222 



THE ARTICULATIONS. 



b. Internal lateral ligaments. — These are also three funicular bands superposed 

 on one another, and arb consequently designated as superficial, middle, and deep. 

 The internal superficial ligament (Fig. 14.3, 6), the strongest and longest of 

 the three, proceeds from the internal and inferior tuberosity of the tibia, 

 diminishing as it descends on the inner side of the tarsus. It is fixed, in mixing 

 with the astragalo-metatarsal ligament and with the posterior tarso-metatareal 

 ligamentous arrangement, to the tuberosity of the astragalus, the scaphoid, the 

 two cuneifoi-m, the superior extremity of the principal metatarsal, and that of the 

 internal rudimentary metatarsal bones. 



The internal middle ligament (Fig. 143, 5) is com- 

 posed of two funicular cords, attached in common beneath 

 the preceding ligament to the internal tibial tuberosity. 

 These two fasciculi, exactly resembling those of the ex- 

 ternal deep ligament, are directed downward and back- 

 ward, and terminate, one at the astragalus, the other 

 at the calcis. 



The internal deep ligament (Fig. 144, 4) is an extremely 

 slender fasciculus, enveloped by the synovial membrane ; 

 it is often reduced to a thin shred, scarcely distinct from 

 the serous covering surrounding it. It is attached, in one 

 direction, to the tibia below the middle ligament ; in 

 the other, to the astragalus, and nearly at the same point 

 as the superior fasciculus of the middle ligament. 



c. Anterior ligament. — This is a membraniform band 

 formed of intercrossed fibres, stronger outwards than in- 

 wards, attached by its upper border above and in front 

 of the tibial surface, fixed by its inferior border to the 

 astragalus, the scaphoid and great cuneiform bones, and 

 the astragalo-metatarsal ligament ; it is confounded at its 

 sides with the two superficial lateral ligaments. Its internal 

 face is lined by articular synovial membrane, while the ex- 

 ternal is covered by the flexor of the metatarsus, the anterior 

 extensor of the phalanges, the anterior tibial arteiy, and 

 several large anastomosing veins, from the junction of 

 which arises the anterior tibial vein. 



d. Posterior ligament. — This is the second membrani- 

 form or capsular band, which protects the articulation 

 posteriorly. It presents, in its centre, a fibro-cartilaginous 

 thickening, on which gUdes the perforans tendon. It is 

 attached, above, to the tibia ; below, to the astragalus and 

 calcis ; at its sides it is mixed with the two superficial 



lateral ligaments, and the astragalian fasciculus of the middle internal ligament. 

 Its internal face is lined by articular synovial membrane ; the external is covered 

 and lubricated by the vaginal serous membrane, which facilitates the gliding of 

 the perforans tendon in the tarsal sheath. 



Synovial membrane. — This membrane is developed at the internal face of the 

 two capsular ligaments, lines the greater part of the three internal ligaments, 

 and also the external deep ligament. It communicates, in front and below, with 

 the synovial membrane proper to the articulation of the two rows of tarsal bones. 

 When it becomes the seat of dropsical effusion, it is always distended forwards 



parsal articitlations 

 (front view). 



, External deep ligament 

 of the tibio-taisal ar- 

 ticulation ; 2, 2, ex- 

 ternal superficial liga- 

 ment ; 4, internal deep 

 ligament ; 5, internal 

 middle ligament ; 6, In- 

 ternal superficial liga- 

 ment ; 7, astragalo- 

 metatarsal ligament ; 8, 

 small cuboido-cunean 

 ligament. A, Pulley of 

 the astragalus; B, cu- 

 boidal insertion belong- 

 ing to tne tendinous 

 cord of the flexor of the 

 metatarsus ; C, vascular 

 canal of the tarsus. 



