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228 OSTEOLOGY. 
base on which the femur can move. Such platycnemic tibize are occasionally met with in the 
more highly civilised races, and are, according to Manouvrier, associated with habits of great 
activity among the inhabitants of rough and mountainous districts. 
Another interesting condition is one in which the upper extremity is more strongly recurved 
than is usual. This retroversion of the head of the tibia was at one time supposed to represent 
an intermediate condition in which the knee could not be fully extended so as to bring the axis 
of the leg in line with the thigh; but such opinion has now been upset by the researches of 
Manouvrier, who claims that it is the outcome of a habit not uncommon amongst peasants and 
countrymen, viz. that of walking habitually with the knees slightly bent. 
Habitual posture also leaves its impress on the form of the tibia, and in races in which the 
use of the chair is unknown, the extreme degree of flexion of the knee and ankle necessitated by the — 
adoption of the squatting position as an attitude of habitual rest is associated with an increase in 
the convexity of the external condylic surface, and the appearance, not infrequently, of a pressure 
facet on the anterior border of the lower extremity, which rests in that position on the neck 
of the astragalus. Cases of congenital 
absence of the tibia have been fre- 
quently described, amongst the most 
recent being those recorded by Clutton, 
Joachimsthal, Bland Sutton, and Waitz. 
Fuses with shaft about 20-24 years 
May appear 
Appears independently 
before birth about 11 years 
Ossification.—The shaft begins 
to ossify early in the second month 
of intra-uterine life. At birth it is 
well formed, and capped above and 
below by pieces of cartilage, in the 
upper of which the centre for the 
superior epiphysis has already usually 
i made its appearance. From this 
the tuberosities and tubercle are 
developed, though sometimes an 
Appears early in 2nd month of foetal life 
appears about the eleventh or twelfth 
years, rapidly joining with the already 
well-developed mass of the rest of 
the epiphysis. Complete fusion be- 
Fuses about 18th year tween the superior epiphysis and the 
At birth. About 12 years. About 16 years. shaft does not take place until the 
twentieth or the twenty-fourth year. 
The centre for the lower articular 
surface and the internal malleolus makes its appearance about the end of the second 
year, and union with the shaft is usually complete by the age of eighteen. Lambertz 
notes the occasional presence of an accessory nucleus in, the malleolus. 
Appears about 13 years 
Fic. 169.—OssIFICATION OF THE TIBIA. 
THE FIBULA. 
The fibula, or peroneal bone, is a slender bone with two enlarged ends. It hes 
to the outer side of the tibia, with which it is firmly united by hgaments, and nearly 
equals that bone in length. 
The first difficulty which the student has to overcome is to determine which is the upper and 
which the lower extremity of the bone. This can easily be done by recognising the fact that 
there is a deep pit on the inner aspect of the lower extremity immediately behind the triangular 
articular surface. Holding the bone vertically with the lower 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 inferior extremity will point to the side to which the 
bone belongs. 
The superior extremity or head of the fibula (capitulum fibule), of irregular 
rounded form, is bevelled on its inner surface so as to adapt it to the form of the 
under surface of the external tuberosity of the tibia. At the border, where this 
surface becomes confluent with the outer aspect of the head, there is a pointed 
upstanding eminence called the styloid process (apex capituli fibule); to this the 
short external lateral ligament is attached, as well as a piece of the tendon of the 
biceps, which is inserted into its fore-part. Immediately to the inner side of this, 
and occupying the summit of the internal sloping surface, there is an articular area 
(facies articularis capitul1), of variable size and more or less triangular shape. This 
independent centre for the latter’ 
