PELVIS 



PEMBA 



19 



an angle with the horizontal which varies from 60 

 to 65. Thus the weight of the upper part of the 

 body which is communicated to the sacrum is 

 directed downwards and transmitted through the 

 innominate bones to the heads of the femora, and 

 so to the inferior extremities. In addition to the 

 ligaments, muscles, blood-vessels, and nerves which 

 constitute the soft parts of the pelvis, there are 

 certain special organs which are present in both 

 sexes, and others which are peculiar to each sex. 



Thus, of those 

 common to both 

 sexes, there are 

 the urinary 

 bladder and the 

 rectum. The 

 urinary bladder 

 is placed behind 

 the symphysis 

 d onl- 



Fig. 2. 

 a, adult male, and 6, female pelvU. 



tes in the anus. 



is supported by two muscles the i 

 which surround it so completely 



pubis, and only 

 rises out of the 

 pelvis into the 

 abdomen when 

 considerably dis- 

 tended. The 

 rectum a name 

 applied to that 

 part of the ali- 

 mentary canal 

 which passes 

 through the 

 pelvis is placed 

 on the front of 

 the sacrum and 

 coccyx, a short 

 distance below 

 which it termin- 

 The lower end of the rectum 

 the levatores ani 



.. . v~..jpletely as to form a 



floor or diaphragm for the pelvis. In addition to 

 these organs there are others which are character- 

 istic of the sexes. In the male we have the vesi- 

 euln seminale* and the prostate gland the latter 

 surrounding the outlet of the urinary bladder. In 

 the female we have the uterus, ovaries, and their 

 various appendages. The diverse functions of these 

 [rgans have led to corresponding and well-marked 

 differences in the size and form of the osseous pelves 

 of the sexes. In the female the bones are more 

 slender, and the muscular impressions less distinct. 

 The true pelvis has a greater breadth and capacity, 

 but its perpendicular depth is less. The inlet is 

 more nearly circular: the ischial tuberositieg are 

 wider apart, and the suhpuhic arch is much wider. 

 11 of these differences indicate special modifica- 

 tions in connection with the necessities of child- 

 bearing Although the depth of the cavity of the 

 true pelvis steadily increases from childhood to 

 Puberty, yet the characteristics of the sexes are 

 discernible even at birth. 



lint not only does the pelvis display features 

 which are characteristic of sex ; it also presents 

 characters which are peculiar to individual races 

 <>f mankind. In this field of study a great amount 

 of valuable work has been contributed by Sir 

 ilham Turner of Edinburgh University, and em- 

 bodied in the re|>orts of the Challenger expedition. 

 In determining those features peculiar to race 

 miniiTous measurements have been made, mostly 

 in relation to the cavity of the true pelvis with 

 i bnm and outlet; but many of the external 

 dimensions of the entire pelvis have also been 

 >ted, as well as the dimensions of individual 

 liomw. One of the most valuable of the external 

 measurements is the comparison between the maxi- 

 mum height ami breadth of the entire pelvis. A 

 common result is obtained by the following formula 



height x 100 ... 



breadth " > whlch establishes what is called a breadth- 

 height index. Another index of great importance 

 is the result of a comparison between the conjugate 

 and transverse diameters at the brim of the pelvis. 

 This is named the pelvic or brim index, and is 

 obtained by the formula, gg^LJ""". * 100 _,, 



transverse diam. ' 



measurements are usually recorded in millimetres. 

 As the result of numerous measurements Sir 

 William Turner has devised a classification of 

 pelves based upon the relation of the conjugate and 

 transverse diameters at the brim of the true pelvis 

 i.e. upon the brim index. Thus, those pelves in 

 which the conjugate diameter of the brim is either 



. _ _ ..... gr-irw ai mv-^i 11 f dim It (VKlViUtf , 



'long ), and in these the brim index is above 95. 

 W hen the transverse diameter of the brim greatly 

 exceeds the conjugate they are named platypellic 

 (platys, 'wide'), and the brim index is below 90. 

 In cases where the transverse diameter is not greatly 

 in excess of the conjugate i.e. where the brim 

 index varies between 90 and 95, both inclusive the 

 term mesatipellic (mesaitatos, 'middlemost') is 

 applied. Grouping the pelves under these headings 

 we find that such races as Australians, Bushmen, 

 Hottentots, Kaffirs, Malays, Andaman Islanders, 

 &c. are dolichopellic. Negroes, Tasmanians, New 

 Caledonians, &c. are mesatipellic. British, French, 

 Germans, Europeans generally, natives of India, 

 Chinese, American Indians, &c. are platypellic. 

 These results are obtained from the examination of 

 male pelves, since, as we have already seen, the 

 female pelvis is modified in its diameters in rela- 

 tion to the special requirements of sex. 



If now we compare the human pelvis with that 

 of the lower mammalia, we shall find that the 

 human pelvis is characterised by breadth and 

 shallowness and the great capacity of the true 

 pelvis. When, therefore, the conjugate diameter 

 at the brim of the pelvis is longer than the trans- 

 verse i.e. when the pelvis is dolichopellic an 

 approach is made to the condition which prevails 

 even to a greater extent among the lower animals, 

 and it is 'a degraded or animalised arrangement ' 

 as compared with platypellic pelvis of Europeans. 



We have seen that in man the weight of the 

 trunk is transmitted to the lower limbs through 

 the pelvis, whereas in quadrupeds the downward 

 pressure of the weight of the trunk is differently 

 disposed. Doubtless, therefore, the attitude has 

 great influence in controlling the expansion of the 

 pelvis in the transverse diameter when the parts 

 are young and plastic. It may therefore be owing 

 to the habits and mode of life of the black races in 

 their aboriginal state that their pelves approach the 

 lower type. Take, for example, the alxmginal 

 Australian who sits on the ground embracing his 

 knees with his amis, or any of the savages whose 

 favourite attitude is 'squatting' i.e. sitting down 

 with the body l>ent forward and the buttocks rest- 

 ing on the heels ; or again, when in pursuit of 

 game a stooping or crouching attitude is adopted. 

 In all these positions the pressure upon the sacrum 

 and pelvis is diminished, and there is a tendency 

 to approximate the conditions to those of the 

 anthropoid apes, while the white man on the other 

 hand preserves the erect attitude whether standing, 

 sitting, or walking. 



Pemba, a coral island off the east coast of 

 Africa, lies 50 miles NE. of Zanzibar Island, has a 

 length of 46 miles and a breadth of 4J ; area, 372 

 sq. m. There are numerous bays on the east coast ; 

 on one of them stands the chief town, Chaka. The 

 inhabitants, 50,000 in number, rear cattle and trade 

 in rice, cloves, and ebony, all products of the 



