. Cunningham's Text-book of anatomy. Anatomy. THE SACBUM. 97 assists in the interlocking of the sacro-ihac joint; this feature is common in the Simiidse and some of the lower races of mankind (Paterson). The surface of bone between and lateral to the first, second, third, and fourth foramina affords attachment to the fibres of origin of the piriformis, which may in some instances extend on to the bodies of the second and third segments (Adolphi), whilst on the edge lateral to and below the fourth foramen the coccygeus is inserted The posterior surface is rough and irregular. Convex from above
. Cunningham's Text-book of anatomy. Anatomy. THE SACBUM. 97 assists in the interlocking of the sacro-ihac joint; this feature is common in the Simiidse and some of the lower races of mankind (Paterson). The surface of bone between and lateral to the first, second, third, and fourth foramina affords attachment to the fibres of origin of the piriformis, which may in some instances extend on to the bodies of the second and third segments (Adolphi), whilst on the edge lateral to and below the fourth foramen the coccygeus is inserted The posterior surface is rough and irregular. Convex from above downwards it displays in the median plane the crista sacralis media, a crest whereon are seen four elongated tubercles—the spines of the upper four sacral vertebrae. Lateral to these the bone orms a groove—the sacral groove—the floor of which is made up of the confluent laminae oi the corresponding vertebrae. In line with the intervals between the spines, and wider apart above than below, another series of tubercles is to be Superior articular processes Transverse process of first sacral vertebra. Anterior sacral foramen Inferior lateral angle Groove for fifth sacral nerve Coccygeal articular surface Fig. 112.—The Sacrum (anterior view). seen. These are due to the fusion of the articular processes of the sacral vertebrae, which thus form faint interrupted ridges on either side of the bone (cristae sacrales articulares). Normally, the spine of the lowest sacral segment is absent, and the laminae do not coalesce medially, thus leaving a gap in which the sacral canal is exposed (hiatus sacralis); whilst inferiorly the tubercles corresponding to the inferior articular processes of the last sacral vertebra form little down-projecting processes—the sacral cornua—by means of which the sacrum is in part united to the coccyx. Just wide of the articular tubercles are the posterior sacral foramina, for the transmission of the posterior branches of the sacral nerves. These are
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1914
