THE STIFLE JOINT 237 
practically of the synovial layer only. It is much stronger posteriorly: here it 
is reinforced by what might be regarded as a posterior ligament. This is a 
strong, flat band which arises from the femur just lateral to the origin of the medial 
head of the gastrocnemius, and extends down to the posterior border of the medial 
condyle of the tibia; it is wider below than above. There are two synovial sacs, 
corresponding to the double nature of the articular surfaces; they do not usually 
communicate, and each is partially divided into an upper and a lower compartment 
by the meniscus. The medial sac pouches upward about half an inch over the con- 
Lateral condyle of 
femur Medial femoro- 
tibial ligament 
Medial condyle of 
Lateral femoro- femur 
tibial ligament 
Stump of pop- 
liteus tendon Medial meniscus 
Lateral meniscus 
Medial condyle of 
Lateral condyle of tibia 
tibia 
Head of fibula 
Interosseous space 
Fic. 249—Lerr Stirte Joint oF Horse; Postertor View. THe Capscre 1s RemMoven. 
1, Femoral ligament of lateral meniscus; 2, posterior ligament of lateral meniscus; 3, anterior cruciate ligament; 4, 
posterior cruciate ligament. 
dyle of the femur. The lateral sac invests the tendon of origin of the popliteus 
muscle, and also pouches downward about three inches (ca. 7.5 em.) beneath the 
peroneus tertius and extensor longus muscles. As stated above, the lateral sac 
sometimes communicates with the femoro-patellar joint cavity, and the medial 
sac usually does so in the adult. 
Ligaments.—There are four of these—two collateral and two cruciate. 
The medial ligament (Lig. collaterale tibiale) is attached above to the prom- 
inent medial epicondyle of the femur, and below to a rough area below the margin 
of the medial condyle of the tibia. 
