TENDON is a term employed in anatomy to designate the white fibrous tissue reach ing from the end of a muscle to bone or some other structure which is to serve as a fixed attachment for it, or which it is intended to move. In accordance with their form, tendons have been divided into the three following varieties: (1) Funicidar, or rope-like, as the long tendon of the biceps muscle of the arm; (2) Fascicular, as the short tendon of that muscle, and as the great majority of tendons generally; and (3) Aponeurotie, or ten dinous expansions, sometimes of considerable extent, and serviceable in strengthening the walls of cavities, as, for example, the tendons of the abdominal muscles.
The tendons commence by separate fascicles from the end of each muscular fiber, and they similarly terminate by separate fascicles in distinct depressions in the bones, besides being closely incorporated with the periosteum. In some birds, whose tendons are black, the periosteum is black also, from this incorporation. If a tendon is ruptured by an accident, or divided by the surgeon, the two ends, if not too far separated, unite with extreme readiness, by the formation of intervening plastic material, which soon acquires great firmness. So rapidly is this process of repair carried on, that, according to Mr. Paget, a specimen, six days after division, could bear the weight of 25 lbs.; while in another specimen, the new material, at the end of 21 days, bore a weight of 56 lbs. When the interval between the two ends of a tendon exceeds a certain limit, there will be only an imperfect bond of union, and either a partial or total loss of the use of the muscle will result. For details regarding this process of repair, which has an intimate bearing on the treatment of ruptured tendons, the reader is referred to Mr. Paget's admirable Lectures on Surgical Pathology.
Among the diseases of tendons, inflammation requires especial notice. "Tendons," says Mr. Tatum, in his article upon Affections of the Muscular System, with their sheaths, are not unfrequeutly inflamed. Independently Of gout and rheumatism, the most frequent cause is a sprain or wrench in the neighborhood of a joint. These injuries are occasionally productive of long-continued wearing pains, assuming much of a rheumatic character, and yield often slowly and unwillingly to the remedies, both local and general, employed in rheumatism."—Holmes's System of Surgery, vol. iii. p. 544. In one of the forms of whitlow (q.v.), known as paronychks graris, or tendinous whitlow, "the tendons and their sheaths in the finger and hand are the seat of a severe and often most destructive inflammation, which, though otters confined to one finger, not unfre quently extends to the hand and arm, attacking not only the tendons and softer parts, but exposing the bones, and disorganizing the joints."—Op. cit., p. 544. It arises from slight punctures or wounds, with or without the inoculation of irritant or poisonous matter, and often without any apparent cause, except a derangement of the general health. It begins with severe and thlrobbing pain in the palmar surface of a finger, which extends upward along the arin. There is extreme tenderness, and a certain amount
of redness and swelling, with great tenseness of the parts. If the inflammation is not checked, suppuration soon ensues, accompanied by much constitutional disturbance. The matter frequently extends among the muscles, and in bad cases occurring in unhealthy persons, the bones and joints became affected in the way already mentioned. In the early stage, free leeching, followed by hot fomentations, may be useful. The hand should be kept elevated, and an active purgative, with low diet, prescribed. If, as is often the case, these measures are unsuccessful, a free incision must be made along the center of the palmar aspect of the finger—an operation which gives extreme relief, by removing the tension, and allowing the escape of blood, even if little or no pus is dis charged. A generous diet, stimulants, and tonics, are now advisable; and under this treatment the disease generally yields; although cases occasionally present themselves in which the suppuration produces such results as to render amputation of the arm neces sary, or even to cause death. A permanently bent finger, from adhesion of the tendon to its sheath, is a common result in severe cases of whitlow of this kind.
Tendons are not very unfrequently the seat of syphilitic enlargements or tumors. Malignant tumors scarcely ever spring from tendons, but fibrous tumors and small car tilaginous enlargements are often found in tendons.
Rupture of the tendons is an accident which is frequently caused by violent muscular action, especially if, from illness or other causes, the muscles have been for some time in a state of inactivity. The, long tendon of the biceps cubiti is very obnoxious to this injury, which, in this case, is more often due to the disorganization caused by chronic rheumatic gout than to mere mechanical violence. The other tendons most frequently ruptured are the tendo Achillis, and the tendons of the rectus femoris and the triceps humeri. When a tendon is ruptured or divided by a surgical operation (teuotomy), "the part which is attached to the muscle is drawn away from the opposite end for about an inch. 'Blood is poured out between the ends, but mach less than in rupture of muscles. The pain is said not to be very great; a considerable shock, however, is felt, as from a blow received on the part, accompanied by cramp of the muscle, and a perfect inability to use the limb; and in rupture of the tendo Achillis, a feeling is described as if the heel were sinking into a hole in the floor."—Holmes's System of Surgery, vol. iii. p. 541. The essential point in the treatment of ruptured tendon is to keep the injured part in a state of constant rest and muscular relaxation, so that the separated ends may be approximated as much as possible, and to prevent any violent extension till firm union, by the process of reparation, has been established. The special methods of treat ing individual cases (as rupture of the tendons of the reetus femoris and the triceps, and of the tendo Achillis) are discussed in Holmes's System of Surgery, and other standard works on surgery.