坐骨下枝とは
「船戸和弥のホームページ」の「坐骨」の解説では「坐骨上枝/坐骨下枝」という名称は見当たらず「坐骨枝」になっている。 ⇒「坐骨の解説全文」
「（坐骨は）寛骨の後下方部にあり、閉鎖孔の後方と下方部を囲む。寛骨臼の後下部とこの下方の肥厚した三角柱状部が坐骨体で、坐骨体から前内側上方へ伸びる細い扁平柱状部が坐骨枝である。」
以下が「Wikipedia」の解説文となる。
「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 the outlet of the pelvis, and presents two ridges and an intervening space.
The ridges are continuous with similar ones on the inferior ramus of the pubis: to the outer is attached the deep layer of the superficial perineal fascia (fascia of Colles), and to the inner the inferior fascia of the urogenital diaphragm.
Tracing these two ridges downward, they join with each other just behind the point of origin of the transversus perinæi. Here the two layers of fascia are continuous behind the posterior border of the muscle.
To the intervening space, just in front of the point of junction of the ridges, the transversus perinæi attaches, and in front of this is a portion of the crus penis vel clitoridis and the ischiocavernosus.
Its lateral border is thin and sharp, and forms part of the medial margin of the obturator foramen.」
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