Morphofunctional features of the transverse abdominal muscle in dogs, cats, and rabbits

The transverse abdominal muscle in all the animal species studied belongs to the dynamic type of muscle, and is the deepest of all the broad abdominal wall muscles. The length of the teeth of the costal part of the transverse abdominal muscle in all studied animals decreases in the caudal direction, the greatest differences in the length of the first and last teeth of the costal part are characteristic of the dog. In all the studied animals, the length of the transverse abdominal muscle bundles is directly dependent on the volume of the abdominal cavity in its various parts. The maximum value of this indicator in a dog and cat reaches in the cranial, in a rabbit in the middle parts of the abdominal cavity. The muscle plate of the transverse abdominal muscle has the maximum thickness in the costal part, in the lumbar part it gradually decreases. The percentage of the mass of the transverse abdominal muscle in a dog and a cat is approximately 25 % of the total mass of all abdominal muscles. In a rabbit, this value is 30-35 %. The ventrally transverse abdominal muscle passes into a broad aponeurosis, which is involved in the formation of the inner wall of the vagina of the rectus abdominis muscle and the white line of the abdomen. The maximum width of the aponeurosis is in the middle part, while the minimum width is in the caudal part.