Page 401 - The Veterinary Care of the Horse
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medial, middle and lateral patellar ligaments. The quadriceps femoris muscle which lies
along the front and both sides of the femur attaches to the patella.
VetBooks.ir lower end of the femur. This groove is called the trochlea. The trochlea has a prominent
As the stifle joint extends and flexes, the patella glides up and down in a groove at the
medial ridge with a knob-like extension on the upper edge. The medial side of the patella has
a cartilage extension which overlies the medial ridge of the trochlea.
This arrangement allows the stifle joint to be locked in an extended position. The joint is
extended by contraction of the powerful quadriceps femoris muscle. As the joint is fully
extended, the patella glides to the upper limit of the trochlea groove. If the patella is then
moved medially, the knob of the medial ridge of the trochlea projects between the medial and
middle patella ligaments (Figures 8.23a and b).
Figures 8.23a and b Ligaments of the stifle joint
This locking mechanism allows the horse to stand for long periods without experiencing
muscle fatigue. The opposite hind limb is rested. To unlock the stifle, the horse’s weight is
shifted to the opposite hind limb. The quadriceps muscle pulls the patella in an upward
direction. The patella is then moved laterally and returned to the trochlear groove.
The stifle joint may be affected by:
