Anatomy def: Round, knotty scar on abdominal skin at L3-L4 IV disc level, site of umbilical cord attachment during intrauterine life.
Outlander def: Umbilicus, omphalos, navel or bellybutton, the name doesna matter. Jamie’s standard for lewd clothing: if it’s too low, the dress must go!
“Aye well, it looks like you!” He came closer, bending to inspect the bodice of the dress. He peered into my cleavage. “Christ, I can see down to your navel! Surely ye dinna mean to go out in public like that!”
While Jamie, from his vantage point a foot above me, had claimed to be able to see my navel, my umbilicus was by and large safe from scrutiny by the French courtiers, most of whom were shorter than I was.
Hi, anatomy students! So great to meet with you again. Today’s Anatomy Lesson #43 uncovers (ha) the posterior (back) thigh. We already met the anterior thigh waaaay back in Anatomy Lesson #7, “Jamie’s Thighs or Ode to Joy!” where we studied the quadraceps. Thus, we have much more to learn about the thigh.
Our object is to study muscles of the posterior thigh with two other thigh muscles thrown in for good measure. Some folks don’t find muscles all that compelling (unless they are Jamie’s, of course!); mayhap this lesson will change their minds. Anatomical tidbits are added to hold your attention.
As always, Outlander books and Starz episodes are blatantly scattered throughout. Let’s start with a great view of Jamie’s posterior thighs (Starz episode 112, Lallybroch). Och! Lad, best tuck in those flapping shirt tails! Oops, nothing to tuck into. Where’s a kilt when you need one?
Lower Extremity: This lesson starts with essential definitions. Anatomists define the lower limb or lower extremity as the appendage from hip joint through toes. Folks (including me, at times) refer to the lower extremity as the upper leg and lower leg but, in anatomy, this is not so. The thigh is that part of the lower limb between hip and knee joints (Image A – between dashed lines). The leg lies between knee and ankle joints and the foot is distal to (beyond) the ankle joint.
Image A
Thigh Overview: Today’s lesson focuses on posterior thigh so let’s define this area. The human thigh is divided into compartments based on connective tissue septa (partitions) and actions; these are best visualized in cross-section (Image B). By convention, cross-sections are interpreted is as if you stand at a person’s feet and look toward the head.
A plane crossing the femur, reveals three compartments, each bearing different muscle groups: anterior (Image B – red), medial (Image B – pink; OK, OK – it’s dusty rose!) and posterior (Image B – lavender). Anterior means front; medial means toward the midline; posterior means back. We will study three muscles of the posterior compartment, one of the anterior and one of the medial.
Image B
Posterior Thigh Muscles: Three muscles make up the posterior thigh compartment; all are typically long and strong.
Semitendinosus
Semimembranosus
Biceps femoris
Try This: Open the space between thumb and forefinger and grip your posterior thigh about mid-femur. Your entire hand should grasp a sturdy muscle mass containing the three posterior compartment muscles. Appreciate the same anatomy with your other thigh or someone else’s. <g>
Topographical Anatomy: Looking at topography or surface anatomy of an intact posterior thigh, is it possible to see grooves and ridges created by its muscles? Yes, if the subcutaneous fat layer is not too thick and if the thigh is well-muscled. Posterior thigh (Image C – right lower extremity) bears three muscles in succession: Blue arrow marks semimembranosus, red arrow marks semitendinosus and green arrow shows biceps femoris.
Image C
Not easy to see? OK, let’s look again using a male body builder (Image D). He is not mooning us, rather, he demonstrates posterior muscles of the lower extremity. Same color coding as Image C and not a challenge to recognize the long columns of posterior thigh muscles. Impressive!
Understand that semitendinosus (red arrow) and semimembranosus (blue arrow) fill the medial (inner) side of posterior thigh and biceps femoris (green arrow) occupies the lateral (outer) side.
Image D
Book Quote: Speaking of long columns of thigh muscles, Diana obligingly (yay!) provides a description of Jamie’s own fine muscular columns, here from Dragonfly in Amber. In case you don’t recognize the scene, these are Claire’s poignant thoughts the eve before she passes through the stones (sob!), back to Frank (gah!). Dinna ken if “seasoned oakwood in the columns of his thighs” refers to anterior or posterior thigh muscles but, knowing Claire, it was very likely both. Snort!
I touched each soft hollow, the hidden places of his body. Felt the grace and the strength of each curving bone, the marvel of his firm-knit muscles, drawn lean and flexible across the span of his shoulders, smooth and solid down the length of his back, hard as seasoned oakwood in the columns of his thighs.
Book quote and photo (Starz episode 204, La Dame Blanche) aren’t a match, but will do in a pinch…the pinch being a love bite on Jamie’s thigh. Man, you are in BIG trubble! Yep, seasoned oakwood it is. Ha, ha!
Remove the skin and, voila, three posterior thigh muscles pop into view (Image E – posterior right thigh).
Semitendinosus: Superficial semitendinosus courses down the medial side of posterior thigh. The muscular part ends roughly midway down the femur, transforming into a long, round tendon and curving behind the knee joint to end in the tibia. Did you know, part of semitendinosus tendon can be harvested during knee reconstructions to replace the ACL or anterior cruciate ligament (Anatomy Lesson #7, “Jamie’s Thighs” or “Ode to Joy!”)? Yep, a very useful muscle.
Semimembranosus:Semimembranosus (Image E) is a broad, flat muscle so named because it has an unusually membranous tendon of origin. Although it lies deep to semitendinosus, it is the most medial of the posterior thigh muscles. Semimembranous also drops across the knee joint to end in tibia. Semimembranosus is variable; it may be reduced, enlarged, duplicated or absent.
Biceps Femoris: Longtime students will ken that we studied biceps brachii back in Anatomy Lesson #20, “Arms! Arms! Arms! – Redux.” Well, like the arm, posterior thigh also has a biceps muscle, biceps femoris. Biceps derives from Latin, meaning two heads and femoris reflects its close association with femur. Indeed, biceps femoris (Image E) does have two heads of origin: the long head courses the length of the thigh and the short head is roughly half as long. Both muscle parts unite as a single tendon ending in the fibula. The short head of b. femoris may be absent but otherwise, the muscle demonstrates few variations.
Clinical Correlation: Recently, a professional soccer player suffered major posterior thigh pain. Imaging revealed a large, anomalous (duplicated?) right semimembranosus which was crossed over and compressed by the tendon of semitendinosus. This unusual anatomy created what is known as entrapment syndrome of the posterior thigh, which compresses the popliteal artery (see below) restricting blood flow. This is especially acute during exercise and hence, pain. Muscles object when deprived of oxygen….. “blood of my blood.” We know the drill.
Image E
Remove gluteus maximus and posterior thigh muscles spring into view (Image F). Remove semitendinosus and long lead of b. femoris and, ta da, semimembranosus and short head of b. femoris say hello! Image F reveals the long, flat membranous tendon of origin for semimembranosus. Short head of b. femoris arises from lower half of femur.
Image F
Moment of Silence, please!: In Image E, the tops of posterior thigh muscles are not visible because gluteus maximus covers them. G. maximus is a large, flat quadrangular-shaped muscle honored in Anatomy Lesson #1, “Jamie’s Tush” and was the original inspiration for Outlander Anatomy lessons! Thus, it is only fitting that we interrupt this lesson to pay homage to lovely body curves created by these, the body’s most massive muscles (Starz, episode 107, The Wedding). Gasp, thud!
Muscle Attachments: Next, let’s suss out bony attachments of the posterior thigh muscles – know these and muscle actions make sense. Image G of the posterior hip bone and femur is busy but nicely shows muscle origins (red) and insertions (blue). Origin means the body site (almost always a bone) giving rise to a muscle. Insertion means the site where the muscle ends by attaching to a different bone. Muscles usually cross one or more joints (there are exceptions) – a site where bones meet to allow for movement. Make sense? Dandy! Succinctly put:
Origin:
Proximal (nearer the body center)
Fixed point (least moveable site)
Insertion:
Distal (further from the body center)
Movable (moves with muscle contraction)
Origins and Insertions: Long head of biceps femoris, semitendinosus, and semimembranosus, all take origin from the ischial tuberosity (Image G) of the respective hip bone, cross the hip joint and pass down the posterior thigh. As noted, the short head of b. femoris takes origin from the lower half of femur (Image G). BTW, the sturdy ischial tuberosities are known at gyms as “sits bones” and, indeed, we do sit on them!
After coursing down the posterior thigh, each muscle claims a different insertion site.
Semimembranosus crosses knee joint to end in medial tibia (Image G – inner leg bone).
Image G
The tendon of semitendinosus swings behind the knee joint and inserts into anteromedial (front/inner) surface of tibia (Image H).
Long and shorts heads of biceps femoris unite as a single tendon which crosses the knee joint to end in the head of fibula (outer leg bone) Image H.
Image H
Actions: Now for the nitty-gritty: What actions do these muscles perform? Well, they are critical for successful lower limb ambulation: walking, running, climbing, kicking, squatting, jumping, etc. Semitendinosus, semimembranosus and long head (not short head) of b. femoris cross the hip joint so as they contract, the hip joint extends or straightens (Image I – bottom right). All three muscles (including short head) cross the knee joint so as they contract, the knee flexes or bends (Image I – top right). All three muscles counteract forward bending at the hips to keep us from doing a face plant. Whew, busy muscles!
Image I
Hamstrings: Now, here’s an interesting tidbit: Anatomists call semitendinosus, semimembranosus and long head of b. femoris true hamstrings; “ham,” from Old English hom, meaning the hollow or bend of the knee and “string” referring to tendons located there. To receive this “anatomical blessing,” a posterior thigh muscle must meet the following criteria:
Take origin from the ischial tuberosity (ergo, short head of b. femoris doesn’t quality)
Cross the hip joint causing extension (short head of b. femoris doesn’t quality)
Cross the knee joint causing flexion
Same innervation (short head of b. femoris has a different innervation)
Hamstringing is an dreadful event wherein a victim is incapacitated by severing hamstring tendons at the back of the lower thigh (Image J – in cartoon form, thank goodness!). This laceration was crippling, painful and often caused death by exsanguination from severed vessels at back of the knee (see below). Hamstringing was a time-honored (eek!) method of permanently crippling animals and humans so they could not reengage in future warfare.
Hamstringing is a very old practice. Identified as houghing in the King James Version of the Bible, both Joshua and David ordered hamstringing of chariot horses. Carthaginians hamstrung their Roman enemies as did Germanic tribes. Romans hamstrung elephants and the practice has been revived most recently in Zimbabwe!
Image J
After he is stabbed in the torso by the mouthy MacDonald, Jamie doesn’t fail us! Pulling a dirk with his left hand, he prepares to strike his attacker (Starz episode 110, By the Pricking of My Thumbs). Who’s the cowering coward behind the tree? The Duke, of course. Off with his head!
And, strike he does! Down goes MacDonald as Jamie’s blade slices into the unguarded right biceps femoris tendon, hamstringing his opponent. Given the state of 18th century medicine, this MacDonald willna be farming his croft. Ei, Ei, Ohhhhh….. Well, Jamie is a warrior – even if he is cute!
Try This: Want to feel your own hamstrings? Sit in a chair or on a sofa with knees bent and right foot turned outward. Place right fingers beneath outer right thigh (near knee). Pull right heel back against chair rung or couch base. Feel the tendon? This is biceps femoris. Relax and place fingers of left hand behind inner lower thigh, this time with turn foot inward. Pull heel back again. Feel two tendons? The superficial one belongs to semitendinsus and the deep is semimembranosus! A+ for you!
“Down by the old mill stream,” the tendon of Jamie’s right biceps femoris muscle is clearly visible as he shifts weight to the mill wheel. See the taut tendon behind his right knee? Oops, lost some of you! Please focus on the hamstring. Don’t see it? Bummer! <G>
Let’s try again. How about both Jamie and Claire this time (Starz episode 101, Sassenach)? “Here’s to you lass, for tipping us to the villains in the rocks, and gieing us a wee bit of fun,” boasts and toasts Rupert. Green arrows mark tendons of biceps femoris muscles. Can you spy a second band of taut tissue, just forward of Jamie’s biceps tendon? This is the iliotibial tract or IT band (orange arrow – Anatomy Lesson #7, “Jamie’s Thighs or Ode to Joy!”). Yep, keep your eyes peeled for all sorts of Outlander anatomy!
BOOK QUOTE: Both Claire and Jamie have something to say about rubbing thighs during that intimate ride together, although Claire’s is slightly more high-brow. From Outlander book:
My companion seemed to be having little trouble, in spite of being unable to use this right hand. I could feel his thighs behind mine, shifting and pressing occasionally to guide the horse. I clutched the edge of the short saddle in order to stay seated; I had been on horses before, but was by no means the horseman this Jamie was….
but then that ride through the dark together – with that lovely broad arse wedged between my thighs…with a bum like that… What does it matter if she’s a f-face like a ah-ah- sheep?”
Baa, baa, bleats Claire! 🙂
It took more than a bit of sleuthing to find an Outlander image showing inner hamstring tendons. Probably the best comes from The Wedding (Starz episode 107). Squee! Shift eyes, ahem, to Jamie’s left inner thigh; green arrow marks a ridge created by tendons of semitendinosus and semimembranosus. Flexed knee brought to you by power of the mighty hamstrings!
Although a bit later in their relationship, this quote from Dragonfly in Amber book says it all!
I scooped out a good bit of the salve and spread it down the long muscle of the thigh, pushing Jamie’s kilt above his hip to keep out of the way. The flesh of his leg was warm; not the heat of infection, only the normal heat of a young male body, flushed with exercise and the glowing pulse of health. I massaged the cream gently into the skin, feeling the swell of the hard muscle, probing the divisions of quadriceps and hamstring. Jamie made a small grunting sound as I rubbed harder. “Hurt?” I asked. “Aye, a bit, but don’t stop,” he answered.
Hamstring Injury: Moving on… anyone who has suffered a hamstring pull understands just how much we rely on these muscles. You can scarcely engage in a single lower-limb activity without feeling the burn. Yeow! This is a short list of things which contribute to hamstring injury:
Sitting for long periods of time
Sitting on a hard surfaces, putting pressure on the hamstrings
Kicking any ball (football, soccer)
Hurdles
Splits
Poorly conditioned folks suddenly trying things they once did as teenagers!
Hamstring Stretch: Because we are so dependent on hamstrings, it is important to keep them supple by stretching. This can be done sitting, standing or reclining (Image K). Anatomically, the reclining stretch is safest because shoulders, head, spine and hips are supported by the floor; sitting and standing stretches can result in hunched backs, arched necks and hips out of alignment. Here are some pointers:
Keep hips and shoulders flat and aligned
Contract abdominal muscles to support the lower back
Flex both ankles
Grip hands behind the thigh (NOT behind the knee)
Gently lift one limb until resistance is met – then stop! Don’t force the lifted limb
Don’t arch the neck or back
Alternatively, flex the down knee to release tension on the raised hamstrings
Alternatively, pass a towel behind the up thigh and gently pull on towel to lift
Image K
Videos can be helpful, so the next one demonstrates a good hamstring stretch. As with the above photo, hands go behind the thigh with the interesting addition of flexing alternating with not flexing the ankle joint. Some yoga practitioners grip the great (peace) toe, which works wonderfully if one is a seasoned hamstring stretcher, otherwise avoid!
Sciatic Nerve: A note about the sciatic nerve, the largest of the body (Image L). This behemoth (in adults, it rivals the size of my thumb!) courses down the back of the thigh hidden by gluteus maximus and hamstrings. It gives off twigs to innervate all the hamstring muscles, crosses the knee joint and supplies most of the leg and foot. It is a very busy nerve, hence its size. Sciatic nerve pain is a common affliction but must wait for another lesson. So sorry!
Popliteal Vessels: Behind the knee lies the popliteal fossa, a potential space filled with fat and blood vessels. The large popliteal artery and vein descend through this space to supply knee, leg and foot. These are at risk during hamstringing. If severed, the victim will bleed out, very quickly!
Image L
Switching gears, do you recall this terrified wee fellow? He served as Colum’s tailor-of-the-day (Starz episode 103, The Way Out). His wife was a MacKenzie, but kinship won’t protect him from Colum’s dirk! The MacKenzie chieftain was mightily p.o.ed at the tailor because his newly minted frock coat was too long. Did the tailor mean to hide Colum’s legs (Anatomy Lesson #27, “Colum’s Legs and Other Things too!”)? Well, erm, aye, he did, but he hadn’t planed to lose his larynx over a Heiland fashion statement (Anatomy Lesson #42, “The Voice – No, not that One!”).
What in the world does a tailor have to do with the posterior thigh? Read on!
Perhaps you recall at lesson start, I mentioned we would cover two other muscles, one from anterior and one from medial thigh compartments (review Image B). Here we go!
Sartorius: The sartorius muscle spirals down the anterior thigh. Its name derives from the Latin sartor meaning, tailor. Why? Because, back when garments were hand sewn, many tailors assumed a cross-legged posture so the knees could support a garment under construction (Image M). Sartorii (pl.) are engaged in adopting the cross-legged position, hence the name.
Image M
The striking sartorius muscles are very apparent in this female body builder (Image N). Thin, flat and superficial, we rarely see sartorii except in folks who are heavily muscled and/or express little subcutaneous fat (Anatomy Lesson #5, “Claire’s Skin – Opal, Ivory and White Velvet”).
Image N
Spiraling down the thigh but superficial to the quadriceps (Image O), sartorius is the body’s longest muscle (love superlatives)! Sartorii can be pulled during activities which require a forcefully push off, as with sprinting, jumping and running. Thus, sports, such as hockey, rugby, football or basketball, place one at higher risk of injuring this muscle, although improperly-performed squats can also do the trick. Pain can occur anywhere along the length of sartorius with groin and inner knee as common sites of complaint.
Image O
Sartorius belongs to the anterior thigh compartment. It takes origin from a knob of hip bone, the anterior superior iliac spine or ASIS (Image P). Crossing both hip and knee joints, the muscle arcs across the front of the thigh to end in the anteromedial tibia.
Image P
As each sartorius contracts, hip and knee joints flex and knee rotate laterally (to the side) as in yoga’s lotus pose (Image Q). Sartorii don’t appear in Image Q because the feet cover them.
Image Q
However, this image of a yoga practitioner entering half-bound lotus pose nicely shows the left sartorius (Image R – double arrow); its tendon creates a skin groove just above the arrow.
Image R
And, Jamie reveals a near perfect sartorius groove (of course) as he scolds new wifey: Lassie, I tell you the truth about Ned Gowan and that strumpet! Ned paid a high price for your splendid wedding dress; a dirty job against which he fought, valiantly. Ha!
Gracilis: Graceful gracilis belongs to the medial thigh compartment (review Image B). Derived from the Latin gracilis meaning slender, this is the most superficial muscle of the medial thigh (Image S). It is thin and flat, broad above, narrow and tapering below. Like true hamstrings and sartorius, gracilis also crosses both hip and knee joints.
Image S
Gracilis takes origin from the pubic bone and inserts on anteromedial tibia (Image T). It helps adduct the thigh (draw toward body midline) and is a weak flexor of both hip and knee joints. Interestingly, gracilis is widely used in reconstructive surgery as a replacement for facial muscles, hand muscles or the external anal sphincter. Loss of the gracilis is not disabling as larger, stronger muscles of the medial compartment are able to compensate.
Clinical Correlation: A few years back, surgeons teaching in my anatomy course presented a case wherein they replaced the external anal sphincter with gracilis muscle, performed on a young woman who had suffered a horrific injury in an auto accident. So shocking and graphic, one of our first year medical students fainted, undoubtedly from vasovagal syncopy wherein heart rate and blood pressure suddenly drop due to extreme emotional distress. Yes, that brought this memorable lecture to a halt! But, the student soon regained consciousness and composure and this gave the surgeon a teaching moment to explain what had happened. I am pleased to report that not only student recovery but the reconstructive surgery were both successful. Surgeons I worked with were very resourceful docs and imaginative thinkers. Their motto: A chance to cut is a chance to cure! Very confident folks, the surgeons.
Image T
Pes Anserinus: Now, perhaps you spy an insertion theme: tendons of sartorius, gracillis and semitendinosus all converge and insert as a unit into anteromedial tibia. At insertion, they form a webbed configuration known as the pes anserinus, Latin for goose foot. The name, “goose foot,” arises from a three-pronged appearance assumed by the three tendons, each from a different thigh compartment (Image U). The order of insertion from front to back can be recalled using the acronym for sergeant: SGT for sartorius, gracilis, semitendinosus. Now, this seems especially appropriate because sergeant comes from the Latin servier meaning “one who serves”; an apt moniker for these three hardworking “guy ropes” as they are sometimes called!
All three pes anserinus muscles are primarily knee flexers but studies show that the peculiar three-pronged insertion provides rotatory stability to the knee, meaning together they stabilize external (outward/lateral) rotation of the knee. Hallelujah! Why? Remember, the knee joint is inherently unstable because its constituent bones do not enjoy a ball and socket type of interaction (Anatomy Lesson #7, “Jamie’s Thighs or Ode to Joy!”). Ergo, the joint is provided with numerous ligaments and tendons, including pes anserinus, to ramp-up stability. Go anatomy!
Image U
Goose Foot: Did you see a goose’s foot in the pes anserinus? No? OK, then, let’s look at a goose’s foot! How about now (Image V) – see the three pronged toes joined by webbing? Still not convinced? Understand that early anatomists didn’t have magazines, internet, social media, TV or movies for creative word imagery so they drew on the natural world to devise a new language describing body parts and passions (Lesson #34, “The Amazing Saga of Human Anatomy”). Many of their words may seem quaint but, some 500+ years ago, they were cutting edge!
Image V
That’s it for the hamstrings and its two closely allied pals. Remember, these muscles are important in virtually all types of ambulation. The next time you stride through a mall seeking new fashions, kick a soccer ball or chase down an errant child, please give a brief nod of thanks for these wonderful muscles!
Do you love art? I love art. Created by Steel Neal and installed at Cooper Square, NYC, “The Agony of Man” is a 1200 pound, 3 times life-size rendition of the human form (Image W). It is constructed entirely of salvaged scrap metal: I-beams, railroad track, rebar, boilers, New York City garbage cans. Teeth (Anatomy Lesson #26, “Jamie’s Chin – Manly Mentus”) were repurposed from road resurfacing equipment. Bony orbits (Anatomy Lesson #30, “Aye, Eye – The Eyes – Part 2!”) were salvaged from original park benches at Madison Square Park. Ribs (Anatomy Lesson #15,“Crouching Grants – Hidden Dagger”) are from the original concrete island of Worth Square.
Sartorii? Yes, there they are, spiraling across the front of thighs – these are made from an extinct type of rebar salvaged from the original foundation of the Union Square Subway Station. Indeed, an evocative rendering of human agony!
Image W
How does human agony fit into a lesson about “hamstring – you make my heart sing?” Well, because we, the wretched, are suffering from drrrrrouuuuughtlander (Photo X)! Gasp! Ron.com, must have a glass of OUTLANDER soon! Dying here!
Welcome anatomy students to another exciting session! Today’s Anatomy Lesson #42 is, The Larynx. Some folks think the larynx only generates “The Voice” (Christina, CeeLo, Blake and Adam, notwithstanding). While this is certainly true, it also serves two other critical functions. Stay tuned for the fascinating saga of laryngeal (adj.) anatomy.
As always, Starz images and Diana’s book quotes are sprinkled throughout to make our studies more endearing. A couple of book spoilers appear, meaning the quotes are from books that have not yet been filmed; these will be preceded by a red flag warning for those who prefer to skip!
First, the sad-bad news. I waited for Starz to depict Dougal’s Demise after a reader asked more than a year ago for a lesson on the voice! I waited patiently because Uncle D’s Death as described in Dragonfly in Amber book is a perfect lead-in for a larynx lesson. Then, horror of all horrors – Starz episode 213, Dragonfly in Amber – didn’t follow the book! Och!
BOOK QUOTE: Dragonfly in Amber describes Jamie’s and Dougal’s shocking Fight with Fate, involving a knife to the throat and a struggle with voice:
A shift, and a jerk, a sudden grunt of effort, one of pain. Dougal stepped back, staggering, face congested and pouring sweat, the hilt of the dagger socketed at the base of his throat… There was a terrible sound from Dougal, a sound of shock and stifled breath… The big body went limp, then spasmed, sliding out of Jamie’s grasp. Dougal lay crumpled on the floor, muscles jerking with involuntary contractions, struggling like a fish out of water. His head was pillowed on Jamie’s thigh. One heave brought his face into view. It was contorted, and dark red, eyes gone to slits. His mouth moved continuously, saying something, talking with great force—but without sound, save the bubbling rasp from his ruined throat.
Imagine my dismay as the Starz scene unfolds wherein Jamie + Claire stab Dougal in the chest – not in the neck! What? To quote Rabbie Burns: “The best laid schemes o’ mice an’ men – gang aft a-gley.” Ah, well, tha sin mar sin!
Many a time, Jamie casts a wary eye at Dougal (Starz episode 101, Sassenach) and for good reason. Mayhap, the ruadh laddie kens that a battle to the death is the only way a male will prevail? One of these fellows must go!
Now for the lesson: Let’s start at the beginning with how to pronounce the word, larynx. Well, it is pronounced ler-inks, not lar-nix. Emma does a swell job, so check this out:
Commonly known as the voice box, the larynx is a splendid structure of startling complexity. A hollow tube with stiff walls, the adult larynx (Image A – orange) lies in the neck where it links pharynx or back of throat (Image A – green) with trachea or windpipe (Image A – trachea).
Just so you are aware, pharynx is pronounced fare-inks, not far-nix. One of my anatomy profs used to declare: “if you say lar-nix one more time, I will rip out your far-nix” (in those days, professors were minor gods)!
The human larynx serves three critical functions:
Maintains the airway so air enters and leaves the lungs during each breath cycle
Excludes food, drink and other unwanted stuff from entering trachea
Creates phonation – “the voice” and other sounds
We will learn how the larynx manages these important functions. But first, the anatomy!
Image A
General Anatomy of Larynx:
A vertical, midline section through the larynx reveals its considerable length, extending from C3 (third cervical) vertebra (Image B – red arrow) through C6 vertebra (Image B – blue arrow). In case you forgot, back in February 2015, we learned about cervical vertebrae in Anatomy Lesson #12, “Claire’s Neck” or “The Ivory Tower.”
The adult larynx is supported by a rigid skeleton of cartilage, ligaments and membranes (Image B – cartilages named). Numerous intrinsic and extrinsic muscles move these cartilages.
The larynx is a dynamic structure that changes throughout life, from the newborn state through old age. It is also a secondary sex organ undergoing marked changes during puberty. Male and female larynges (pl.) respond differently to the internal hormonal milieu, a quality known as sexual dimorphism (Anatomy Lesson #39 “Dem Bones – the Human Skeleton”). We will return to these issues later in this lesson.
Image B
Laryngeal Skeleton:
The laryngeal (adj.) skeleton features nine cartilages: three large, unpaired and three small, paired. Only unpaired cartilages (epiglottis, thyroid and cricoid) are visible from a front (anterior) view (Image C). The rounded, curved tip of epiglottis peeks above the hyoid bone. The thyroid cartilage is shaped like a helmet visor; two broad plates (laminae) meet anteriorly at a pronounced angle, the laryngeal prominence (Image C – red arrow). The cricoid cartilage is a complete ring, thin in front but expanded in back.
Image C
Laryngeal cartilages do not float, they are anchored by strong connective tissue elements (Image D). The thyroid cartilage hangs from the hyoid bone (Anatomy Lesson #12, “Claire’s Neck” or “The Ivory Tower”) via a tough thyrohyoid membrane. Cricoid and thyroid cartilages are united by the cricothyroid ligament and a cricotracheal ligament (Image D – red arrow) binds cricoid cartilage to trachea. Although not shown in Image D, ligaments also hold the epiglottis in a mostly vertical position. The trachea is not part of the larynx but its wall is also formed of cartilage rings (see below).
Image D
WARNING! The first RED FLAG means a book spoiler quote is next! Skip, if need be.
BOOK SPOILER: Larynx and hyoid bone appear in Diana’s 9th book, Written in My Own Heart’s Blood. An important character’s name is omitted to “protect the innocent!”
McEwan’s broad fingers were cold on his neck; he felt the icy touch delicate on his skin as it traced the line of the rope scar, then firmer as the healer prodded gently round his damaged larynx… McEwan fitted his hand snugly round _______ neck, just under the chin… “Do you know what a hyoid bone is?” “If I had to guess, it’s something in the throat.” “Why?” … “It’s just there,” the healer said, pressing with his thumb, high up under _______ chin. “And if it had been here”—he moved the thumb down an inch—“ you’d have been dead, sir. It’s a fragile wee bone. Easy to strangle someone by breaking it—with your thumbs or a rope.”
Question #1: Do any of the above structures appear as mounds at the skin surface? Hyoid bone, epiglottis and cricoid cartilages are not visible because these are embedded too deeply or are too small to create a skin mound. But, we often see a bulge that moves during swallowing, talking, singing, etc.; the bulge is created by the laryngeal prominence of the thyroid cartilage, commonly known as the Adam’s apple (Image E). Great tattoo, although most of it lies below the laryngeal prominence. Ha!
Try This: Place two fingers over your laryngeal prominence – don’t press hard as it causes discomfort. If you cannot find it, gently tilt head backwards and feel a firm mound under your fingers. Now, straighten the neck and feel the prominence lift as you prepare to swallow and fall as the act completes. Now cough or sing a few bars and see what happens. I hope you are surprised by its mobility. Remember, this is only a small part of the larynx; much more is happening that you cannot feel.
Try This: Next, tilt head back again and run fingers down the laryngeal prominence until you feel soft tissue; this is the cricothyroid ligament. Below it lies a thin hard line of cricoid cartilage. Below this is another bit of soft tissue, the cricotracheal ligament binding cricoid cartilage to first tracheal ring. From this point, the trachea continues down the throat and into the thorax (Anatomy Lesson #15 “Crouching Grants – Hidden Dagger”). Appreciate that the larynx is solidly built and well-anchored.
Clinical Correlation: If an “owner” desires a smaller laryngeal prominence, then chondrolaryngoplasty is available. The neck is entered via surgical incision and the prominence reduced by shaving. Erroneously called a tracheal shave (trachea isn’t involved), it usually leaves a modest scar.
Image E
Time for a Jamie fix! Jamie’s laryngeal prominence is clearly visible (Starz episode 210, Prestonpans – red arrow) as, tilting his head back with immense pleasure, he relieves a full bladder! Hot-shot lad that he is, he attempts to win a bet by peeing into a pot without looking. Splish-splash! Odds?
BOOK QUOTE: Diana describes the delightful scene featuring Jamie’s Adam’s apple (Dragonfly in Amber):
Grinning at the success of his joke, he raised his kilt further, grasped his clearly visible weapon and took careful aim. He squinted his eyes, bent his knees slightly, and his fingers tightened their grip. Nothing happened. “It’s a misfire!” crowed one of the English. “His powder’s wet!… Jamie squinted dubiously at his equipment, bringing on a fresh riot of howls and catcalls. Then his face cleared. “Ha! My chamber’s empty, that’s all!” He snaked an arm toward the array of bottles on the wall, cocked an eyebrow at me, and when I nodded, took one down and upended it over his open mouth. The water splashed over his chin and onto his shirt, and his Adam’s apple bobbed theatrically as he drank. “Ahhh.”
Back to Anatomy: The best way to see remaining laryngeal cartilages is flip the structure into a posterior view (Image F). The odd, leaf-like epiglottis is fully visible from this perspective; it’s curved superior surface peeking above the hyoid bone. Thyroid cartilage, visor-shaped, is incomplete, posteriorly. The cricoid cartilage expands in back, much like the dome of a signet (class) ring. Perched atop the cricoid are the important, paired arytenoid cartilages, each shaped like a three-sided pyramid. Atop each arytenoid is another small curved cartilage (corniculate) which we will ignore along with a couple of other tiny cartilages. Although difficult to visualize from this perspective, a lumen (channel) runs vertically through the center of the laryngeal cartilages; remember, this lumen is lined with mucous membrane.
Posteriorly, the tracheal rings are incomplete, but the C-shaped cartilages are united by strong connective tissue sheets. This brilliant engineering feat allows food blobs and globs to slide and glide down the esophagus (see Image B – esophagus behind trachea) without getting hung up on tracheal rings.
Image F
One last structural component to consider are the paired vocal ligaments. A vertical section of the larynx, through the midline, reveals internal anatomy of the left side of larynx (Image G). Locate the left vocal ligament, a band of elastic tissue reaching from thyroid cartilage in front to arytenoid cartilage, in back. This arrangement is duplicated on the right side. More about the vocal ligaments below.
Image G
Intrinsic Laryngeal Muscles: Intrinsic muscles arise and insert within the larynx itself. There are 6 (8 by some counts) pairs of intrinsics; thin, tiny muscles moving various laryngeal cartilages. I can bear witness that these are very difficult to dissect! One of a pair of intrinsic muscles is clearly visible from a side view (Image H – red arrows). Naming intrinsic muscles will bog us down. Suffice it to say, the one in Image H is the cricothyroid, so named because it arises from cricoid cartilage and inserts on thyroid cartilage. Get the idea? Grand!
Image H
Remaining intrinsic muscles are visible from a posterior view (Image I). These are strategically oriented to move the various laryngeal cartilages in specific ways and again, named by the cartilages they attach to or the function they perform.
Image I
The following is a short list of how intrinsic muscles act on various laryngeal cartilages.
Rock thyroid cartilage forward to lengthen vocal ligaments and deepen the voice (Image J – top)
Rotate arytenoid cartilages together to open airway and allow airflow (Image J – middle, left)
Rotate arytenoid cartilages apart to close airway and stop airflow (Image J – middle, right)
Narrow the airway to reduce airflow (Image J – lower, left)
Ergo, these intricate adjustments, caused by muscle contraction, allow nuanced movements of laryngeal cartilages to manage airflow and to produce and modulate sound. And, these amazing, small muscles contract very rapidly with great capacity for prolonged work, as any singer can verify. Lastly, the lower right image shows muscle fibers stretched from thyroid to arytenoid cartilages; these tiny muscles lie inside the vocal folds (see below).
Image J
Extrinsic Laryngeal Muscles: Not only do intrinsic muscles move the larynx, eight pair of strap-like extrinsic muscles also effect laryngeal position. Extrinsic laryngeal muscles are so-named because they take origin from or insert into body parts outside the larynx. Located in the neck or beneath the mandible, extrinsic muscles connect mandible (Anatomy Lesson #26, “Jamie’s Chin – Manly Mentus”), sternum, scapula and skull to thyroid cartilage and hyoid bone. Read more about these muscles in Anatomy Lesson #12 “Claire’s Neck” or “The Ivory Tower.”
Image K identifies extrinsic laryngeal muscles but more importantly, shows upward or downward directional pulls (red arrows); four pair of extrinsic muscles depress (lower) and four pair elevate (lift) hyoid bone and thyroid cartilage. Further, the pulls are not strictly upwards or downwards. Rather, the upper four pair of muscles pull hyoid bone up and forward or up and backward; the lower four pair of muscles pull hyoid bone and thyroid cartilage down and forward or down and backward. The larynx, suspended from that wee hyoid bone, is mostly carried along for the ride!
Thus, these many muscles and their attachments allow for nuanced changes of laryngeal position during talking, laughing, screaming, singing, coughing, clicking, sneezing, snorting, swallowing, etc. Impressive!
Image K
Thyroid Gland: Remove the extrinsic muscles and we see an important and intimate relationship between larynx and the highly vascular thyroid gland. The bilobed thyroid gland straddles the larynx, its lobes connected by an isthmus (bridge) of thyroid tissue overlying the second and third tracheal rings (Image L).
Image L
Vocal Folds: Next, let’s consider vocal folds. Vocal folds, commonly known as vocal cords, are paired folds of mucous membrane, each containing a vocal ligament (see Image G) and the tiny (vocalis) muscle (see image J, lower right).
Looking down the pharynx via laryngoscope (laryngoscopy), true vocal folds appear as pale thin bands (Image M). Below these, are epiglottis and tongue base. Above the folds are bumps created by mucosa overlying arytenoid cartilages. Vocal folds carry out the first and third critical functions listed below:
provide airway
exclude unwanted materials
generate sound
Let’s discuss each of these functions in greater detail.
Provide Airway: As muscles rotate arytenoids together, vocal folds open allowing air to flow through the lumen or glottis (Image M – left side). As other muscles rotate the arytenoids apart, the folds close and air flow slows or stops (Image M – right side). Psst: Just so you know, vocal cords lie horizontally in the neck; their vertical orientation in Image M is how they appear on a screen during laryngoscopy.
Image M
True vocal folds are so named to distinguish them from false folds. Find the false vocal foldsin Image M. False vocal folds do not produce sound but do add resonance to the voice. Two exceptions are Tibetan Chant and Tuvan throat singing, both of these produce an undertone using small spaces (laryngeal ventricles) between true and false vocal folds (ventricles not visible in Image M).
If you find animals endlessly fascinating, get this: Male gorillas and some other primates, such as the gibbon shown in Image N, enlarge their necks by deliberately forcing air into their laryngeal ventricles. The ventricles of some primates are so large, they may extend into the thorax! In most humans, they are small.
Image N
Remember the second crucial function of the larynx? It closes to exclude unwelcome materials. Yep, it discriminates!
Exclude Undesirables: The weird-looking epiglottis helps with the second laryngeal function, to exclude unwanted stuff from the larynx. Here is how it works: During swallowing, hyoid bone lifts and tongue depresses pushing the epiglottis downwards and backwards to cover the laryngeal inlet (Image O – black arrow). This helps prevent food, drink, spit, etc., from entering the larynx as only air is welcome (Image O – white arrow). The epiglottis also has a shape which encourages food and drink to flow around its sides and backwards into the esophagus where it belongs! Does it sometimes, fail? Well, sure, especially if we try to swallow and speak at the same time. In such instances, stuff gets into the larynx , eliciting a paroxysm of coughing! Expel the infidel!
Try this: Wait! Wait! If you have a sensitive gag reflex, don’t try this. Otherwise, do you want to feel the tip of your epiglottis? Here’s how: open mouth wide and relax tongue. Lay one (clean) index finger atop tongue. Slide it gently backward and downward along the tongue surface until you touch the rounded, thin tip of the epiglottis. Don’t gouge it with your fingernail and avoid touching soft palate, sides or back of throat as this initiates the gag reflex! Did you feel it? Good job to those who dared!
Image O
Generate Sounds: Last but not least, vocal folds produce sounds. During phonation, vocal folds open and close, change shape and vibrate. This brief video shows the fluid movements involved in this process – watch until the end, to see and hear the patient sing. The folds are a pale pink V in the still shot below. The tracheal inlet is the dark hole In middle. Mounds near the top are arytenoid cartilages – these move dramatically during the film clip. The thin mobile curl at the bottom of the video is the tip of epiglottis. Oh, and the sticky material coating the vocal folds is mucus, a viscous fluid that lubricates and protects the folds. Hope you watch all of this fascinating footage!
Clinical Correlation: Please understand that if the larynx is blocked or narrowed by trauma, infection, birth defects, cancer, polyps, scar tissue, etc., the impediment must be removed or bypassed to restore the airway. Two sites commonly used for bypass are cricothyroid membrane and trachea. An opening through the cricothyroid membrane (see Image D) is a cricothyrotomy or cricothyroidotomy. An opening between tracheal rings, is a tracheotomy; if a breathing tube is inserted into the opening, then it is termed a tracheostomy (Image P).
Tracheotomy is not new as it was depicted on Egyptian artifacts dating as far back as 3600 BCE! Here’s an startling tidbit: Alexander the Great purportedly saved a soldier from suffocation by making an incision into the man’s trachea with the point of his sword! Gah! I don’t recall seeing Colin Farrel do that in Alexander.
Image P
Red flag and wee black dog are back. Must be another book spoiler! Best skip if you haven’t read ahead of Starz episodes!
BOOK SPOILER: This quote is very pertinent to our lesson, from Herself’s fifth book, The Fiery Cross, as it mentions structures and procedures covered in this lesson. Yay, Diana!
A cricothrotomy? Fast, and requiring no great skill, but difficult to keep open—and it might not be sufficient to relieve the obstruction.
I massaged the isthmus of the thyroid, pushing it out of the way, hard toward his head, and with my other hand, pressed the knife blade down into the fourth tracheal cartilage.
The cartilage here was U-shaped, the esophagus behind it soft and vulnerable; I must not stab too deeply. I felt the fibrous parting of skin and fascia, resistance, then the soft pop as the blade went in. There was a sudden loud gurgle, and a wet kind of whistling noise; the sound of air being sucked through blood.
… she could hear the faint whistle of air through the tube in his throat. Claire had commandeered Mr. Caswell’s imported English pipe, ruthlessly breaking off the amber stem. Rinsed hastily with alcohol, it was still stained with tobacco tar, but seemed to be functioning well enough.
Way to Hustle, Claire: Claire assiduously avoids cutting the thyroid gland isthmus, otherwise, blood would quickly flood the surgical field. She also likely pressed her knife through the soft connective tissue between 3rd and 4th tracheal rings. And, she performed a tracheostomy, inserting a pipe stem into the tracheal incision to serve as a breathing tube. Yay, Claire!
Newborn Larynx: At lesson start, I promised to consider age- and sex-related differences of the larynx. Here we go! The larynx is a tiny organ in the newborn which sits much higher in the neck (C2-C3 vertebrae) than in the adult (Image Q – infant left, adult right). The higher position of an infant larynx allows epiglottis and soft palate to touch during suckling (Image Q – left side). This important juxtaposition enables the infant, an obligate nose-breather, to simultaneously suckle and breathe. Otherwise, they would have to swallow, stop, take a breath, stop – repeat. Exhausting for such a tiny body!
Many a nursing mam knows that if her wee bairn bites down (ouch!), she can stop this by gently closing off its nostrils – the babe must let go to breathe!
It should be noted that although infant larynges are much smaller than those of adults, their vocal folds and higher lung pressure enable them to produce very audible howls, yowls and growls!
Childhood Larynx: The larynx continues to grow throughout childhood in proportion to the remaining body with no significant differences between male and female larynges.
Image Q
Adolescence: Then, puberty raises its provoking head, accompanied by some fascinating changes! Both sexes experience facial development, descent of the larynx in the neck, increased circumference of chest wall and greater lung capacity, all of which typically deepen and strengthen the voice. But, the larynx of a pubescent male is also exposed to a flood of androgens (mainly testosterone) which induces growth of laryngeal cartilages.
Adult Male Larynx: By 20 y.o., the average male larynx is about 40% taller and vocal folds about 60% longer than the female’s (Table A). Plates of the male thyroid cartilage meet at a 90º angle making the thyroid eminence more prominent than that of the 120º female angle (i.e., female angles are more open, so eminence is less pronounced). Male intrinsic muscles become larger and stronger and vocal folds thicker and longer leading to a drop of about one octave in voice pitch. These differences illustrate sexual dimorphism of the larynx; its responsiveness to hormones qualifying it as a secondary sex organ.
Adult Female Larynx: But, did you know that female vocal folds also respond to hormonal changes? Puberty causes the female voice to drop about 1/3 octave. But, female vocal folds also respond to hormone (progesterone and estrogens) fluctuations during each menstrual cycle becoming more edematous in the latter half which often lends the voice a breathy or husky quality. After menopause, the female voice becomes even lower due to increased circulating androgens.
After 20, the larynges of both sexes remain stable until about midlife when cartilages begin to ossify (bone replaces cartilage). Ossification is not usually a problem but one of my young readers (<20 y.o.) has ossified laryngeal cartilages and they are problematic for this person.
An astute student might ask, why would nature make the male voice deeper and stronger? Well, scientists have some suggestions about that: Perhaps, male voices have deepened over the course of evolution to signal dominance and/or to increase the speaker’s attractiveness. Studies do confirm that vocal frequencies correlate with a speaker’s hormonal status – which may or may not be attractive in a potential mate. Gals tend to like Jamie’s baritone voice. Mmphm!
Table A Mean Measurements of Male and Female Larynxes
MALES
FEMALES
Height
44 mm
36 mm
Transverse diameter
43 mm
41 mm
Front-back diameter
36 mm
26 mm
Circumference
136 mm
112 mm
Sexual Dimorphism: Let’s turn to all things Outlander to witness sexual differences of the larynx. Here, in Outlander Starz episode 202, Not in Scotland Anymore, we see a near perfect example of the female Adam’s apple – or is it an Eve’s apple? Bwahahaha!
A small bump of the laryngeal prominence appears on Claire’s lovely ivory tower as she casts stink eye at stinky Duke! Love, love, love those earrings – perfect accessory for her swan-like neck!
Compare and contrast Claire’s gentle laryngeal prominence with that of a typical male. Weil, now, perhaps not entirely typical, but certainly impressive! Jamie obligingly lifts his chin to reveal his prominent Adam’s apple (Starz episode 107, The Wedding). Lots of testosterone plus Claire help him have a vera fine time. Whinny and snort!
The Voice: Let’s end this lesson with a brief discussion of The Voice…No, not the TV show! – just voice in general, the third important function of the vocal folds. Phonation is arguably less critical than maintaining the airway, but very important for communication and quality of life.
Roman physician Galen (130 – c. 200 CE) declared the larynx as the “first and supremely most important instrument of the voice.” Was he correct? Yes, because sounds are normally generated by vibrations of vocal folds and action of laryngeal muscles (side note: people lacking functional vocal folds can be taught esophageal speech and/or use of an electrolarynx). However, sound quality is nuanced by numerous other factors including:
Lung capacity
Extrinsic laryngeal muscles
Tongue movement
Lip action
Mouth anatomy
Pharynx, cheeks and soft palate changes
Paranasal sinus configuration
The cumulative effect of these factors grants to humans a voice that can be modulated to an amazing degree; never more evident than during singing. Consider the movements of lips, tongue, soft palate, etc. in this wonderful MRI of a man singing opera. The movements are astounding. Try to locate epiglottis and arytenoids. I hope you enjoy watching this internal byplay on the screen!
Question #2: Readers have asked why our taped voices and spoken voices sound differently to our own ears? Answer: Taped voices are recorded via sound waves traveling through air before reaching our ears. The spoken voice creates vibrations transmitted to the inner ear (Anatomy Lesson # 25, “If a Tree Falls – The Ear”) mostly via bone and soft tissues, lending the voice a less tinny quality. Most folks seem to favor the spoken voice over the taped version. Make sense?
Final Outlander Fixes: Happily, Outlander gives us many treacherous throat and larynx scenes to consider!
Barely out of the chute, Claire is confronted with Captain of Dragoons’ blade at her neck (Starz episode 101, Sassenach). Good way to lose a Lovely Larynx! Fortunately for our nimble nurse, his threat is only virtual. The man’s got skills, ye ken?
Puir not-a-wet-nurse Claire doesna get a break in episode 101. Next, Dougal jerks her around and tells her to stay with the rest of his troop of hairy-merry lads or he will obligingly slit her throat (Starz episode 101, Sassenach)! Lovely larynx at risk, again!
Remember the Sadist’s Shave? Captain Jack-Rat’s larynx is fully exposed to a vera sharp blade (Starz episode 106, The Garrison Commander). Too bad Corporal Milksop’s hand didna slip. Would have saved team Fraser a world of grief!
Oops. Flip-flop and the tables are turned. Corporal Hawkins’ hand DID slip – now, he is under the blade, getting the absolute worst: a dry-neck shave (Starz episode 106, The Garrison Commander)! Vera unpleasant, especially at the hands of the foul fearsome fiend!
BOOK QUOTE: Now, a few fabulous apropos lines about a dearly departed larynx from Dragonfly in Amber book:
Mary sneezed, and wiped her nose hastily with a fold of her plaid. She stared at Murtagh, eyes wide and baffled. I gazed down at the bulging saddle-bag, feeling a sudden deep chill that owed nothing to the weather outside. But it was Hugh Munro’s widow who sank to her knees, and with steady hands opened the bag and drew out the head of the Duke of Sandringham.
In Starz episode 211, Vengeance is Mine, Jamie, Claire and contrary-Mary witness Sandringham, forever separated from his smooth-speaking larynx. No more mocking jibes from this oily opportunist. Sure and true, Murtagh’s ax seeks its mark!
Diana, author of both Starz episode 211 and Dragonfly inAmber book, offers two different routes to the Duke’s Demise although the outcome is identical…. grand example of “the end justifies the means?”
The Duke, he lost his larynx,
Along with his pharynx.
The ax performed a hi-jinx.
Murtagh’s work is done!
(Let’s hear it for the Godfather!)
Final voice Issue: According to 13 August 2016, New Scientist, and Buzz Feed,Appen, a voice recognition firm working for Google, a call for help has been posted on Reddit’s Edinburgh page for people with Scottish accents to submit recordings of themselves reading certain phrases to help train its software! Users with certain accents – particularly Scottish – have complained that voice recognition systems such as those used by Good Now and Apple’s Siri struggle to understand them. Here is a great comment to illustrate the dilemma. Well, at least Siri got “street” right! Am I right?
I hope you enjoyed learning about the incredible human larynx. Give a brief salute the next time you take a breath or utter a no-no word! Have a wonderful breath-taking day.
