page_title: Medicine in the medieval Islamic world
section_title: Human anatomy and physiology
hierarchical_section_title: Medicine in the medieval Islamic world / Medical contributions / Human anatomy and physiology
caption_attribution_description: English: Drawing of the human nervous system with the pairs of nerves in different colors of ink from the manuscript of Mansur ibn Ilyas, Tashrih-i badan-i insan [Anatomy of the Human Body], National Library of Medicine, MS P 19, folio 11b. فارسی: صفحه‌ای از کتاب تشریح بدن انسان اثر منصور بن الیاس دانشمند ایرانی. Bahasa Melayu: Mansur ibn Ilyas: Tashrih-i badan-i insan [Anatomi Badan Manusia].
context_page_description: In the history of medicine, Islamic medicine is the science of medicine developed in the Islamic Golden Age, and written in Arabic, the lingua franca of Islamic civilization.
  Islamic medicine preserved, systematized and developed the medical knowledge of classical antiquity, including the major traditions of Hippocrates, Galen and Dioscorides. During the post-classical era, Islamic medicine was the most advanced in the world, integrating concepts of ancient Greek, Roman, Mesopotamian and Persian medicine as well as the ancient Indian tradition of Ayurveda, while making numerous advances and innovations. Islamic medicine, along with knowledge of classical medicine, was later adopted in the medieval medicine of Western Europe, after European physicians became familiar with Islamic medical authors during the Renaissance of the 12th century.
  Medieval Islamic physicians largely retained their authority until the rise of medicine as a part of the natural sciences, beginning with the Age of Enlightenment, nearly six hundred years after their textbooks were opened by many people. Aspects of their writings remain of interest to physicians even today.
context_section_description: It is claimed that an important advance in the knowledge of human anatomy and physiology was made by Ibn al-Nafis, but whether this was discovered via human dissection is doubtful because "al-Nafis tells us that he avoided the practice of dissection because of the shari'a and his own 'compassion' for the human body".
  The movement of blood through the human body was thought to be known due to the work of the Greek physicians. However, there was the question of how the blood flowed from the right ventricle of the heart to the left ventricle, before the blood is pumped to the rest of the body. According to Galen in the 2nd century, blood reached the left ventricle through invisible passages in the septum. By some means, Ibn al-Nafis, a 13th-century Syrian physician, found the previous statement on blood flow from the right ventricle to the left to be false. Ibn al-Nafis discovered that the ventricular septum was impenetrable, lacking any type of invisible passages, showing Galen's assumptions to be false. Ibn al-Nafis discovered that the blood in the right ventricle of the heart is instead carried to the left by way of the lungs. This discovery was one of the first descriptions of the pulmonary circulation, although his writings on the subject were only rediscovered in the 20th century, and it was William Harvey's later independent discovery which brought it to general attention.
  According to the Ancient Greeks, vision was thought to a visual spirit emanating from the eyes that allowed an object to be perceived. The 11th century Iraqi scientist Ibn al-Haytham, also known as Al-hazen in Latin, developed a radically new concept of human vision. Ibn al-Haytham took a straightforward approach towards vision by explaining that the eye was an optical instrument. The description on the anatomy of the eye led him to form the basis for his theory of image formation, which is explained through the refraction of light rays passing between 2 media of different densities. Ibn al-Haytham developed this new theory on vision from experimental investigations. In the 12th century, his Book of Optics was translated into Latin and continued to be studied both in the Islamic world and in Europe until the 17th century.
  Ahmad ibn Abi al-Ash'ath, a famous physician from Mosul, Iraq, described the physiology of the stomach in a live lion in his book al-Quadi wa al-muqtadi. He wrote:
  When food enters the stomach, especially when it is plentiful, the stomach dilates and its layers get stretched...onlookers thought the stomach was rather small, so I proceeded to pour jug after jug in its throat…the inner layer of the distended stomach became as smooth as the external peritoneal layer.  I then cut open the stomach and let the water out.  The stomach shrank and I could see the pylorus…
  Ahmad ibn Abi al-Ash'ath observed the physiology of the stomach in a live lion in 959. This description preceded William Beaumont by almost 900 years, making Ahmad ibn al-Ash'ath the first person to initiate experimental events in gastric physiology.
  According to Galen, in his work entitled De ossibus ad tirones, the lower jaw consists of two parts, proven by the fact that it disintegrates in the middle when cooked. Abd al-Latif al-Baghdadi, while on a visit to Egypt, encountered many skeletal remains of those who had died from starvation near Cairo. He examined the skeletons and established that the mandible consists of one piece, not two as Galen had taught. He wrote in his work Al-Ifada w-al-Itibar fi al_Umar al Mushahadah w-al-Hawadith al-Muayanah bi Ard Misr, or "Book of Instruction and Admonition on the Things Seen and Events Recorded in the Land of Egypt":
  All anatomists agree upon that the bone of the lower jaw consists of two parts joined together at the chin. […] The inspection of this part of the corpses convinced me that the bone of the lower jaw is all one, with no joint nor suture.  I have repeated the observation a great number of times, in over two hundred heads […] I have been assisted by various different people, who have repeated the same examination, b
caption: Mansur ibn Ilyas: Anatomy of the human body (تشريح بدن انسان, Tashrīḥ-i badan-i insān), c. 1450, U.S. National Library of Medicine.
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