250 



OSTEOLOGY. 



Fuses with shaft about 20-24 years 



May appear 



Appears independently 



before birth about 11 years 



ankle. The front and back of the distal end of the bone are crossed by tendons, which mask 

 to a certain extent its form. 



Ossification. The body begins to ossify early in the second month of intra-uterine 

 life. At birth it is well formed, and capped proximal ly and distally by pieces of cartilage, 



in the proximal of which the centre 

 for the proximal epiphysis has al- 

 ready usually made its appearance. 

 From this the condyles and tuber- 

 osity are developed, though some- 

 times an independent centre for the 

 latter appears about the eleventh 

 or twelfth years, rapidly joining with 

 the already well-developed mass of 

 the rest of the epiphysis. Complete 

 fusion between the proximal epi- 

 physis and the body does not take 

 place until the twentieth or the 

 twenty-fourth year. The centre for 

 the distal articular surface and the 

 medial malleolus makes its appear- 

 ance about the end of the second 

 year, and union with the shaft 

 is usually complete by the age of 

 eighteen. Lambertz notes the occa- 

 sional presence of an accessory 

 nucleus in the malleolus. The prox- 

 imal end is the so-called "growing 

 end of the bone." 



Appears about 1J years 



Fuses about 18th year 



At birth. About 12 years. About 16 years. 



FIG. 249. OSSIFICATION OF THE TIBIA. 



The Fibula. 



The fibula is a slender bone with two enlarged ends. It lies to the lateral 

 side of the tibia, with which it is firmly united by ligaments, and nearly equals that 

 bone in length. 



The first difficulty which the student has to overcome is to determine which is the proximal 

 and which the distal extremity of the bone. This can easily be done by recognising the fact that 

 there is a deep pit on the medial aspect of the distal extremity immediately behind the triangular 

 articular surface. Holding the bone vertically with the distal extremity downwards and so 

 turned that the triangular articular area lies in front of the notch already spoken of, the 

 subcutaneous non-articular aspect of the distal extremity will point to the side to which the 

 bone belongs 



The proximal extremity or head of the fibula (capitulum fibulae), of irregular 

 rounded form, is bevelled on its medial surface so as to adapt it to the form of the 

 distal surface of the lateral condyle of the tibia. At the border where this 

 surface becomes confluent with the lateral aspect of the head there is a pointed 

 upstanding eminence called the apex capituli fibulae; to this the short fibular 

 collateral ligament is attached, as well as a piece of the tendon of the biceps, 

 which is inserted into its anterior part. Immediately to the medial side of this, 

 and occupying the summit of the medial sloping surface, there is an articular area 

 (facies articularis capituli), of variable size and more or less triangular shape. This 

 area articulates with the lateral condyle of the tibia. The long fibular collateral 

 ligament, together with the remainder of the tendon of the biceps muscle which 

 surrounds it, is attached to the lateral and proximal side of the head in front 

 of the apex capituli. On the front and the back of the head there are usually 

 prominent tubercles'. The anterior of these is associated with the origin of the 

 peronaeus longus muscle ; the posterior furnishes an origin for the proximal fibres 

 of the soleus, and serves to deepen the groove, behind the proximal tibio-fibular 

 joint, in which the tendon and fleshy part of the popliteus muscle play. 



The constricted portion of the body distal to the head is often referred to as 

 the neck ; around the lateral side of this the common peroneal nerve winds. 



