112 



BONES OF THE LOWER LIMB. 



PERIODS OF OSSIFICATION OF THE BONES OF THE LOWER LIMB. 



I. Os Innominatum. 



The chief nucleus of the ilium appears in the 8th or 9th week. 



The chief nucleus of the ischium appears in the third month. 



The chief nucleus of the pubis appears from the 4th to the 5th month. 



Ossification in the Y-shaped cartilage of the acetabulum appears about puberty ; 



and in the epiphysis of the iliac crest, anterior inferior spinous process, ischial 



tuberosity, and symphysis pubis somewhat later. 

 The rami of the pubis and ischium unite about the 7th or 8th year. 

 The parts which meet in the acetabulum unite about the 16th or 17th year. 

 The main bone and epiphyses unite about the 25th year. 



Fig. 103. 



Fig. 103. OSSIFICATION OF THE FEMUR. 



A, femur of a foetus of about eight months ; the body is osseous ; both ends are 

 cartilaginous. 



B, femur of a child at birth, showing a nucleus in the lower epiphysis. 



C, femur of a child of about a year old, showing a nucleus in the articular head. 



D, femur of the fifth or sixth year. Ossification has extended from the shaft into the 

 neck, and a nucleus has appeared in the great trochanter. 



E, femur of about the age of puberty, showing more complete ossification and a nucleus 

 in the lesser trochanter. 



1, shaft ; 2, lower extremity ; 3, head ; 4, great trochanter ; 5, small trochanter. 



II. Femur. 



The nucleus of the shaft appears in the 7th week. 



The nucleus of the lower epiphysis appears in the 9th month. 



The nucleus of the head appears at the end of the 1st year. 



The nucleus of the great trochanter appears in the 4th year. 



The nucleus of the small trochanter appears in the 13th or 14th year. 



The small trochanter and shaft unite about the 17th or 18th year. 



The great trochanter and shaft unite about the 18th year. 



The head and shaft unite about the 18th or 19th year. 



The lower epiphysis and shaft unite after the 20th year. 



III. Tibia. 



The nucleus of the shaft appears in the 7th week. 



The upper epiphysis appears sometimes before, sometimes after birth. 



