Page:The New International Encyclopædia 1st ed. v. 18.djvu/894

* SYNONYM.. 780 SYNOVITIS. In the course of semasiological evolution, how- ever (see Semasiology), the particular words which tend to become synonymous overlap in meaning. This process may then continue till the words become identical in meaning. In this ease the result is suppression of one of the terms, either complete, or, less usually, partial. The latter process gives the so-called supplctive or composite inflection, illustrated in such English verbs as «m, be, iriis. or go, went, in which verb- roots originall}' distinct have coalesced. If. on the other hand, synonyms do not become identical, they tend to become so specialized in meaning with respect to each other that they not only retain for the most part their original distinc- tions, but frequently develop others. The main stylistic use of synonyms is to give variety and accuracy of diction. One of the criteria of ex- cellence of a language is its synonyms, and herein English lanks as one of the foremost tongues. Consult, for English S3'nonj'ms: Roget, Thesaurus of Eiiylish Words (new ed,, London, 1883) ; Soule, Dictionary of English Synonyms (new ed., Philadelphia, 1895) ; Crabbe, English Synonyms (new ed.. New York, 1891) ; Smith, Synonyms Discriminated (4th ed., London, 1890). SYNOVIAL MEMBRANE and FLUID (from Neo-Lat. synoriulis, from synovia, lubri- cating fluid secreted by a synovial membrane, so called because it resembles the white of an egg, from Gk. cvv, syn, together + Lat, ovum, egg). In every joint in which a considerable range of motion is required, the osseous segments (or contiguous extremities of bones) are sep- arated by a space, which is called the cavity of the joint. The end of each of the bones enter- ing into the composition of the joint is incrustcd by a laj'cr of articular cartilage adapted to its form, and the entire cavity of the joint is lined by a delicate membrane, which is termed the synovial membrane, which secretes a peculiar viscid matter, termed synoria, or synovial fluid, for the purpose of lubricating the inner surface. Being a serous membrane, a synovial membrane is always a closed bag, like the pleura, for ex- ample, with an attached and a free surface, the latter being smooth and moist. The minute structure of a synovial membrane is much the same as that of serous membranes elsewhere. (See Histology.) A very simple form of syno- vial membrane — anatomically knoAvn as a bursa — is employed to facilitate the gliding of a tendon of a muscle or of the integument over a projec- tion of bone. It consists of a bag connected by areolar tissue with the neighboring parts, and secreting a fluid in its interior. These bags are sometimes prolonged into synovial sheaths, which surround long tendons, such as those of the flexor and extensor muscles of the fingers and toes. In felon ( q. v. ), when inflammation extends to one of the sheaths, and gives rise to the forma- tion of adhesions, the motion of the inclosed tendon is destroyed, and a permanently stiff fin- ger is the result. See Synovitis. The synovial fluid, or synovia, consists of water holding in solution mucin, albumen, fat, and inorganic salts. Excessive movement diminishes its amount, makes it more inspissated, and in- creases the mucin, but diminishes the salts. SYNOVITIS (Neo-Lat., from synovia. lubri- cating fluid secreted by a synovial membrane). Inflammation of a synovial membrane. Although inflammatory processes involving joints frequent- ly start in an inflammation of the .synovial mem- brane, they rarely confine themselves to this nu'nd)raiie, but spread to and involve the sur- rounding tissues. It is for this reason that, especially in discussing the pathology of joints, the term .synovitis, which properly means inflam- mation of the synovial membrane only, has been displaced by the term arthritis, which signifies inflammation of the joint in general, including the sj-novial membrane. Acute Arthritis is usually an exudative in- flammation and may be serous, serofibrinous, or suppurative in character. In serous arthritis there is congestion of the synovial membrane with a serous exudate into the joint cavity. With the subsidence of the inflammation the serum may be absorbed and the joint return to its normal condition, or, becoming infected, may pass on to suppuration. The acuteness of the con- dition may pass off and the joint go on to a chronic inflammation. In sero-iibrinous arthritis there is in addition to the serum more or less fibrin in the joint cavity. Suppurative arthritis is an infectious condition due to the presence of bacteria. The exudate is purulent, while the synovial membrane is usually thickened, dull, and infiltrated with pus cells. Suppurative ar- thritis is apt to accompany or follow some one of the infectious diseases, as e.g. pyaemia, puer- peral fever, pneumonia, gonorrhn?a, diphtheria, and scarlet fever. Acute rheumatic arthritis or acute articular rheumatism is usually an exu- dative inflammation in which the exudate is se- rous in character and in which there is a suc- cessive involvement of different joints. Chronic Arthritis. The most important forms of chronic arthritis are simple chronic arthritis, arthritis deformans, rheimiatic arthritis, gouty arthritis, and tubercular arthritis. In simple chronic arthritis there is a serous exudation into the joint cavity: the synovial membrane is thick- ened, pale, and rough. The exudate may be clear, tliin, and watery, or may be cloudy and thick from the presence of minute particles of fibrin, or of lymphoid or endothelial cells. The amount of fluid is sometimes large and may result in rupture of the joint capsule or in so separating the joint surfaces that dislocations occur. In that peculiar form of chronic inflammation of the joints known as arthritis deformans there is a combination of destruction of parts of the joint with new bone formation which leads to extensive deformities. The joints most commonly involved are those of the fingers, hips, knees, and feet. In gouty arthritis there is a deposit of urates in and about the joints. These deposits take place in the cartilages and in the connective tissue and in the ligaments around the joints or even in the subcutaneous tissue. The deposit may be in the form of crystals or of whitish con- cretions. In tubercular arthritis the lesion is that of a tubercular inflanunation modified by the nature of the tissues in which the inflamma- tion occurs. The process may originate in the joint, but more frequently represents an extension to the joint of tubercular inflammation of the bones. Tubercular arthritis is always charac- terized by the growth of tubercle tissue in and about the joint. Like tubercle tissue in other parts of the body, this tissue may vai'v in char- acter; and, dependent upon these variations, sev- eral types of tubercular arthritis are recognized.