RIAZAN, or RYAZAN, Russia, (1) city, capital of the government of Riazan, on the Trubesh, a branch of the Oka. It is hi an agri cultural region, in which the chief product ex ported is rye. The chief manufactures of the city are woolen and linen goods, leather and needles. Nearby is the village of Grishina, in which are large cutlery works. Pop. about 48,000. (2) The government of Riazan has an area of 16,254 square miles. It is drained by the Oka and its tributaries. The chief maim factures are cotton, linen and woolen goods and leather. Rye is the principal grain exported. Pop. about 1,900,000.
RIB. The ribs are a series of flattened, narrow bones which together with the sternum in front and the vertebral column behind form the bony cage which encloses the thoracic organs and supports the muscular structures surrounding the chest cavity. In man there are 12 pairs of ribs, of which the first seven articu late directly with the sternum by. means of their costal cartilages and are called the true ribs. The cartilages of the eighth, ninth and 10th ribs join the cartilage of the seventh rib and are, therefore, termed false ribs, while the 11th and 12th ribs are free at their anterior extremities and are spoken of as the floating ribs. The seventh rib is the longest of the series, the others decreasing progressively in size to the first and to the 12th. The seventh is considered the most representative rib, and is described as having an anterior or sternal extremity, a shaft and a posterior or vertebral extremity. The sternal end is hollowed slightly to receive the cartilaginous prolongation by which it is connected with the sternum. The shaft is flat tened and has an external and an internal sur face. Its lower edge is slightly grooved to shelter the intercostal vessels and nerve which run parallel to and close to it. The head presents two facets which articulate with the bodies of two adjoining dorsal vertebra, and the neck is the short portion between the head and the beginning of the shaft. At the junc tion of the neck with the shaft there is a small swelling called the tubercle which has an articular facet for contact with the transverse process of the lower of the two vertebra with which the head articulates, and a roughened area for the attachment of a ligament. The rib presents two curvatures, one around a ver tical axis and the other about a horizontal axis, the effect of which is that the bone cannot be laid on a plane surface in such a way that both ends and the shaft between shall be in contact with it. The point at which the curvature is most acute is called the angle of the rib. Most
of the ribs are so placed in the body that their sternal extremities are much lower than their points of attachment to the vertebral column, and through this arrangement as well as their peculiar curvature, when they are raised in in spiration the capacity of the thorax is increased both in its anteroposterior and lateral diameters. In some diseases, notably rickets (q.v.) and emphysema (q.v.), which are characterized by changes in the shape of the chest, the ribs undergo alteration in curvature. In children having rickets the anterior portion of the ribs sinks in so that the sternum becomes more prominent and the ends of the ribs may he enlarged and beaded, forming what is called the "rachitic rosary." If, in addition to rachitis there is present some respiratory obstruction from such causes as adenoids, nasal catarrh, etc., the "pigeon" or "keel" breast may result. In this the lateral compression is carried to a more extreme degree and the cross-section of the chest approaches the triangular shape with the apex forward. A funnel-shaped depression over the lower point of the sternum is some times caused by rickets, but may be congenital or due to the habitual pressure of a work bench or tools, as in cobblers, for example. In the emphysematous chest the ribs are thick and run more nearly horizontal so that an increase in the anteroposterior direction and outward bulg ing of the middle portion are caused, giving rise to the so-called barrel-shaped chest. The flat chest is the opposite of this, as its name implies, and has a short anteroposterior diam eter. It is often associated with a tendency to pulmonary tuberculosis. Very rarely the ribs are more or less numerous than normal, but a not unusual deformity is the non-attachment of the anterior end of the 10th rib, so that it, too, is a floating rib. This abnormality is by some authorities considered as an indication of a tendency to neurasthenia. Fractures of the ribs are not infrequent injuries. Owing to the more sheltered position of the upper and the greater mobility of the lower members of the series it is most often the fourth to the eighth ribs that are fractured. Unless there is some complica tion, such as internal injury, the outlook is usu ally good. The treatment consists chiefly in immobilizing the side of the chest affected by adhesive plaster strapping. In treating collec tions of purulent fluid in the pleural cavity, it if often necessary for the surgeon to resect portions of one or more ribs in order to secure free drainage. See ANATOMY; OsnoLoGY; THORAX.