ARTICULATIONS OF THE POSTERIOR LIMBS. 215 



moulded to the cavity, and, like it, is excavated by a rugged fossa which is entirely 

 ocoupied by the insertion of the interarticular Ligaments. 



Mode of union. — Tliis joint is maintained by a peripheral capsule, and by an 

 interarticular band constituting the coxo-feuioral ligament. 



a. Capsular ligament (Fig. 140, 4). — This is a membranous sac, like that of 

 the scapulo-humeral articulation, embracing the head of the femur by its inferior 

 opening, and attached by its opposite border to the margin of the cotyloid cavity 

 and its surrounding fibro-cartilage. This ligament is composed of intercrossed 

 fibres, and is strengthened in front by an oblique fasciculus which descends to the 

 body of the femur, along with the crureus muscle, near which it is fixed. Its 

 internal face is co\'ered by the articular synovial membrane, and its external face 

 is in contact, through the medium of adipose cushions, with : in front, the crureus 

 and the rectus femorls ; behind, the gemini, the internal obturator, and the 

 pyraniidalis muscles ; outwards and upwards, the small gluteal muscle ; within 

 and below, the external obturator. 



b. Co.w-femoraJ ligament {ligamentiim teres, Fig. 140, 6). — A thick and short 

 f uniole of a triangular shape, deeply situated between the two bony surfaces, which 

 it cannot, notwithstanding its shortness, maintain exactly in contact without the 

 other muscular or ligamentous structures enveloping the articulation. In Solipeds, 

 it is divided into two portions — a cotyloid and a jmbir. The cotyloid portion is 

 short and entirely concealed in the interior of the articulation (Fig. 140, 6). Its 

 upper insertion occupies the internal moiety of the bottom of the cotyloid ca\'ity ; 

 and its inferior extremity is fixed into the rough fossa in tlie head of the femur. 

 It is enveloped by the synovial membrane. 



The pubic portion (Fig. 140, 7, 8) arises, like the preceding, from the fossette 

 in the head of the femur, and, passing upwards and outwards, enters the internal 

 notch of the cotyloid cavity, is inflected downwards on the fibrous band whicli 

 converts that notch into a foramen, and is at last lodged in the inferior fuiTow on 

 the pubis, becoming confounded with the prepubic tendon of the abdominal 

 muscles, at the anterior border of the pubis. Longer and stronger than the cotyloid 

 portion, this fasciculus is included, in its pubic part, between the two branches of 

 the pectineus ; its interarticular part is covered by synovial membrane. 



Synovial membrane. — This membrane is very extensive ; it lines the internal 

 face of the capsular and cotyloid ligaments, and is reflected on the interarticular 

 ligaments, to form around them a serous vaginal covering. It is even prolonged 

 into the synovial fossa occupying the centre of the cotyloid cavity. 



Movements. — The coxo-femoral articulation is one of the joints wliich are 

 endowed with the most varied and extensive movements. It permits the flexion, 

 extension, abduction, adduction, circumduction, and rotation of the thigh on the 

 jjelvis. The mechanism of these movements is so simple, that they need no 

 particular consideration. 



The domesticated animals other than Solipeds, are distinguished by the com- 

 plete absence of the pubio-femoral ligament ; so that in them the movements of 

 abduction, which are limited in Solipeds by the tension of this ligament, are much 

 more extensive ; and it is the absence of the ligament in question which explains 

 the facility with which the larger Ruminants are enabled to strike sideways — a 

 movement known as a " cow's kick." 



Id Man, the head of the femur is more detached than in the domesticated animals, and 

 the cotyloid cavity, encircleil by the cotyloid ligament, id deeper. The femur is united to the 

 eoxa : 1. By a capsular ligament. 2. By a triangular ligament, fixed above, to the cotyloid 



