PELVIS. 



137 



According to Dupuytren, the female 

 pelvis differs very little from that of the 

 male till puberty, at which period it has a 

 general triangular form in both sexes, but, 

 after that period, it becomes rapidly developed, 

 and soon assumes its distinctive sexual cha- 

 racter. The transverse diameters begin to 

 exceed the conjugate, and, in the female, 

 attain a great preponderance, constituting 

 one of the great characteristics of the fully 

 formed human pelvis, as distinguished from 

 that of the lower animals. 



In Autenrieth's method of calculating the 

 pelvic dimensions, the dorsal, or posterior 

 part, bears a proportion to the anterior or 

 abdominal part, as 10 to from 11 to 14, in 

 the infant of two years ; while, in the adult 

 pelvis, it was as 10 to from 16 to 22. 



In advanced adult age, the pelvic inclination 

 is said by Cruveilhier to be increased in con- 

 sequence of the forward curvature, or droop- 

 ing of the spinal column, which tends to 

 arrive at the horizontal position, as in quadru- 

 peds. To keep the centre of gravity between 

 the lower extremities, the femurs, in old 

 persons, are more flexed upon the pelvis, so 

 as to be more directed towards the line of 

 the superior pelvic plane. 1 have found, 

 however, that in old subjects, although the 

 angle of the pelvic plane with that of the ichole 

 spinal column is increased, yet the angle with 

 the lumbar vertebra only, is not so much 

 changed, and that, apparently, the increased 

 muscular traction on the sacrum and posterior 

 part of the ilia by the muscles of the back act- 

 ing upwards, and of those of the front of the 

 thigh acting downwards, upon the anterior 

 part of the pelvic lever, in order to pre- 

 serve the erect position, produce this in- 

 creased obliquity of the pelvis, which is ge- 

 nerally accompanied by a corresponding de- 

 crease of the sacro-vertebral angle. This will 

 be more fully comprehended when consider- 

 ing the mechanism of the pelvis. 



MUSCULAR ATTACHMENTS OF THE PEL- 

 VIS. To afford a fixed point for the attach- 

 ment of the numerous and powerful muscles 

 acting on the trunk and extremities is one of 

 the important offices of the pelvis. These 

 may be classed as jiosterior spinal and abdo- 

 minal groups acting on the trunk and spinal 

 column ; extensor, flexor, adductor, abductor, 

 and rotator groups acting on the lower extre- 

 mity ; and perineal groups forming the move- 

 able floor of the pelvis and acting on the 

 genital and excretory organs. 



1 . Muscles acting on the trunk and spine. 

 The posterior spinal group. The longissimus 

 dorsi and multijidus spines, to the upper part 

 of the posterior surface of the sacrum ; the 

 interspina/es, to the superior border of the 

 sacral crest; and, according to some, the ex- 

 tensor coccygis, to the contiguous posterior 

 surfaces of the sacrum and coccyx ; the sacro- 

 lumbalis, to the middle part of the posterior 

 third of the iliac crest, and to the contiguous 

 sacral surface ; and the latissinnts dorsi, through 

 the lumbar fascia to the external lip of the 

 posterior half of the iliac crest and to the 



sacral crest. This muscle acts on the arm. 

 The abdominal grottjy. The obliquus cxtcr- 

 nus and interims, and transvcrsalis abclo- 

 min/s, to the external lip, middle ridge, and 

 internal lips respectively of the iliac crest, and 

 also by their aponeurotic tendons to the angle, 

 crest, spine, and pectineal line of the pubis 

 (the external oblique tendon, under the name 

 of Poupart's ligament, stretching across, from 

 the anterior superior iliac spine to the spine 

 of the pnbis, and, under the name of Gim- 

 bernat's liga.nent, passing backwards to the 

 linea-ilio pectinea; and the internal oblique 

 and transversalis tendons enclosing the rectus 

 abdominis muscle, and uniting to form the 

 conjoined tendon) ; the quadratus lumborum, 

 to the posterior fourth of the inner lip of the 

 iliac crest ; the rectus and pi/ramidalis abdo- 

 minis, to the crest of the pubis ; and the 

 psoas parvus, when present, to the pectineal 

 eminence. 



2. Muscles acting on the leg. The Jtcxor 

 group. The rectus femoris, to the anterior in- 

 ferior iliac spine and outer part of the coty- 

 loid rim; the iliacus, to the whole anterior 

 concave surface of the iliac wing the psoas 

 magnus is not attached to the pelvis, but acts 

 upon it by passing over it along the pelvic 

 brim ; and the sartorius, to the anterior supe- 

 rior iliac spine and notch below it. 



The extensor group. The biceps Jlexor 

 cruris, semitendinosus, and semimembranosus, 

 to the depending middle and posterior parts 

 of the ischial tuberosity ; and the glutens 

 maximus, to the quadrilateral gluteal impres- 

 sion on the dorsum of the ilium, to the pos- 

 terior surfaces of the two lower pieces of the 

 sacrum, and of the two or three upper pieces 

 of the coccyx, to the oblique sacro-iliac and 

 great sacro-sciatic ligaments, and to the lum- 

 bar fascia. 



The adductor group. The adductor magnus, 

 to the anterior part of the ischial tuberosity, 

 and to the united ischio-pubic rami; the ad- 

 ductor longus, to the anterior surface of the 

 angle of the pubis ; the adductor brcvis below 

 the foregoing, to the same surface; the pec- 

 tinens, to the spine, pectineal line, and hori- 

 zontal ramus of the pubis ; and the gracilis, 

 to the rough internal border of the ischio- 

 pubic raini and symphysis pubis. 



The abductor group. The glutens medius, 

 to the dorsum of the ilium, between the crest 

 and superior curved line ; the glutens minimus, 

 to the same surface between the curved lines ; 

 and the tensor vagina: femoris, to the outer 

 surface of the anterior superior iliac spine. 



The rotator group. The pt/riformis, to the 

 anterior surface of the sacrum between the 

 four upper sacral holes, and passing out 

 through the great sciatic notch ; the obturator 

 cxternus, to the inner half of the external cir- 

 cumference of the obturator foramen, and to 

 the external surface of the membrane closing it; 

 the obturator interims, to the internal surface 

 of the same ligament, and to the borders of the 

 foramen, and also to the surface of bone oppo- 

 site the cotyloid cavity (this muscle passes out 

 through the small sciatic notch, over which 



