THE KNEE JOINT 411 



fetlocks or speedy cutting is sure to be manifested ; if too great, the awkward 

 gait known as "dishing" is established. Extension is not nearly so com- 

 plete as in the human subject, being limited by the greater length and 

 breadth of the olecranon pi'ocess, the upper part of which forms a prominence 

 which fits into the corresponding fossa of the humerus, and thus serves as 

 a check to the extension of the fore-arm. In most men the upper arm and 

 fore-arm can be made to fall into one straight line, but in the horse there 

 is always a considerable angle. 



THE KNEE JOINT (CARPUS, OR WRIST) 



This articulation is a very complicated one, and in order to understand 

 it thoroughly, it will be necessary to examine the parts composing it under 

 three divisions. 1st. The articulations between the several carpal bones. 

 2nd. The Eadio-carpal articulation ; and 3rd. The Carpo-metacarpal joint ; 

 to which must be added (4) the examination of certain ligaments, common 

 to all three. 



1. The two rows of carpal bones, which have been described in the dry 

 state at page 380, are furnished with cartilages on the faces, by which they 

 correspond, thus forming a series of nearly plane arthrodial surfaces, having 

 .synovial capsules, but embracing several of them in one. It may be remem- 

 bered that these bones are arranged in two rows, the upper one consisting 

 of the scaphoid, lunar, cuneiform, and pisiform bones, while the lower com- 

 prehends the OS magnum, the trapezoid, and the unciform bones. 



The upper roiv is united together by six ligaments, three anterior and tltree 

 interosseous. The anterior ligaments consist of flattened bands of fibres 

 which lie in front of the knee, and connect the four bones together, passing 

 laterally from one to the other. The interosseous are strong and short 

 fibres concealed between these bones, and attached to the rough excavations 

 between the distinct facettes on the several bones to which allusion has 

 been made at page 380, the ligament connecting the pisiform bone with the 

 :Scaphoid being particularly well marked. 



The hones of the second rotv are, in a similar way, united by anterior and 

 interosseous ligaments, but instead of being three, there are only two of 

 •each, in correspondence with the diminished number of bones. It is un- 

 necessary to describe them more minutely. 



The tivo roivs again, between which is a partial hinge joint, are united 

 by three sjyecial ligaments, in addition to those common to the whole knee 

 joint, which will be presently described. Two of the special ligaments 

 ■consist of very short fibres lying behind the carpal bones, and covered by 

 the great posterior ligament. The third is larger than these, and extends 

 from the pisiform bone to the unciform, and to the head of the external 

 small metacarpal bone (see ^^ Fig. 48). It is united on the outer side 

 with the external lateral ligament, and internally with the common posterior 

 ligament. To its posterior border are attached the outer fibres of the sheath 

 of the flexor tendons. 



The synovial capsules proper to these articulations line all the above 

 ligaments and articular surfaces, being reflected from one to the other, and 

 forming also pouch-like prolongations upwards between the bones of each 



