239 OSTEOLOGY. | ’ 
ossify about the third or fourth year, and union with the shaft is not complete until a 
Appears about Ex Fuses with shaft period somewhat later than that for the inferior 
3-4 years | oo 20-24 years eniphysis. The mode of ossification of the 
lower extremity is an exception to the general rule 
that epiphyses which are the first to ossify. are the last 
to unite with the shaft. 
In its earlier stages of development it has been stated, 
on the authority of Leboueq, Gegenbauer, and others, that 
the fibula as well as the tibia is In contact with the femur. 
This is, however, denied by Grunbaum (“ Proc. Anat. Soe.,” 
Journ. Anat. and Physiol., vol. xxvi. p. 22), who states that 
after the sixth week the fibula is not in contact with the 
femur, and that prior to that date it is impossible to 
differentiate the tissue which is to form femur from that 
which forms fibula. 
Variations.—The fibula may be ridged and grooved in 
a remarkable manner, as is the case in many bones of pre- 
historic races. This is probably associated with a greater 
or perhaps more active development of the muscles attached 
tO It: 
The superior articular facet varies much in size. Ben- 
nett (Dublin Journ. Med. Sc., Aug. 1891) records a case in 
which it was double, and also notes the occurrence of 
US Rea specimens in which it was absent and in which the head of 
tk the bone did not reach as high as the tibial tuberosity. 
Many instances of partial or complete absence of the 
bone have been published. (Lefebre, P., Contribution &@ 
Fra, 172.—Ossirication oF Frsuna. étude de Vabsence congénitale du péroné. Lille. 1895.) 
Appears about middle of 2nd month of foetal life 
Appears about 
2nd year 
At About About 
birth. 12 years. 16 years. 
BONES OF THE FOOT. 
The bones of the foot, twenty-six in number, are arranged in three groups: the 
tarsal, seven in number; the metatarsal, five in number; the phalanges, fourteen 
in number. 
Comparing the foot with the hand, the student will be struck with the great pro- 
portionate size of the tarsus as compared with the carpus, and the reduction in size 
of the bones of the toes as compared with the fingers. The size of the metatarsal 
segment more nearly equals that of the metacarpus. 
THE TARSUS. 
The tarsus (ossa tarsi) consists of seven bones—the astragalus, os calcis, navi- 
cular or scaphoid, three cuneiforms, and the cuboid. Of irregular form and varying 
size, they may be described as roughly cubical, presenting for examination dorsal 
and plantar surfaces as well as anterior, posterior, internal, and external aspects. 
THE ASTRAGALUS. 
The astragalus (talus) is the bone through which the body weight is trans- 
mitted from the leg above to the foot below. Superiorly the tibia rests upon it, 
whilst on either side it articulates with the internal and external malleolar processes 
of the tibia and fibula respectively ; inferiorly it overlies the os calcis, and anteriorly 
it articulates with the navicular. For descriptive purposes the bone is divisible into 
two parts—the body (corpus tali) blended in front with the neck (collum tali), 
which supports the head (caput tali). 
The upper surface of the body is provided with a saddle-shaped articular surface 
(trochlea tali), broader in front than behind, for articulation with the under surface 
of the tibia. The inner edge of the trochlea is straight; whilst the outer border, 
which is sharp in front and more rounded behind, is curved inwards posteriorly, 
where it is bevelled to form a narrow, elongated, triangular facet, which is in contact 
with the transverse or inferior tibio-fibular ligament during flexion of the ankle 
