HIP-JOINT. 221 



ARTICULATIONS OF THE LOWER EXTREMITY. 



The articulations of the Lower Extremity comprise the following groups. 1. 

 The hip-joint. 2. The knee-joint. 3. The articulations between the tibia and 

 fibula, -i. The ankle-joint. 5. The articulations of the tarsus. 6. The tarso- 

 nietatarsal articulations. 7. The metatarso-phalangeal articulations. 8. The 

 articulation of the phalanges. 



1. HIP-JOINT (fig. 138). 



This articulation is an enarthrodial or ball-and-socket joint, formed' by the 

 reception of the head of the femur into the cup-shaped cavity of the acetabulum. 

 The articulating surfaces are covered with cartilage, that on the head of the femur 

 being thicker at the centre than at the circumference, and covering the entire 

 surface with the exception of a depression just below its centre for the ligamen- 

 tum teres ; that covering the acetabulum is much thinner at the centre than at the 

 circumference, being deficient in the situation of the circular depression at the 

 bottom of this cavity. The ligaments of the joint are the 



Capsular. Teres. 



Ilio-femoral. Cotyloid. 



Transverse. 



Fig. 138. Left Hip-joint laid open. 



The Capsular Ligament is a strong, dense, ligamentous capsule, embracing the 

 margin of the acetabulum above, and surrounding the neck of the femur below. 

 Its upper circumference is attached to the acetabulum two or three lines external 

 to the cotyloid ligament ; but, opposite the notch where the margin of this cavity 

 is deficient, it is connected with the transverse ligament, and by a few fibres to the 

 edge of the obturator foramen. Its lower circumference surrounds the neck of the 

 femur, being attached, in front, to the spiral or anterior inter-trochanteric line ; 

 above, to the base of the neck ; behind, to the middle of the neck of the bone, 

 about half an inch from the posterior inter-trochanteric line. It is much thicker 



