328 PEOFESSOR OWEN ON THE SKELETON 



This (fig. 10, h) is long and narrow, extending further proximad by half its length than 

 the ulnar condyle (ib. i) does. The ulnar condyle is shorter and thicker : both project 

 towards the palmar aspect, and do not terminate the bone distally. The broad articular 

 surface of the ulna is adapted to both condyles, but covers only the distal half of the radial 

 one, the radius gliding upon the upper half. The breadth of both condyles is 5 lines. 

 The anconal surface (fig. 9) is divided into two grooves by three ridges, the ulnar one 

 (i) being the longest, the radial one (I) the shortest ; and the ulnar anconal groove is 

 consequently larger than the radial one. All the three anconal ridges project distally 

 beyond the condy'es. There is a well-marked flat surface above the ulnar condyle for 

 the attachment of a strong lateral ligament. 



The shaft of the humerus contains a narrow medullary cavity (fig. 9'). The orifice 

 of the medullary artery is close to the anconal border, about an inch below the ulnar 

 edge. 



The radius (PI. LI. 54) and ulna (55), connected only at their extremities, have oppo- 

 site curves, leaving a wide interosseous space. The radius is but half the thickness of 

 the ulna, and is more bent. A tuberosity projects on the radial side just below the 

 thickened proximal articular end : below this the shaft is slightly contracted ; it then 

 expands and becomes compressed, with the radial border more convex than the ulnar 

 one is concave. The anconal surface is longitudinally channelled near the radial edge, 

 deepening towards the wrist, where there is a second but short groove ulnad of the 

 longer one. 



The olecranon is short, obtuse, with a longitudinal groove on each side of its base, 

 narrowing the bone between the process and the articular surface of the ulna. A sesa- 

 moid in the biceps flexor tendon plays in the palmar groove ; it is the homotype of the 

 patella : two other sesamoids in the triceps extensor tendon play in the two grooves in 

 the anconal part of the distal end of the humerus : these answer homotypally to the 

 fibular extension which plays in the popliteal groove of the outer femoral condyle. The 

 shaft of the ulna, though compressed, is at the proximal half three-sided, the narrowest 

 side being toward the radius, and contracting to a sharp border at the distal half. There 

 are no quill-pits. The distal articular surface is convex from the radial to the ulnar 

 side, but slightly concave transversely, and is accordingly somewhat trochlear. A 

 tuberosity projects above it on the outer side, near the radius. The length of the anti- 

 brachium is 2 inches 4 lines. 



The radial carpal bone (ib. se) presents a trochlear surface, concave from the radial 

 to the ulnar end, convex transversely to the magnum, here confluent with the base of 

 the mid metacarpal (iii). The ulnar carpal (55') is the smaller bone, and off'ers a deeper 

 groove to the convex compressed process of the base of the fourth or " annulus " meta- 

 carpal (iv) The second or index metacarpal (11) is 6 lines long, compressed, and con- 

 fluent by its whole length to that of the medius. It supports a phalanx (1), 10 lines 

 long and pointed at the end, which does not quite reach that of the mid metacarpal. 



