The ventricular system of the brain is an interconnected system of cavities and ducts within the brain through which cerebrospinal fluid (CSF) circulates. The CSF is produced in the choroid plexuses located within the ventricles.

 There are two large curved lateral ventricles, each found within a cerebral hemisphere. They connect with the third ventricle via an opening called the "foramen of Monro". The third ventricle connects with the fourth ventricle by way of a slender canal called the "cerebral aqueduct" or the "aqueduct of Sylvius".

The third ventricle is found deep within the brain between the right and left diencephalic portion of the cerebrum.

The fourth ventricle is located between the pons of the brain stem anteriorly and the cerebellum posteriorly. This ventricle has a rhomboidal shape and it connects with the external aspect of the brain and the subarachnoid space. Failure of this CSF drainage from the ventricles to the subarachnoid space can lead to pathological accumulation of CSF within the ventricles and hydrocephalus.

The line drawn image shows a lateral view of the brain with a superimposed image of the ventricular system. If you click on this image, you will see a superior view of a cast of the ventricular system (by Retzius). 

The dissection image shows a posterior view of the brain stem and the cerebellum which has been opened in the median plane to expose the 4th ventricle. Click on the image to see a larger version.

Line images in the public domain by Henry VanDyke Carter, MD. (Gray's Anatomy) Dissection images property of CAA, Inc. Photographer E. Klein

The cerebrospinal fluid (CSF) is a colorless, transparent fluid produced from the arterial flow of blood by the choroid plexuses found within the ventricular system of the brain. The CSF exits the ventricular system and enters the subarachnoid space and its cisterns. It is then absorbed at the level of the arachnoid granulations into the venous component of the cardiovascular system.

The CSF has many functions, some of them being protection, the creation of a fluid environment where the brain 'floats", cleansing, and others. For a more detailed description of the CSF, click here.

The CSF is produced at an average rate of 550-700ml/day. It is absorbed at the same rate. An imbalance between production and absorption of CSF (as well as a blockage within the ventricular system) can lead to an accumulation of CSF within the brain, causing hydrocephalus.

This article is part of the series "A Moment in History" where we honor those who have contributed to the growth of medical knowledge in the areas of anatomy, medicine, surgery, and medical research.

Hippocrates

Hippocrates of Cos (460 BC - 370 BC). A Greek physician, Hippocrates was born on the Greek island of Cos (Kos) c. 460BC. Considered the "Father of Medicine" he removed Medicine from the realms of superstition and magic. He was the first to record medical writings and is considered the first one to use and maintain proper medical terminology. There are many writing attributed to Hippocrates, but there is no assurance that these were actually written by Hippocrates himself. Hippocrates changed the art of medical diagnosis by replacing supernatural precepts with observation-based methodology. Natural, rather than supernatural causes, would from here on explain all disease processes, what was known as Rational Medicine.

He is known for having set the oath that governs medical principles, the Hippocratic Oath, although there are many authors that contend that this oath was written long time after he died.

Sources:
1. "Hippocrates himself" JAMA. 1968;204(12):1138-1139
2. "Hippocrates: father of medicine" Tan, S Y (01/01/2002). Singapore medical journal(0037-5675), 43(1), p.5.

Anterior view of the thorax, showing surface
relations of bones, lungs (purple), pleura (blue),
and heart (red outline).
P. Pulmonary valve. A. Aortic valve.
B. Bicuspid valve. T. Tricuspid valve

This is a combined word arising from terms [atrium], [ventricle], and [sulcus]. For the etymology of each word, click on the corresponding link.

The atrioventricular sulcus, also know as the "coronary groove" or "coronary sulcus" is an evident incomplete groove between the atria and ventricles of the heart. It is complete posteriorly and is separated anterosuperiorly by the roots of the aorta and the pulmonary trunk.  It contains the right coronary artery on the right side, and the circumflex artery on the left side, hence the name "coronary groove". These coronary arteries are not visible as they are usually covered by the epicardium and subepicardial fat.

The atrioventricular sulcus (and the corresponding coronaries) are also in relation to the deeper situated atrioventricular (AV) valves, the tricuspid valve on the right; and the mitral or bicuspid valve on the left side. The accompanying image depicts the location of the AV valves, and therefore the location of the AV sulcus. The image is an anterior view of the thorax, showing surface relations of bones, lungs (purple), pleura (blue), and heart (red outline). P. Pulmonary valve. A. Aortic valve. B. Bicuspid valve. T. Tricuspid valve 

Sources:
1. "The Origin of Medical Terms" Skinner, HA 1970 Hafner Publishing Co.
2. "Medical Meanings - A Glossary of Word Origins" Haubrich, WD. ACP Philadelphia
3 "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain
4. "Anatomy of the Human Body" Henry Gray 1918. Philadelphia: Lea & Febiger
Image modified by CAA, Inc. Original image by Henry Vandyke Carter, MD., courtesy of bartleby.com

This article is part of the series "A Moment in History" where we honor those who have contributed to the growth of medical knowledge in the areas of anatomy, medicine, surgery, and medical research.

Galen of Pergamum

Galen of Pergamon (129AD - 200AD).  A Roman physician of Greek origin, Galen is a seminal character in Medicine and Physiology for the ages. He has been known as Galen, Galenus, Aelius Galenus, Claudius Galenus, Claudius Clarissimus Galen, and Galen of Pergamus. He was born in 129 A.D. in a Roman-Greek community in Pergamum (today's Turkey). As a very young man, he studied Medicine at the Pergamum  temple of Asclepius.  After traveling for additional studies, Galen obtained the appointment of "physician to the gladiators" back at this hometown of Pergamum.

The post required of him to study and develop hygiene, preventive medicine, as well as dealing with the gladiator's injuries. The horrible wounds allowed him to observe and study human anatomy and develop incredible skills at treating battle wounds. Galen traveled to Rome, where he was appointed Physician to the Emperor Marcus Aurelius.

Galen performed human and animal anatomical dissections, writing over 300 medical, pharmaceutical, and philosophical treatises in Greek, many of which were translated into other languages, especially Latin and Arabic.

Even though most of the original books were lost, the translations and interpretations of Galen's work have survived until today. His teachings and dictums were considered undisputable for over 1,500 years. In fact, in Medieval times and early Renaissance doubting Galen's teachings was considered heresy!

Galen's name is preserved in the eponymical "Vein of Galen", the great central cerebral vein.

Sources:
1. "Claudius Galenus of Pergamum: Surgeon of Gladiators. Father of Experimental Physiology" Toledo-Pereyra, LH; Journal of Investigative Surgery, 15:299-301, 2002
2. "Galen: history’s most enduring medic" Tan, SY; Singapore Med J 2002:3 (43):116 –117
3. "Galen and His Anatomic Eponym: Vein of Galen" Ustun, C.; Clinical Anatomy 17:454–457 (2004)
Original image in the public domain, courtesy of the National Library of Medicine 

Click for a larger image

The temporal bone is a complex bone composed of several regions. The image shows an anterior view of the right temporal bone. To see the location of the bone, look at the inset that shows by transparency the location of the bone. Click on the image for a larger picture.

A. Squamous portion: From the Latin [squama], and meaning "scale-like", this portion of the bone is very thin, articulating with the parietal and sphenoid bones.

B. Zygomatic process: an anterior extension that articulates with the corresponding temporal process of the zygomatic bone.

C. Mastoid process: A Greek term from [-mast-] meaning breast, and the suffix [-oid] meaning "similar to".

D. Styloid process: Another Greek term from [stylos] meaning a "pillar", but also a "pen", therefore "shaped or similar to a pen". This is a slender and long inferior bony process. Close to the syloid process there are other processes, the pterygoid processes.

E. Petrous process: From the Latin [petrus] meaning "rock". The petrous process contains the components of the external auditory canal, the middle and inner ear, and a large canal through which passes the internal carotid artery.

First image modified from the original: "3D Human Anatomy: Regional Edition DVD-ROM." Courtesy of Primal Pictures.
Animation via Wikimedia Commons, public domain. Polygon data generated by Database Center for Life Science (DBCLS), CC BY-SA 2.1 JP.