STIFLE JOINT. 377 
ARTICULATORY SURFACES.—To constitute this articulation, the femur 
opposes at one part its two condyles to the large undulating surfaces on 
the upper extremity of the lateral tuberosities of the tibia: at the other 
part its trochlear articulatory surface, to the wate 
posterior face of the patella. Between the tibia 
and femur are the two semilunar cartilages. 
The semilunar fibro-cartilages are two crescent- 
shaped bodies, placed on the articulating surfaces 
at the head of the tibia, and interposed between 
these and the condyles of the femur. The outer 
border of each is thick and convex, the inner 
thin and concave ; leaving the central parts of 
the superior surface of the tibia uncovered by 
them. Zhe internal semilunar cartilage is nearly 
of a semi-circular form ; larger and thinner than 
the external, it is inserted by its anterior ex- 
tremity to an excavation in front of the tibial 
spine, and by its posterior extremity to a little 
pit behind the spine: it is in close relation 
with the posterior crucial ligaments. Zhe ex- 
ternal semilunar cartilage fixes itself in front, 
near the anterior insertion of the opposite fibro- 
cartilage: its posterior extremity gives off two 
cords, one superior, the other inferior. The 
former, which is the longer and stronger of the Fis *0.—Postenton View o# 
two, is attached to the fossa at the back of , Ja ior tnind of femur 
the space between the condyles. The latter, 8: B. Condyles. i 
thinner and broader, is spread out upon the 2. Saperior third of the tibia. 
F 
2 
ae 2 . Fibula. 
posterior edge of the external tibial articulating F. Patella. 
- . Internal lateral ligament of 
surface. ; the patella. : 
The synovial membrane lines the contiguous 2 External lateral ligament of 
: : the femoro-tibial articula- 
surfaces of the parts entering into the compo- tion. 
sition of the stifle joint. Commencing to trace % ternal lateral ligament ot 
the reflections of this membrane at the border of tion. ice 
the patella, it will be found to line the capsule, Oe paras 
but below that bone it is separated from the an- 
terior ligaments by a considerable quantity of adipose tissue, which prolongs 
itself to the inter-condyloid hollow, where it is attached ; from this it is 
reflected over the semilunar cartilages, around the crucial ligaments, and 
forms a partial covering for them, inclosing them as far as their attach- 
ments. At the sides of the patella it forms two slight folds, the ligamenta 
alaria. Jinally it ascends in front of the femur, and passes downward to 
the margin of the patella. 
The ligaments are, first, those which unite the femur to the tibia, con- 
sisting of the lateral, the crucial, the posterior, the transverse, and the 
capsular ; and, secondly, those uniting the patella to the tibia, which are 
three, an externai, a middle, and an internal. 
1. The lateral ligaments are fibrous bands, situated on the sides of the 
articulation, more behind than in front; they become relaxed during 
flexion, and hold the bones strongly together during extension. The 
Ext®rnal, a rounded, cord-like fasciculus of fibres (the longer and stronger) 
passes from the tuberosity of the external condyle of the femur to the 
head of the fibula ; its direction is almost vertical. ‘The Internal, broad 
and flat, connects the tuberosity of the internal condyle of the femur 
Sues 
