ARTICULATIONS OF THE LOWER EXTREMITIES. 299 



of the second and third joints of the finger is, by this reflection 

 of the synovial membrane, extended upwards between the pha- 

 lanx and the flexor tendons nearly one-third of the whole length 

 of the phalanx,* a circumstance worth attending to in the ac- 

 cidents of the part. 



CHAPTER IX. 



OF THE ARTICULATIONS OF THE LOWER EXTREMITIES. 



Of the llio-Femoral, or Hip Articulation. 



THE basis of this articulation is laid by the head of the os fe- 

 moris being received into the acetabulum. Both surfaces are 

 covered by thick cartilage: in the former it is interrupted, how- 

 ever, by the depression near the centre, and becomes very thin 

 near the margin; and, in the latter, the cartilage is deficient in 

 the whole extent of the rough surface at its lower part. A 

 cotyloid ligament, a fibrous capsule, the round or inter-articu- 

 lar ligament, and a synovial membrane, are moreover, con- 

 cerned in this joint. 



The Cotyloid Ligament (Lig. Cotyloideum) is a fibrous pris- 

 matic ring which tips the margin of the acetabulum, and there- 

 by increases its depth; it can only be seen by cutting open the 

 capsule. Its thickness is unequal, being considerable on the 

 anterior third of the circumference of the acetabulum, where 

 it assists in converting the notch into a foramen, but not so 

 much so elsewhere. Just below the anterior inferior spinous 

 process, the acetabular head of the rectus femoris sends some 

 tendinous fibres to it. Its base is broader than its margin, and 

 is marked off from the articular cartilage by a line, or narrow 

 groove, between them. Its acetabular side is covered by the 

 synovial membrane;- the other side has the capsular ligament 



* Bichat, loc. cit. 



