Ischial ramus

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Description:

The ischial ramus is the slender, branch-like, anteroinferior-projecting arm of the U-shaped ischium. This ramus joins the inferior ramus of the pubis. The ischial ramus has an external or anterior surface that is the attachment surface for the obturator externus and part of the adductor magnus muscle. Its internal or posterior surface contributes to the lateral wall of the pelvis and perineum. The ramus has two borders, lateral and medial. The lateral border forms a sharp edge that contributes to the margin of the obturator foramen. The medial border is thick, rough and rounded. This border is the attachment for the superficial perineal fascia, the inferior fascia of the urogenital diaphragm, the transversus perinei profundus muscle, the posterior portion of the crus of the penis or clitoris, and the ischiocavernosus muscle.