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

Tab. 2.
This muscle almost supports the previous one in the common act of consumption.

Obliquus Ascendens Internal Oblique Muscle.

It is placed next beneath the descending oblique and, endowed with ascending fibers, it arises with a fleshy face from the appendage of the ilium, but it becomes membranous from the processes of the same vertebrae, as before; from there, ascending to the eleventh and twelfth ribs with a fleshy margin, it is extended into a wide, double tendon, to which the Rectus muscle is attached; it proceeds from there to the linea alba and the semilunar line, and is inserted into the ninth, tenth, eleventh, and twelfth ribs. This muscle is certainly and most easily shown during dissection if you first seek the nerve, which is found in the middle between this muscle and the transverse one, next to the ilium, from where it arises.

Use.

The use and principal action of this pair, if we believe Columbus, is here, that it draws the muscles of the thorax downward, nature establishing in this a series of fibers opposite and contrary to those prior ones in the descending oblique, so that a tighter compression is made.

Obj.

To which can be added, unless my mind deceives me, that because this obliquely ascending muscle is pierced obliquely near the pubic bone by the Cremaster muscles and the spermatic veins and arteries, this is done a little above the opening of the descending oblique muscles, so that the obliquely ascending muscles, placed next beneath the descending oblique ones, by the contrary motion of the fibers, force them into obliquely ascending angles.

Furthermore, when the various muscles of the abdomen, contracting themselves inward in various ways, by the same operation push down the excrement of the viscera, and by the contrary motion of the fibers returning into themselves, restore the ventricle and intestines to their own place and natural position, it must be observed, however, that the motion of the abdominal muscles is opposite and hostile to the motion of the diaphragm, and vice versa the motion of the diaphragm to the motion of the abdominal muscles, for when the diaphragm by its motion dilates the thorax so that it may more comfortably receive the lung, swelling and distended from the ingress of air, its surface, approaching closely to the form of a plane and horizontal surface, so depresses the stomach and intestines that the chyle is insinuated little by little into the chyliferous duct by a very gentle motion. Conversely, with the pressure of the diaphragm itself ceasing, the lungs, with the air extruded, returning to their prior position and state, then the abdominal muscles play their parts and, while the diaphragm is pushed into an arc, they take, as it were, vengeance by pressing upward and constricting the thorax, whence the ventricle immediately slackening, they draw the intestines and stomach inward and upward, through the contraction of the abdominal muscles.

An anatomical engraving of a male figure standing in a classical landscape. The man is shown from the front, looking toward the left. He uses both hands to pull back a flap of skin and outer muscle from his abdominal region, revealing the layers of musculature beneath, including the rectus abdominis and the internal and external obliques. The background features a detailed landscape including a river with a small boat, a formal garden with topiary and a statue or fountain, a classical building in the distance, and a tall wooden post set in the ground to the right of the figure.