FIRST LECTURE.

Tab. 1.

Obliquus Descendens External Oblique Muscle.

This muscle compresses the abdomen from the side.

THIS first pair of muscles, with which nature has covered the abdomen like a veil, is clothed in fibers arranged obliquely and is called the pair that descends from "descending". It arises from the lower part of the sixth, seventh, eighth, and ninth ribs, fitted in a serrated manner and applied to the Serratus Anterior Major; it becomes membranous at the transverse processes of the lumbar vertebrae, and in the part of the ilium, then passing through the linea alba to the pubic bone, it is carried into the middle of the abdomen by a wide, nervous tendon. Obs. This muscle adheres so tightly to the underlying tendon that it can scarcely be pulled away without laceration. This tendon, together with its partner, whether loose or widened beyond measure, causes either the omentum or certainly the intestines to prolapse into the groin or scrotum, from which arises the hernia that surgeons and physicians have called omental or intestinal, depending on whether it is the omentum or intestines that fall into the groin or scrotum. If you wish to dissect this muscle skillfully, you will separate the latissimus dorsi from it, where it is first inserted and joined to the descending muscle, for in this way it will happen that you will obtain the origin of the descending muscle, which must be sought in the loins, more easily and more clearly by dissecting.

Use. The principal use of this muscle, as Columbus and Laurentius, reliable witnesses, affirm, is to be placed in the contraction of the thorax, which it frequently drives upward, and it serves respiration an incredible amount. It is entirely worthy of mention in this place, which Laurentius left written about this muscle, since indeed, contrary to what usually happens in other muscles of the human body, it is perpetually curved and turned inward upon itself before it acts, whereby it happens that, by compressing and constricting the internal cavities of the ventricle and abdomen more easily, it restrains the laxity of the lower belly by an internal effort that tends upward, and by the same operation it extrudes and casts out the ballast of the viscera. Obs. Furthermore, I would also like it to be observed that these muscles constrict the intestines in obliquely descending angles.

A detailed anatomical engraving of a skinless (écorché) male figure standing in a coastal landscape. The figure is posed classically, leaning his left elbow on a stone pedestal. The superficial muscles of the torso are revealed, with a banner across the lower abdomen labeled "Obliquus descendens". In the upper right corner, a hand emerges from clouds holding a pointer aimed at the figure's neck. The background shows a calm sea or lake with trees on the far shore.