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.

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.

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.

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 courtesy of Images from the History of Medicine at nih.gov

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

This term has combined Greek components. The prefix [ect-] comes from [ectos], meaning "outside", and the root term [-top-] from [topos], meaning "place or location". The suffix [-ic] of course means "pertaining to". The word [ectopic] then means "outside its (normal) place or location".

The words has several uses. As an example, in atrial fibrillation, the atria of the heart will depolarize in abnormal or ectopic locations, causing a dysrhythmia. Another common use is in endometriosis, where there are abnormal or ectopic implantation sites of endometrium.