KNEE, in ship-building, an angular piece of wood or iron used to connect the deck beams with the ribs of the vessel's sides. The knees are fastened on both vertically, above and below, and horizontally, whereby great stability is imparted to the whole framework of the ship.
THE, is the articulation between the femur or thigh-bone, above, and the tibia or shin-bone below. A third bone, the patella, or knee-cap—one of the sesa mold bones (q.v.), and not a true bone of the skeleton—also enters into the structure of thisjoint anteriorly. The articular surfaces of these bones are covered with cartilatre, lined by a synovial membrane or sac, which is the largest and most extensive in the holly, and connected together by ligaments, some of which lie external to the joint, while others occupy its 'Mello'.
The most important of the external ligaments are the anterior or ligamentu1.2, patei5r, which is in reality that portion of the quadriceps extensor cruris which is continued from the knee-cap to the tubercle of the tibia; one internal, and two external lateral ligaments; a posterior ligament; and a capsular ligament, which surrounds the joint in the intervals left by the preceding ligaments. The positions of these ligaments are sufficiently indi cated by their names. Of the internal ligaments. the two crucial, so called because they cross one another, are the most important. The external and internal semi-lunar
cartilages are usually placed amongst the internal ligaments; they are two crescentric plates of cartilage. The outer part of each cartilage is thick; the inner free border thin. Each cartilage covers nearly the outer two-thirds of the corresponding articular surface of the tibia, and by its form deepens the.a surfaces for firmer articulation with the„catt dyles of the femur.
The chief movements of this joint are those of a hinge-joint—namely, flexion and extension, but it is also capable of slight rotatory motion when the knee is half-flexed. During flexion the articular surfaces of the tibia glide backwards upon the condylcs of the femur; while in extension they glide The whole range of motion of this joint, from extreme flexion to extreme extension, is about 150*. Judging from its artic ular surfaces, which have comparatively little adaptation for each other, it might be inferred that this was a weak and insecure joint; and yet it is very rarely dislocated. Its real strength depends on the large the articular ends of the bones, on the number and strength of the ligaments, and on the powerful muscles and fascite by which it is invested.