OCR Text |
Show 1870.] DR. J. MURIE ON SAIGA TARTARICA. 471 The lunare or semilunar bone has a figure-of-eight shape, but with numerous prominent angular facets. It is smaller than the scaphoid. The proximal surface articulates chiefly with the median fossa of the radius and the crest on the outer border of the inner facet. Its lateral constrictions are filled by the corresponding eminences of the scaphoid and cuneiform. Distally it presents two small flattish quadrangular facets, and behind these a couple of grooved ones ; these coincide with the approximate parts of the magnum and unciform. The cuneiform offers two angular faces, which wedge into the neighbouring concavity of tbe lunare. Proximally the cuneiform articulates by a raised portion with a small part of the radius; and outside this there is a deep oblique groove for the reception of the styloid process of the ulna. The distal surface rests solely upon the unciform bone ; a posterior outer and downward process rests in the fossa on the outside of the unciform. The long diameter of the pisiform is vertical. It is a rather large, ovoid, convex, and laterally compressed bone, the inner surface being deeply grooved for the transmission of tendon. The os magnum differs from all the bones of the row in being relatively thin, flattish, wide and diamond-shaped. The upper surface is quite level on the outer half for the reception of the scaphoid; and on the inner half it presents fore and aft facets, upon which, as aforesaid, those of the lunare rest. Its articular surface with the unciform is concave. The metacarpal articular surface is quite a horizontal plane, except the trapezoidal portion, which is rather more indented. The homologue of the trapezoid bone is only indicated by a tuberous condition of the inner posterior angle of the magnum. The unciform, like the magnum, has a very smooth under surface, which plays on the proximal end of the fourth metatarsal (i. e. the outer one present). The upper surface of the bone is uneven, and possesses several facets at different angles and planes, which articulate with parts of the lunare and cuneiform. That fossa outside, wherein the descending process of the cuneiform lies, is well marked. The cannon bone is a long and beautifully finished pillar, a slight mesial groove indicating third and fourth metacarpal elements. A nutritious foramen penetrates the bone at either end of the said furrow. A delicate spicular rod of bone 2\ inches long, and representing a second metacarpal, is seen in the College of Surgeons' skeleton ; this must either have been cut away or was absent in the Society's specimen. Behind the digital end of the connate metacarpals are two pairs of large-sized sesamoid bones, each pair appositely placed with a median groove for the long flexor tendons. Futhermore, in the Hunterian specimen three additional free and minute ossicula have been preserved; of these, two are placed on the inner and one on the outer side of the metacarpo-phalangial joint. The phalanges, proximal, median, and distal, are of fair strength, and, all more or less, laterally compressed. The last or ungual digits are comparatively short and high. Behind the lower extremities of the second phalanges two large sesamoids are met with. |