Fun Fact – urinate

urinate

Scientific def: to discharge urine from the body (to micturate)

Outlander def: Act of peeing with your godfather el fresco!

Learn about urination in…Well, I haven’t actually written an Anatomy Lesson about the urinary bladder, the organ that stores urine and contracts during urination. The closest I can come to the topic at at this point are Anatomy Lesson #8, “Jamie Takes a Beating and Claire’s Healing Touch,” and Anatomy Lesson #15, “Crouching Grants – Hidden Dagger”; these lessons introduce the kidneys, organs that produce urine.

In the meantime, here’s a wee (Ha, ha) lesson on urination to contemplate: do ye ken it takes 21 seconds for most mammals to urinate? Yep! A researcher and his colleagues were awarded a 2015 Ig Nobel prize** for this finding. Such research may seem frivolous, but it could lead to an early medical diagnostic tool for men. If the time to empty the urinary bladder exceeds established urination times, a prostate exam may be in order (New Scientist, 31 October 2015).

Read about Claire’s need to urinate while interrogated by BJR at Fort William. From Outlander book:

The tension was slightly relieved by the entrance of an orderly, bearing a tray of tea things. Still silent, Randall poured out and offered me a cup. We sipped some more. “Don’t tell me,” I said finally. “Let me guess. It’s a new form of persuasion you’ve invented—torture by bladder. You ply me with drinkables until I promise to tell you anything in exchange for five minutes with a chamber pot.” He was so taken by surprise that he actually laughed.

Or where Jenny Murray’s new daughter baptizes her father’s shirt (Outlander book):

“Hello, wee Maggie,” he whispered, touching the tiny button of a nose with one fingertip. His new daughter, unimpressed by the introduction, closed her eyes in concentration, stiffened, and urinated on her father’s shirt.

See Jamie and Murtagh pee on the walls of Castle Leoch in Starz, episode 109, The Reckoning! Yep, these BFFs formulate and celebrate as they urinate and consecrate Colum’s real estate! Do ye ken there are 444 English words that rhyme with urinate? Hee, hee!

A deeply grateful,

Outlander Anatomist

** Ig Nobel Prizes honor achievements that make people LAUGH, and then THINK. The prizes are intended to celebrate the unusual, honor the imaginative — and spur people’s interest in science, medicine, and technology.

 

Anatomy Lesson #34: The Amazing Saga of Human Anatomy

Welcome, all anatomy students to Anatomy Lesson #34, The Amazing Saga of Human Anatomy! This topic is a divergence from our usual Outlander themes but before you decide to skip it, please consider that herein lays oodles of interesting illustrations and startling titbits about the checkered past of human anatomy. This blog doesn’t have the luxury of covering all of anatomical history as entire books have been written on the topic so it covers only major milestones relating to western medicine.

But first, is tying the history of anatomy into Outlander a reach? Nay, anatomy, especially abnormal anatomy (pathology) is all over the place in Diana’s books and the Starz series. Anatomy follows Nurse Claire, like… well, like girls cling to Jamie! From the moment she steps into Davie Beaton’s surgery (Starz episode 101, Sassenach), her senses are on high alert: déjà vu, sixth sense, the training of a scientist? Hmm…there’s something mighty eerie about this place.

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Claire’s  anatomical knowledge is required during her first encounter with Jamie as Herself wrote in Outlander book:

You have to get the bone of the upper arm at the proper angle before it will slip back into its joint,” I said, grunting as I pulled the wrist up and the elbow in. The young man was sizable; his arm was heavy as lead.

Claire successfully realigns Jamie’s humerus and glenohumeral joint thereby reducing the dislocation (Starz episode 101, Sassenach). Read about the technique Claire used in Anatomy Lesson #2, “When Claire Meets Jamie” or “How to Fall in Love While Reducing a Dislocated Shoulder Joint!”

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Now for our lesson: anatomy is the oldest of the medical sciences with a rich and very blemished history. The word “anatomy” derives from the Greek ana “up” and temnō “I cut”, implying dissection (pronounced dis-section not di-section) of an organism to discern its design. Anatomy is the study of the structure of organs, tissues and cells through all stages of maturation. The anatomist is concerned with names, shape, size, position, relationships, blood supply and innervation of structures while physiologists study function and biochemists follow processes, although these distinctions typically blur in the research lab.

Nowadays, anatomy is a tree with many branches: Zootomy is the anatomy of all animals; phytotomy is the anatomy of all plants. Comparative anatomy contrasts anatomy between species. Anthropotomy (an-thro-pot-o-my) is the proper (but rarely used) term for anatomy of the human body. Gross anatomy describes structures that are visible with the naked (unaided) eye. Microscopic anatomy (histology) uses magnification to study cell, tissue and organ structure. Surface anatomy focusses on an organism’s external features. Developmental anatomy (embryology) studies structures of the developing organism. Radiologic anatomy employs imaging modalities such as x-ray, ultrasound, MRI or CT to reveal internal structures. The following images are examples of two such fields of anatomy.

This image shows comparative anatomy of the upper limb from four different animals: shape, size and disposition of corresponding upper limb bones are contrasted and compared. Homologous (comparable) bones are color coded for ease of identification (Image A).

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Image A

The next image shows a poignant example of radiologic anatomy: an MRI scan reveals brain anatomy of a mother tenderly cradling her sleeping child as they nest within the tube of an MRI scanner (Image B). The neuroscientist overseeing this work pursues the field of brain development. Surprisingly, she informs us, “… I am a neuroscientist, and I worked to create this image; and I am also the mother in it curled up inside the tube with my infant son.”

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Image B: MRI from Smithsonian, December 2015

Human anatomy is the foundation of medicine and is typically the first course taught in medical curricula; when appropriate, cadaveric dissection lies at its core (Image C). Why is this so? Well, if your beloved dishwasher, car, or god forbid, computer goes on the blink, you wouldn’t want joe blow tinkering with it would you? Likewise, who hands their body over to a practitioner who knows next to nothing about its design? Not me!

As course director of gross anatomy (now retired), I routinely told my first year medical students: “The human body is a living, breathing, basic science laboratory and you get to take care of it; it is best that you know your anatomy well!”

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Image C: Dissection by Body Region

An important consideration: Religion and science are periodically at odds in the anatomical time line as they are often viewed as opposing forces – in my thinking, they are not because they ask and answer different questions.

The roots of human anatomy arguably began about 2,600 BCE with the religious practices of ancient Egypt; a culture that believed mummification allowed a soul to retrieve its preserved body before journeying into the underworld. Heart, lungs, liver and bowels were removed and stored in canopic jars (Image D) or treated and replaced into body cavities. The brain was removed (encephalectomy) via the nostril (preferably the left) but was destroyed in the process. These incursions into the body revealed anatomy to embalmers albeit for religious purposes. Egyptian physicians likely benefitted from such anatomical expertise because ancient papyri (e.g. Edwin Smith and Ebers papyri, ca. 1600-1500 BCE) contain highly sophisticated medical instructions for surgeons and physicians including such details as the first known appearance of the word for “brain”.

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Image D: Anubis Oversees Embalming – from Sarcophagus of Pedusiri

After Alexander the Great founded the ancient city of Alexandria, the Greek Ptolemaic dynasty began – a culture that deeply valued the natural realm much like the ancient Egyptians pursued the religious realm. Ptolemy I (367-283 BCE), successor to Alexander the Great, conceived the Library of Alexandria (Image E) aiming to make it the center of western knowledge.

Although forbidden in the ancient world, Ptolemy I legalized dissection and released the bodies of condemned criminals for this purpose (unethical by today’s standards). Thus, in the 3rd century BCE,  Greek physicians Herophilus and Erasistratus began the first known human dissections for scientific purposes. Their meticulous work laid the foundation of human anatomy and corrected many misconceptions embraced by practitioners of medicine but their texts were destroyed with the Alexandrian library.

Three hundred years later, following the rise of Christianity, both anatomists were denounced as “butchers of Alexandria” and accused of dissecting living humans. This denouncement came centuries later and although widely circulated as truth, the accusations are based on inference. Subsequently, human dissection was deemed blasphemous and outlawed leaving practitioners of western medicine woefully ignorant of human anatomy.

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Image E: Library at Alexandria

Enter one Claudius Galenus (Galen) of Pergamon (130 – c. 200 CE), a Greek who was born and raised in present day Turkey (Image F). Widely educated, he chose a career in medicine, eventually settling in Rome as physician to the gladiators. There, he achieved fame through accurate diagnoses, treatments, public lectures, discussions, demonstrations and writings. He correctly diagnosed Emperor Marcus Aurelius’ ailment as indigestion, for which he was appointed court physician.

Galen performed animal dissections and the anatomy was inferred to humans. His writings and teachings were marked by brilliant observations and wise therapeutic application but also by colossal error and pompous hubris. His ego was monumental as evidenced by this quote:

Never as yet have I gone astray, whether in treatment or in prognosis, as have so many other physicians of great reputation. If anyone wishes to gain fame all that he needs is to accept what I have been able to establish.

Galen was the last great Greek physician-scientist of the ancient world. His writings in Greek were lost but survived in Latin, Arabic and occasionally, Hebrew translations. After Galen, anatomical research ceased and his flawed texts became the ultimate medical authority for over 1200 years!

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Image F: Galen by Robert Thom

Over the next millennium, anatomical images became firmly linked with astrology and magic. Mistress Claire was confronted with this reality when Colum assigned her to Davie Beaton’s “closet of horrors” at Castle Leoch. Lifting the lid of a medicament chest, the top displayed the woeful state of anatomical knowledge at Beaton’s “Skulkery”: a rudimentary image of human organs linked to signs of the zodiac (Starz episode 103, The Way Out). The sight draws a faint smile from our resident anatomist. And, Herself recorded:

There were a number of more or less harmless substances in Beaton’s jars, as well as several containing dried herbs or extractions that might actually be helpful… I discarded jars of dried snails; OIL OF EARTHWORMS which appeared to be exactly that; VINUM MILLEPEDATUM millipedes, these crushed to pieces and soaked in wine; POWDER OF EYGYPTIANE MUMMIE an indeterminate-looking dust, whose origin I thought more likely a silty streambank than a pharaoh’s tomb; PIGEONS BLOOD, ant eggs, a number of dried toads painstakingly packed in moss, and HUMAN SKULL, POWDERED. Whose? I wondered…

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Returning to our anatomical time line, let’s fast forward a brief millennium (ha!) during which political and religious powers outlawed human dissection. However, gradually, religious authorities changed their attitudes and legislations were enacted to allow human dissection for teaching purposes.

These events culminated in the first officially sanctioned human dissection since Herophilus and Erasistratus, performed by physician-anatomist Mondino de Cuzzi (1275-1326) of Bologna. Human dissection quickly spread to other European universities, the process immortalized in a woodcut from the first anatomical text ever printed (Image G). This puzzling image requires a note of explanation: three individuals were involved in the aforementioned dissection. A lecturer orchestrated the affair from a raised dais while reading from anatomical texts, usually Galen. A barber surgeon performed the dissection and the individual to his right (your left) identified the structures. The elevated position of the lecturer is thought to be the origin of the term chairman of the department. The individual using the baton to identify structures became known as the demonstrator of anatomy.

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Image G: First print of Human Dissection

The history of anatomy would be incomplete without mentioning archetypal Renaissance man, Leonardo da Vinci (1452-1519). During his lifetime, only physicians or barber surgeons could legally dissect human cadavers but da Vinci received a special church dispensation to perform his own dissections; from these, he created the earliest and most accurate anatomical sketches (Image H). Although his paintings were famous, only a few close associates knew of his anatomical research. Unfortunately, da Vinci never worked as a professional anatomist; he never taught the subject and never published his observations which would have greatly advanced the science of anatomy (Anatomy Lesson #20, Arms! Arms! Arms! – Redux). In the meantime, dissection at universities continued to involve lecturer, barber surgeon, demonstrator of anatomy and Galen.

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Image H: Human Skeleton by Leonardo Da Vinci

Our next major milestone is embodied by one Andreas Vesalius (1514 – 1564); born in Brussels, he descended from a long line of medical men. During his studies at University of Paris, he became convinced that human dissection was vital to understanding structure and function (Image I). To that end, he visited gallows and cemeteries to obtain specimens which he studied until he could identify any human bone blindfolded. Later, at the University of Padua, he graduated as Doctor of Medicine with highest distinction and the following day, at 23 years old, he was appointed Professor of Surgery! With good reason Vesalius is generally considered the “father” of modern human anatomy.

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Image I: Andreas Vesalius by Edouard Hamman

Understand that at this time, professors believed Galen’s teaching so infallible that should dissections yield information contrary to his writings then either the cadaver was abnormal or mankind’s decadence and degeneration had caused anatomy to change since Galen!

Discovering by direct observation that 1400 years of Galen’s anatomy were wrong, Vesalius performed a public dissection to demonstrate correct anatomy and dissuade those attached to Galen’s theories (Image J – yes, it was a woman). His public demonstrations continued and proved so successful they attracted medical students, physicians, civic officials, sculptors, and artists. While admired, Vesalius’ work also incurred wrath and vilification by those who considered Galen to be infallible.

The following is a brief list of Vesalius’ work that corrected Galen’s mistakes; his accomplishments are staggering:

  • Accurately described sphenoid and temporal bones (bones of skull)
  • Human sternum made of three fused bones (Anatomy Lesson #15)
  • Sacrum made of five fused bones (Anatomy Lesson #10)
  • Hepatic veins (of the liver)
  • Azygos vein (of thorax – Anatomy Lesson #15)
  • Ductus venosus (fetal blood vessel)
  • Omentum (large abdominal membrane)
  • Stomach and its pyloric region plus spleen, colon and appendix
  • Pleurae (membrane surrounding each lung)
  • Lungs
  • Brain and most of the cranial nerves (nerves arising from the brain)
  • Four chambers of the heart (Galen declared there were two)
  • Great vessels carrying blood to and from heart
  • Mandible as a single bone (Anatomy Lesson #26)
  • Ventilation (respiration)

Vesalius also proved that the human spine does not contain the revered bone of Luz, a bone that by religious and cultural tradition was deemed indestructible and required for resurrection of the body.

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Image J: Vesalius’ Public Dissection by Robert Tomm

In 1543 Vesalius wrote the monumental De Humani Corporis Fabrica (On the Fabric of the Human Body), the most comprehensive anatomical text yet written and arguably the greatest single contribution ever made to human anatomy. Fabrica displayed brilliant illustrations created as intricate woodcut plates by various artists from the “studio of Titian”. Bodies in varying degrees of dissection are arranged in allegorical poses complete with pastoral environs (Image K). During the 20th century, Vesalius’ original plates were housed in Munich but, sadly, a World War II bombing raid destroyed them.

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Image K

Again in 1543, Vesalius conducted a public dissection on the body of a notorious felon. Later, he assembled the bones and donated the skeleton to the University of Basel. This preparation (“The Basel Skeleton”) is the world’s oldest surviving anatomical preparation and is still displayed at the Anatomical Museum of the University of Basel (Image L).

Later, Vesalius served as court physician to Emperor Charles V and his son. He died at the age of 50 on a Greek island during a return trip from the Holy Land. To the present day it is claimed that Vesalius was forced on the pilgrimage for performing an autopsy on an aristocrat while the heart was still beating. Modern historians consider this story without merit because it was circulated by a competitor. There is an odd bit of wisdom that states, academic fights are so bitter because there is often so little at stake (grin)!

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Image L

Time for a brief break and another anatomy lesson from Mistress Beauchamp! This time she ascertains that Geordie’s femoral artery (Anatomy Lesson #9, The Gathering or Gore By a Boar) was not severed by the wild boar’s tusk so she should be able to stem the bleeding (Starz episode 104, The Gathering) . Sadly, this hopeful thought was quickly amended as she spied puir Geordie’s fatal abdominal wound. We read in Outlander book:

There was a deep wound, running at least eight inches from the groin down the length of the thigh, from which the blood was gushing in a steady flow. It wasn’t spurting, though; the femoral artery wasn’t cut, which meant there was a good chance of stopping it.

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Following the work of Vesalius, human anatomy enjoyed a brilliant burst of anatomical illustration; artists and anatomists sometimes competing for elegant form versus anatomical accuracy. The result is some of the most famous and astonishingly beautiful anatomic illustrations ever created. Consider the priceless 1632 painting by Rembrandt “The Anatomy Lesson of Dr. Nicholaes Tulp” (Image M). This painting recreates another public dissection and while undeniably elegant and riveting, it is also anatomically incorrect. Why? Well, because Rembrandt wasn’t an anatomist so details such as the correct origin of the long flexor muscles of the digits (see Anatomy Lesson #22, Jamie’s Hand – Symbol of Sacrifice) were misrepresented.

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Image M

Then, in 1871 an eight volume compendium Traite’ complet d’anatomie de l’homme (Complete Treatise of the Anatomy of the Man) was published by French anatomist Bourgery, and illustrator Jacob (Image N)! Their anatomical images combined accuracy with elegance and are amongst the most beautiful ever rendered.

Anatomical illustrations were created by other famous Renaissance artists such as Bidloo, Donatello, Michelangelo, Titan, Rembrandt, Albinus, D’Agoty, Genga, and Ruben. And, models depicting human anatomy exploded on the scene: carved from ivory, made of papier-mȃché, copper engravings, woodcuts, chalk, wax, bronze, and finally by the end of the 19th century, photography.

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Image N

Today’s anatomical “bible” is, of course, Gray’s Anatomy. My own 39th edition is a real door stopper! Weighing in at 10 pounds, the single-spaced text appears in size 8 font and more 1500+ pages in length! And, it still doesn’t contain all that currently is known about human anatomy.

The size of this giant tome is somewhat amusing as the book was conceived in the 1850s by 28 year old Henry Gray (Image O), a teacher at St. George’s Hospital Medical School, London. Sharing his idea with artist and colleague, Dr. Henry Vandyke Carter, who was also Demonstrator of Anatomy at St. George’s, the pair conceived a light weight (hee hee), well-illustrated, and accurate pocket text designed for students. The first edition (1858) was an instant success; periodically updated and enhanced, it has been published continuously for over 150 years!

Poor Henry enjoyed a successful but short life. While attending to a nephew ill with smallpox (Anatomy Lesson #21, Small Pox and the Devil’s Mark), Henry fell victim to the disease and swiftly died at the youthful age of 35.

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Image O

Please understand that a discussion of anatomical history is incomplete if limited to structures discoverable in a dissection lab as our bodies are made of cells and tissues elements that are invisible to the naked eye. Identifying these structures required the invention of magnifying lenses.

Enter Antonie van Leeuwenhoek (1632-1723), a Dutch draper (merchant of fabrics). Wishing to assess the quality of woven threads, Van Leeuwenhoek determined to improve their visibility. Microscopes existed in his time but the best could only magnify 9x – meaning 9 times the size of the object observed. Self-taught, Antonie began experimenting with glass processing and lens making. Working in a hot flame with small rods of soda lime glass, he created tiny, high-quality glass spheres to use as single lenses which he housed in small silver or copper frames – these became his simple microscopes (with one viewing lens). These tiny handheld instruments were only about 5 cm (2”) long but capable of 275x magnification! He created 25 simple microscopes, several of which still  survive (Image P).

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Image P

Turns out, van Leeuwenhoek examined much more than threads! Eventually he sent The Royal Society a manuscript, Microscopiorum, complete with written descriptions and meticulous drawings of single-cell life (called animalcules) including spermatozoa, red blood cells (erythrocytes), bacteria, yeasts and life forms in a drop of water, all observed with his microscopes. Although his lens research was heartily embraced by the Society, his biologic findings were initially met with skepticism and derision, an old but common experience in the field of science (Image Q).

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Image Q: 3rd edition of Microscopiorum

Fast forward three hundred years to a modern compound light microscope (Image R). Like the earliest microscopes, compound microscopes use light from the visible spectrum to illuminate an object but they also employ two lenses to achieve greater magnification: one near the eye and one near the object viewed, hence the term, compound.

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Image R

In the 1930s, the electron microscope was invented substituting a electromagnetic lens for glass. It also used a high voltage electron beam not light waves to illuminate an object. Today, there are different types of electron microscopes including the transmission (TEM) and scanning or (SEM) electron microscopes (Anatomy Lesson #6).

Typical TEMs magnify objects about 500,000x although some can magnify much more and are able to reveal subcellular structures. Image S shows a 1,000,000 volt electron microscope at the Max Planck Institute in Germany, one of only a handful in the world. In the ‘80s I took micrographs (photographs taken with a microscope) on one of these big boys in Colorado. The instrument was three stories tall and hummed like Luke Skywalker’s light saber!

Microscopes have opened a new world to researchers and students allowing health practitioners to understand the cellular and subcellular basis of health and disease.

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Image S

Time for another example of Claire’s anatomical expertise: who can forget the image of Jamie’s puir hand mangled by Black Jack the Ripper (Starz episode 116, To Ransom a Man’s Soul)?

Claire reveals her anatomical chops once again by describing the extent of Jamie’s wounds. Here from Outlander book:

I took his good hand as well, and felt carefully down each finger of both the good hand and the injured, making comparisons. With neither X rays nor experience to guide me, I would have to depend on my own sensitivity to find and realign the smashed bones… I began to lose myself in the concentration of the job, directing all my awareness to my fingertips, assessing each point of damage and deciding how best to draw the smashed bones back into alignment. Luckily the thumb had suffered least; only a simple fracture of the first joint. That would heal clean. The second knuckle on the fourth finger was completely gone; I felt only a pulpy grating of bone chips when I rolled it gently between my own thumb and forefinger, making Jamie groan.

What a woman! What a man!

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Back to our timeline: unfortunately, the explosion of anatomic knowledge and illustration from the time of Vesalius forward was marred by a dark underbelly: from 15th through the 19th centuries, bodies of executed criminals were relegated to the dissection lab as apt punishment for crimes. But, as capital punishment decreased, fewer bodies of criminals were available so some turned to grave robbing,  body snatching and even murder to meet supply and demand (Image T). Bodies were then sold for dissection to students, teachers and schools of medicine.

Body snatching, by the way, is the surreptitious disinterment of bodies after burial. Those practicing body snatching were called resurrectionists or “bag ‘em up boys” (urban speak has a different meaning, och!). These practices became such a problem that some cemeteries built watchtowers and families hired guards to protect the graves of their loved ones.

There follows some heartily unsavory tales: 1827-1828, two Irish fellows, Burke and Hare, immigrated to Scotland where they murdered 16 citizens near Edenborough to supply corpses for medical dissection. Not to be outdone, across-the-pond cities of Philadelphia, Baltimore, and New York were also  notorious for body snatching. But, England was the first to address such atrocities; the Anatomy Act of 1832 halted these activities by allowing unclaimed bodies and those donated by relatives to be used for the study of anatomy, and requiring the licensing of anatomy teachers. Unfortunately, many unclaimed bodies were those of poor people relegated to workhouses during a time when dissection was considered a just punishment for being poor!

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Image T: Painting from a public house in Penicuik, Scotland

Finally, during the second half of the 20th century, universities, medical schools and hospitals employed trained anatomists for teaching and research. In addition, voluntary body donation programs arose as primary sources of bodies for anatomical dissection.

Nowadays, worldwide innovative programs are being introduced into body donation programs by medical schools to teach students respect, compassion and empathy towards the human body, dead or alive. Thus, human dissection is indispensable for many reasons:

  • Teaches structure of the human body
  • Provides the language of medicine
  • Forms student’s first health care team
  • Increases powers of observation
  • Demonstrates anatomical variations as no two bodies are alike!
  • Introduces student to pathology  (abnormal anatomy)
  • Becomes  the student’s first patient
  • Promotes humane qualities among future health care providers
  • Allows surgeons and other specialists to safely develop new surgical techniques
  • Provides new anatomical knowledge through research

At my university, I served three major roles: course director of gross anatomy, director of the body donation program, and demonstrator of anatomy (state legislated position). I also taught microscopic anatomy and embryology.

At the termination of the gross anatomy courses for which I was responsible, students (under supervision) organized and presented memorial services to honor body donors and their families. Poems, readings, music and numerous thank you messages were shared by the students with the families, after which donor families were invited to respond. No dry eyes in that auditorium!

I’ve enjoyed teaching human anatomy to almost four decades of students: medical, physical therapy, physician assistants, respiratory technologists, and nursing students as well as surgeons and surgical residents, and the public (Image U – the excited grins are because a person recognized an anatomical structure they had always wondered about – no one was being disrespectful).

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Image U: 2011 Body World Exhibit

I have had the privilege of dissecting and teaching dissection with more than 500 donor bodies and I deeply thank them for the privilege of learning from their temples of flesh. I can candidly state that dissecting the human body is an awe-inspiring honor that has forever changed me (Image V).

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Image V: 2011 Body World Exhibit

This brings our saga of human anatomy to an end and will be my last anatomy lesson for 2015. I will continue to post anatomy Fun Facts until January of the New Year and then, a new anatomy lesson! Wishing you all the grandest and most glorious season ever!

Och, but dinna despair. The last words of this lesson are from Claire (and Jamie) who gave the world the finest appraisal and greatest appreciation of male human anatomy in the history of written literature (Starz episode 107, The Wedding). Snort!

Herself writes:

Because I want to look at you,” I said. He was beautifully made, with long graceful bones and flat muscles that flowed smoothly from the curves of chest and shoulder to the slight concavities of belly and thigh. He raised his eyebrows. “Well then, fair’s fair. Take off yours…”

Whew! Alrighty then – amen and amen!

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A deeply grateful,

Outlander Anatomist

Photo creds: Starz,, Bender, G. A. Great moments in Medicine. Northwood Institute Press, 1966 (Images F and J), Delaunay, ed., 1829 (Image N), Fasciculus Medincinae (compendium, authors unknown), 1491 (Image G), Greenspan, Robert E. Medicine Perspectives in History and Art, 2006 (Images H & M), Jean-Baptiste Marc Bourgery and Nicolas-Henri Jacob. Traite’ complet d’anatomie de l’homme, 1832- 1851. (Image N), Moore, Keith L. and Dalley, Arthur F. Clinically Oriented anatomy. Philadelphia: Lippincott, Williams & Wilkins, 2006. (Image B), Outlander Anatomist, private collection (Images U & V), Smithsonian, December 2015. (Image C), www.anatomymyatlases.org (Image L), www.ancientpeoples.tumblr.com (Image E), www.colepaler.com (Image R), www.en.wikipedia.org Images A, K, O & T), www.fotolibra.com (Image Q), www.steninageo.com (Image S), www.study.com (Images D & P), www.thephysicianspalate.com (Image I)

EyeMax – “The Eye, Part 5”

Greetings anatomy students! Whew! Nine weeks have elapsed since our first eye lesson and today marks the final installment about the effective, efficient, elegant eye. So, welcome to today’s Anatomy Lesson #33, EyeMax – The Eye – Part 5.

The lesson contains some fun tests to perform with our eyes. You know the drill: try this – try that. It also includes possible spoiler alerts with excerpts from two of Diana’s later books; as always, no names, no dates, and no places are revealed.

Let’s begin where we left off with The Eye – Part 4. We have already covered most eye structures so today we will finish with two humors of the globe, retina and visual centers of the brain.

You may recall that the eyeball has three important chambers: anterior chamber between iris and cornea (Photo A, red area); posterior chamber between iris, lens and suspensory ligaments  (Photo A, green area); and the large vitreous chamber behind the lens (Photo A, blue area). You may also recall the ciliary body (Photo A, red arrow); it contains the ciliary muscle, attaches to suspensory ligaments/zonular fibers (Anatomy Lesson #32), and produces aqueous humor (humour).

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Photo A

As watery  aqueous humor is made by the ciliary body, it collects in the posterior chamber and then flows forward through the pupil into the anterior chamber (Photo B). A spongy trabecular meshwork fills the angle between cornea and iris (Photo B) and contains the canal of Schlemm, a circular lymphatic-like vessel. From the anterior chamber, aqueous humor drains into the canal of Schlemm and from there into the venous system. A normal eye produces and absorbs about 3-4 ml (~¾ tsp.) of aqueous humor every 24 hours; a delicate balancing act thus exists between production and absorption of this fluid..

Aqueous humor serves two main purposes; it provides oxygen and nutrients to parts of the avascular lens and cornea and it assists the corneal refraction of light rays.

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Photo B

For those preferring a video, this gif shows production and absorption of aqueous humor:

But, sometimes the unthinkable happens and production of aqueous humor outstrips absorption. The eye is a closed system (no external opening), so if aqueous humor builds up, then intraocular pressure (IOP) rises. Known as glaucoma, this condition must be diagnosed and controlled with medication or surgery (or both) otherwise the optic nerve may be damaged resulting in decreased vision or blindness. Understand that glaucoma is not a single condition, rather, there are several different types of glaucoma.

POSSIBLE SPOILER ALERT and Clinical Correlation #1: In Diana’s 6th book, A Breath of Snow and Ashes, our ever resourceful Claire treats a patient with an acute attack of closed-angle glaucoma (a true medical emergency)!

I had long suspected that the cause of (her) blindness was glaucoma—rising pressure inside the eyeball that if untreated eventually damages the optic nerve. She was plainly having an acute attack… I abstracted the largest needle, a three-inch length of steel… The left eye bulged noticeably beneath its lid, vividly bloodshot… With a quick prayer to Saint Clare—who was, after all, patroness of sore eyes, as well as my own patron saint—I ran the needle through the flame of the lamp, poured pure alcohol onto a rag, and wiped the soot from the needle. I shoved the needle hard into the sclera of the eye, near the edge of the iris.

Closed-angle glaucoma occurs because the Canal of Schlemm is blocked or does not drain properly so aqueous humor accumulates with a sudden and dramatic increase in IOP (Photo C). Although crude, Claire’s 18th century treatment (no access to modern medications and procedures!) released aqueous humor from the anterior chamber relieving IOP. Her treatment could not restore sight, but it could offer the patient temporary relief from horrific pain.

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Photo C

The vitreous humor (vitreous body) is a transparent, avascular gelatinous mass occupying the vitreous chamber (see Photo A). Photo D is a model illustrating the vitreous as a blue mass marked by the black line. Vitreous humor is mostly water but other molecules lend it a gel-like consistency although it may liquefy with age. Unlike aqueous humor, the vitreous is not continuously renewed. Vitreous humor serves three important functions: it fills the globe augmenting its spherical shape, it secures the retina by pressing it against the choroid coat (see Photo A), and it helps refraction of light rays.

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Photo D

Now, let’s consider the complex retina and its parts. The extensive retina covers about 65% of the inner surface of the eyeball (Photo E – yellow layer).

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Photo E

As an eye specialist peers into your eye via ophthalmoscope, the fundus or back of the eyeball is revealed. In everyday terms, the photographic red eye is a reflection of light from the fundus of the eye.

Viewing the fundus reveals the inner surface of the retina, an extension of the brain. Photo F is the fundus of a right eye and Photo G is the fundus of a left eye. Each black arrow points to the bright optic disc or blind spot, where the optic nerve (Cranial Nerve II) forms; sight is absent at the blind spot because it lacks photoreceptors (see below). Red branches emerging/converging at each optic disc are retinal vessels that provide oxygen and nutrients to or remove waste products from the inner retina. Blue arrows point to the maculae (pl.), pale regions each containing a dark central spot, the fovea (orange arrows). Each fovea contains the fovea centralis, a central pit marking the site of greatest visual acuity.

Fundic examination is important because it helps reveal the health of the retina; it is also the only site where the microcirculation (small blood vessels) can be observed and the only region where part of the brain can be seen directly without tissue disruption or intervention.

Clinical Correlation #2: Macular degeneration (MD) is a common disorder causing decreased visual acuity and even blindness. This condition is aptly named because retinal cells of the maculae are damaged along with other associated changes. There are several types of MD with various risk factors but the most common is age-related MD and it is considered incurable. As always, science presses onward and (mostly) upward! Last month London eye surgeons treated a British patient using a tiny patch of stem cell-derived tissue to successfully restore eyesight lost through macular degeneration!

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Photo F

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Photo G

Hey, hey, students!  Are ye awake and paying attention?  JAMMF is checkin’ ye out just to be sure!

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Try this: Let’s test our blind spots the sites where optic nerves form. Close your left eye and stare with your right eye at the cross in Photo H. You should see the elephant in your peripheral vision but keep focused on the cross. If you can’t see the elephant, then move away from the screen until you can. While looking at the cross, slowly move closer to the screen. At about one foot (~ 31 cm) away from the cross, the elephant will disappear from view because its image is falling on your right blind spot! Now, for fun, close the right eye and stare at the elephant. Move in and out until the cross disappears; again, this happens because its image is falling on your left blind spot. Excellent job, students!

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Photo H

Try this: Let’s test our fovea centrales (pl.) by staring at the words “Jamie and Claire” in the sentence below; these words should be crisp and clear because their images fall directly on the fovea centrales of our retinae (pl.), sites of greatest visual acuity. Notice that the remaining words of the sentence are unclear because their images fall elsewhere on the retinae where vision is less acute.

FANS ARE HEAD OVER HEELS FOR JAMIE & CLAIRE, OUR FAVORITE SI-FI CHARACTERS.

Returning to retinal anatomy Photo I (right side) shows an enlarged graphic representation of the retina. The retina has about 10 named layers, but for this lesson we will cover only three.

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Photo I

Photo J is a schematic of a wee bit of retina (cornea lies to the left). The yellow arrow shows light rays approaching the retina. The black arrow shows that light rays pass through the retina until they reach a layer of  rods and cones, two types of photoreceptor cells. Some light rays bypass the rods and cones to reach the deeper retinal pigment epithelium or RPE (Photo J – green arrows). RPE contains brown melanin that absorbs extraneous light rays bypassing rods and cones and thus improving our quality of vision.

To the left of the RPE are the photoreceptive rods and cones. Cones (Photo J – lavender cells) are responsible for chromatic (color) vision. Rods (Photo J – yellow cells) are responsible for achromatic (non-color) vision. To the left of rods and cones are several other retinal cell types which we will not cover. However, the innermost layer are ganglion cells; their processes (axons) form the optic nerve (Photo J – blue cells).

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Photo J

Photo K shows rod and cone cells by scanning electron microscopy (RPE is absent); the names derive from the shape of their outer segments. Rods cells have long, thin outer segments (Photo K – grey columns). Cone cells have cone-shaped outer segments (Photo K – artificially colored blue, green or red). Rod and cone outer segments contain photosensitive molecules that respond to light.

Each human retina contains about 120 million rod cells that are absent from the fovea but increase in numbers away from the fovea. Rods contain one type of photosensitive molecule, respond to dim light and are used for night vision; they play little or no role in color vision. Amazingly, experiments have shown that a single photon (elementary particle) of light can activate one rod cell.

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Photo K

The retina contains about 6 million cone cells that are concentrated in the fovea but decrease in numbers away from the fovea. Cones contain one of three types of photosensitive molecules that vary slightly in configuration: L cones respond to red (long-wave length) light, M cones respond to green (medium-wave length) light and S Cones respond to blue (short-wave length) light. Working together, the three types of cones give us color vision (Photo L). Cones function best in bright light, perceive finer visual details and respond faster to stimuli than rods. The cone-rich fovea is the only area of the retina where 20/20 vision is achievable and is critical for seeing fine detail and color. Truly fascinating fact: recent studies suggest that some women may have a fourth type of cone and perhaps a broader perception of color although future studies are needed to define this phenomenon.

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Photo L

Hey now! Don’t get all bleary-eyed on me. Take after Himself here and open up them peepers! There’s more to come!

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Clinical Correlation #3: As you are aware, some folks are red-green color blind lacking the inability to detect green and/or red colors. About 1 in 50 people, mostly men, lack functioning red- and/or green-sensitive cones, leaving them able to experience only one or two main colors.

Try this: Gaze at Photo M – left image; what do you see? Gaze at Photo M – right image; what do you see? People with normal color vision see a faint number 42 in the left image and the number 12 in the right. People who are red-green color blind cannot see either number.

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Photo M

Clinical Correlation #4: Most humans see a wondrous array of colors such as the dishes of powered pigments shown in Photo N. But, some people have achromatopsia meaning they see no color at all and their visual experience consists of different shades of grey ranging from black to white, a bit like images from a black and white TV set (Photo O). Achromatopsia is extremely rare, effecting about one in 33,000 persons.

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Photo N

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Photo O

Try this: Here’s one last demonstration to compare differences between rods and cones. In 2002, neurobiologist Margaret Livingstone found that the Mona Lisa (Photo P) demonstrates the different processing capabilities of rods and cones. Because da Vinci painted the lips with low-detailed brush strokes, rods perceive this feature better than cones. The eyes were painted with high-detailed brush strokes best perceived by cones. Thus, her test subjects who stared at the mouth, saw the lass as less cheerful than if they focused on her eyes. As Livingstone put it, “She smiles until you look at her mouth, and then it fades, like a dim star that disappears when you look directly at it.” Try it and see if it works for you.

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Photo P

Now, time has come to put everything together. Take a deep breath and let’s “see” how normal vision works in three easy steps! Ha, ha.

Step #1 – Light from object to retina: think of each eye as a separate camera and imagine looking at a stop sign (Photo Q). Because each eye faces forward and is housed in a different bony orbit, each eye detects a slightly different image of the stop sign. As light rays travel from the stop sign, they strike the corneas and are refracted; then, lenses and humors add further refraction such that the image arrives at the retina upside down and backward (Photo Q). I didn’t mentioned this wee fact before but ‘tis true!

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Photo Q

Step #2 – Light activation of rod and cone cells: Light rays from the stop sign pass through the retinal layers (Photo R – box 1) to reach rods and cone cells. Photons strike photosensitive molecules of rod and cone cells (Photo R – box 2) and presto, MAGIC! Just joshing you…. Light rays striking the photosensitive molecules causes them to undergo phototransduction, a complex process wherein light photons are converted into electrical signals that propagate back through the retinal cells to the ganglion cells (Photo R – box 3). Signals reach the ganglion cells and follow their axons to the optic nerve (Photo R – box 4).

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Photo R

Step #3 – Projection of visual electrical signals to the brain: This step is challenging but stay with me, students! Step three is where everything comes together!

NOTE: Photo S is a schematic of eyes, optic nerves and brain as if seen from a patient’s feet; thus, the subject’s right is on your left! OK, hold on and let’s go!

Retinal signals from the stop sign image follow the optic nerves, each a bundle of about one million axons. Optic nerves form at the back of each eyeball and meet just behind the pituitary gland at the optic chiasm (Photo S). Here nasal retinal nerve fibers cross over such that fibers carrying signals from the right temporal retina (lavender) and the left nasal retina (lavender) project to the right visual cortex (lavender) of the brain; fibers carrying signals from the left temporal retina (green) and the right nasal retina (green) project to the left visual cortex (green). The visual cortices (pl.) are located in right and left occipital lobes of the brain. Crossing over (decussation) of the nasal fibers aids in the integration of visual information. After the chiasm, the optic nerves are renamed optic tracts. Optic tracts have other connections along the way to the visual cortices but these are beyond the scope of this lesson.

Try this: Open fingers of one hand and grip the most projecting part of the back of your skull; this is your occipital bone (from Latin ob, behind, and caput, head). Both occipital lobes lie deep to the occipital bone.

Visual cortices are essential for vision because, here, the stop sign image from each retina is received as electrical signals. Occipital cortices integrate info, recognize form, identify objects, determine location, evaluate spatial cues, detect motion and provide memory. They also augment depth perception where visual fields from both eyes overlap (Photo S – binocular field). The cortices also relay info to other brain sites involved with balance, meaning, etc.

Understand that if vision is normal, all three steps occur in fractions of seconds. Neuroscientists perform numerous studies to discern how the visual cortices work. Simply put, eyeballs collect visual information but we “see” with our brains!

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Photo S

Peek to the right…peek to the left…do you see what I seeee?

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Possible Spoiler Alert: Speaking of depth perception, our genius author, Diana, writes about binocular vision in her 5th  book, The Fiery Cross: here our beloved Claire treats another patient:

“You don’t have any binocular vision,” I said… He looked down into the palm of his hand, closing one eye, then the other, as though some answer might be found among the lines there. “Your eyes are fine,” I assured him. “It’s just that they don’t work together… for one reason or another, the brain never learns to merge the images coming in from both eyes in order to make a three-dimensional image.”

The ability to see in three dimensions is called depth perception, binocular vision or stereoscopic vision. Claire (Diana, snort!) is absolutely correct; if the eyes (and extraocular muscles) are otherwise normal, the ability to see in 3-D occurs in the brain. Recall that each eye collects a slightly different version of an object because our eyes face forward and each lies in a different bony orbit (if our eyes were on the sides of our heads we would not enjoy depth perception). The visual data from the two slightly different images are sent to visual centers of the occipital lobes and there is integrated into a single 3-D image. Our amazing brain does this instantaneously without conscious direction!

Try this: Photo T is a pair of stereoscopic photos of the moon. With your face about 10 cm / 16 inches from the screen, widen your eyes slightly. Now, gently start to cross your eyes until the moons fuse into a 3-D moon in the center. If you can perceive the depths of the moon’s cratered surface, this is was done by your remarkable brain! Did it work? If not, try the next image.

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Photo T

This is a pair of stereoscopic images of Machu Picchu each overlain with a red diamond and an outline of the hand (Photo U). Gaze at the two images using the screen distance mentioned above. Gently cross eyes until the two diamonds fuse into one central 3-D diamond. See the city with mountains behind it? Grand!

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Photo U

Some students have asked for explanations of nearsightedness and farsightedness so let’s finish the lesson with these topics. The following are simplistic explanations because optical science is detailed.

Myopia, also known as being nearsighted (US) or short-sighted (Britain), is a condition wherein light entering the eyeball focuses in front of the retina rather than directly on it (Photo V – left image). Close objects appear in focus but distant objects are blurry. In most instances, myopia is caused by an elongated eyeball or a steep corneal curvature and the eye’s lens cannot correct the problem. Nearsightedness can be treated with eyeglasses, contact lenses or refractive surgery.

Myopia can be corrected using a diverging lens that spreads light rays from distant objects bringing them to focus on the retina (Photo V – right image). An eye specialist determines the correct lens for myopia using optical measurements of the eye.

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Photo V

This is a startling statistic: twenty-five percent of the world’s population is nearsighted and the rate is increasing (Photo W)! Evidence suggests that indoor living, close work (e.g. computers), and inside play are contributing factors. A recent Chinese study showed that children who played outdoors 40 minutes longer per day than a control group had a 23% reduced likelihood of developing myopia (JAMA, Sept. 15, 2015). Reminder of the adage, “use it or lose it!”

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Photo W

Hyperopia, also known as farsightedness (US) or long-sightedness (Britain) is a condition wherein light entering the eyeball focuses behind the retina rather than directly on it (Photo X – left image): close objects appear blurry but distant objects are in focus. In most instances, the eyeball is too short or the cornea is too flat and the eye’s lens cannot correct the problem. Farsightedness can be treated with eyeglasses, contact lenses or a lens implant.

Hyperopia can be corrected using a converging lens that bends light rays from near objects to focus on the retina (Photo X – right image). Again, an eye specialist determines the correct lens for hyperopia using optical measurements of the eye.

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Photo X

Okay, students, the bell just rang and this lesson is over. But, let’s not leave without at least one more glimpse of Jamie! Okay, how about two? Mmphm…..as ye ken, Starz episodes contain a plethora of subtleties that are spied using our astute and wonderful vision.

Here’s a good  example: do ye ken the scene wherein Jamie flips Dougal the middle finger? In western cultures giving someone the finger or flipping someone “the bird” communicates extreme contempt. Oh, you dinna believe Jamie did that to Dougal? Well, look closely (Starz, episode 102, Castle Leoch): remember when Jamie takes a beating for Longhair and her loose ways? He bows to Colum and then glares at his uncle Dougal. Yep, that’s the one!

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That beating was administered by Rupert but was orchestrated by the masterfully manipulative Maestro Dougal. See Jamie’s shrewd subtle show of utter contempt for his black-booted uncle? Here, this one’s for you, big bad-ass brother of my mother! Hee hee!

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That’s it! Hope you have enjoyed our last five anatomy lessons on the amazing, astounding, astonishing eye. Much more is known about the molecular biology and neurochemistry of vision but it is too detailed for our lessons. Let’s be grateful for our vision that is so easily taken for granted!

 

The Eyes Have It!

Now, let’s get this straight,

The eyes are just great,

As they bring our world into view!

Crisp vision’s a trait

That we shouldn’t berate,

Seeing clearly gives us a clue.

Please don’t agitate,

If a lens is your fate,

Not worth getting into a stew.

Let’s all celebrate,

The eyes are a gate,

Into the wonderful soul that is you!

 

A deeply grateful,

Outlander Anatomist

Photo creds: Starz, www.boundless.com (Photo E), www.brainhq.com (Photo L), www.colourblindawareness.org (Photos N, O), www.commons.wikimedia.org (Photo S), www.studydroid.com (Photo D), www.digital-photography-tips.net (Photo U), www.en.wikipedia.org (Photos A, F, G), www.faculty.virginia.edu (Photo J, by Benjamin Cummings), www.hobart.com (Photos P, V), www.kaiserscience.wordpress.com (Photo Q), www.livingwelldementia.org (Photo K), www.mikenudleman.com (Photo T), www.myeyes.com (Photo X), www.peoi.org/Courses (Photos H, M, P), www.healthisright.com (Photo C), www.seekingalpha.com (Photo W), www.studyblue.com (Photo B), www.vi.cl (Photo R), www.webvision.med.utah.edu (Photo I)