the name of the inferior or short^ superficial 

 posterior sacro-iliac Sgament. This ligament 

 has been hitherto apparently confounded with 

 the great sacro-sciatic, which is attached to 

 its lower border by a thin fibrous extension. 



fts. 81. 



124 PELVIS. 



great sacro-sciatic ligament (r), I think merits pelvis postictnn magnum, fg. 81. c) is attached 

 - - ~ ' *--~i behind, to the posterior inferior spine ot the 



ilium by a membranous expansion (e); to the 

 superficial posterior sacro-iliac ligaments with 

 which its fibres are blended; to the posterior 

 surface and borders of the two last pieces of 

 the sacrum ; and to the posterior sacro- coccy- 

 gean ligament and borders of the two or three 

 upper coccygeal bones. From this broad at- 

 tachment its fibres pass downwards, forwards, 

 and outwards to be implanted into the whole 

 length of the raised inner border of the great 

 tuberosity of the ischium. The fibres of this 

 ligament are arranged in fasciculi, which cross 

 each other in an X-like manner, so as to 

 present, at the extremities, an expanded 

 appearance, and in the centre a thick con- 

 tracted rounded outline. The fibres which 

 are placed superiorly in one extremity of 

 insertion cross at the contracted part to 

 become inferior at the other extremity, while 

 those which are internal cross in the opposite 

 direction to become external. Its superior 

 border, consequently, is directed outwards 

 and forwards, and its inferior border inwards, 

 and both present a curvilinear outline. At its 

 insertion into the sciatic tuberosity, the fibres 

 of the lower border present a falciform margin 

 having the concavity directed upwards along 

 the inner edge of the tuberosity, where it is 

 united to the fascia covering the obturator in- 

 ternus muscle. Its superficial or external 

 fibres are continued over the tuberosity in- 

 feriorly into the tendons of the biceps flexor 

 cruris, and semi-tendinosus muscles. Near the 

 posterior extremity, this ligament is almost 

 invariably perforated by a small hole, through 

 which passes the coccygeal branch of the 

 ischiadic artery. To the whole length of its 

 external or posterior surface is attached the 

 great glutens muscle, which causes it when 

 dissected to be very rough and flocculent. At 

 the posterior half of its inner surface it is 

 blended intimately with the lesser sacro-sciatic 

 ligament, anterior to which it is smooth, and 

 forms part of the boundary of the ischio- 

 rectal fossa. 



The lesser or internal sacro-sciatic ligament 

 (ligamentum pelvis posticum parvum, Jig. 81. 

 d) lies internal to the last, in common with 

 which it is attached posteriorly to the side of 

 the two last pieces of the sacrum and of the 

 two upper pieces of the coccyx. At its an- 

 terior extremity it is contracted into a pointed 

 insertion into the spine of the ischium. The 

 direction of this ligament is horizontally for- 

 wards and outwards, and its shape is triangular, 

 so that its anterior contracted portion diverges 

 from the great sacro-sciatic ligament, leaving 

 a triangular opening between them through 

 which pass the obturator muscle out of, am' 

 the pudic vessels and nerves into the pelvis 

 This ligament, thus passing from the sacrum 

 across to the ischium, converts the sacro- 

 sciatic notch into a triangular or oval foramen 

 through which pass the pyramidalis muscle, 

 the gluteal, ischiadic and pudic vessels, and the 

 superior gluteal and great and lesser sciatic 

 and pudic nerves out of the pelvis. With its 



Posterior view of the ligaments of the pelvis. 



a, oblique posterior sacro-iliac ligament ; b, infe- 

 rior posterior superficial sacro-iliac ligament; c, 

 great sacro-sciatic ligament ; d, lesser sacro-sciatic 

 ligament ; e, membranous expansion over the pyri- 

 formis muscle. 



The ligaments which may be considered as 

 accessory to this articulation are three in 

 number the ilio-lumbar ligament above, and 

 the greater and lesser sacro-sciatic ligaments 

 below. 



The ilio-lumbar ligament (fig. 80. c} is a 

 triangular fascicular ligament, thickest at 

 the edges, and passing from the tip of the 

 last lumbar transverse process, to which its 

 apex is attached, horizontally outwards, and a 

 little backwards to the posterior fifth of the 

 inner lip of the crest of the ilium, along which 

 its fibres spread as far forward as the inner 

 projecting point of the posterior curve. To 

 the outer side and behind this ligament is 

 attached the quadratus lumborum muscle 

 with the tendon of the transversalis abdo- 

 minis, and to its front the psoas magnus 

 muscle. Meckel describes this ligament as 

 sometimes reaching as high as the transverse 

 process of the fourth lumbar vertebra. He 

 also describes a second ligament lower than 

 the preceding, but arising from the iliac crest 

 a little behind it. They are called by him, 

 respectively, the upper and lower anterior 

 pelvic ligaments, the latter corresponding to 

 the sacro-vertebral ligament before described. 

 The great sacro-sciatic ligament (ligamentum 



