THE ANTERIOR LIMBS. 



77 



Fig. 44. 



process the olecranon flattened on both sides, and presenting: 1, An 

 external face, slightly convex; 2, An internal excavated face; 3, An 

 anterior border, thin and sharp superiorly, 

 notched below to for mthe sigmoid cavity .- 1 an 

 articular surface concave from above down- 

 wards, rounded from one side to the other, 

 which corresponds with the humeral cavity, 

 and is surmounted by a salient prolongation 

 named the beak of the olecranon ; 4, A con- 

 cave and smooth posterior border; 5, The 

 summit, a kind of thick roughened tuberosity 

 which terminates the olecranon above, and into 

 which are inserted the extensor muscles of the 

 fore-arm. 



At its inferior extremity, the ulna ends, 

 towards the lower fourth of the principal por- 

 tion of the fore-arm, in an acute point, and 

 sometimes by a small knob (capitulum ulnaz). 

 It is not rare to see it prolonged, especially 

 in the Ass and Mule, to the inferior external 

 tuberosity of the radius. This tuberosity then 

 appears to belong to it, at least in part ; and 

 all that portion which is situated behind its 

 vertical groove might be justly considered as 

 belonging to the ulna. 



Structure and development. The ulna con- 

 tains much compact tissue, even in the region 

 of the olecranon ; it is also very solid. It is 

 an imperfect bone, developed from two centres 

 of ossification only, one of these being for the 

 apex of the olecranon. 



FORE-FOOT OK HAND. 



The anterior foot, or hand, is the region 

 which presents the greatest differences when it 

 is inspected in the various individuals of the 

 animal series. Nevertheless, in all the mam- 

 malia the constitution of the hand is funda- 

 mentally the same, and may be divided into 

 three sections: the carpus, metacarpus, and 

 pJialangeal region. 



The hand is formed by five parallel or 1, Radius; 2, Groove for the an- 

 quasi-parallel rays that constitute the digits, terior extensor of the P halaE 

 each of which is effectively or virtually com- 

 posed of two superposed carpal, a metacarpal, 

 and Ihree pJialangeal bones, forming altogether 

 the digit, properly so called. But this typical 

 composition, established through the labours 

 of MM. Joly and Lavocat, is rarely found to 

 be realised in a complete manner. 



The following is what is presented in the hand of Man, who is the most 



EIGHT FORE-FOOT OF A HORSE. 



ges, 3, Scaphoides; 4, Lunare; 

 5, Cuneiform ; ' 6, Trapezium ; 

 7, Magnum ; 8, Unciform ; 9, 

 Metacarpal; 10, Small meta- 

 carpal; 11, Sesamoid bone; 12, 

 Suffraginis; 13, Coronary; 14, 

 Navicular; 15, Pedal 5 16, Its 

 ala. 



The greater sigmoid cavity of Man. 



