The word [interstice] is a derivation of the Latin term [interstitium] meaning "interval" or "spaces between". The plural form is [interstices]. The terms is used in anatomy to denote small spaces within a structure. As an example, bone marrow and venous sinuses are found in the [interstices] of the cancellous bone in the body of a vertebra.

The term is also used to describe different pathologies such as insterstitial cystitis and instertitial lung disease.

Word suggested by:Sara Mueller

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The word [parietal] has its origin in the Greek term [paries] meaning "wall". [Parietal] then means "pertaining to a wall", wall-related", or simply stated, "wall". Following are some examples of the use of this term.

The parietal bones of the cranium (os parietale), create the lateral "wall" of the cranium. These quadrangular bones join in the midline forming the sagittal suture. (see image). Click here for a detailed description of the parietal bone.

The term [parietal] is also used to denote membranes that are related to the body wall. The parietal peritoneum is the portion of the peritoneal membrane that is found away from the viscera and in relation to the abdominal wall.

The pleura is a membrane that lines the lungs, and it has a component that is related to the wall of the thorax. This is the [parietal] pleura.

There is a couple of cases where the use of term [parietal] is not related to a wall, but rather as "away from a viscus". An example of this would be the parietal pericardium, where the parietal component is the membrane that is away from the visceralpericardium.

An interesting use of the term is legal, where a [parietal] law, is used to denote a law that establishes boundaries or "walls" between legal parties.

Original image and links courtesy of bartleby.com

These two terms are related by the Greek root term [-gnos-] which means "knowledge".

The first word [diagnosis] has the prefix [dia-] meaning "apart" or "to take apart". [Diagnosis] then means "to discern", or in a more detailed explanation, it is "knowledge by taking apart", identifying a pathology by looking at all its components.

The second word [prognosis] has the prefix [pro-] meaning "forward". Prognosis is then "forward knowledge", an statement of outcome of the course of a pathology.

Words suggested by:Sara Mueller

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The term [coronary] comes from the Latin root [corona] meaning "crown", therefore [coronary] is used to denote a structure that surrounds another as a crown or a garland. In the heart, the coronary arteries and their branches form a crown that surrounds the heart at the level of the atrioventricular sulcus. There are two coronary arteries, the right coronary artery (RCA), and the left coronary artery (*). Both these coronary arteries are the only branches that arise from the ascending aorta.

The right coronary artery passes from the anterior to the posterior surface of the heart, ending in a terminal branch, the posterior descending artery, or PDA. The left coronary artery, sometimes called the "left main", gives origin to two branches: the circumflex artery (CFX) and the left anterior descending artery (LAD). Each one of these arteries gives origin to several named branches. 

There can be interesting anatomical variations in the coronary arteries of the heart. Heart and coronary artery anatomy is one of the topics developed and delivered by CAA, Inc.

Image property of: CAA.Inc..  Artist: Victoria G. Ratcliffe

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The Latin word [ventriculus] means "little sac" or "little belly" and arises from the Latin term [venter] meaning "belly" or "abdomen". Originally the term [ventricle] was used to denote the stomach. This use of the word has changed and now the term [ventricle] denotes a "sac" or "cavity", as in the "ventricles of the brain". The term [ventricular] means "pertaining or related to a ventricle".

In the case of the heart, the ventricles represent the two inferior chambers of the heart. (see image, items "C=right ventricle" and "D=left ventricle"). The anatomy of the right and left ventricles is quite different. The left ventricle has a thicker lateral muscular wall, almost three times thicker than the lateral wall of the right ventricle.

Image property of:CAA.Inc.Photographer:D.M. Klein

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The term [perineum] has two definitions:

1. It is the area of the trunk inferior to the pelvic diaphragm. As such, the perineum contains the ischioanal fossa, the urogenital diaphragm, and the superficial genitalia.

2. It is the area of the body between the upper thighs containing the external openings of urethra, vagina, and anus. This area is delimited (see image) by the symphysis pubis, ischial tuberosities, and coccyx.

The perineum, as described in the second definition, is formed by two large triangular regions. The anterior region (in purple) is called the urogenital triangle, and the posterior region (in yellow) is called the anal triangle. 

There is another definition in use that is wrong! Please understand that I post it here as an example only. "The perineum is the area that is found between the scrotum (or vagina) anteriorly and the anus posteriorly". This is NOT the definition of perineum, it is the definition or location of the perineal body, the center of the pelvic floor where 17 named muscles attach of cross. The muscles are:

• Iliococcygeus (2)
• Pubococcygeus (2)
• Superficial transverse perineal (2)
• Deep transverse perineal (2)
• Puborectalis (2)
• Bulbospongiosus (2)
• Pubovaginalis (2)
• Sphincter urethae (1)

Image property of: CAA.Inc.. Artist: D.M. Klein.
Word suggested and edited by:Dr. Sanford S. Osher, MTD Contributor