The attachment on the femur is about 1 cm. from the margin of the articular surface, except above, where 2 to 3 cm. of the neck is intracapsular. A thin oblique band corresponding in direction with the rectus parvus muscle reinforces the antero-external part of the capsule; this appears to be the feeble homologue of the very strong ilio-femoral ligament of man. The capsule is very thin under the ilio-psoas, and is adherent to the muscle. Internally, its fibrous part is perforated by the pubo-femoral and round ligaments and the articular vessels. The =round ligament= (Ligamentum teres) is a strong hand which is attached in the subpubic groove close to the acetabular notch, passes outward, and ends in the notch on the head of the femur (Fig. 456). The =pubo-femoral ligament= (Ligamentum accessorium) does not occur in the domestic animals other than the equidæ. It is a strong band detached from the prepubic tendon of the abdominal muscles (Fig. 456). It is directed outward, backward, and upward, passes through the acetabular notch above the transverse ligament, and ends behind the round ligament in the notch on the head of the femur. The origin of the pectineus muscle is perforated by the ligament, which furnishes attachment to the greater part of the fibers of the muscle. [Illustration: FIG. 155.—LEFT STIFLE JOINT OF HORSE, EXTERNAL VIEW, IN PARTIAL FLEXION. The capsules have been removed. _18_, Femur; _20_, patella; _21_, tibia; _a″_, internal patellar ligament; _b_, external femoro-patellar ligament; _d_, external semilunar cartilage. (After Ellenberger-Baum, Anat. für Künstler.) ] The =synovial membrane= is reflected over the intracapsular parts of these ligaments and covers the fossa acetabuli. A pouch also extends from the acetabular notch for a variable distance along the subpubic groove above the pubo-femoral ligament. =Movements.=—This joint is capable of all the movements of a ball-and-socket joint, viz., flexion, extension, abduction, adduction, rotation, and circumduction. The greatest range of movement is displayed in flexion and extension. When standing at rest, the joint is partially flexed, the articular angle (in front) being about 100° to 115°. The other movements occur to a very limited extent in normal action. Abduction appears to be checked by tension of the round ligament. The pubo-femoral ligament is tensed most promptly by inward rotation of the thigh. THE STIFLE JOINT This joint (Articulatio genu), which corresponds to the knee-joint of man, is the largest and most elaborate of all the articulations. Taken as a whole, it may be classed as a ginglymus, although it is not a typical example of the group. In reality it consists of two joints—the =femoro-patellar= and the =femoro-tibial=. The =femoro-patellar articulation= (Articulatio femoro-patellaris) is formed between the trochlea of the femur and the articular surface of the patella.