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They are two in number, and distinguished into: 1. Obliquus Externus Abdominis seu descendens externus seu descendens seu major, (F.) Ilio-pubo costo-abdominal, Costo-abdominal (Ch.), Grand oblique, Oblique externe. One of the broadest muscles of the body. It is situate at the lateral and anterior part of the abdomen; and is flat and quadrilateral. It is attached, above, to the outer surface and lower edge of the 7 or 8 last ribs: below, to the anterior third of the external lip of the crista ilii: before, it terminates at the linea alba by means of a broad and strong aponeurosis, which covers the rectus, and presents towards its inferior part two very solid fibrous fasciculi, which are inserted,-the one at the symphysis, the other at the spine of the pubis,-under the name of Pillars of the Abdominal Ring. These pillars leave between them an opening, which forms the inferior orifice of the inguinal canal. The obliquus externus abdominis depresses the ribs, and carries them backwards during a strong expiration. It impresses on the chest a movement of rotation, and bends the thorax upon the pelvis, and conversely. It contracts, also, the abdominal cavity. 2. Oblique Internus Abdominis seu ascendens seu minor seu internus seu ascendens internus, Musculus acclivis, (F.) Ilio-lombo-costo-abdominal, Ilio-abdominal (Ch.), Muscle petit oblique ou oblique interne, is broad, especially before; thin, and irregularly quadrilateral, like the preceding, beneath which it is situate. It is attached, above, to the inferior edge of the cartilages of the 5th, 4th, 3d, and 2d false ribs; below, to the anterior two-thirds of the interstice of the crista ilii, to the posterior part of the crural arch, and to the pubis; behind, to the spinous processes of the last two lumbar vertebrae, and to those of the first two portions of the sacrum; before, to the linea alba. Its upper fibres run obliquely upwards and forwards; the middle are horizontal; and the lower pass obliquely downwards and forwards. These last, in the male, are dragged down through the inguinal ring, when the testicle descends, and form the two fasciculi of the cremaster. The obliquus internus resembles the O. externus in function.