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internal ear

History of anatomy

The history of anatomy as a science extends from the earliest examinations of sacrificial victims to the sophisticated analyses of the body performed by modern scientists. It has been characterized, over time, by a continually developing understanding of the functions of organs and structures in the body. The field of Human Anatomy has a prestigious history, and is considered to be the most prominent of the biological sciences of the 19th and early 20th centuries. Methods have also advanced dramatically, advancing from examination of animals through dissection of cadavers to technologically complex techniques developed in the 20th century.

Anatomy teaching is one of the cornerstones of a doctor’s medical education. Despite being a persistent portion of teaching from at least the renaissance, the format and the amount of information being taught has evolved and changed along with the demands of the profession. What is being taught today may differ in content significantly from the past but the methods used to teach this have not really changed that much. For example all the famous public dissections of the middle ages and early renaissance were in fact prosections. Prosection is the direction in which many current medical schools are heading in order to aid the teaching of anatomy and some argue that dissection is better. However looking at results of post graduate exams, medical schools (specifically Birmingham) that use prosection as opposed to dissection do very well in these examinations . This would suggest that prosection can fit very well into the structure of modern medical training.

Ancient anatomy

Egypt

The study of anatomy begins at least as early as 1600 BCE, the date of the ancient Egyptian papyrus. This treatise shows that the heart, its vessels, liver, spleen, kidneys,hypothalmus, uterus and bladder were recognized, and that the blood vessels were known to come from the heart. Other vessels are described, some carrying air, some mucus, and two to the right ear are said to carry the "breath of life", while two to the left ear the "breath of death". The Ebers papyrus (c. 1550 BCE) features a treatise on the heart. It notes that the heart is the center of the blood supply, with vessels attached for every member of the body. The Egyptians seem to have known little about the function of the kidneys and made the heart the meeting point of a number of vessels which carried all the fluids of the body – blood, tears, urine and sperm.

Greece

The earliest medical scientist of whose works any great part survives today is Hippocrates, a Greek physician active in the late 5th and early 4th centuries BCE (460 - 377 BCE). His work demonstrates a basic understanding of musculoskeletal structure, and the beginnings of understanding of the function of certain organs, such as the kidneys. Much of his work, however, and much of that of his students and followers later, relies on speculation rather than empirical observation of the body.

In the 4th century BCE, Aristotle and several contemporaries produced a more empirically founded system, based animal dissection. Works produced around this time are the first to identify the difference between arteries and veins, and the relations between organs are described more accurately than in previous works.

The first use of human cadavers for anatomical research occurred later in the 4th century BCE when Herophilos and Erasistratus performed dissections of cadavers in Alexandria under the auspices of the Ptolemaic dynasty. Herophilos in particular developed a body of anatomical knowledge much more informed by the actual structure of the human body than previous works had been.

Galen

The final major anatomist of ancient times was Galen, active in the 2nd century. He compiled much of the knowledge obtained by previous writers, and furthered the inquiry into the function of organs by performing vivisection on animals. His collection of drawings, based mostly on dog anatomy, became the anatomy textbook for 1500 years. The original text is long gone, and his work was only known to the Renaissance doctors through the careful custody of Arabic medicine. Hampered by similar religious restrictions as anatomists for centuries after him, Galen assumed that anatomical structures in dogs were the same as for humans.

Medieval anatomy

After the fall of the Roman Empire, the study of anatomy became stagnant in Christian Europe but flourished in the medieval Islamic world, where Muslim physicians and Muslim scientists contributed heavily to medieval learning and culture. The Persian physician Avicenna (980-1037) absorbed the Galenic teachings on anatomy and expanded on it in The Canon of Medicine (1020s), which was very influential throughout the Islamic world and Christian Europe. The Canon remained the most authoritative book on anatomy in the Islamic world until Ibn al-Nafis in the 13th century, though the book continued to dominate European medical education for even longer until the 16th century.

The Arabian physician Ibn Zuhr (Avenzoar) (1091-1161) was the first physician known to have carried out human dissections and postmortem autopsy. He proved that the skin disease scabies was caused by a parasite, a discovery which upset the theory of humorism supported by Hippocrates and Galen. The removal of the parasite from the patient's body did not involve purging, bleeding, or any other traditional treatments associated with the four humours. In the 12th century, Saladin's physician Ibn Jumay was also one the first to undertake human dissections, and he made an explicit appeal for other physicians to do so as well. During a famine in Egypt in 1200, Abd-el-latif observed and examined a large number of skeletons, and he discovered that Galen was incorrect regarding the formation of the bones of the lower jaw and sacrum.

Ibn al-Nafis

The Arabian physician Ibn al-Nafis (1213-1288) was one of the earliest proponents of human dissection and postmortem autopsy, and in 1242, he was the first to describe the pulmonary circulation and coronary circulation of the blood, which form the basis of the circulatory system, for which he is considered the father of the theory of circulation. Ibn al-Nafis also described the earliest concept of metabolism, and developed new systems of anatomy and physiology to replace the Avicennian and Galenic doctrines, while discrediting many of their erroneous theories on the four humours, pulsation, bones, muscles, intestines, sensory organs, bilious canals, esophagus, stomach, and the anatomy of almost every other part of the human body.

Early modern anatomy

The works of Galen and Avicenna, especially The Canon of Medicine which incorporated the teachings of both, were translated into Latin, and the Canon remained the most authoritative text on anatomy in European medical education until the 16th century. The first major development in anatomy in Christian Europe, since the fall of Rome, occurred at Bologna in the 14th to 16th centuries, where a series of authors dissected cadavers and contributed to the accurate description of organs and the identification of their functions. Prominent among these anatomists were Mondino de Liuzzi and Alessandro Achillini.

The first challenges to the Galenic doctrine in Europe occurred in the 16th century. Thanks to the printing press, all over Europe a collective effort proceeded to circulate the works of Galen and Avicenna, and later publish criticisms on their works. Vesalius was the first to publish a treatise, De humani corporis fabrica, that challenged Galen "drawing for drawing" travelling all the way from Leuven to Padua for permission to dissect victims from the gallows without fear of persecution. His drawings are triumphant descriptions of the, sometimes major, discrepancies between dogs and humans, showing superb drawing ability. Many later anatomists challenged Galen in their texts, though Galen reigned supreme for another century.

A succession of researchers proceeded to refine the body of anatomical knowledge, giving their names to a number of anatomical structures along the way. The 16th and 17th centuries also witnessed significant advances in the understanding of the circulatory system, as the purpose of valves in veins was identified, the left-to-right ventricle flow of blood through the circulatory system was described, and the hepatic veins were identified as a separate portion of the circulatory system. The lymphatic system was also identified as a separate system at this time.

17th and 18th centuries

The study of anatomy flourished in the 17th and 18th centuries. The advent of the printing press facilitated the exchange of ideas. Because the study of anatomy concerned observation and drawings, the popularity of the anatomist was equal to the quality of his drawing talents, and one need not be an expert in Latin to take part. Many famous artists studied anatomy, attended dissections, and published drawings for money, from Michelangelo to Rembrandt. For the first time, prominent universities could teach something about anatomy through drawings, rather than relying on knowledge of Latin. The only impediment was a possible reprimand from the Church, which frightened several anatomists of that time from performing dissections on their own kind. Though a very fruitful period for the sciences, the Renaissance could be dangerous, as seen in the case of Galileo. Some scientists were scared enough to keep moving from city to city. Descartes is a prime example. Only certified anatomists were allowed to perform dissections, and sometimes then only yearly. These dissections were sponsored by the city councilors and often charged an admission fee, rather like a circus act for scholars. Many European cities, such as Amsterdam, London, Copenhagen, Padua, and Paris, all had Royal anatomists (or some such office) tied to local government. Indeed, Nicolaes Tulp was Mayor of Amsterdam for three terms. Though it was a risky business to perform dissections, and unpredictable depending on the availability of fresh bodies, attending dissections was perfectly legal. Many anatomy students traveled around Europe from dissection to dissection during the course of their study - they had to go where a fresh body was available (eg after a hanging) because before refrigeration, a body would decay rapidly and become unsuitable for examination.

Many Europeans interested in the study of anatomy traveled to Italy, then the center of anatomy. Only in Italy could certain important research methods be used, such as dissections on women. M. R. Columbus and Gabriele Falloppio were pupils of Vesalius, the 16th century anatomist. Columbus, as his immediate successor in Padua, and afterwards professor at Rome, distinguished himself by rectifying and improving the anatomy of the bones, by giving correct accounts of the shape and cavities of the heart, of the pulmonary artery and aorta and their valves, and tracing the course of the blood from the right to the left side of the heart, by a good description of the brain and its vessels, and by correct understanding of the internal ear, and the first good account of the ventricles of the larynx. Osteology at nearly the same time found an assiduous cultivator in Giovanni Filippo Ingrassias.

19th century anatomy

During the 19th century, anatomists largely finalised and systematised the descriptive human anatomy of the previous century. The discipline also progressed to establish growing sources of knowledge in histology and developmental biology, not only of humans but also of animals. Extensive research was conducted in more areas of anatomy. England was particularly important in this research. Demand for cadavers grew so great there that body-snatching and even murder came into use as a means of obtaining them. In response, the English Parliament passed the Anatomy Act 1832, which finally provided for an adequate and legitimate supply of corpses by allowing dissection of destitutes. The relaxed restrictions on dissection provided a suitable environment for Gray's Anatomy, a text that was a collective effort and became widely popular. Now seen as unwieldy, Gray's Anatomy was born out of a need to create a single volume on anatomy for the traveling doctor.

The shift from the largely public displays of dissection in anatomy theatres to dissections carried out in classrooms meant that there was a drastic change in who could observe a dissection. Females for example, who at this time were not allowed to attend medical school, could broaden their knowledge by attending the anatomy theatres. So the shift from prosection to dissection meant a reduction in the number of people that could benefit from a single cadaver. At this point as well tighter regulation of the medical profession and donations of bodies resulted in various implications for carrying out dissections. Private medical schools which offered summer schools and various other courses involving cadaveric dissection allowed one route into gaining membership to the Royal College of Surgeons. However from 1822 the Royal College of surgeons would no longer accept these qualifications, this as result would see these largely unregulated schools begin to close . Not only as a result of this, but the Anatomy Act 1832 made it much harder (more bureaucracy) to obtain bodies for dissection. The act resulted in only the large teaching hospitals feasibly being able to continue teaching anatomy courses due to agreements with patients that if they donated their body they would receive free treatment. So towards the end of 19th century anatomy courses had been largely professionalised at established medical schools and public dissection was no longer common place.

Another source of anatomy teaching began with the foundation of many medical schools (particularly within the provincial medical schools) and the medical museums found within them. A large portion of training occurred within these up until and for some time after the Second World War. The medical museum was a very important and a lot of effort was put into creating something impressive. This was particularly so in provincial medical schools which were just being established that needed credibility not only from other medical schools (namely Oxford and the London teaching hospitals) but also from the public. The museums were not only for students but also members of the public paid to see the exhibits within the museum. This brought not only much needed income but prestige as well . The more exhibits within the museum the more established the medical school appeared to be (at least to the public). Significant amounts of teaching occurred in the museum as well with students claiming they learnt far more in the museum than they ever did in the lecture theatre. The decline of the museums within medical schools was largely due to the demand in floor space for teaching and new disciplines and less importantly the great improvements in photography and colour texts. For example the museum at Birmingham Medical School is now a computer cluster and teaching rooms, the only remains of the museum are the preserved specimens decorating the walls around the computer cluster.

Modern anatomy

Anatomical research in the past hundred years has taken advantage of technological developments and growing understanding of sciences such as evolutionary and molecular biology to create a thorough understanding of the body's organs and structures. Disciplines such as endocrinology have explained the purpose of glands that anatomists previously could not explain; medical devices such as MRI machines and CAT scanners have enabled researchers to study the organs of living people or of dead ones. Progress today in anatomy is centered in the development, evolution, and function of anatomical features, as the macroscopic aspects of human anatomy have been largely catalogued. The subfield of non-human anatomy is particularly active as modern anatomists seek to understand basic organizing principles of anatomy through the use of advanced techniques ranging from finite element analysis to molecular biology.

With increasing demands on the healthcare system and what could be deemed chronic under-training of doctors (numbers of doctors per capita compared to other industrialised countries) during the latter half of the 20th century, medical schools are now facing massive pressure to train as many doctors as possible. This has meant in recent years cohort sizes have doubled and more in size, in order to try and meet the demand. This has resulted in increased pressure of the facilities at all medical schools in the country. Anatomy is one department in particular that has had to evolve to accommodate the number of students. At Birmingham dissection was once essential to the teaching of anatomy but since the end of the 1980s the medical school has adopted prosection over dissection. At the time new directives from the General Medical Council (GMC) on the direction medical education was the major factor according the current head of anatomy. There are also many other reasons why prosection maybe favoured (discussed below). It has probably now become near impossible to restart dissection at Birmingham even if one wanted to. This is due to the fact that current prosection uses a very similar number of cadavers as dissection previously did. If dissection was to be brought back the number of cadavers would be very large due the current cohort size. To increase provision of prosection the medical school is currently investing in the region of £800,000-900,000 on a new prosectorium. This will allow up to about 40 students to observe prosected material in any one session. The vast amount of money required just to increase the amount of prosection demonstrates that it is no longer possible to carry out dissection at Birmingham (and is the case for many other universities). Prosection makes more efficient use of a cadaver when compared to dissection. A single cadaver when dissecting would be used by up to 5 students whereas prosection allows if necessary and entire cohort to observe the prosected cadaver. Prosection also allows students to observe more than one cadaver whereas in dissection you would tend to just use a single one. Logistically prosection allows more flexibility than dissection as there is no commitment to provide a cadaver per a certain number of students, this in fact create opportunities for cadavers to be used, for example at Birmingham, for Special Study Modules (SSMs) and postgraduate teaching.

Also there are many more aids to teaching anatomy then merely the prosectorium; improvements over the last century in colour images and photographs means that an anatomy text is no longer an aid to dissection but rather a central material to learn from. Plastic models are also regularly used in anatomy teaching sessions and they offer a good substitute to the real thing. One argument against plastic models is that they may provide a false sense of conformity in the human body; there is no doubt quite a difference between a plastic model and a prosected cadaver. Use of living models for anatomy demonstration is once again becoming popular within teaching of anatomy; during the 18th and 19th Centuries teaching with a live model was common site in an anatomy lecture. Anatomy is dynamic, for example the anatomy of the musculoskeletal system is by definition the anatomy of movement. So to provide an example of this to the audience (students) and be able to demonstrate the possible movements is beneficial. Surface landmarks that can be palpated on another individual also provide practice for future clinical situations. It is possible to do this on oneself and a good example of this being implemented is Integrated Biology at the University of Berkeley; students are encouraged to “introspect” on themselves and link what they are being taught to their own body. This may seem like a relatively obvious idea but to formally link it into teaching of anatomy should aid memory recall .

Donations of bodies have also declined in recent years with a marked decline of public confidence in the medical profession. With scandals such as Alder hay and Bristol, people are less confident that their wishes on what will happen to their body will be carried out, so instead have not donated to medical science when in the past they may have . The resultant legislation from these scandals (namely the Human Tissue Act 2004) has tightened up the availability of resources to anatomy departments. Another factor facing body donations is the problems arising from the outbreaks of Bovine Spongiform Encephalitis (BSE) in the late 80s and early 90s and the restrictions of handling of brain tissue that resulted from this. The exact pathology of the human form, variant Cruztfeld Yakub disease (vCJD) has meant that patients donating their body who suffered from Alzheimer’s or dementia and of course vCJD means their brains cannot be handled. As the method of transmission of these diseases and the link between them (i.e. is Alzheimer’s vCJD and vice versa) is not fully understood these precautions have to be taken . Very symptomatic patients are also not normally accepted for cadavers . However this means that students are more limited on what they can dissect within the head, this is particularly a problem in medical schools where dissection is still carried out. It is less of a problem where prosection is carried out as the specimen will have already been dissected.

Conclusion

Anatomy teaching has changed considerably over the last 1000 years though it is still very much at the heart of the philosophy of western medicine. Western medicine seeks to find a cause to all disease and attempt to cure it; very much cause and effect. Without a good understanding of the arrangement of the human body then this becomes somewhat challenging. Western medicine is in fact taking a more holistic approach today, with the psychosocial biomedical model of disease. However most practicing doctors if it was proven that there was a biological cause to all the various idiopathic diseases then they would readily adapt their thoughts and treatments accordingly. Anatomy is often regarded as being little left to discover, in that we know what and where most of the body is and does, but there is still many mysteries left to work out. Public awareness of anatomy cannot detrimental if it sparks interest in the discipline. The recent controversies with Gunther von Hagens and public displays of dissection may divide opinions on what is ethical (even the legality of a public dissection but this surely at least gets people thinking about how doctors learn anatomy and why in some it inspires them to pursue a career. The future of dissection may be uncertain and indeed if pressure on cadavers continues even the few medical schools that continue to do dissection may have to halt. This hopefully however will not reduce the number of people able to benefit from a single cadaver if current prosection methods become the prevalent method of demonstrating gross anatomy.

Notes

Bibliography

  • Porter, R. (1997). The Greatest Benefit to Mankind: A Medical History of Humanity from Antiquity to the Present. Harper Collins. ISBN 0-00-215173-1.

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