Introduction. The abdominal walls consist mainly of the skin, yellow 
elastic tissue, a fibrous aponeurosis, particularly strong in herbivora, the 
muscles, a layer of fat, and the peritoneum. The muscular fasciculi partly 
overlie and cross one another, and have numerous tendinous expansions. In 
herbivora the stout, thick abdominal walls, which always appear distended, 
have to support the bulky digestive organs, and effectually protect them from 
external injury, but render examination of them almost impossible. The 
abdominal walls are externally clothed with skin, possessing a well-developed 
subcutis, whilst their inner surface is covered with peritoneum, which both 
lines the cavity and invests its contained organs. The uninjured peritoneum 
is smooth and shining, allowing the abdominal viscera to play easily over each 
other; but when inflamed, exudation occurs, and the surfaces may become 
adherent. Except as a result of penetrating wounds (more rarely of bruises), 
the abdominal organs are seldom injured from without. Voulton (Stockfleth) 
found, however, the rumen of an ox ruptured by a blow from a horse s foot. 
Death rapidly followed from peritonitis. 
In horses, ruptures of the spleen have been observed. 
The abdominal walls receive their blood from tw r o sources : the lumbar 
arteries enter between the lumbar muscles, pass obliquely aciossthe abdomen, 
between the outer and inner oblique abdominal muscles, and between the 
latter and the transverse abdominal muscle, and communicate frequently with 
the vessels of the abdominal parietes. The anterior abdominal artery aiises 
from the internal thoracic artery and passes backwards. The posterior abdo¬ 
minal artery, arising from the prepubic artery, takes a course close below the 
peritoneum in the middle line, passes 'the inner abdominal ring in a forward 
direction, and anastomoses with the anterior abdominal and with the lumbar 
arteries. 
I.—BRUISES OF THE ABDOMINAL PARIETES. 
These occur rather frequently in the domestic animals, and are caused 
by kicks, thrusts with the horn, treads, by animals rushing together, or 
by collisions with vehicles. The nature of the injury mainly depends on 
the character of the injuring body, and the force with which it is applied. 
Sometimes the walls are ruptured,—a condition described later ; whilst 
the skin, on account of its greater elasticity, remains intact. Sharp 
objects produce surface wounds, sometimes perforate the abdominal walls, 
and may even penetrate the internal organs; these last accidents will also 
be considered later. Bruises of the soft portions of the abdominal parietes 
from horn-thrusts, &c., are frequent in herbivora, on account of the 
tension of the abdominal walls ; and, as in other regions, are characterised 
by a subcutaneous solution of continuity in the vessels and tissues. When 
