128 HIP JOINT. 



LIGAMENTS OF THE LOWER EXTREMITY. 



The ligaments of the lower extremity, like those of the upper, may 

 be arranged in the order of the joints to which they belong ; these 

 are, the 



1. Hip joint. 



2. Knee joint. 



3. Articulation between the tibia and fibula. 



4. Ankle joint. 



5. Articulation of the tarsal bones. 



6. Tarso-metatarsal articulation. 



7. Metatarso-phalangeal articulation. 



8. Articulation of the phalanges. 



1. Hip Joint. The articulation of the head of the femur with the 

 acetabulum constitutes an enarthrosis, or ball and socket joint. 

 The articular surfaces are the cup-shaped cavity of the acetabulum 

 and the rounded head of the femur; the ligaments are Jive in 

 number, viz. : 



Capsular, 



Ilio-femoral, 



Teres, 



Cotyloid, 



Transverse. 



The capsular ligament (fig. 50, 8) is a strong ligamentous cap- 

 sule, embracing the acetabulum superiorly, and inferiorly the neck 

 of the femur, and connecting the two bones firmly together. It is 

 much thicker upon the upper part of the joint, where more resist- 

 ance is required, than upon the under part, and extends farther upon 

 the neck of the femur on the anterior and superior than on the pos- 

 terior and inferior side, being attached to the intertrochanteric line 

 in front, to the base of the great trochanter above, and to the middle 

 of the neck of the femur behind. 



The ilio-femoral ligament* (fig. 50, 9) is an accessory and radiating 

 band, which descends obliquely from the anterior inferior spinous 

 process of the ilium to the anterior intertrochanteric line, and 

 strengthens the anterior portion of the capsular ligament. 



The ligamentum teres (fig. 51, 7), triangular in shape, is attached 

 by a rounded apex to the depression just below the middle of the 

 head of the femur, and by its base, which divides into two fasciculi, 

 into the borders of the notch of the acetabulum. It is formed by a 

 fasciculus of fibres of variable size, surrounded by synovial mem- 

 brane ; sometimes the synovial membrane alone exists, or the liga- 

 ment is wholly absent. 



The cotyloid ligament (fig. 51, 6) is a prismoid cord of fibro-car- 



* Called also ligamentum adscilitium. 



