_The Hip-joint._--The hip-joint is an =enarthrosis=, or ball-and-socket joint in which more than half the spherical head of the femur is received into the acetabulum. The depth of the acetabulum is increased by a rim of fibrocartilage about its margin, forming the =labrum glenoidale=. This passes across the acetabular notch, forming the =transverse ligament= of the acetabulum; beneath it blood-vessels and nerves pass into the acetabular cavity.
The =capsule of the joint= is large and loose. It is attached about the margin of the acetabulum, and passes over the head of the femur, to be attached to the bone several millimeters distad of the head. It thus encloses both the head and the neck of the femur.
The =ligamentum teres=, or round ligament, is a very strong, short ligament which passes from the depression in the head of the femur to the bottom of the acetabulum.
=The Knee-joint= (Figs. 60 and 61).--The joint between the femur and the tibia is very complex. The surfaces of the condyles of the femur do not correspond to those of the condyles of the tibia. Between the ends of the two bones are placed two disks of cartilage, the =menisci=, or semilunar cartilages (Fig. 60, _c_ and _d_; Fig. 61, _a_ and _b_), of such a form that the congruity of articular surfaces is restored. Each meniscus has a proximal surface corresponding to the form of one of the condyles of the femur, and a distal surface corresponding to a condyle of the tibia. The menisci are held in position by ligaments. The knee-joint permits not only backward and forward movement, but also a small amount of rotary motion.
The joint has two =capsules=, one on the dorsal (convex) side, the other on the ventral side. The two communicate only by a small passageway lying within the joint between the ends of the bones. The dorsal one is attached to the femur several millimeters proximad of the patellar surface and some distance on each side of the latter. The patella is imbedded in its outer wall, and it is attached to the tibia on the edges of the articular surface of the latter, from the crest to the tuberosities. The capsule is also attached laterally and medially to the sides of the menisci, and is closely united to the patellar ligaments. Its cavity contains a mass of yellow fat.