Search results
Results from the WOW.Com Content Network
The sacrum (pl.: sacra or sacrums [1]), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1–S5) between ages 18 and 30. [2] The sacrum situates at the upper, back part of the pelvic cavity, between the two wings of the pelvis. It forms joints with four other bones.
The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the ilium bones of the pelvis, which are connected by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. The joint is strong, supporting the entire weight of the upper body.
The same human pelvis, front imaged by X-ray (top), magnetic resonance imaging (middle), and 3-dimensional computed tomography (bottom). The pelvis (pl.: pelves or pelvises) is the lower part of an anatomical trunk, [1] between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton [2] (sometimes also called bony pelvis or pelvic skeleton).
The posterior border of the ala of sacrum, shorter than the anterior, also presents two projections separated by a notch, the posterior superior iliac spine and the posterior inferior iliac spine. The posterior superior iliac spine serves for the attachment of the oblique portion of the posterior sacroiliac ligaments and the multifidus.
The false pelvis is that portion superior to the pelvic brim; it is bounded by the alae of the ilia laterally and the sacral promontory and lumbar vertebrae posteriorly. [4] The true pelvis is the region inferior to the pelvic brim that is almost entirely surrounded by bone. [4] The pelvic inlet is the opening
The sacroiliac joint is a true diarthrodial joint that joins the sacrum to the pelvis. [1] [8] [16] [17] The sacrum connects on the right and left sides to the ilia (pelvic bones) to form the sacroiliac joints. The pelvic girdle is made up of two innominate bones (the iliac bones) and the sacrum.
The sacrotuberous ligament is attached by its broad base to the posterior superior iliac spine, the posterior sacroiliac ligaments (with which it is partly blended), to the lower transverse sacral tubercles and the lateral margins of the lower sacrum and upper coccyx.
The posterior sacroiliac ligament is situated in a deep depression between the sacrum and ilium behind; it is strong and forms the chief bond of union between the bones.. It consists of numerous fasciculi, which pass between the bones in various directions.