Human Anatomy - Kotsan I. Ya. 2009

Anatomy of the Axial Skeleton
Articulations of the Sacrum and Coccyx

In youth, a Sacrococcygeal joint (articulatio sacrococcygea) is located between the apex of the sacrum and the Base of the coccyx, which later in life transforms into a symphysis. In women, the cavity of the sacrococcygeal symphysis is larger than in men. This is of practical importance during childbirth, as it allows the coccyx to deviate significantly backward, thereby increasing the anteroposterior dimension of the pelvic outlet. In elderly individuals, the cleft within the intervertebral disc disappears, and the symphysis turns into a synchondrosis. In men, it ossifies almost completely.

The sacral and coccygeal cornua are connected by means of a syndesmosis (syndesmosis).

The sacrococcygeal junction is reinforced by the following ligaments.

1. The anterior sacrococcygeal ligament (lig. sacrococcygeum anterius) is a continuation of the anterior longitudinal ligament; it consists of two bundles that converge and decussate on the anterior surface of the coccyx.

2. The deep posterior sacrococcygeal ligament (lig. sacrococcygеum posterius profundum) is a continuation of the posterior longitudinal ligament.

3. The superficial posterior sacrococcygeal ligament (lig. sacrococcygеum posterius superficiale) extends as two bands from the lateral margins of the sacral hiatus to the posterior surface of the coccygeal bone (the analog of the ligamentum flavum).

4. The lateral sacrococcygeal ligament (lig. sacrococcygеum laterale) runs from the lower edge of the lateral sacral crest to the rudimentary transverse process of the first coccygeal vertebra (the analog of the intertransverse ligaments of THE Vertebral Column).