254 



A DICTIONARF. 



synovia, or joint oU; and cellular mem- 

 brane, or tissue, is the common connecting 

 substance of most parts of the body. 



Mesentery. — A thin membrane by 

 which the bowels are held together, and 

 over wldch the lacteals, or chyle vessels, 

 pass. Besides the chyle vessels, there are 

 considerable veins and arteries passing over 

 the mesentery. The arteries are distributed 

 to the bowels, and the veins terminate in 

 the vena porta, or great vein of the liver. 



Metacarpus. — The metacarpus of the 

 horse consists of one great bone, commonly 

 named the canon, shank bone, or fore leg, 

 and tw'O small bones, or splent bones, at- 

 tached by ligaments to the back part of the 

 canon bone, rather towards the sides. The 

 suspensory ligament passes down on the 

 back part of the canon bone, and between 

 the two splents. The flexor tendons, or back 

 sinews, pass down over the suspensory lig- 

 ament. When the bones only of the fore 

 leg are spoken of, they are termed meta- 

 carpus. They begin at the knee, and end 

 at the fetlock joint. 



Metatarsus. — The hind leg, between 

 the hock and fetlock joints. 



Metatarsal Bones. — The hind canon, 

 or shank bone, wdth the two small splent 

 bones attached to it. The large blood- 

 vessels and nerves, in this situation, are also 

 named metatarsal. 



Miasmata. — Poisonous effluvia. 



Midriff. — (See Diaphragm.) 



Molares. — The name of the grinding 

 teeth. 



Molten Grease. — A name which Mr. 

 Blaine has given to dysentery. 



Morbid Displacements of the Intes- 

 tines, etc — Rupture^ or Intestinal Hernia* 

 Hernia, in its strict sense, is a protrusion of 

 any viscus out of its natural cavity ; hence 

 we have hernia of the brain, of the lungs, 

 and of the various viscera of the abdomi- 

 nal regions. Hernia, as we propose to 

 consider it, is a displacement of the intes- 

 tines from the abdominal cavity, either 

 through some of the natural openings, or 



* "Blaine's Outlines," by Mahew. 



through artificial ones, the effects of acci- 

 dent. When such protrusion takes place 

 through a moderate opening, and the por- 

 tion of gut can be readily returned, it is 

 called a reducible hernia ; but Avhen it oc- 

 curs through a small opening, and the in- 

 testine cannot be replaced, it is termed an 

 irreducible hernia. If the mouth of the 

 opening, round the intestine, constringe, 

 and prevent the return of the bowel, it then 

 forms a strangulated hernia, and usually 

 proves fatal, unless relief be promptly ob- 

 tained. 



The hernia, by far the most common in 

 the horse, is the inguinal, of which the 

 scrotal, or when the bowel descends into 

 the scrotum, is most frequently observed in 

 the stallion. Bubonocele, or that of the 

 groin, is a very rare form of disease, but it 

 is occasionally witnessed in geldings. In 

 the former, the intestine accompanies the 

 spermatic cord by the inguinal canal 

 through the abdominal rings into the scro- 

 tum : in the latter, the bowel alone lodges 

 in the groin. The ruptures we have named 

 may be considered as the only ones com- 

 mon to the horse. Some of them are very 

 rarely seen : hernia is more frequently on 

 the right than on the left side ; and scarcely 

 ever appears in mares. However, ventral 

 hernia, or rupture of the muscles of the 

 abdominal sides, and protrusion beneath 

 the skin of a portion of intestine, is some- 

 times beheld in either sex, and perhaps, of 

 the two, is more frequently witnessed in 

 the female. 



The causes which produce hernia are 

 various, but all arise from violence of exer- 

 tion, or the effects consequent upon external 

 injuries. With us the cflbrts used in racing, 

 and the leaps taken in hunting, are causes, 

 as we may readily suppose ; when we con- 

 sider that the dilatation of the abdomen, 

 restrained as it is by weight and tight girth- 

 ings, must press backwards the intestinal 

 mass. Rearing and kicking also, and being 

 cast for operations, particularly the rising 

 up after castration, have all brought it on. 

 Blows with a thick stick, or from the horn 

 of a cow, may likewise induce it. 



