Chap. Y] THE SKELETON 75 



scribe the bone as divisible into three portions : (1) the ihum (plural 

 ilia), (2) the ischium (plural ischia), (3) the pubis (plural pubes). 

 The ilium is the upper broad and expanded portion which forms 

 the prominence of the hip. The ischium is the lower and strongest 

 portion of the bone, while the pubes is that portion which forms 

 the front of the pelvis. Where these three portions of the bone 

 meet and finally ankylose is a deep socket, called the acetabulum, 

 into which the head of the femur fits. Other points of special 

 interest to note in the hip bones are : — 



(1) The spinous process formed by the projection of the crest 

 of the ilium in front, which is called the anterior superior spinous 

 process, and which is a well-known and convenient landmark 

 in making anatomical and surgical measurements. 



(2) The largest foramen in the skeleton, known as the thyroid 

 foramen, situated between the ischium and pubis. 



(3) The symphysis pubis, or pubic articulation, which also 

 serves for a convenient landmark in making measurements. 



The pelvis. — The pelvis, so called from its resemblance to a 

 basin, is stronger and more massively constructed than either the 



Female Pelvis. 



cranial or the thoracic cavity. It is composed of four bones, the 

 two hip bones forming the sides and front, the sacrum and coccyx- 

 completing it behind. It is divided by a narrowed bony ring into 



