PELVIS, 



117 



commences in the primitive pieces, immediately after that in the vertebrae, 

 firstly in the ilium, then in the ischium, and lastly in the pubes ; the first 

 ossific deposits being situated near to the future acetabulum. At birth the 

 acetabulum, the crest of the ilium, and the ramus of the pubes and ischium, 

 are cartilaginous. The secondary centres appear at puberty, and the en- 

 tire bone is not completed until the twenty-fifth year. 



Articulations. With three bones ; sacrum, opposite innominatum, and 

 femur. 



Attachments of Muscles and Ligaments . To thirty-five muscles; to the 

 ilium, thirteen ; by the outer lip of the crest, to the obliquus externus for 

 two-thirds, and to the latissimus dorsi for one-third its length, and to the 

 tensor vaginae femoris by its anterior fourth ; by the middle crest, to the 

 internal oblique for three-fourths its length, by the remaining fourth to the 

 erector spinas ; by the internal lip, to the transversalis for three-fourths, 

 and to the quadratus lumborum by the posterior part of its middle third. 

 By the external surface, to the gluteus medius, minimus and maximus, 

 and to one head of the rectus ; by the internal surface, to the iliacus ; and 

 by the anterior border to the sartorius, and the other head of the rectus. 

 To the ischium, sixteen; by its external surface, the adductor magnus and 

 obturator externus ; by the internal surface, the obturator internus and 

 levator ani ; by the spine, the gemellus superior, levator ani, coccygeus, 

 and lesser sacro-ischiatic ligament ; by the tuberosity, the biceps, semi- 

 tendinosus, semi-mem branosus, gemellus inferior, quadratus femoris, erec- 

 tor penis, transversus perinei, and great sacro-ischiatic ligament ; and by 

 the ramus, the gracilis, accelerator urinse, and compressor urethra. To 

 the os pubis, fifteen; by its upper border, the obliquus externus, obliquus 

 internus, transversalis, rectus, pyramidalis, pectineus, and psoas parvus ; 

 by its external surface, the adductor longus, adductor brevis, and gracilis ; 

 by its internal surface, the levator ani, compressor urethras, and obturator 

 interims ; and by the ramus, the adductor magnus, and accelerator urinse. 



Fig. 56. 



PELVIS. 



The pelvis considered 

 as a whole is divisible into 

 a false and true pelvis ; 

 the former is the expanded 

 portion, bounded on each 

 side by the ossa ilii, and 

 separated from the true 

 pelvis by the lineajlio : pec- 

 tinea. The true pelvis is 

 all that portion which is 

 situated beneath the linea : 

 ilio-pectinea. This line 

 forms the margin or brim 

 of the true pelvis, while 

 the included area is called 

 the inlet. The form of the 

 inlet Ts heart-shaped, ob- 

 tusely pointed in front at 



* A female pelvis. 1. The last lumbar vertebrae. 2, 2. The Intervertebral substance 

 connecting the last Iv.mbar vertebra with the fourth and sacrum. 3. The promontory 



