=Movements.=—This joint is a typical ginglymus, the only movements being flexion and extension around an axis which passes through the upper attachments of the lateral ligaments. In the standing position the articular angle (in front) is about 140° to 150°. The range of movement is about 55° to 60°. Complete extension is prevented chiefly by the tension of the lateral ligaments and the biceps muscle. (The axis of movement is slightly oblique, so that in flexion the forearm is carried somewhat outward.) [Illustration: FIG. 144.—LEFT CARPAL JOINTS OF HORSE, EXTERNAL VIEW. The capsule has been removed, _g_, Radius; _12_, large metacarpal bone. (After Ellenberger-Baum, Anat. f. Künstler.) ] [Illustration: FIG. 145.—LEFT CARPAL JOINTS OF HORSE, ANTERIOR VIEW. The capsule has been removed. The smaller ligaments are shown. (After Ellenberger-Baum, Anat. f. Künstler.) ] THE RADIO-ULNAR ARTICULATION In the foal the shaft of the ulna is attached to the radius above and below the interosseous space by the =interosseous ligament=. Below the space the two bones become fused before adult age is reached. Above the space the ligament usually persists, but may undergo more or less ossification in extreme old age. The =transverse= or =arciform ligaments= (Ligamentum transversum ulnare et radiale ulnæ et radii) consist of fibers which pass above the interosseous space from either border of the shaft of the ulna to the posterior surface of the radius. The proximal radio-ulnar articulation, formed by two small convex facets on the ulna and the corresponding facets on the posterior surface of the proximal extremity of the radius, is inclosed in the capsule of the elbow joint and does not require separate consideration. The distal extremity of the ulna fuses early with the radius, and is, therefore, regarded usually as a part of the latter. =Movement.=—This is inappreciable, the forearm being fixed in the position of pronation. THE CARPAL JOINTS These joints taken together constitute the composite =articulatio carpi=, or what is popularly termed the “knee-joint” in animals.[33] This consists of three chief joints, viz., (1) The =radio-carpal joint=, formed by the distal end of the radius and the proximal row of the carpus; (2) the =intercarpal joint=, formed between the two rows of the carpus; (3) the =carpo-metacarpal joint=, formed between the distal row of the carpus and the proximal ends of the metacarpal bones. The proximal and middle joints may be regarded as ginglymi, although they are not typical or pure examples of hinge-joints. The distal joint is arthrodial. In addition there are arthrodial joints formed between adjacent bones of the same row (Articulationes interosseæ). All these constitute a very composite joint, with numerous ligaments. The articular surfaces have been described in the Osteology.