DISSECTION OF THE POSTERIOR LIMB. 89 



its fibres are inserted into the astragalus, os calcis, cuboid, large meta- 

 tarsal bone, and external small metatarsal. It is perforated by the 

 thecal canal for the passage of the peroneus tendon. The deep 

 division of the ligament extends downwards and backwards from its 

 point of attachment to the forepart of the external malleolus of the 

 tibia, and it becomes inserted by distinct slips into the astragalus and 

 os calcis. In order to expose it thoroughly, the superficial division 

 should be cut at its point of attachment to the tibia, and dissected 

 downwards, the difference of direction serving to distinguish the fibres 

 of the two divisions. 



The Internal Lateral Ligament is, like the preceding, a composite liga- 

 ment, and consists of three divisions, which may be distinguished as 

 superficial, middle, and deep. The superficial division, the largest of 

 the three, is fixed, on the one hand, to the internal malleolus of the 

 tibia, and, on the other, to the astragalus, scaphoid, large and small 

 cuneiforms, and large and internal small metatarsal bones. The middle* 

 division is of intermediate size ; and in order to expose it the superficial 

 division must be cut and dissected downwards. Above it is attached 

 to the internal malleolus of the tibia; and, passing downwards and 

 backwards, it is inserted by distinct slips into the astragalus and os 

 calcis. The deep division is very slender, and stretches between the 

 tibia and the astragalus, under cover of the middle fasciculus, which 

 must be removed in order to expose it. 



The Anterior Ligament is membranous and four-sided. It is fixed 

 above to the tibia; and below to the astragalus, scaphoid, cuneiform 

 magnum, and astragalo-metatarsal ligament ; while on each side it 

 blends with the lateral ligament. The posterior surface of the liga- 

 ment is lined by the synovial membrane of the joint. The anterior 

 surface is related to the anterior tibial vessels, and to the flexor meta- 

 tarsi and extensor pedis tendons. Towards its inner side the ligament 

 is unsupported ; and hence, when the synovial membrane becomes 

 dropsical, the distension shows at that point, constituting a "bog- 

 spavin." 



The Posterior Ligament is of a similar form to the preceding. It is 

 fixed above to the tibia, below to the astragalus and os calcis, and at 

 the sides to the lateral ligaments. Its anterior surface supports the 

 synovial membrane of the joint ; while the posterior is lined by the 

 synovial membrane of the tarsal sheath, and presents a fibro-cartila- 

 ginous thickening where the perforans tendon plays over it. This 

 tendon affords support to the posterior ligament, which therefore does 

 not bulge so readily as the anterior ligament ; but in a case of extreme 

 distension of the synovial membrane the swelling shows itself at the 

 back trf the joint. 



The Synovial Membrane is supported by the anterior, posterior, and 



