THE LOWER LIMB 



501 



Tibialis 

 Amicus 



Extensor 



Longiis 



_ Digitorum 



which is continuous with that investing it as it passes through the 

 lambdoid ligament. 



The inferior anterior annular or lambdoid ligament is a more 

 defined structure than the superior. Being placed in front of 

 the ankle-joint, it serves to strap down the extensor tendons as 

 they are entering upon their horizontal course on the dorsum of 

 the foot. It may be likened 

 either to the capital letter 

 -< placed upon its side as 

 indicated, or to the Greek 

 letter '< (lambda), also 

 laid upon its side, as 

 shown. From the former 

 resemblance it may be 

 called the Y annular liga- 

 ment. The outer part, 

 which is a single narrow 

 band, is attached to a 

 depre'ssion on the upper 

 surface of the os calcis at 

 its anterior and outer part, 

 immediately in front of the 

 interosseous groove. This 

 part forms a loop through 

 which the tendons of the 

 extensor longus digitorum 

 and peroneus tertius pass, 

 invested by one synovial 

 sheath. From the fact 

 that it forms a loop it 

 has been called by Retzius 

 the fundi form ligament. It 

 gives partial origin to the 

 extensor brevis digitorum, 

 and at its inner end it is 

 continued into two diverg- 

 ing bands, upper and lower. 

 The upper band is attached 

 to the internal malleolus, 

 and the tendon of the 

 extensor proprius hallucis 

 passes underneath it, being 

 surrounded by a synovial sheath. The tendon of the tibialis 

 anticus passes throu^ it, the main portion of the band being 

 underneath that tendon, and a small expansion from it passing 

 superficial to the tendon. The tendon of the tibialis anticus 

 has its own synovial sheath, which is prolonged upwards from 

 this point along the tendon, to be continuous with the synovial 



Veath investing it as it passes behind the superior anterior 



Fig. 



242. — The Synovial Sheaths at the 

 Ankle (Anterior View) (after L. 

 Testut's 'Anatomie Humaine'). 



i 



