上関節突起 - Processus articularis superior
The superior articular processes project from it on either side; they are oval, concave, directed backward and medialward, like the superior articular processes of a lumbar vertebra. They are attached to the body of the first sacral vertebra and to the alæ by short thick pedicles.
This definition incorporates text from a public domain edition of Gray's Anatomy (20th U.S. edition of Gray's Anatomy of the Human Body, published in 1918 – from http://www.bartleby.com/107/).
一般解剖学 > 骨、骨格系 > 軸骨格 > 脊柱 > 仙骨；仙椎[1－5] > 仙骨底 > 上関節突起