Myographia nova sive Muscolorum omnium (in copore humano hactenus repertorum) accuratissima descripto, in...

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Transversalis Transverse Muscle.

Tab. 5.

It presses the abdomen inward.

It arises from the transverse processes of the loins, from the iliac bone, and from the internal cartilaginous part of the lower ribs, enclosed by a nervous membrane, and proceeding from the same ligament as the pyramidal muscle. It also has a fleshy origin from the internal part of the ribs, which are called false or spurious, and ends in a wide tendon at the semilunar membranes and the linea alba, and thus downwards as far as the pubic bone. It adheres firmly to the adjacent peritoneum membrane lining the abdominal cavity throughout its whole length as far as the pubis, but is separated at the pubis. Bartholinus says that its principal use lies in the compression of the colon. But it is agreed among all anatomists that these muscles serve to pull the abdomen inward, an action certainly entirely necessary for the contraction of the lower ventricle. Spigelius assigns it another action, namely that it turns the thorax towards the sides in a circular motion, in that way fostering and exciting the natural heat. It is added that these muscles, when thicker than usual, provide a certain protection to the parts lying beneath them.

Observation.

The transverse muscle is perforated obliquely by the cremaster muscles and by the spermatic veins and arteries, a little above the obliquely ascending muscle, so that the openings of the descending and ascending abdominal muscles, neatly accommodated to one another, intercept and obstruct the passage of the intestines in lines not perpendicular or straight downward, but horizontal, lest they fall into the scrotum. The transverse muscles, passing across the breadth of the abdomen, meet the fibers of the rectus, which restrain the intestines descending through the length of the abdomen, just as the transverse fibers, passing transversely, cut the fibers of the rectus at right angles, and thus protect the intestines transversely, or across the breadth of the abdomen.