Synonyms in a broader sense
Medical: Disease:
- Articulatio sacroiliaca
- Sacroiliac joint
- Sacroiliac joint
- SIG (sacroiliac joint)
- ISG Blocking
- Scroiliitis
Declaration
The ISG (medical: Articulatio sacroiliaca) is the articulated connection between the sacrum (Os sacrum) and the ilium (Os Ilium). The articular surfaces (Facies auricularis) between these two bones have a boomerang to c-shaped form and are located between the 1st and 3rd sacral vertebrae. They consist of an upper and a lower pole, whose transition point is located approximately at the level of the 2nd sacral vertebra (part of the sacrum). Between the upper and lower pole there is a kink, whose angle is 100-120°.
Gender-specific differences in the joint surfaces
With the woman the joint surface is of clearly more even shape, so that a clearly larger movement clearance exists than with the ISG of the man. The stabilizing factors of the joint in women are on the one hand the position of the sacrum in the pelvic ring and on the other hand the muscle and ligamentous apparatus. One speaks of the so-called force closure of the joint.
The surfaces of the joint surfaces in men are characterized by numerous grooves and elevations, so that a great deal of force must be applied to achieve a displacement of the joint surfaces against each other. The result is great stability but only limited mobility of the joint. One speaks of the so-called form closure of the joint.
Stabilizing factors of the ISG
In addition to the surface condition of the joint surfaces and the position of the sacrum in the pelvic ring, a number of ligaments are responsible for the stability of the ISG. The most important ligaments are briefly described below.
- Posterior sacroiliac ligaments (Ligg.
sacroiliaca dorsalia) These are fibrous bands that connect the ilium with the sacrum.
- Anterior sacroiliac ligaments (Ligg. sacroiliaca ventralia)These ligament structures also connect the ilium with the sacrum, are rather thin and have a connection with the capsule. In their upper fibrous course they form a connection with the iliolumbar ligament.
- Ligg.
sacroiliaca interosseaThese ligaments, whose fiber courses are very dense and short, also connect with the joint capsule and fill the sacral sulcus. Through their direct positional relationship to the capsule and by filling the sacral sulcus, they assume an important function in stabilizing the ISG.
- Ligg. sacrospinaleThis ligament has its origin at the lower outer surface of the sacrum and the base of the coccyx, runs in front of the Ligamentum sacrotuberale with which it is closely connected and starts in the area of the spina ischiadica.
- Lig.
sacrotuberaleThis triangular band originates in the lateral areas of the sacrum/rump and ilium (Spina iliaca posterior superior (SIP)) and attaches to the ischiadic tuberosity. This ligament also plays an important role in stabilizing and moving the ISG. Together with the sacrospinal ligament, it is the strongest ligament for stabilizing the nutation movement.
The Ligamentum sacrospinale and the Ligamentum sacrotuberalemachen from the Incisura ischiadica major and minor a Foramen isciadicum majus and minus. These represent important points of passage for vessels, nerves and muscles.
- Lig. iliolumbaleThey continue the posterior sacroiliac ligaments upwards and extend from the ilium to the 4th and 5th lumbar vertebrae . These ligaments are responsible for stabilizing the ventral ISG area.
