2. Os lunare, (os semilunare v. !anal= ; Fr. le semilunaire ; Germ. das situated between the scaphoid and the cunei form bones, it presents four articular surfaces; an upper one, convex and somewhat triangular in its outline, articulated with the radius; an inferior one, very much hollowed from before backwards (to the crescentic form of which the bone owes its name), articulated with the os magnum; an external surface, plane and square, adapted to the cuneiform bone ; and, lastly, an internal surface, by which it articu lates with the scaphoid.
3. Os cuneiforme (os triquetrum s. pyra midale; Fr. le pyramidale; Germ. dasdreiseitige &in). This bone terminates the superior carpal row on the ulnar side ; its upper surface is partly smooth, encrusted with cartilage in the recent state, where it is in contact with the triangular ligament of the wrist-joint, and partly rough where it gives attachment to liga ments. Externally it articulates with the cunei form bone, and inferiorly with the unciform by a large and concave surface. The inner half of its anterior surface articulates with the pisiform bone, and the radial half of the same surface is rough for ligamentous insertion.
The three bones just described, constituting the superior row of the carpus when united, present on their superior aspect a convex arti cular surface which forms the carpal portion of the radio-carpal joint, the scaphoid and lunar being articulated with the radius, while the cuneiform glides upon the triangular carti lage of the wrist.
4. Os pisiforme (from pisum, a pea; Fr. le pisiforme ; Germ. this Erbscnbein). This little bone projects at the anterior part of the ulnar extremity of the superior carpal row ; it forms what some anatomists designate cminentia carpi ulnoris superior, being part of the bony ridge already referred to on the ulnar side of the carpus. The prominence produced by this bone is easily felt during life, more especially during flexion of the wrist-joint. It is round every where, except posteriorly, where it presents a flat circular surface, by which it is articulated with the cuneiform bone. This bone is intimately connected with and as it were inclosed in the terminal portion of the tendon of the flexor carpi ulnaris.
5. Os trapezium (os multangulam wajus ; Fr. le trapeze; Germ. das grossc vicheinkliche
Bein). This bone is situated at the radial extremity of the inferior carpal row, having the seaphoid above it and the metacarpal bone of the thumb below it. We may describe six surfaces upon it, four articular and two non articular. a. A large articular surface, situated oil the external and inferior aspect of the bone. This surface is for articulation with the meta carpal bone of the thumb : it is somewhat oval in form, the long axis passing from without inwards and downwards ; in this direction it is concave, from before backwards it is convex. The three remaining articular surfaces the on the internal and superior aspects of the bone.
b. Internally, a very small plane surface, adapted to a corresponding one on the radial side of the carpal extremity of the second metacarpal bone. c. Above the last described surface and separated from it merely by a slight ridge, we find one of a somewhat triangular form and slightly concave, articulated with the radial side of the trapezoid. d. Quite on the superior aspect a small semicircular surface, adapted to the scaphoid. Of the non-articular surfaces, one is on the palmar aspect of the bone, and is easily distinguished by the prominent ridge or tubercle at its outer part, which gives attach ment to the annular ligament, (tuberculum, eminentia carpi radialis inferior ;) and on the ulnar side of this ridge a groove in which the tendon of the flexor carpi radialis glides. The second non-articular surface is on the dorsal aspect : it is more extensive than the last, rough and tuberculated, affording insertion to ligaments.
G. Os trapczoides (os nzultangnlum minus ; Fr. le trapezoide ; Germ. das Kleine viel winhliche Bein). This is the second bone of the inferior carpal row ; it has the os trapezium on its radial and the os magnum on its ulnar side, the scaphoid above and the second meta carpal bone below it. We describe four articular surfaces and two non-articular. a. The inferior one the largest, quadrilateral, much narrower in front than behind, convex from side to side, slightly concave from before backwards, is entirely devoted to articulation with the second metacarpal bone. b. On the radial side, a slightly convex surface for the trapezium.