136 



THE BONES OF THE LOWER LIMB. 



OSSIFICATION OF TH3J BONES OF THE LOWER LIMB. 



Hip-bone. The hip-bone is formed from the three principal pieces previously mentioned, 

 viz., the ilium, ischium, and os pubis, and from various others of an epiphysial nature. Ossifi- 

 cation commences in the cartilage of the ilium a little later than in other large bones, the 

 deposit of bone beginning- above the ilio-sciatic notch in the 8th or 9th week. This is followed 



Fig. 157. OSSIFICATION OF THE HIP- BONK. (R. Quain.) 



A, the condition of the bone at birth. Bone has spread from three nuclei into the ilium, ischium, 

 and pubis, which meet in the cartilage of the acetabulum. 



B, from a child under six years of age. The rami of the ischium and pubis are farther ossified, but 

 still separate. 



C, a bone of two or three years later, in which the rami are united. 



D, the bone of the right side from a person of about twenty years. Union has taken place in the 

 acetabulum, and the additional epiphyses are seen on the crest of the ilium, the anterior inferior spine, 

 the ischial tuberosity, and the margin of the symphysis pubis. 



In A, B, and C, 1, ilium ; 2, ischium ; 3, pubis ; in D, 5, epiphysis of the crest ; 6, that of the tube- 

 rosity of the ischium ; 7, that of the symphysis pubis ; 8, that of the anterior inferior spine of the ilium. 



by similar deposits in the thick part of the ischium below the acetabulum in the 3rd month, 

 and in the superior ramus of the pubis in the 4th or 5th month. At birth the greater part of 

 the acetabulum. the crest of the ilium, the tuberosity and ramus of the ischium, the body and 

 inferior ramus of the pubis are still cartilaginous ; ossification from the three primary centres 

 has however extended into the margin of the acetabulum. In the 7th or 8th year the rami of 



Fig. 158. ACETABULAR REGION OF THE HIP-BONE 



AT 14 YEARS OF AGE. (G. D. T.) \ 



1, ilium ; 2, ischium ; 3, pubis ; 4, os acetabuli ; 

 o, bony nodules between ilium and ischium ; 6 and 

 7, epiphysial laminae on ilium and ischium. 



the ischium and pubis become completely united 

 by bone. In the acetabulum the three parts are 

 still separated by a Y-shaped strip of cartilage, 

 which is continuous with that lining the cavity. 

 This cartilage begins to be ossified from several 

 centres about the 12th year. The most constant of 

 these gives rise to a triangular piece of bone at the 

 fore part of the acetabulum, which is known as 

 the os acetabuli* and forms the whole of the. so- 

 called pubic portion of the articular cavity. It 

 becomes united first with the pubis, and later with 

 the ilium and ischium. Between the ilium and 



ischium there are only some irregular nodules of bone, and other small osseous points form a 

 more or less perfect lamina over the iliac and ischial portions of the articular surface. The 

 union of the several portions in the acetabulum is completed from the 18th to the 20th year. 



1 W. Leche. Internat. Monatschr. f. Anat. u. Histol., 1884, 363 ; W. Krause, ib., 1885, 150. 



