133 



PELVIS. 



it is bent as over a pulley) ; the gemellus su- 

 pcrior, to the outer surface of the ischiadic 

 spine; the gemellus inferior, to the posterior 

 extremity of the ischiadic tuberosity ; and the 

 (jitadratus femoris, to the external border of 

 the same tuberosity. 



3. Muscles acting on the perineum and ge- 

 nitals. The posterior perineal group. The 

 levator ani, to the middle of the inner surface 

 of the symphysis pubis, to the inner surface 

 of the ischiadic spine, and to the tip of the 

 coccyx; the ischio-cocci/gcus, to the same inner 

 surface of the ischiadic spine, to the lateral 

 border of the coccyx, and to the inner surface 

 of the small sacro-sciatic ligament ; and the 

 sphincter ani, to the tip of the coccyx. 



The anterior perineal group. The trans- 

 versus perinei, to the middle of the inner 

 border of the ischial tuberosity ; the accelerator 

 urince (or, in the female, the sphincter vagina;}, 

 to the anterior part of the inner border of the 

 ischial tuberosity ; the erector penis (or, in the 

 female, ctitoridii), to the ascending ramus of 

 the ischium ; and the compressors urethra;, 

 to the descending ramus of the pubis, and to 

 the sub-pubic ligament. 



FASCIAL ATTACHMENTS. Besides the fore- 

 going, the pelvis also affords attachment to 

 many important fasckc, which are susceptible 

 of division into lumbar, abdominal, crural, 

 pelvic, and perineal. 



The lumbar fascia is formed by the junction 

 of the tendon of the latissimus dorsi muscle 

 with the fascia vertebralis, and the united 

 posterior tendons of the internal oblique and 

 external division of the transversalis tendon, 

 and it is attached along the sacral crest and 

 posterior surface of the fourth sacral bone, 

 and to the posterior half of the iliac crest, 

 enclosing the sacro-lumbalis muscle. 



The abdominal fascia: are three in number, 

 viz., the fascice transversalis, attached along 

 the inner lip of the iliac crest, to Poupart's 

 ligament, and to the crest, spine, and pec- 

 tineal line of the pubis ; the fascia of the qua- 

 dratics lumborum muscle, or anterior division of 

 the tendon of the transversalis, attached to 

 the inner lip of the posterior fourth of the 

 iliac crest, and to the ilio-lumbar ligament ; 

 and the iliac fascia, attached to the ilio-lumbar 

 ligament, along the inner margin of the iliac 

 crest, and to the anterior superior iliac spine. 



The crural fascia or fascia lata is divided into 

 three portions, named, from their respective 

 attachments to the three portions of the inno- 

 minate bone, iliac, pubic, and ischiadic. The 

 outer lip of the iliac crest, the anterior superior 

 spine, and Poupart's ligament, give attachment 

 to the iliac portion, which separates the lateral 

 abdominal from the external leg muscles ; the 

 spine, crest, angle, pectineal line, and descend- 

 ing ramus of the pubis, to the pubic portion, 

 which separates the internal leg muscles from 

 the anterior abdominal and anterior perineal 

 group of muscles ; and the tuberosity and 

 ascending ramus of the ischium to the ischiadic 

 portion, which separates the posterior leg 

 muscles from the posterior muscles of the 

 perineal group. 



The pelvic fascia is composed of two por- 

 tions, the rccto-vesical and obturator, which, 

 having a common attachment to the anterior 

 surface and promontory of the sacrum, to the 

 anterior and lateral parts of the pelvic brim, 

 and to the iliac fascia, separate opposite the 

 line of origin of the levator ani muscle, which 

 arises between them, from the symphysis pubis 

 to the ischiadic spine. The obturator division 

 is attached to the inner margins of the ischiadic 

 tuberosity and ischio-pubic rami, being con- 

 nected with the falciform margin of the great 

 sacro-sciatic ligament behind, and secluding 

 the obturator muscle from the ischio-rectal 

 fossa ; the recto-vcsical division, forming the 

 anterioi ind lateral true ligaments of the 

 bladder, is attached to the posterior surface 

 of the symphysis pubis above the origin of the 

 levator ani, and to the inner surface of the 

 ischiadic spine. 



The perineal fascia is divided into two por- 

 tions, deep and superficial, which enclose be- 

 tween them the superficial muscles of the 

 anterior perineal group, and also the bulb of 

 the urethra and the crura of the penis. The 

 deep perineal fascia or triangular ligament is 

 subdivided into two layers, anterior and pos- 

 terior, which enclose between them the mem- 

 branous urethra, with its compressor muscles 

 and Cowper's glands. They are both attached 

 to the lower border of the pubic symphysis 

 and sub-pubic ligament, and to the inner 

 border of the united ischio-pubic rami, and 

 intervene between the posterior and anterior 

 perineal groups of muscles. The superficial 

 perineal fascia covers in the anterior perineal 

 region, and is attached to the anterior part of 

 the inner border of the ischio-pubic rami, and 

 to the anterior surface of the angle of the 

 pubis. 



The crura of the penis, or, in the female, 

 those of the clitoris, may also be mentioned 

 as implanted on the rough inner border of the 

 ischio-pubic rami about their junction ; as 

 well as the round uterine tigameut, in the fe- 

 male, to the anterior surface of the pubis. 



MECHANICS OF THE HUMAN PELVIS. 

 When we consider the pelvis with regard to 

 its architectural adaptations, and compare it 

 with the principles of engineering, we are 

 struck with the beautiful simplicity of the 

 means by which it combines strength with 

 elasticity, and lightness with capacity and 

 unity of design. The weight of the trunk is 

 to be transmitted through the lumbar ver- 

 tebra to the sacrum, and from thence to 

 points of support, which vary with the posi- 

 tion of the inferior extremities. In the erect 

 position, these points are the femora, lu the 

 sitting position they are the tuberosities of 

 the ischia. 



The experiments of Weber have proved 

 that though the centre of gravity of the 

 trunk itself (without the legs) is placed in 

 the transverse vertical plane as high as the 

 sterno-xiphoid joint, yet the centre of gravity 

 of the whole body, as marked by the point of 

 section of the before-mentioned transverse- 

 vertical with a horizontal plane, is placed only 



