ARTICULATIONS OF THE PELVIS 



293 



The anterior sacrococcygeal ligament (ligamentum sacrococcygeum anterius) 

 consists of a few irregular fibres which descend from the anterior surface of the 

 sacrum to the front of the coccyx, becoming blended with the periosteum. It 

 is a continuation of the anterior common ligament. 



The posterior sacrococcygeal ligament (ligamentum sacrococcygeum posterius} 

 (Fig. 241) is divided into two portions, the deep and the superficial. The deep 

 portion (ligamentum sacrococcygeum posterius profundum), which is a continua- 

 tion of the posterior common ligament, is a flat band of a pearly tint, which arises 

 from the margin of the lower orifice of the sacral canal, and descends to be inserted 

 into the posterior surface of the coccyx. This ligament completes the lower 

 and back part of the sacral canal. Its superficial fibres are much longer than 

 the more deeply seated. This ligament is in relation, behind, with the Glutens 

 maximus. The superficial portion (ligamentum sacrococcygeum posterius super- 

 ficiale) is composed of longitudinal fibrous bands which extend from the lower 

 portion of the middle sacral ridge to the posterior surface of the coccyx and 

 closes partly the sacral hiatus, and of fibrous bands which extend from the sacral 

 cornua to the coccygeal cornua. A portion of this ligament corresponds to the 

 ligamenta subflava and the balance to the capsular ligament. 



APEX OF SACRUM 

 LATERAL SACRO- 

 COCCYGEAL LIGAMENT 

 SUPERFICIAL PORTION OF POST 

 SACROCOCCYGEAL LIGAMENT 

 DEEP PORTION OF POSTERIOR 

 SACROCOCCYGEAL LIGAMENT 



FIG. 241. Ligaments between the sacrum and the coccyx. (Spalteholz.) ' 



A lateral sacrococcygeal or intertransverse ligament (ligamentum sacro- 

 coccygeum laterale) (Fig. 241) connects the transverse process of the coccyx to 

 the lower lateral angle of the sacrum on each side. 



A fibrocartilage or articular disk is interposed between the contiguous surfaces 

 of the sacrum and coccyx; it differs from that interposed between the bodies of 

 the vertebrae in being thinner, and its central part firmer in texture. It is some- 

 what thicker in front and behind than at the sides. Occasionally, a synovia! 

 membrane is found and the coccyx is freely movable. This is especially the case 

 during pregnancy. 



The different segments of the coccyx are connected by an extension downward 

 of the anterior and posterior sacrococcygeal ligaments, a thin annular articular 

 disk being interposed between each of the bones. In the adult male all the 

 pieces become ossified, but in the female this does not commonly occur until a 

 later period of life. The separate segments of the coccyx are first united, and at 

 a more advanced age the joint between the sacrum and coccyx is obliterated. 



