Page 86 - Adams and Stashak's Lameness in Horses, 7th Edition

52 Chapter 1

Sartorius m. (cut)
VetBooks.ir Rectus femoris m.

Gracilis m. (cut)
Vastus medialis m.

Adductor m.

Medial femoropatellar
ligament

Semimembranosus m.
Medial meniscus

Medial femorotibial
ligament
Semitendinosus m.
Medial patellar ligament

Tendon of gracilis m. (cut)

Figure 1.47. Deep dissection of medial aspect of left stifle. Tendon of adductor muscle is incised to reveal medial collateral
ligament of the stifle.

Cranial and caudal ligaments anchor each meniscus to joint through action of the quadriceps femoris, tensor
the tibia, and a meniscofemoral ligament attaches the fasciae lata, and cranial division of the biceps femoris
caudal aspect of the lateral meniscus to the caudal sur­ muscles is limited by tension from the collateral and
face of the intercondyloid fossa of the femur. cruciate ligaments. Flexion of the joint by the sem­
In addition to the support rendered by medial and itendinosus, middle division of the biceps femoris,
lateral collateral ligaments, the femur and tibia are joined popliteus, and gastrocnemius muscles is limited only
by the two cruciate ligaments that cross one another in by the caudal muscle masses. During flexion the crus
the intercondyloid space between the two synovial sacs is rotated slightly mediad, and the femoral condyles
of the femorotibial joint. The caudal cruciate ligament, and menisci move slightly caudad on the tibial
the more substantial of the two, extends from the cranial condyles.
part of the intercondyloid fossa of the femur to the pop­ When a horse shifts its weight to rest on one hindlimb,
liteal notch of the tibia, crossing the medial aspect of the the supporting limb flexes slightly as the con tralateral
cranial cruciate ligament. From its attachment on the relaxed limb is brought to rest on the toe. The pelvis is
caudolateral side of the intercondyloid fossa, the cranial tilted so that the hip of the supporting limb is higher.
cruciate ligament attaches to a central fossa between the The stifle on the supporting limb is locked in position as
articular surfaces of the condyles. the medial patellar ligament and parapatellar cartilage
The stifle is supplied principally by the descending are pulled proximad and mediad to engage the medial
genicular artery that originates from the femoral artery ridge of the femoral trochlea. The locked position
and descends toward the medial aspect of the stifle joint achieved by this configuration together with the support
deep to the sartorius and vastus medialis muscles. rendered by the other components of the stay apparatus
minimizes muscular activity in the supporting limb
while the relaxed contralateral hindlimb is resting.
Movements of the Stifle Joint
A very small amount of muscle tone in the vastus
In the standing position, the caudal angle of the medialis is necessary to stabilize the stifle in the locked
stifle joint is around 150°. Extension of the stifle position. 38
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