128 ANATOMY IN A NUTSHELL 



Ossification from eight centers. 



There is one primary center for the ilium which appears at the eighth or 

 ninth week. One for the ischium at about the third month, and one for the os 

 pubis between the fourth and fifth month. These three primary centers unite 

 through a Y-shaped piece at about the age of puberty. There are five secondary 

 centers- one for the crest of the ilium, one for the anterior inferior spin- 

 01 - proi ess, one for the tuberosity of the ischium, one for the symphysis 

 pubis, and one or more for the bottom of the acetabulum. Epiphyses appear 

 about the age of puberty and unite with the rest of the bone between the 

 twentieth and twenty-fifth years. 



Articulates with its fellow of the opposite side, the sacrum and femur. 



Attachment ok muscles to the ilium, sixteen. To the outer lip of crest, 

 the (1) Tensor vagina 1 femoris, (2) Obliquus externus abdominis, and (3) Lat- 

 issimus dorsi; to the internal lip. the (4) Iliacus, (5) Transversalis, (6) Quad- 

 rants lumborum, and (7) Erector spina?; to the interspace between the lips, the 

 (8) Obliquus internus. To the outer surface of the ilium, the (9) Gluteus max- 

 inii!-. (10) Gluteus medius, (11) Gluteus minimus, reflected tendon of the (12) 

 Meet ns; to the upper part of the great sacro-sciatic notch, a portion of the (13) 

 Pyriformis; to the internal surface, the Iliacus, to that portion of the internal 

 surface below the linea ilio-pectinea, the (14) Obturator internus and the (15) 

 Multifidus spina' to the internal surface of the posterior superior spine; to the 

 .interior border, (16) the Sartorius and straight tendon of the Rectus. 



To the ischium, fourteen: — To the outer surface of the ramus, the (1) Ob- 

 turator externus and (2) Adductor magnus; to the internal surface, the (3) Ob- 

 turator internus and (4) Erector penis. To the spine, the (5) Gemellus superior, 

 (6) Levator ani, ami (7) Coccygeus. To the tuberosity, the (8) Biceps, (9) Semi- 

 tendinosug, (KM Semimembranosus, (11) Quadratus femoris, (12) Adductor 

 magnus, (13) Gemellus inferior, (14) Transversus perinsei, Erector penis. 



To the os pubis, sixteen: (l)Obliquus externus, (2) Obliquus internus, (3) 

 Transversalis. (4) Rectus, (5) Pvramidalis, (6) Psoas parvus, (7) Peetincus, (8) 

 Adductor magnus. (9) Adductor longus, (10) Adductor brevis, (11) Gracilis, 

 (12) Obturator externus, (13) Obturator internus, (14) Levator ani, (15) Com- 

 pressor met In a', and occasionally a few filters of the (16) Accelerator urinae. 



LESSON XXXI II. 



Tin: Os Pubis. 



The os pubis which consists of a body and two rami forms the anterior wall 

 of the pelvis, and bounds the obturator foramen above and partly in front. The 

 SYMPHYSIS PUBIS is the junction of this bono with its fellow. It is the inner ex- 

 tremity of the bone fat Lng inward b< ing of an oblong surface marked by trans- 

 \ erse ridg< s. The des< ending r \.\us pass< s down and out from the symphysis. 

 It is thin and Hat ami joins the ramus of the ischium at a point little more than 

 half way from the body of the pelvis to the tuberosity of the ischium. The 

 superior or ascending ramus is the upper part of the bone. This ramus ends 



