Sacrococcygeal symphysis

The sacrococcygeal symphysis (sacrococcygeal articulation, articulation of the sacrum and coccyx) is an amphiarthrodial joint, formed between the oval surface at the apex of the sacrum, and the base of the coccyx.

Ligaments
It is homologous with the joints between the bodies of the vertebrae, and is connected by similar ligaments. They are:


 * Anterior sacrococcygeal ligament
 * Posterior sacrococcygeal ligament
 * Lateral sacrococcygeal ligament
 * Interposed fibrocartilage ligament
 * Interarticular ligament

Movements
The movements which take place between the sacrum and coccyx, and between the different pieces of the latter bone, are forward and backward; they are very limited. Their extent increases during pregnancy.