.
Closing with this fun poem from Mr. R’s World of Math and Science:
An ear splitting sound!
A crash and a boom!
Ringing so loudly,
It shook the whole room!
But I didn’t hear it,
I couldn’t at all,
My left and right ear,
Had gone to the mall!
My left and right ear,
My organs that hear,
Had gone to go shopping,
And that’s what I fear…
Without my 2 ears,
That spectacular pair,
I can’t hear sound waves,
Move through the air!
The deeply grateful,
Outlander Anatomist
Photo creds: Starz, Basic Histology, Junqueira & Carneiro, 11th ed., Concise Histology, Bloom & Fawcett, 2nd ed., Netter’s Atlas of Human Anatomy, 4th ed., Clinically Oriented Anatomy, 5th ed., www.aviationknowledge.wikidot.com (ampullae), www.clearwaterclinic.com (otoliths), www.fairview.org (mastoiditis), www.kids-ond.com (ossicles), www.mhhe.com (ampula hair cells), www.sciencepoems.net (Mr. R’s ear poem), www.student.com (ossicles with inner ear), www.teachmeanatomy.info (mastoid air cells), www.otopathologynetwork.org (ossicles on dime), www.wallpaper.com (fallen tree), www.wikipedia.org (mastoiditis with subperiosteal abscess)
Anatomy Lesson #24 “Hear, Here – The Ear”
Welcome to summer school Outlander Anatomy students! Today’s topic is Anatomy Lesson #24: The Ear – Part I so listen up! We’ll start with a Starz Outlander scene followed by the anatomy lesson, then a short quiz and end with a Pinna Poll (you’ll soon know what that is grasshopper!). Are you game? Of course you are – it’s summah time and the livin’ is easy!
I’m saying it right up front: the ear is one of the body’s most elegant organs. Yes, I ken I already “handed” that distinction to the hand, but surely there’s room on the winner’s podium for yet another awesome body part? This one truly deserves our collective “Hear, Here!”
I started planning an ear lesson waaaay back during Starz episode 3, The Way Out. Remember the tanner’s lad whose ear was nailed to the pillory? Herself describes the scene in Outlander book:
He had in his custody a youth, perhaps twelve years old… a tanner’s lad. The priest had the boy gripped… the crowd drew back a bit to allow the locksman free movement for the ear-nailing. The lad… uttered a high, thin scream when the nail was driven in…
Ouch! After an hour nailed to the pillory, the two-bannock thief is free to go but first he must tear his ear free! Cute cagey Claire is no having that! She drags Jamie MacTavish into a 20th century freedom march for the lad; she will feign a faint for crowd control while Jamie has a chit-chat with the wee laddie. Again, from Outlander book:
‘Na then, lad, he said clicking his tongue. Got yourself in a rare swivet, have ye no? Och, laddie… yon’s no job to be making heavy weather of. A wee snatch o’ the head and its over. Here shall I help ye?
And, continuing the quote:
The ear was pinned firmly through the upper flange, close to the edge, and a full two inches of the nail’s square, headless shank was free….
So, Mr. MacTavish grabs the nail with his looong strong fingers (Aye, we all ken the fine work they do. Snort!) and lickety-split out comes the spike! Hie home lucky laddie!
That likely got us in the mood, so let’s get on with the anatomy lesson: the ear is very important for our well-being. Those who have suffered hearing and/or balance loss can attest to the importance of sensory input provided by the ear. Herself writes about such loss in “Written in My Own Heart’s Blood.”
…Artilleryman, from his uniform. So something big had exploded near him— a mortar, a cannon?— and not only burned his face nearly to the bone but also likely burst both his eardrums and disturbed the balance of his inner ear.
Yep, she’s right! The Human ear is the organ that collects, processes and interprets sound waves as well as aids in balance and awareness of head position. The paired ears of vertebrates are symmetrically placed on opposite sides of the head for the purpose of localizing sound sources; if only one ear is operative, the direction and distance from which a sound arises is difficult to pinpoint.
We often refer to these visible flaps of flesh as the ears but this is only the beginning (Photo A – left ear).
Photo A
Have you read Diana Gabaldon’s article about story telling and the Rule of Three? Well, you may be surprised to learn that anatomy also has a Rule of Three as many body parts come in trios (like Jamie’s acromion, clavicle and humerus – see Anatomy Lessons #3, #19 and #20) and we will cover several in this lesson.
The human ear actually includes three distinct ears: an outer ear (Photo B – green overlay), a middle ear (Photo B – yellow overlay), and an inner ear (Photo B – blue overlay). Today’s lesson will cover only the outer (external) ear.
Photo B
The outer ear consists of three (yes, three) parts: ear flap, ear canal and outer layer of the ear drum (Photo C). Anatomy has two names for the ear flap and either one works: pinna (Latin meaning feather or wing) or auricle (Latin meaning ear). The ear canal is the external acoustic meatus (Latin meaning passage). The ear drum is the tympanic (Greek meaning to strike) membrane. Let’s examine each of these three parts.
Photo C
But, wait! First, do you recall from Anatomy Lesson #6 that finger print whorls are formed by dermal ridges and the pattern is unique to each human? Even humans with identical DNA (e.g. identical twins) do not have identical finger prints (Photo D – small dots are openings of sweat gland ducts).
Photo D
In a similar vein (ha ha), the venous pattern on the dorsum of hand (Anatomy Lesson #22 & Anatomy Lesson #23) is entirely unique to an individual; so much so, that some board examinations now require test takers to undergo an infrared scan of the hand venous network for identification purposes as it is more reliable and interpretable than a fingerprint (Photo E).
Photo E
Hmmm, has this prof’s mind gone bye-bye? Why is she writing about fingerprints and hand venous patterns when the lesson is about the ear? Because, I want to emphasize a small cohort of unique body parts which includes the pinna as no two are alike. The pinna bears hills and valleys all of which are named (this is how anatomists make a living) but its overall shape and relationships are unique to its owner.
The pinna includes a fleshy earlobe/auricular lobule (Photo F – blue overlay) and the rest of the ear flap (Photo F – green overlay). The earlobe is soft and flexible because it is made of skin and collagen.
Photo F
One can even find references to the earlobe in Diana’s books (I swear anatomy abounds in her written works). This quote from Outlander book:
I wriggled closer and pulled Jamie’s head down as though overcome by amorousness. “What is it?” I whispered in his ear. He seized my earlobe between his teeth and whispered back. “The horses are restless. Someone’s near.
The way earlobes connect to facial skin is an interesting and disputed topic. Common wisdom is that earlobes come in two varieties: attached, wherein the lobe slopes to connect with facial skin (Photo G – red arrow) or free, wherein a distinct cleft separates earlobe from facial skin (Photo G – blue arrow). Science teachers often teach basic Mendelian genetics using earlobes as an example: earlobes are either free or attached and this trait is controlled by a single gene. But family studies have shown that this is not so. There is a broad range of earlobes all the way from “free” to “attached” with many variations in between. This range means that lobe attachment is a multifactorial trait that is not determined by a single gene.
Try this: check out your earlobes and those of friends and family. Are the lobes attached, free or some variant between the two? Do your earlobes look like those of your father or mother? What about your biological children – do their earlobes look like yours or those of the other parent?
Photo G
The remainder of the pinna is well-defined with skin tightly bound to an underlying endoskeleton of cartilage (Photo F – green overlay). The body contains three types (Three, again. I kid you not!) of cartilage: hyaline cartilage covers the surfaces of moveable joints; fibrocartilage forms much of an intervertebral disc and elastic cartilage shapes most of the pinna. (NOTE: the three cartilage types are found in other sites too but these will be covered in later lessons). The curved elastic cartilage of the pinna is complex with elevations and depressions; it also forms the outer 1/3 of the ear canal (Photo H – dissected human auricular cartilage of right ear).
Try this: fold one of your pinnae (pl.) down and release – it immediately springs back to its normal configuration. This is because elastic cartilage contains special elastic fibers that have shape memory (sort of like Spanx!). Now, this next image may be a bit gross (it is gross anatomy, after all) but pretend it’s Play-Doh!
Photo H
Next, let’s examine details of the pinna. The outer rim of the pinna is the curled helix extending from just above the ear canal to the earlobe (Photo I – yellow arrow); it looks like a bit like a question mark – ? – with the lobe serving as the dot. Roughly 10-11% of people bear a nodule on the upper helix known as “Darwin’s tubercle” (Photo I – black arrow), a bump that may represent the point of the mammalian ear (Photo I – white arrow). First described by Charles Darwin in The Descent of Man (1879) as the Woolnerian tip (sounds like something Angus might find betwixt his toes or Rupert might have in his beard), for decades it has been considered a dominant genetic trait controlled by a single gene. Again, family studies have also shown this is not so.
Stay tuned! Science does stumble, but its general direction is onward and upward!
Photo I
Now moving inward, the next mound (ahh…such a great anatomical word…describes so many…oops, I digress) is the stout Y-shaped antihelix (Photo J). The tragus (Greek meaning goat) is a mound (hee hee, there it is again! Say it with me…m-o-u-n-d) covering the opening of the ear canal, so named for a conspicuous tuft of hair that often graces its surface in men. Opposite the tragus is a small hillock the antitragus (Photo J).
Try this: Feel one of your pinnae (pl.) and note that although the earlobe (auricular lobule) is very flexible, the skin overlying the remainder of the pinna is tightly bound to the underlying cartilage. Palpate the curve of one helix; do you have a Darwin’s tubercle? It may be absent from both pinnae, present in one but not the other, or present in both. Check out Photo J or use a partner (I am a huge fan of playing doctor – extra credit for students who do!) to identify Darwin’s tubercle, helix, antihelix, tragus, and antitragus.
Photo J
Between elevations (another great word…quick! Name three body parts that can elevate!) of the pinna are valleys and depressions. The trough-like scapha separates helix and antihelix; the cymba of the concha is a pit in front of the upper antihelix; the cavity of the concha is the major depression leading to the ear canal. Finally a cleft between tragus and antitragus is the intertragic notch (Photo K).
Photo K
So, how do pinnae make a living? The complex array of bumps, depressions and whorls of each pinna is designed to gather sound waves from the environment and transmit them to the ear canal. But, here’s a fine fascinating factoid: the oddly-shaped pinna can also slightly amplify (increase) or attenuate (decrease) sounds of certain frequencies. Yes it can!
I will likely get shot down for this next comment, but you understand that the pinna wasn’t designed for hanging earrings, seating earplugs or hosting earspools (Photo L)? Sure we all do it; just saying!
Piercing earlobes has been done successfully for eons but the now popular ear cartilage piercings are cause for a bit more concern. Why? Cartilage has no blood supply and because it is bloodless, defensive/immune cells or antibiotics are more difficult to deliver when needed to fight infection. Thus, chondritis (inflammation of cartilage) or pericondritis (inflammation of the covering of cartilage) can be challenging to treat and if unchecked, either can seriously deform the pinna.
Photo L
Here’s an interesting Clinical Correlation on the pinna: defects of the pinna are not uncommon and include abnormal folds or location of the pinna, low-set ears, no opening to the ear canal, small pinna or no pinna or ear canal (anotia). Microtia (Latin meaning small ear) is a condition in which the pinna is small and/or distorted. Reconstruction of the pinna is a sophisticated multistep process in which either “harvested” cartilage or synthetic material is skillfully configured to mimic the shape of the pinna cartilage and inserted beneath the pinna skin. The results can truly be remarkable as shown in this series of photos over time (Photo M).
Photo M
Now, we all ken that many mammals turn their pinnae together or even independently. Such creatures have strong auricular muscles that swivel the pinnae to more effectively collect, modify and direct sound waves into the ear canal (Photo N – impala).
Photo N
We humans are equipped with three auricular muscles (anterior, superior & posterior) per pinna. However, these are so dinky they can’t effectively move the pinnae for sound wave collection (Photo O). Most humans I know are proud if they can pull back/wiggle their ears even a wee bit. What this doc wants to know is can Dougal wiggle his ears?
Photo O
Moving inward, the next structure is the ear canal or external acoustic meatus (EAM). I swear everything anatomical eventually appears in Diana’s books. Claire has just traveled through the stones and meets Jonathan Randall, Esq., Captain of his Majesty’s Eighth Dragoons (Outlander book):
I had by this time recovered my breath, and I used it. I screamed directly into his earhole, and he jerked as though I had run a hot wire into it. I took advantage of the movement to get my knee up, and jabbed it into his exposed side, sending him sprawling into the leaf mold.
Yep. You have to love it even though earhole isn’t a scientific term and yet, very close to another word (may I have an A please, Pat?) I frequently use for the wicked Wolverton wretch. Ha!
EAM is about 2.5 cm (1”) long with a slightly S-shaped path that slopes forward, inward and downward. It is lined with thin skin sporting protective hairs and ceruminous (wax) glands. The first part of the wall contains elastic cartilage (Photo P – black arrow) but bone encircles the rest of the canal (Photo P – red arrow). Throughout the EAM skin tightly adheres to the underlying cartilage or bone; for this reason, a disturbance as innocuous as a blackhead (comedone) can be very painful as there is little room to accommodate swelling and/or inflammation. I’m going to digress again for a moment but can you imagine getting a blackhead in your ear canal in the 18th Century? No wait, don’t answer that. Moving on!
Photo P
The purpose of the EAM is to modify, direct and deliver sound waves to the ear drum. Although kids will likely disagree, the canal is not for housing beans, peas, BBs, toys, gum, paperclips, etc. (Photo Q)! One does have to wonder though what sorts of items Angus stored in his pinna…
Photo Q
Speak o’ the devil himself…a big shout out to Professor Angus – not only is he good with a sgian dubh (Anatomy Lesson #15), he demos how polite wedding guests should clean the EAM (Starz episode 107, The Wedding). Och, for safety sake, inserting anything smaller than a pinky finger into the ear canal is unwise!
Finally we arrive at the third part of the outer ear, the ear drum or tympanic membrane (TM). TM is a membranous sheet that stretches across EAM and separates outer and middle ears. Photo R shows the external surface of the right TM. Only two of about 10 parts are labelled: the malleus is a small bone of the middle ear and the cone of light is a reflection from the beam of an otoscope.
Photo R
Drawings are great but they may fail to capture subtle details easily revealed in a photograph. If a health care provider examines a normal TM using an otoscope, (s)he sees this image (Photo S – right TM): the red arrow marks the handle of malleus and the blue arrow indicates the cone of light. Infections of the middle ear, perforations, blockages or other disturbances are readily identified using this remarkable instrument. The first time I saw the TM of a volunteer student via otoscope, I squealed (not in her ear, mind you – was a she); it was an absolutely awesome experience!
Photo S
OK, you paid attention very well! Pop Quiz time! Pull out paper and pencil and let’s see how you do. There are five questions followed by five answers. Keep score to determine your grade at the end.
Question #1: Name the bump at the tip of the black arrow.
Answer #1: Darwin’s tubercle. Verra guid! Here, Father Bain smells the “vapors of hell” on Claire (Starz episode 103, The Way Out) because her medical meddling endangers Tammas Baxter’s immortal soul!
Question #2: Name the mound at the tip of the red arrow.
Answer #2: Antihelix. The good Father hears Claire’s remarkable confession no doubt aided by this Y-shaped mound of cartilage and skin (Starz episode 116, To Ransom A Man’s Soul).
Question #3: Name the mound at the tip of the red arrow.
Answer #3: Tragus. Excellent! Ye can barely see the tragus because it’s covered by all the long red curls. Jamie messes with Claire’s ears in this scene (Starz episode 102, Castle Leoch) as Herself informs us in Outlander book:
The lad had nice feelings… he sat down, gathered me firmly onto his lap with his good arm and sat rocking me gently, muttering soft Gaelic in my ear and smoothing my hair with one hand.”… No wonder he was good with horses, I thought blearily, feeling his fingers rubbing gently behind my ears, listening to the soothing, incomprehensible speech. If I were a horse, I’d let him ride me anywhere.
Question #4: Name the gap at the tip of the arrow.
Answer #4: Intertragic notch. Does this notch really lie between two tragedies? Weel, sort of: puir Tammas Baxter lies ‘tween Claire’s belladonna decoction and Father Bain’s “driving out the demon” approach to universal health care (Starz episode 103, The Way Out)! But, Mrs. Fitz saves the day!
Question #5: Is darling Roger’s wee earlobe (lobule of the auricle) attached or free?
Answer #5: Free. Have ye ever seen a sweeter face (Starz episode 109, Both Sides Now)? What a cutie. May he have another biscuit, please? True story: when one of my grandsons was about wee Roger’s age, he called his earlobes, ear loaves. Butter mine please!
How did you do with the self-graded pop quiz? 5 of 5 is a AAAAA; 4 of 5 is an AAAA; 3 of 5 is an AAA; 2 of 5 is an AA; 1 of 5 is an A; but 0 of 5 is a “please reread the ear lesson!”
Okey dokey, now it’s time for the fun part, the PINNA POLL: which one of the following pinnae do you like BEST? There are six choices and all are awesome so please choose your favorite and leave your vote in the comments! The votes will be tallied and reported at the next anatomy lesson.
First up is Dougal MacKenzie, Jamie’s favorite Jacobite uncle on his mum’s side (Starz episode 109, The Reckoning). He’s pissed because Colum snags a bag of gold meant for the “bonny Stewart Prince across the water!” Isn’t his helix absolutely fab!
Next is Geillis, wife of “the man knows no guile” Arthur Duncan, procurator fiscal of Cranesmuir (Starz, episode 103, The Way Out). This wily witch has a one beguiling pinna and plenty of guile to go around!
Then, the villain that everyone loves to hate, BJR (Starz episode 115, Wentworth Prison)! Being an officer and a gentleman (yeah, right), he’ll not give into his baser instincts. Vote for his pinna if you like it best.
Next we have Murtagh, everyone’s favorite godfather. It’s snowing so his pinna is chilled to the cartilage. He is just about to hock a big ol’ loogie to demo Dougal-disdain (Starz episode 109, The Reckoning). No love lost between those two! Does your vote go for Murtagh’s pinna?
Next up is Claire’s beautiful, wing-like pinna– it looks like porcelain illuminate by the light. NO Jamie, she doesna want to tell her secrets to Geillis (Starz episode 103, The Way Out). Take her outta the fiscal’s house you big, gorgeous strong-fingered hunk!
Finally, for the last pinna of the poll! Actually I think this is only time Jamie’s pinna is fully exposed during the entire season one (Starz episode 116, To Ransom a Man’s Soul). Claire’s fingers “ached, wanting to trace the line of his small, neat ear …” (Outlander book). Need an ear rub Jamie? Snuggle up!
The middle and inner ears will be covered in our next anatomy lesson, but for now, please understand this: sound waves must travel through gas/air (outer ear), solid (middle ear) and liquid (inner ear) before they are converted into electrical signals that make their way to the brain. The brain translates the electrical signals into a “sound” that we can recognize and understand.
Thanks for playing along! Remember that the outer ear is all about augmenting the hearing function of the ear; it isn’t involved in balance. We’ll learn about hearing and balance in the next lesson. Until then, enjoy stanza III from “The Bells,” a poem by Edgar Allan Poe (1809-1849):
Yet the ear, it fully knows,
By the twanging,
And the clanging,
How the danger ebbs and flows;
Yet, the ear distinctly tells,
In the jangling,
And the wrangling,
How the danger sinks and swells,
By the sinking or the swelling in the anger of the bells–
Of the bells–
Of the bells, bells, bells, bells,
Bells, bells, bells–
In the clamour and the clangour of the bells!
The Deeply Grateful,
Outlander Anatomist
photo creds: Starz, Gray’s Atlas of Anatomy for Students, 2005, Human Anatomy by Martini and Timmons, 1995, Netter’s Atlas of Human Anatomy, 4th ed., Clinically Oriented Anatomy, 5th ed., www.blissbiology.wordpress.com (free & attached earlobes), www.clker.com (pinna), www.nola.com (toys from ear), www.pinna.hawkelibrary.com (elastic cartilage), www.karenscottaudiology.com (three parts of ear), www.microtia.us.com (microtia), www.si.wikipedia.org (Darwin’s tubercle & earplugs), www.wikipedia.org (impala), www.s1.zetaboards.com (attached & free earlobes)