110 THE BONES OF THE LOWER LIMB. 



V. THE PELVIS AND LOWER LIMB. 



The divisions of the lower limb are the haunch or hip, thigh, leg, and foot. In 

 the haunch is the hip-bone, which enters into the formation of the pelvis ; in the 

 thigh is the femur ; in the leg the tibia and fibula ; and at the knee a large sesamoid 

 bone, the patella. The foot is composed of three parts, viz., the tarsus, metatarsus, 

 and phalanges. 



THE HIP-BONE. 



The hip-bone, os coxa, or innominate bone, with its neighbour of the opposite side 

 and the addition of the sacrum and coccyx, forms the pelvis ; it transmits the weight 

 of the body to the lower limb. It is constricted in the middle and expanded above 

 and below, and is so curved that, while the upper part is nearly vertical, the lower 

 part is directed inwards. On the external aspect of the constricted portion is the 

 acetalulum, a cavity which articulates with the femur, and perforating the inferior 

 expansion is a large opening, the thyroid or obturator fwamen. The superior wider 

 part of the bone forms part of the abdominal wall ; the inferior enters into the 

 formation of the true pelvis. The hip-bone articulates with its fellow of the opposite 

 side, with the sacrum, and with the femur. 



In the description of this bone it is convenient to recognise as distinct the three 

 parts of it which are separate in early life, viz., the ilium, os pubis and ischium. 

 These three portions meet at the acetabulum, in the formation of which they 

 all take part ; and the os pubis and ischium also meet on the inner side of the 

 obturator foramen. 



The ilium constitutes the superior expanded portion of the bone, and forms a 

 part of the acetabulum by its inferior extremity. Above the acetabulum it is limited 

 anteriorly and posteriorly by margins which diverge at right angles one from the 

 other, and superiorly by an arched thick border, the crest of the ilium. Viewed from 

 above, the crest is curved like the letter /, the fore part being concave inwards, the 

 hinder part concave outwards : it is narrow in its middle third, broadened in front 

 and behind, and forms a marked projection externally in its anterior third : on it 

 may be distinguished external and internal lips and an intermediate ridge. The 

 anterior extremity of the crest forms a projection forwards called the anterior superior 

 spine of the ilium, and, separated from it by a concave border, and placed imme- 

 diately above the acetabulum, is another eminence called the anterior inferior spine : 

 the projecting posterior extremity of the crest forms the posterior superior spine, and 

 separated from it by a small notch is the posterior inferior spine, below which the 

 posterior border of the bone is hollowed out into the ilio-sciatic (or great sciatic^) notch. 

 The external surface or dorsum of the ilium is convex in front, below the prominence 

 of the crest, and concave behind this. It is traversed by three curved gluteal lines, 

 which limit the areas of attachment of the gluteal muscles. The posterior or superior 

 gluteal line leaves the iliac crest about one-fourth of its length from the posterior 

 superior spine, and curves downwards and forwards towards the hinder part of the 

 ilio-sciatic notch : the middle gluteal line begins in front at the iliac crest, about one 

 inch and a half from its anterior extremity, and arches backwards and downwards 

 to the upper margin of the ilio-sciatic notch : the inferior gluteal line, less strongly 

 marked than the middle, commences at the anterior border of the ilium, just above 

 the anterior inferior spine, and is continued backwards nearly parallel to the margin 

 of the acetabulum to the fore part of. the ilio-sciatic notch. Behind the posterior 

 gluteal line is a narrow semilunar surface, the upper portion of which is rough and 

 gives attachment to the gluteus maximus muscle, while the lower part is smooth and 



