Page 56 - ASOP ROT Study Guide

5 . 5 Blood Supply

The blood supply to the proximal part of the ankle is by numerous small vessels and is not usually a
source of problems. The blood supply of the talus however is unusual in that the whole of the talus
receives its blood supply from the distal end, i.e. from the foot. This means that if the talus breaks
the proximal end may be without a blood supply (avascular). Luckily the talus is rarely broken in
ankle injuries but if it is the consequences of avascular necrosis can be very serious as loss of
the talus means destruction of the normal walking pattern.

6. THE FOOT

The foot is a complicated structure of bones, synovial joints, ligaments and tendons. It is not our
intention to go into the intricate detail of this structure but rather to stress the main anatomical
features: its shape, the main bones and the two most important joints. The complexity of the foot is
simply a reflection of the various demanding functions required of it. These include:
♦ load distribution (without it the end of the leg would get severely damaged!)
♦ provision of a stable ground contact that stays flat when the ground is sloping
♦ shock absorption
♦ transmission of propulsion forces

6 . 1 Shape and Stability
The bones in the foot are all interconnected by synovial joints and held together by strong
ligaments. The tendons of the muscles of the calf further contribute to the shape and stability of the
foot by pulling on the bones and holding them in a certain position or posture. The load bearing
and shock absorbing functions of the foot stem partly from two arch shaped arrangements of some
of the foot bones. (An arch gives high structural strength for a minimum amount of structural
material). The most important and obvious arch is the longitudinal arch (Figure 21). This feature
is obvious when viewing the medial side of the foot and it gives the footprint its characteristic
shape.

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