THE LOWER LIMB 



493 



pit in the bottom of the acetabulum, and is simply a collection 

 of adipose tissue covered by the synovial membrane. The hga- 

 mentum teres rests upon it, and the synovial membrane which 

 covers it is thicker and more vascular than elsewhere. It serves 

 as a cushion for the head of the femur. 



Mu5cular Relations. — Commencing at the inner aspect of the 

 capsular hgament and passing over its anterior, outer, and posterior 

 surfaces to its lower part, the muscles in contact with the hgament 

 are as follows : (i) pectineus on the inner aspect and adjacent part 

 of the anterior surface ; (2) iho-psoas in front ; (3) the two heads 

 of the rectus femoris, with the tendon formed by their union, 

 and the gluteus minimus on the outer and upper aspects ; (4) pyri- 

 formis, gemellus superior, obturator intemus, and gemellus inferidr 

 on the upper and posterior aspects ; and (5) obturator extemus on 

 the posterior and inferior aspects. Between the iho-psoas and the 

 ligament there is a bursa, which sometimes communicates with 

 the synovial membrane of the joint through an opening in the 

 capsule. 



Arterial Supply. — The hip- joint receives its arterial supply from 

 the following sources : 



1. The transverse branch of the internal circumflex. 



2. The ascending branch of the external circumflex. 



3. The external terminal branch of the obturator. 



4. The inferior branch of the deep division of the gluteal. 



5. The sciatic. 



Nerve-supply. — The hip- joint receives its nerves from the following 

 sources : 



1. The nerve to the rectus femoris, which is a branch of the pos- 

 terior division of the anterior femoral. 



2. The anterior or superficial division of the obturator nerve, or 

 the accessory obturator when it is present. 



3. The nerve to the quadratus femoris, or, if that nerve does not 

 supply an articular branch, the great sciatic. 



The first two nerves are branches of the lumbar plexus, and the 

 others are derived from the sacral plexus. 



Movements. — These are as follows : flexion, extension, abduction,- adduc- 

 tion, rotation, and circumduction. 



Flexion. — This is of two kinds — ventral and dorsal. In ventral flexion 

 the thigh is dra^^Ti upwards towards the cinterior abdomiucd wall. In dorsal 

 flexion the thigh is carried backwards beyond the perpendicular. The extent 

 of ventral flexion depends upon the condition of the knee-joint, being greater 

 when that joint is flexed and more hmited when it is kept extended. Assuming 

 the knee-joint to be flexed, ventrcd flexion is hmited by the coming into contact 

 of the fleshy parts of the front of the thigh and anterior abdominal wall. 

 \Mien the knee-joint is kept extended, ventral flexion is checked earUer by 

 the tension of the hamstring musclee. Dorsal flexion is in most persons soon 

 checked by the tightening of the front part of the capsulai- hgament. 



Extension. — In extending the hipnjoint from the position of ventral flexion 

 the movement is limited by the tightening of the front part of the capsular 

 ligament. When a person stands at rest the hip-joint is in a state of exten- 

 sion. The vertical Une passing through the centre of gravity then falls behind 

 the centre of rotation at the hir -joint, and there is thus a tendency on the 



