172 THE SKELETON 



by the posterior border. The capsule of the hip-joint is attached to the lateral part 

 and the pirifonnis, the great sciatic and posterior cutaneous nerves, the inferior 

 gluteal (sciatic) artery, and the nerve to the quadratus jemoris lie on the surface 

 as they leave the pelvis. Inferiorly this surface is limited by the obturator groove, 

 which receives the posterior fleshy border of the obturator externus when the thigh 

 is flexed. Of the three borders, the external, forming the prominent rim of the 

 acetabulum, separates the posterior from the external surface and gives attach- 

 ment to the glenoid lip. The inner border is sharp and forms the lateral 

 boundary of the obturator foramen. The posterior border is continuous with the 

 posterior border of the ihum, with which it joins to complete the margin of the 

 great sciatic notch [incisura ischiadica major]. The notch is converted into a 

 foramen by the sacro-spinous (small sacro-sciatic) ligament, and transmits the 

 'piriformis muscle, the gluteal vessels, the superior and inferior gluteal nerves, the 

 sciatic and posterior cutaneous nerves, the internal pudic vessels and nerve, and 

 the nerves to the obturator internus and quadratus jemoris. Below the notch is 

 the prominent ischial spine, which gives attachment internally to the coccygeus 

 and levator ani, externally to the gemellus superior^ and at the tip to the sacro- 

 spinous ligament. Below the spine is the small sciatic notch [incisura ischiadica 

 minor], covered in the recent state with cartilage, and converted into a foramen by 

 the sacro-tuberous (great sacro-sciatic) ligament. It transmits the tendon of the 

 obturator internus, its nerve of supply, and the internal pudic vessels and nerve. 



The rami form the flattened part of the ischium which runs first downward, 

 then upward, forward and medially from the tuberosity toward the inferior 

 ramus of the pubis, with which it is continuous. The rami together form an L- 

 shaped structure with an upper vertical ramus [ramus superior] and a lower 

 horizontal ramus [ramus inferior]. The outer surface of the rami gives origin to 

 the adductor magnus and obturator externus; the inner surface, forming part of the 

 anterior wall of the pelvis, receives the crus penis (or clitoridis) and the ischio- 

 cavernosus, and gives origin to a part of the obturator internus. Of the two borders, 

 the upper is thin and sharp, and forms part of the boundary of the obturator 

 foramen; the lower is rough and corresponds to the inferior ramus. It is some- 

 what everted and gives attachment to the fascia of Colles, and the transversus 

 perinei. To a ridge immediately above the impression for the crus penis (or 

 clitoridis) and the ischio-cavernosus , the urogenital trigone (triangular ligament) 

 is attached. The posterior and inferior aspect of the superior ramus is an ex- 

 panded area forming the tuberosity [tuber ischiadicum]. 



The tuberosity is that portion of the ischium which supports the body in the sitting posture. 

 It forms a rough, thick eminence continuous with the inferior border of the inferior ramus, 

 and is marked by an oblique line separating two impressions, an upper and lateral for the 

 semimembrannsHS, and a lower and medial for the common tendon of the biceps and semitendi- 

 nosus, while the lower part is markedly uneven and gives origin to the adductor magnus. The 

 upper border gives origin to the inferior gemellus; the inner border, sharp and prominent, re- 

 ceives the sacro-tuberous (great sacro-sciatic) ligament, while the surface of the tuberosity 

 immediately in front is in relation with the internal pudic vessels and nerve. The outer 

 border gives origin to the quadratus Jemoris. 



The pubis [os pubis] consists of a body and two rami — superior and inferior. 

 The body is somewhat quadrilateral in sliape and presents for examination two 

 surfaces and three borders. The anterior surface looks downward, forward and 

 slightly outward, and gives origin to the adductor longiis, the adductor hrevis, the 

 obturator externus, and the gracilis. The posterior surface is smooth, looks into 

 the pelvis, and affords origin to the levator ani, the obturator internus, and the pubo- 

 prostatic ligaments. The upper border or crest of the liody is rough and presents 

 laterally a prominent bony ])oint, known as the tubercle [tu])orculum pubicum] 

 or spine, for the attachment of the inguinal (Poupart's) ligament. The upper 

 border extends from the pul^ic tuberck> mcdialward to the upper end of the 

 symphysis, with wliich it forms the angle of the pubis. The upper border is a 

 short hori/ontal ridge, which gives attachment to the rectus abdominis aiulpyram- 

 idalis. The medial border is oval in shape, rough, and articular, forming with 

 the bone of the opposite.' side the symphysis pubis [facies symphyseos]. The 

 lateral border is sharp and forms part of the boundary of the obturator foramen. 



The inferior ramus, like the inferior ramus of the ischium, with which it is 

 continuous, is thin and flattened. To its anterior surface are attached the 



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