• Anatomist and Physician Andreas Vesalius, 1514
  

Vesalius was born to Andries van Wesele and Isabel Crabbe on 31 December 1514, in Brussels, which was then part of the Habsburg Netherlands. His great grandfather, Jan van Wesel, probably born in Wesel, received his medical degree from the University of Pavia and taught medicine in 1528 at the then newly founded University of Leuven. His grandfather, Everard van Wesel, was the Royal Physician of Emperor Maximilian, while his father, Anders van Wesel, went on to serve as apothecary to Maximillian, and later a valet de chambre to his successor Charles V. Anders encouraged his son to continue in the family tradition, and enrolled him in the Brethren of the Common Life in Brussels to learn Greek and Latin according to standards of the era.

In 1528 Vesalius entered the University of Leuven (Pedagogium Castrense) taking arts, but when his father was appointed as the Valet de Chambre in 1532, he decided to pursue a career in medicine at the University of Paris, where he moved in 1533. Here he studied the theories of Galen under the auspices of Jacques Dubois (Jacobus Sylvius) and Jean Fernel. It was during this time that he developed his interest in anatomy, and was often found examining bones at the Cemetery of the Innocents.

Vesalius was forced to leave Paris in 1536 due to the opening of hostilities between the Holy Roman Empire and France, and returned to Leuven. Here he completed his studies under Johann Winter von Andernach and graduated the next year. His thesis, Paraphrasis in nonum librum Rhazae medici arabis clariss. ad regem Almansorum de affectuum singularum corporis partium curatione, was a commentary on the ninth book of Rhazes. He remained at Leuven only briefly before leaving after a dispute with his professor. After settling briefly in Venice in 1536, he moved to the University of Padua (Universitas artistarum) to study for his doctorate, which he received in 1537.

On graduation he was immediately offered the chair of Surgery and Anatomy (explicator chirurgiae) at Padua. He also guest lectured at Bologna and Pisa. Previously these topics had been taught primarily from reading classic texts, mainly Galen, followed by an animal dissection by a barber - surgeon whose work was directed by the lecturer. No attempt was made to actually check Galen's claims; these were considered unassailable. Vesalius, on the other hand, carried out dissection as the primary teaching tool, handling the actual work himself while his students clustered around the table. Hands-on direct observation was considered the only reliable resource, a huge break with medieval practice.

He kept meticulous drawings of his work for his students in the form of six large illustrated anatomical tables. When he found that some of these were being widely copied, he published them all in 1538 under the title Tabulae Anatomicae Sex. He followed this in 1539 with an updated version of Galen's anatomical handbook, Institutiones Anatomicae. When this reached Paris one of his former professors published an attack on this version.

In 1538 he also published a letter on venesection, or bloodletting. This was a popular treatment for almost any illness, but there was some debate about where to take the blood from. The classical Greek procedure, advocated by Galen, was to let blood from a site near the location of the illness. However, the Muslim and medieval practice was to draw a smaller amount blood from a distant location. Vesalius' pamphlet supported Galen's view, and supported his arguments through anatomical diagrams.

In 1539 a Paduan judge became interested in Vesalius' work, and made bodies of executed criminals available for dissection. He soon built up a wealth of detailed anatomical diagrams, the first accurate set to be produced. Many of these were produced by commissioned artists, and were therefore of much better quality than those produced previously.

In 1541, while in Bologna, Vesalius uncovered the fact that all of Galen's research had been based upon animal anatomy rather than the human; since dissection had been banned in ancient Rome, Galen had dissected Barbary Apes instead, and argued that they would be anatomically similar to humans. As a result, he published a correction of Galen's Opera omnia and began writing his own anatomical text. Until Vesalius pointed this out, it had gone unnoticed and had long been the basis of studying human anatomy. However, some people still chose to follow Galen and resented Vesalius for calling attention to such glaring mistakes.

Vesalius, undeterred, went on to stir up more controversy, this time disproving not just Galen but also Mondino de Liuzzi and even Aristotle; all three had made assumptions about the functions and structure of the heart that were clearly wrong. For instance, Vesalius noted that the heart had four chambers, the liver two lobes, and that the blood vessels originated in the heart, not the liver.

Galen assumed arteries carried the purest blood to higher organs such as the brain and lungs from the left ventricle of the heart, while veins carried blood to the lesser organs such as the stomach from the right ventricle. In order that this theory could be correct some sort of holes were needed to interconnect the ventricles, and so in the spirit of Galen's time, he claimed to have found them, adjusting the facts to suit his theory. So paramount was the authority of Galen that for the next 1400 years, a succession of anatomists claimed to find these holes until finally Vesalius declared he could not find them. However, while Vesalius dared to admit he could not find these holes, he did not dream of disputing Galen on the distribution of blood, and so imagined it distilled through the unbroken partition between the ventricles.

Other famous examples of Vesalius disproving Galen in particular was his discovery that the lower jaw was only one bone, not two (which Galen had assumed from animal dissection) and his proof that blood did not pass through the interatrial septum.

In 1543, Vesalius conducted a public dissection of the body of Jakob Karrer von Gebweiler, a notorious felon from the city of Basel, Switzerland. With the cooperation of the surgeon Franz Jeckelmann, he assembled the bones and finally donated the skeleton to the University of Basel. This preparation ("The Basel Skeleton") is Vesalius' only well preserved skeletal preparation today, and is also the world's oldest anatomical preparation. It is still displayed at the Anatomical Museum of the University of Basel.

Later that year Vesalius asked Johannes Oporinus to help publish the seven volume De humani corporis fabrica (On the fabric of the human body), a groundbreaking work of human anatomy he dedicated to Charles V. Most believe it was illustrated by Titian's pupil Jan Stephen van Calcar. A few weeks later he published an abridged edition for students, Andrea Vesalii suorum de humani corporis fabrica librorum epitome, and dedicated it to Philip II of Spain, son of the Emperor.

Though Vesalius' work was not the first such work based on actual autopsy, nor even the first work of this era, the production values, highly detailed and intricate plates, and the fact that the artists who produced it were clearly present at the dissections themselves made it into an instant classic. Pirated editions were available almost immediately, a fact Vesalius acknowledged would happen in a printer's note. Vesalius was 30 years old when the first edition of Fabrica was published.

Soon after publication, Vesalius was invited as Imperial physician to the court of Emperor Charles V. He informed the Venetian Senate that he was leaving his post in Padua, which prompted Duke Cosimo I de' Medici to invite him to move to the expanding university in Pisa, which he turned down. Vesalius took up a position in the court, where he had to deal with the other physicians mocking him as being a barber.

Over the next eleven years Vesalius traveled with the court, treating injuries from battle or tournaments, performing pastes and postmortems, and writing private letters addressing specific medical questions. During these years he also wrote Radicis Chynae, a short text on the properties of a medical plant, whose use he defended, as well as defense for his anatomical findings. This elicited a new round of attacks on his work that called for him to be punished by the emperor. In 1551, Charles V commissioned an inquiry in Salamanca to investigate the religious implications of his methods. Vesalius' work was cleared by the board, but the attacks continued. Four years later one of his main detractors published an article that claimed that the human body itself had changed since Galen had studied it.

After the abdication of Emperor Charles V he continued at court in great favor with his son Philip II, who rewarded him with a pension for life and by being made a count palatine. In 1555 he published a revised edition of De Corporis.

In 1564 Vesalius went on a pilgrimage to the Holy Land. He sailed with the Venetian fleet under James Malatesta via Cyprus. When he reached Jerusalem, he received a message from the Venetian senate requesting him again to accept the Paduan professorship, which had become vacant by the death of his friend and pupil Fallopius.

After struggling for many days with the adverse winds in the Ionian Sea, he was wrecked on the island of Zakynthos. Here he soon died in such debt that a benefactor kindly paid for his funeral. At the time of his death he was scarcely fifty years of age.

For many years it was assumed that Vesalius's pilgrimage was due to pressures of the Inquisition. Today this is generally considered to be without foundation (C.D. O'Malley Andreas Vesalius' Pilgrimage, 1954) and is dismissed by modern biographers. It appears the story was spread by Hubert Languet, who served as de Saxe under Emperor Charles V and then under the Prince of Orange, who claimed in 1565 that Vesalius was performing an autopsy on an aristocrat in Spain when it was found that the heart was still beating, leading to the Inquisition condemning him to death. The story went on to claim that Philip II had the sentence commuted to a pilgrimage. The story re-surfaced several times over the next few years, living on until recent times.

In 1543, Vesalius asked Johannes Oporinus to help publish the seven volume De humani corporis fabrica (On the fabric of the human body), a groundbreaking work of human anatomy he dedicated to Charles V and which most believe was illustrated by Titian's pupil Jan Stephen van Calcar, though others believe was illustrated by different artists working in the studio of Titian, and not from Van Calcar himself.

A few weeks later he published another version of his opera, entitled De humani corporis fabrica librorum epitome (Abridgement of the Structure of the Human Body) more commonly known as Epitome, with a stronger focus on illustrations than text, so as to help readers easily understand his findings. The actual text of Epitome was an abridged form of his work in De fabrica, and the organization of the two books were quite varied. He dedicated it to Philip II of Spain, son of the Emperor.

The Fabrica emphasized the priority of dissection and what has come to be called the "anatomical" view of the body, seeing human internal functioning as an essentially corporeal structure filled with organs arranged in three dimensional space. This was in stark contrast to many of the anatomical models used previously, which had strong Galenic / Aristotelean elements, as well as elements of astrology. Although modern anatomical texts had been published by Mondino and Berenger, much of their work was clouded by their reverence for Galen and Arabian doctrines.

Besides the first good description of the sphenoid bone, he showed that the sternum consists of three portions and the sacrum of five or six; and described accurately the vestibule in the interior of the temporal bone. He not only verified the observation of Etienne on the valves of the hepatic veins, but he described the vena azygos, and discovered the canal which passes in the fetus between the umbilical vein and the vena cava, since named ductus venosus. He described the omentum, and its connections with the stomach, the spleen and the colon; gave the first correct views of the structure of the pylorus; observed the small size of the caecal appendix in man; gave the first good account of the mediastinum and pleura and the fullest description of the anatomy of the brain yet advanced. He did not understand the inferior recesses; and his account of the nerves is confused by regarding the optic as the first pair, the third as the fifth and the fifth as the seventh.

In this work, Vesalius also becomes the first person to describe mechanical ventilation.

"When I undertake the dissection of a human cadaver I pass a stout rope tied like a noose beneath the lower jaw and through the zygomas up to the top of the head... The lower end of the noose I run through a pulley fixed to a beam in the room so that I may raise or lower the cadaver as it hangs there or turn around in any direction to suit my purpose; ... You must take care not to put the noose around the neck, unless some of the muscles connected to the occipital bone have already been cut away...." -- Andreas Vesalius, 595:2 of Bynum & Porter, Oxford Dictionary of Scientific Quotations 2005

In 1538, Vesalius wrote Epistola, docens venam axillarem dextri cubiti in dolore laterali secandam (A letter, teaching that in cases of pain in the side, the axillary vein of the right elbow be cut) which demonstrated a revived venesection, a classical procedure in which blood was drawn near the site of the ailment. He sought to locate the precise site for venesection in pleurisy within the framework of the classical method. The real significance of the book attempt to support his arguments by the location and continuity of the venous system from his observations rather than appeal to earlier published works. With this novel approach to the problem of venesection, Vesalius posed the then striking hypothesis that anatomical dissection might be used to test speculation.

Skeletal system

• Vesalius believed the skeletal system to be the framework of the human body. It was in this opening chapter, or book, of De fabrica that Vesalius made several of his strongest claims against Galen's theories and writings which he had put in his anatomy books. In his extensive study of the skull, Vesalius claimed that the mandible consisted of one bone, whereas Galen had thought it was two separate bones. He accurately described the vestibule in the interior of the temporal bone of the skull.
• In Galen's observation of the ape, he had discovered that their sternum consisted of seven parts which he assumed held true for humans. Vesalius discovered that the human sternum only consisted of three parts.
• He also disproved the common belief that men had one rib fewer than women and noted that fibula and tibia bones of the leg were indeed larger than the humerus bone of the arm, unlike Galen's original findings.

Muscular system

• Vesalius' most impressive contribution to the study of the muscular system may be the illustrations that accompany the text in De fabrica, which would become known as the "muscle men". He describes the source and position of each muscle of the body as well as providing information on their respective operations.

Vascular and circulatory systems

• Vesalius' work on the vascular and circulatory systems was his greatest contribution to the complex and modern medicine. In his dissections of the heart, Vesalius became convinced that Galen's claims of a porous Intraventricular septum were false. It took until the second edition that he said that the septum was indeed waterproof, discovering (and naming), the mitral valve to explain the blood flow.
• Vesalius believed that the cardiac systole is synchronous with the arterial pulse.
• He not only verified Estienne's findings on the valves of the hepatic veins, but he described the Azygos, and discovered the canal which passes into the fetus between the umbilical vein and vena cava.
• He also took note of the inferior mesenteric and haemorrhoid veins.

Nervous system

• Vesalius defined a nerve as the mode of transmitting sensation and motion and thus refuted his contemporaries' claims that ligaments, tendons and aponeuroses were three types of nerve units. He believed that nerves do not originate from the heart, as was the Aristotelian belief, but that nerves stemmed from the brain.
• Upon studying the optic nerve, Vesalius came to the conclusion that nerves were not hollow.

Abdominal organs

• Although Vesalius accepted Galen's inaccurate claim that the liver was the locale of blood production, he would not accept that the vena cava stems from the liver. He also disproved Galen's belief that the liver consisted of five lobes, and stated that is, instead, two lobes.
• In De fabrica, he corrected an earlier claim he made in Tabulae about the right kidney being set higher than the left. Vesalius claimed that the kidneys were not a filter device for the urine to pass through but rather that the kidneys serve to filter blood as well and that the excrement then traveled through the ureters to the bladder.
• He described the omentum, and its connections with the stomach, the spleen and the colon gave the first correct views of the structure of the pylorus.
• He also observed the small size of the caecal appendix in man and gave the first good account of the mediastinum and pleura.
• Vesalius admitted that due to a lack of pregnant cadavers, he was unable to come to a significant understanding of the reproductive organs. However, he did find that the uterus had been falsely identified as having two distinct sections.

Heart

• Through his work with muscles, Vesalius believed that a criterion for muscles was their voluntary motion. On this claim, he deduced that the heart was not a true muscle due to its obvious involuntary nature of its motion.
• He identified two chambers and two atria. The right atrium was considered a continuation of the inferior and superior venae cavae and the left atrium was considered a continuation of the pulmonary vein.
• Interestingly, he also addressed the controversial issue of the heart being the center of the soul. He wished to avoid making any conclusions due to the possible conflict with contemporary religious beliefs.

Brain

• Vesalius' most significant contribution to the study of the brain was his trademark illustrations in which he depicts the corpus callosum, the thalamus, the caudate nucleus, the lenticular nucleus, the globus pallidus, the putamen, the pulvinar, and the cerebral peduncles for the first time.

Miscellaneous

• Vesalius introduced the notion of induction of the extraction of empyema through surgical means.
• Due to his impressive study of the human skull and the variations of its features he is said to have been responsible for the launch of the study of physical anthropology.
• Vesalius always encouraged his students to check their findings, and even his own findings, so that they could better understand the structure of the human body.
• In addition to his continual efforts to study anatomy he also worked on medicinal remedies and came to such conclusions as treating syphilis with chinaroot.
• Vesalius believed that the brain and the nervous system are center of the mind and emotion in contrast to the common Aristotelian belief that the heart was the center of the body.
• Claimed medicine was arranged into three parts: drugs, diet, and 'the use of hands' - mainly suggesting surgery and the knowledge of anatomy and physiology through dissection.
• Vesalius was a supporter of 'parallel dissections' in which an animal cadaver and a human cadaver are dissected simultaneously in order to demonstrate the anatomical differences and thus uncover Galenic errors.

Modern medicine is forever in debt to the efforts put forth by Vesalius and his ethic to provide the most accurate form of the human body. The manner in which Vesalius tended to his work could arguably be thought of as more significant than the work itself. By overthrowing the Galenic tradition and relying on his own observations, Vesalius created a new scientific method. His desire to strive for the truth is most evident through his ability to correct his own claims and to continually reshape his thoughts on the human body. Through his attention to detail, he was able to provide clear descriptions and unprecedented anatomical drawings that set a new standard for future medical books.

The influence of Vesalius' plates representing the partial dissections of the human figure posing in a landscape setting is apparent in the anatomical plates prepared by the Baroque painter Pietro da Cortona (1596 – 1669), who executed anatomical plates with figures in dramatic poses, most with architectural or landscape backdrops.

During the twentieth century, the American artist, Jacob Lawrence created his Vesalius Suite based on the anatomical drawings of Andreas Vesalius.