BONES OF THE TRUNK. 19 



INNOMINATUM. 



This is a large flat bone forming the haunch or hip of common 

 language, resembling in some measure the figure 8. In youth it 



Fig. 6. 



consists of three different parts, united in the acetabulum, viz. the 

 ilium, ischium, and pubes. 



Ilium. — This is the largest piece, and forms the wall of the upper 

 pelvis. Its exter7ial surface is convex and rough, with a semicircular 

 ridge crossing it; above this ridge arises the gluteus medius, and 

 below it the gluteus minimus muscle ; the posterior part of this sur- 

 face is the roughest, and gives origin to the gluteus maximus. 



The intenial surface^ or costa, is concave ; the anterior portion is 

 smooth, and gives origin to the iliacus internus ; the posterior is 

 rough and has a large nrticular mark for the sacrum, behind which 

 arise muscles and ligaments. The edge or criua is arched and curved 

 like the italic/. In front there are two eminences, one of which is 

 called the anterior swperior spinous jjrocess^ givino- orio-in to the 

 sartorius and tensor vagina3 muscles and Poupart's ligament ; the 

 other is the anterior inferior spinous^ process, and gives orio-in to 

 the rectus muscle; ihe space between the two i^ives oricrin to the 

 gluteus medius. Below these processes is a large prominence" 

 caWed ilio-pectineal ; in the groove above this passes the iliacus 

 internus and psoas magnus muscles. Behind these are the posterior 

 superior and inferior spinous processes. The crista has three lips, 

 from the internal of which arises the transversalis muscle, from the 

 middle arises the internal oblique, and into the external is inserted 

 the external oblique. The inferior border of the ilium presents a 

 notchy called sciatic. 



