3!6 ANTHROPOLOGY. 



a sitting posture. Between the spine and the tuberosity is the lesser sciatic 

 notch, converted into a foramen by the great sciatic ligament. The third 

 process is the ramus, ascending from the tuber forwards and inwards, and 

 joining the descending ramus of the pubes. 



The OS pubis {pi. 122, fig. 5") is situated at the anterior part of the pelvis, 

 and is smaller than the ilium or ischium. It may be divided into the body 

 and processes. The body is the most external portion, and constitutes the 

 internal and superior part of the acetabulum. From the body the first pro- 

 cess, the horizontal ramus, proceeds forwards and outwards, grooved beneath 

 where it bounds the obturator foramen. At the internal extremity of this 

 ramus is the second process, the tuberosity or spine. This is a prominent 

 tubercle, into which Poupart's ligament is inserted. The third process, the 

 cyvst, leads transversely inwards from this spine, and at its internal end is 

 the fourth process, the symphysis. From the lower end of the symphysis 

 descends the fifth process, the inferior or descending ramus ; this, with the 

 ramus of the opposite pubes, forms the arch of the pubes ; the outer edge 

 of the ramus assists in bounding the thyroid hole. 



b. The Pelvis as a lohole. Considering in the next place the pelvis as a 

 whole, we commence with the acetabulum {pi. 12S, fig. 43'), constituted by 

 the junction of the bodies of the three bones. It is surrounded by a promi- 

 nent border with a deep notch or deficiency internally, and two others of 

 less extent, inferiorly and superiorly. The great notch which is opposite 

 the thyroid foramen, between the ischium and pubes, is converted into a 

 foramen by a ligament passing between these two bones. The cotyloid 

 cavity {fig. 45'') in the acetabulum for the reception of the head of the 

 thigh bone, is of a hemispherical form, and about two inches and a half in 

 diameter. 



TJie obturator, or thyroid foramen, is situated at the inner side of the ace- 

 tabulum and at an inferior level, and is the large anterior hole in the pelvis 

 bounded by the ischium and pubes. 



The superior circumference or base of the pelvis is formed on each side 

 by the crest of the ilium ; posteriorly by the promontory of the sacrum, 

 anteriorly by the iliac spines, ilio-pubal eminences, the intervening grooves, 

 and the crests and symphysis of the pubic bones. The lower or perineal 

 circumference (strait, or outlet, of the pelvis) is directed downwards and a 

 little forwards ; bounded by the rami of the pubes, the rami and tuberosities 

 of the ischium, the coccyx, and in the recent state by the sacro-sciatic 

 ligament of each side. When, as in the artificial skeleton, the latter are 

 removed, this strait presents three notches : first, the arch of the ptubes, 

 triangular and placed beneath the symphysis ; second and third, the sacro- 

 sciatic notches between the sacrum and os innominatum of each side. 

 Each of these is divided into a superior and an inferior by the sciatic 

 ligaments. 



The internal surface of the pelvis is divided into two parts by the ilio- 



pectineal line. The upper of these parts, properly part of the abdomen, is 



known as the false pelvis, the inferior being the true. The latter is a sort 



of curved canal, wider about the centre than at either end ; with smooth 



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