SINUS

sinus Latin= a curve, anything hollowed out, the fold of a garment, a bay or gulf of water

1. In anatomy, the paranasal sinuses are cavities inside the bones near the nose (para Greek preposition ‘beside, near’). Also called the accessory nasal sinuses, they are lined with epithelial mucosa and act to moisten, warm, and filter air and perhaps they act as resonators for the human voice. Compare music critics who rave about a singer’s “head tones.” Some head tones depend on exquisitely placed and bounteously spaced sinuses.

2. A sinus is also a channel for venous blood, for example, the aortic sinus is a widened part of the aorta or pulmonary artery opposite a semilunar valve.

3. A draining sinus is a pathological passageway formed to permit the escape of pus from an abscess.

Sinusitis

sinus +-itis a common suffix of disease names from Greek now signifying “inflammation of [the organ named in the front of the word].” Compare appendicitis, neuritis and otitis media (inflammation of the middle ear from medius Latin ‘middle, inner, inside’).

Without proper drainage, a paranasal sinus may become blocked, due to viral or bacterial infection or allergies. In acute suppurative sinusitis (sub>sup Latin ‘under’ + pus, puris Latin ‘pus’), pus, pain, fever, chills, and headache must be relieved by bed rest, possible antibiotics, extra fluid intake, and hot packs. In chronic hyperplastic sinusitis, polyps crowd the lumen of a sinus and surgical remedy may be necessary.

Lumen is a medical word from Latin denoting the hollow portion of any tubular structure, e.g. the lumen of a vein, the lumen of the intestine, the bore of a hollow needle, the lumen of a catheter. Illustrated below is the lumen of an artery.

 

Sinus Node or Sinoatrial Node

This small mass of nerve fibers and cells is the natural pacemaker of the human heart. Lodged in the muscles of the heart’s right auricle it transmits ‘contraction commands’ through a remarkable network of Purkinje’s fibers. It was named by early anatomists who did not fully understand the structure of the mammalian heart, and thought it was like the sinus venosus of lower animals, like the first chamber in the heart of fish and reptiles, a chamber which receives blood from the veins and contracts to pump the blood into a second atrial chamber.

 Sinus Rhythm in the Heart

Sinus rhythm describes the normal beating of the heart impelled by electric impulses of the sinus node, detected by ECG or electrocardiogram.

 

 Sinus in Latin

A toga fashion parade from the Roman forum

Perhaps the commonest use of the noun sinus in Latin referred to the loose hanging fold in the front part of that formal Roman attire called the toga. A small purse was sometimes carried in the fold of the toga and loose coins were kept within the sinus also. Columella, a Roman writer on animal husbandry, wrote aere sinus plenos urbe reportare ‘to carry back to the city toga-folds filled with coins,’ that is, to return home very rich.

 

The umbo is the knob-like protrusion at the front of the toga where one fold is tucked into the crossband. The Latin word also means the boss of a shield and is used in scientific vocabulary as the name of certain structures in botany and zoology. Umbo is related to the Latin and Greek words for belly button, namely umbilicus and omphalos. Consider the umbilical cord and the fancy term omphaloskepsis ‘meditation while gazing at the navel,’ a practice common in Washington and Ottawa.

Other Related English Words

Insinuate

In Latin sinus frequently meant ‘the bosom’ or the innermost part of a thing, the part folded in. The Latin verb sinuare ‘to wind, to bend, to curve’ has a compound form that gives our English verb to insinuate. I may insinuate in a sly, underhanded way the idea that our teacher is stupid so that I am not punished. Were I some government hack, I might also insinuate myself into the good graces of an Ottawa nuclear-power lobbyist, for I too would appreciate a bribery-financed summer place in the Gatineau Hills where I could overlook scenic hills and nuclear safety failures. Just making up an exemplary sentence, folks.

Sinuous

A related adjective is sinuosus ‘full of curves’ from which descends our modern English sinuous. A sinuous rill is a little stream with bends and curves. A sinuous nymph may dance around you in a foreign café displaying her bodily curves and bends.

Derivatives in other languages

Most of the western languages use the Latin term as well: Spanish: seno, Turkish sinüs, Italian seno, French and German sinus.

Russian medical vocabulary uses the Latin word merely transliterated as синус.

Sine as a Term in Trigonometry

A sine is a function in trigonometry whose precise definition I shall not attempt. Look it up in an online mathematical dictionary, if you care. Here I’m interested to point out that Latin sinus which became English sine was used as a translation of a similar metaphor in the Arabic original where the trigonometric function was compared using the Arabic noun jaib ‘inner fold of a garment,’ (Arabic jaib equalling Latin sinus in meaning) all this when some of the original tenets of trigonometry were being introduced to European mathematics from original trig treatises in Arabic. I do recall from my high-school trig class that ‘the sine of an obtuse angle is numerically equal to that of its supplement.’

Sine Wave

In a sine wave or sinusoid, a signal rises and falls in a repeating pattern, which is wave-like. It's a sine from Latin sinus because the waves bend and fold rhythmically.

 

The Oxford English Dictionary tells us that a sine wave is “a periodic oscillation of pure and simple form in which the displacement at any point is proportional to the sine of the phase angle at that point.” A sine wave is a wave or curve resembling a segment of this in form.

That's it, folks. Sine-ing off for now. I think a wave is appropriate.

 

© 2007 William Gordon Casselman

 

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