_l.c.a._, _l.c.p._, Depressions for attachment of anterior and
posterior crucial ligaments; _l_, _m_, _m_, depressions for
attachment of semilunar cartilages.
]
The =distal extremity= is fused with the tibia, constituting the
external malleolus.
=Development.=—This resembles that of the ulna. The embryonic
cartilaginous fibula extends the entire length of the leg, but does not
articulate with the femur. The lower part of the shaft is usually
reduced to a fibrous band. Three centers of ossification appear, one
each for the shaft and the extremities. The distal end unites early with
the tibia, forming the external malleolus.
It is interesting to note that in some cases the entire shaft of the
fibula develops, a reversion to the condition in the Miocene ancestors
of the present horse.