Sacroiliac joint

The right and left sacroiliac joint (Latin articulatio iliosacralis ), sacroiliac joint, sacrum -iliac joint or short sacroiliac joint is the articulation between the sacrum ( os sacrum ) and the ilium ( ilium ).

Anatomy

The sacroiliac joint is a tight, little movable joint ( amphiarthrosis ) with a narrow joint cavity. The two contiguous articular surfaces are each called auricular facies. These joint surfaces is fibrocartilage ( ligaments sacroiliac interosseous ) establishes the additional connection. Due to the ( frictionless imaginary) joint space, the joint areas of the sacroiliac joint exclusively transmitted normal pressure forces. The ligaments ( ligament sacrotuberous, sacrospinous ligament, ligaments. Sacroiliaca anteriora, ligaments. Sacroiliaca posteriora and ligaments. Iliolumbalia ) must compensate all other powers to the extent that the resultant force always passes through the instantaneous center of motion of the joint ( static equilibrium condition real Diarthrosen ).

Movements

The small movements in the sacroiliac joint find almost exclusively in the transverse plane, they are referred to as nutation and Kontranutation.

Through a nutating motion in the sacroiliac joint and the strain related to the symphysis pubis, the width of the pelvic ring, which has a practical meaning for the passage of the child's head at birth, under which there is a hormonally -based softening of the ligaments increased. Here the promontory (Latin for " promontory " ) of the sacrum and the coccyx kaudoventral is shifted kraniodorsal, whereby the sagittal diameter ( Conjugata recta ) of the pelvic outlet and the larger diameter of the pelvic inlet conjugata is smaller. The sacrum, in doing so flexion (flexion ), the ilium rotation (rotation) with displacement of the iliac crest ( iliac crest ) backwards ( retroversion, posterior ilium ). The axis of the rotational movement is located in the region of the attachment points of the ligaments. interosseous sacroiliac.

Diseases

Fractures and dislocations of the sacroiliac joint can occur from falls, jerky movements and rotations of the pelvis. Acute and chronic dermatitis. In ankylosing spondylitis are very often the sacroiliac joints affected.

The joint plays an important role in many alternative medical directions; For example, in manual medicine, osteopathy, chiropractic of, Craniosacral Therapy and Dorn therapy ( " Beck blockade ").

The joint can be affected by osteoarthritis, see Iliosakralgelenksarthrose.