Dictionary

sinus barotrauma See aerosinusitis.

sinus node See sinoatrial node.

sinus rhythm The normal regular rhythm of the heart that is set by the sinoatrial (or sinus) node, which is located in the wall of the right atrium (the right upper chamber of the heart). Normal electrical impulses of the heart start there and are transmitted to the atria and down to the ventricles (the…

sinus tachycardia Fast heartbeat (tachycardia) that occurs because of overly rapid firing by the sinoatrial node. Sinus tachycardia is usually a rapid contraction of a normal heart in response to a condition, drug, or disease, such as pain, fever, excessive thyroid hormone, exertion, excitement, low blood oxygen level (hypoxia), or stimulant drugs, such as caffeine,…

sinusitis Inflammation of the lining membrane in any of the hollow areas (sinuses) of the skull around the nose. Sinusitis may be caused by anything that interferes with air flow into the sinuses and the drainage of mucous out of the sinuses. The sinus openings, called ostia, may be obstructed by swelling of the tissue…

situs inversus totalis See reversal of organs, total.

sixth cranial nerve See abducens nerve.

sixth disease See measles.

Sjogren’s syndrome An autoimmune disease that classically combines dry eyes, dry mouth, and another disease of the connective tissues, commonly rheumatoid arthritis, but sometimes lupus, scleroderma, polymyositis, or another autoimmune condition. Sjogren’s syndrome is an inflammatory disease of glands and other tissues of the body. Inflammation of the glands that produce tears (lacrimal glands) leads…

shunt 1 To move a body fluid, such as cerebrospinal fluid, from one place to another. 2 A vessel (tube) that is used as a passageway to transport fluid from one body area to another. For example, a spinal shunt carries cerebrospinal fluid from a ventricle in the brain to another area of the body….

shunt, ventriculoatrial A shunt that is used to drain fluid from the cerebral ventricle into the right atrium of the heart.

shunt, ventriculoperitoneal A shunt that is used to drain fluid from the cerebral ventricle into the abdomen.