544 MR. YOUATTS VETERINARY LECTURES. 
lies towards the posterior edge—in the central ones it is more 
centrically situated,—in the posterior ones it lies towards the an¬ 
terior edge. This joint has also a separate capsular ligament, 
and it admits of a rotatory motion. 
Union with the Cartilage .—Before the ribs reach the sternum 
below, they terminate in a cartilaginous prolongation, or the 
lower part of the rib may be said to be cartilaginous. There is 
also between the bone and the cartilage a joint, not a very 
polished one, but with a true capsular ligament, and admitting of 
some motion ; and when the sternal rib unites with the sternum 
there is a fourth joint, the socket is perfect and deep, and the 
capsular ligament is complete. The cartilages of the posterior 
ribs are united to the bony portion by a kind of joint, but, not 
reaching so low as the sternum, are attached to each other be¬ 
low ; the extremity of one lying upon the body of that which is 
immediately before it, bound down upon it by cellular substance 
approaching to the nature of ligament, yet having some separate 
motion; and all of them connected indirectly with the sternum, 
by means of the last sternal rib. 
Description of the Ribs .—You will perceive that the first pair 
of ribs are shorter, thicker, and stronger than any of the others. 
The cartilage is very short, and in the same direction with the 
bone. Their office is to support the pressure of the head and 
neck, and w 7 hich would be overwhelmingly great, considering the 
length of the lever from w hich the head is appended, were not a 
very great portion of it borne by the proper ligament of the neck 
above. They consequently have little motion: they are mere 
fixed points on which the others act. The second rib also is long 
and straight, and discharges somewhat of the same function, and 
has little motion. The cartilages from the others take a sudden 
direction anteriorly, in order to be inserted into the sternum, and 
form an angle with the rib more or less acute, and most so an¬ 
teriorly. 
The Differences .—The ox has but thirteen ribs on each side, 
eight of them sternal, and five posterior. The dog also has 
thirteen, nine of them sternal. The swine has fourteen, and 
compared with those of any of our other patients, thin and weak. 
The ribs of the ox are larger and thicker, and more rounded than 
those of the horse; and the articulation between the bone and 
the cartilage of the rib is imperfect, and devoid of synovial mem¬ 
brane. 
The Sternum. 
The sternum, or breastbone, is more complicated than it at first 
appears to be. It constitutes the floor of the thorax.;—a long, 
