Ischium Posteriorly the ramus forms a large swelling, the tuberosity of the ischium, where the hamstrings originate. The inferior ramus of the ischium (ascending ramus) is the thin, flattened part of the ischium, which ascends from the superior ramus, and joins the inferior ramus of the pubis—the junction being indicated in the adult by a raised line. The outer surface is uneven for the origin of the obturator externus and some of the fibers of the adductor magnus; its inner surface forms part of the anterior wall of the pelvis. Its medial border is thick, rough, slightly everted, forms part of
Squamous part of occipital bone Squamous part of occipital bone The squamous part of occipital bone, is situated above and behind the foramen magnum, and is curved from above downward and from side to side. The external surface is convex and presents midway between the summit of the bone and the foramen magnum a prominence, the external occipital protuberance and inion. Extending lateralward from this on either side are two curved lines, one a little above the other. The upper, often faintly marked, is named the highest nuchal line, and to it the epicranial aponeurosis is attached. The lower is termed the superior nuchal line.