THE RIBS. 29 



The respective ends of the fiist eight ribs iorm movable joints with the 

 spine and breast bone ; the first articulating with the last neck vertebra and 

 first dorsal vertebra ; the second with the first and second dorsal vertebras, 

 and so on. They are rigidly connected to their cartilages, of which those of 

 the first eight, or true, ribs form movable joints with the breast bone. 

 Commencing from the spine, "the ribs pass outwards and backwards, and 

 then in an arched direction downwards, their cartilages inclining inwards and 

 forwards" {Strangeways), Owing to the peculiar manner in which the ribs 

 are curved, and to the fact that the ends of the true ribs can pivot round in 

 the joints which they foim with the spine and breast bone, while the false 

 ribs also form movable joints with the spine ; the capacity of the chest is 

 capable of becoming much enlarged when the middle portion of the 

 ribs are pulled forward by muscles that are attached to them. The 

 mobility of the ribs, which is all but absent in the first one, gradually 

 increases as they go backwards. They also increase in rotundity in the same 

 manner, the first one being the fattest The first rib is the shortest, and 

 each succeeding one is longer than the one next in front of it, till the eighth 

 or ninth rib, the ribs behind which gradually decrease in length up to the 

 last one, which is nearly as short as the first rib. Owing to the direct 

 connection which the first eight ribs have with the breast bone, their power 

 of movement and, consequently, their action in increasing the capacity of the 

 chest is less than that of the false ribs. Hence, when seeking for signs of 

 good breathing power in a horse, we should attach far more importance to 

 rotundity of the rear portion of the chest than of the front part. As a 

 practical guide I might say that the former region might, in the saddled horse, 

 be regarded roughly as the portion of the ribs behind the saddle flaps, and the 

 latter as that covered by them. " It can be proved by observation, that the 

 middle false ribs are those which have the greatest power of being drawn 

 forwards and outwards. The ribs behind them successively lose more and 

 more their power of displacement up to the last one, the lower end of which 

 can be raised and lowered a little, without appreciably altering its distance 

 from the point of the hip " {Colin). 



The fore limb is connected to the trunk by muscles, to which I shall 

 allude on page 31. 



The shoulder joint is a ball and socket articulation, which possesses 

 considerable power of motion. 



The elbow is a hinge joint, which can be bent and extended. 



In the knee w^e have three hinge joints, of which that between the radius 

 and first row of bones is capable of a large amount of motion ; that between 

 the two rows of much less ; while that between the second row and cannon- 

 bones possesses hardly any powder of movement 



The bones at the back of the knee are united together by an extremely 

 strong ligament, one of the bands of which closes up the gap left between 

 the point of the trapezium and the inside of the knee, so as to form a channel 

 for the "back tendons" to pass through. 



The sesamoid bones are fixed immovably to the back of the fetiock joint 



