BONES OF THE SHOULDER 43 



obturator foramen ; on it is a broad groove for the tendon of the obturator 

 externus muscle. Its posterior margin assists in forming the great sacro- 

 sciatic notch. 



Spine}* for the gemellus superior, coccygeus, and levator ani muscles, and 

 the lesser sacro-sciatic ligament. 



Lesser Sacro-sciatic Notch}* below the spine, transmits the obturator muscle, 

 its nerve, and the pudic vessels and nerve as they re-enter the pelvis, hav- 

 ing crossed the spine of the ischium. The sacro-sciatic notches are con- 

 verted into foramina by the sacro-sciatic ligaments; the greater notch by 

 the lesser ligament, the lesser notch by the greater ligament. 



Tuberosity} 2 - the lowest and most prominent part, gives attachment to the 

 greater sacro-sciatic ligament, and to several muscles. On it one rests 

 when sitting. 



Ascending Ramus, bounds the obturator foramen inferiorly, articulates with 

 the descending ramus of the pubes, and gives attachment to the obturator 

 membrane and several muscles. 



Describe the Pubes. The pubic or pectineal bone forms the anterior portion 

 of the innominate. It presents the following, viz. 



Body, lies between the rami, with its fellow forms the Symphysis, giving 



origin to several muscles and ligaments. 

 Crest, 9 is the upper part of the body, terminates externally in the Spine, and 



internally in the Angle. 



Spine, affords attachment to one end of Poupart's ligament. 

 Linea Ilio-pectinea, in part ; gives attachment to the conjoined tendon, Ginv 



bernat's ligament, and the triangular ligament. 

 Horizontal Ramus, forms part of the brim of the pelvis, of the margin of the 



obturator foramen, and of the acetabulum. On its under surface is a groove 



for the obturator vessels and nerve. 



Pectineal Eminence? gives attachment to the psoas parvus muscle. 

 Descending Ramus?* flat and thin, joins the ascending ramus of the ischium, 



and bounds the obturator foramen internally. 



What Muscles are attached to the Os Innominatum ? 36, comprising 

 those of the abdomen, thigh, perineum, floor of the pelvis, and rotators of the 

 hip-joint. 



BONES OF THE UPPER EXTREMITY. 



THE SHOULDER. 



What Bones form the Shoulder ? The clavicle and scapula connecting the 

 arm with the trunk, and in this respect homologous to the innominate bone ia 

 the lower part of the body. 



