This term can be a suffix or a word by itself. It arises from the Greek Arabic  [στάσις] (stasis) and means "to stand still" or "to stop". This term can be found in several medical words:

• Hemostasis: Stoppage of blood flow

• Metastasis: The prefix [meta-] means "beyond", or "at a distance". Something that stops at a distance, such as a cancer tumor that stops away from the primary tumor

• Bacteriostasis: To stop bacteria. A [bacteriostatic] agent stops bacterial invasion

• Intestinal stasis: Stoppage of flow of intestinal content

The [ligamentum nuchae] is the Latin term to describe the nuchal ligament. It arises from the word [nucha] meaning the “back” or “nape” of the neck.

The ligamentum nuchae is a midline or median structure found in the posterior aspect of the neck. It is a fibroelastic tendon-like bilaminar structure with a triangular shape. Because of its location the ligamentum nuchae froms a septum that divides the posterior aspect of the neck in the midline providing an attachment for several muscles. These muscles are the trapezius, splenius capitis, rhomboid minor and serratus posterior superior.

The ligamentum nuchae attaches superiorly to the inion (external occipital protuberance) and the midline of the occipital bone. Inferiorly it attaches to the spinous process of C7 (vertebra prominens). Anteriorly it attaches to the posterior tubercle of C1 and all the cervical vertebrae in the midline. Interestingly, anatomical studies have shown the ligamentum nuchae to have small attachments to the spinal dural (thecal) sac superior and inferior to C1

There is a discussion as to the relationship of the ligamentum nuchae and the supraspinous and interspinous ligaments. Some say that the ligamentum nuchae is a discrete structure distinct from the supraspinous and interspinous ligaments, while others contest that the ligamentum nuchae is a continuation of the supraspinous and interspinous ligaments.

Thanks to Jackie Miranda-Klein for suggesting this article.

Posterior view of the head and neck. Image modified from the original: "3D Human Anatomy: Regional Edition DVD-ROM." Courtesy of Primal Pictures

Empedocles presented himself as an immortal god. Versed in magic and incantations, he was seen as a healer by people that followed him.

A philosopher, Empedocles developed the theory that nature consists of the combination of four “elements”— earth, water, air, and fire —with each of these elements being a combination of two qualities:  water is wet and cold, air is dry and cold, fire is dry and hot, and earth is wet and hot. Empedocles went further to explain that the combination of these elements is based on the balance of love and hate. The balance of the elements represented balance in life.

Further development of this theory by observation of the human body, led to the “Humor theory” or “bodily fluids” theory based on four fluids whose imbalance led to disease. The four humors were “blood” or sanguineous, which belongs to the air element, “phlegm”, which belongs to water, “yellow bile”, which corresponds to fire, and “black bile” or “melancholy” which corresponds to earth. This theory dominated human physiology and medicine until the 17th century.

Empedocles’ death is the stuff of legend. To maintain his image as a god, he threw himself into the Etna volcano to disappear. This was foiled as it is said that the volcano spew one of his golden sandals. Others said that he made a “divinity” party and after dinner when everyone was asleep he disappeared, making everyone believe he had risen to heaven. Fact is, we do not know.

Sources
1. “Mythical Conceptions of the Problem of the Unity of Culture” Tagliacozzo, G. Am Behav Scient Apr 1963; 6-8
2. “The Nature and Formation of Teeth According to Spanish Authors from the 16th to the 18th Centuries” Romero-Maroto, M. J Dent Res (2008) 87(2):103-106
3. “The evolution of Modern Medicine” Osler, W. 2nd Ed. Yale University Press 1922
4. “Empedocles” N Brit Rev Vol LXV (1866) 420-440

This term is originally Arabic  [nukha] and at the time of its first use it meant "spinal marrow".  It was used by Avicenna with this meaning around 1000 A.D.

Today it is used to mean the "nape" or the "back of the neck". Apparently at some point in time the Arab word [nukha] was confused with another Arab term [nugraf] which actually means "back of the neck". The error has persisted to our times. In French the word is [nuque] and in Spanish [nuca]. The term is used in some medical and anatomical terms such as:

• Ligamentum nuchae: Nuchal ligament. A thick ligament in the back of the neck that reinforces the supraspinous ligament

• Nuchal cord: An obstetrical condition where the umbilical cord is wrapped around the neck of the fetus

The fourth ventricle is one of the components of the ventricular system of the brain. It is a rhomboidal-shaped cavity located between the pons of the brain stem anteriorly and the cerebellum posteriorly.

The fourth ventricle is the last of the components of the ventricular system of the brain. It receives cerebrospinal fluid (CSF) from the Acqueduct of Sylvius, adds CSF produced in the choroid plexuses located in the roof of the fourth ventricle, and allows passageway of CSF to the external aspect of the brain and the subarachnoid space by way of a posteroinferior midline opening called the "foramen of Magendie". There are two small and sometimes absent or non-functional lateral openings to the fourth ventricle which also connect with the subarachnoid space called the "foramina of Luschka". These foramina are found at the end of the lateral recesses of the ventricle.

Posterior view of the 4th ventricle. The cerebellum has been opened in the midline