THE TARSOMETA TARSAL ARTICULATIONS 351 



Synovial Membrane (Fig. 280). The synovial membrane of these joints is part of the great 

 tarsal synovial membrane. 



Movements. The movements permitted between the cuneiform bones are limited to a slight 

 gliding upon each other. 



8. THE ARTICULATION OF THE EXTERNAL CUNEIFORM BONE WITH THE 



CUBOID (Fig. 276). 



These bones are connected by 



Dorsal, Plantar, and Interosseous Ligaments. 



The dorsal ligament (ligamentum cuneocuboideum dorsale) (Fig. 277) consists 

 of a band of fibrous tissue which passes transversely between these two bones. 



The plantar ligament (ligamentum cuneocuboideum plantare) has a similar 

 arrangement. It is strengthened by a process given off from the tendon of the 

 Tibialis posticus. 



The interosseous ligament (ligamentum cuneocuboideum interosseum) (Fig. 

 270) consists of strong transverse fibres which pass between the rough non- 

 articular portions of the lateral surfaces of the adjacent sides of these two bones. 



Synovial Membrane (Fig. 2<80). The synovial membrane of this joint is part of the great 

 tarsal synovial membrane. 



Movements. The movements permitted between the external cuneiform and cuboid are 

 limited to a slight gliding upon each other. 



Nerve Supply. All the joints of the tarsus are supplied by the anterior tibial nerve. 



Applied Anatomy. In spite of the great 'strength of the ligaments which hold the tarsal 

 bones together, dislocation at some of the tarsal joints occasionally occurs; these bones, on account 

 of their spongy character, are, as the result of direct violence, more frequently broken than dis- 

 located. When dislocation does occur, it is most commonly in connection with the astragalus; 

 for not only may this bone be dislocated from the tibia and fibula at the ankle-joint, but the 

 other bones may be dislocated from it, the trochlear surface of the bone remaining in situ in the 

 tibiofibular mortise. This constitutes what is known as the subastragaloid dislocation. Or, 

 again, the astragalus may be dislocated from all its connections from the tibia and fibula 

 above, the os calcis below, and the scaphoid in front and may even undergo a rotation, either 

 on a vertical or horizontal axis. In the former case the long axis of the bone becoming directed 

 across the joint, so that the head faces the articular surface on one or other malleolus; or, in the 

 latter, the lateral surfaces becoming directed upward and downward, so that the trochlear sur- 

 face faces to one or the other side. Finally, dislocation may occur at the mediotarsal joint, the 

 anterior tarsal bones being luxated from the astragalus and calcaneum. The other tarsal bones 

 are also, occasionally, though rarely, dislocated from their connections. 



Pes planus, flat-foot, or splay-foot is a condition in which there is abduction, eversion, and 

 loss of both the longitudinal and the transverse arch. The head of the astragalus passes down- 

 ward and inward; the anterior portion of the foot is turned outward and the inner side of the 

 foot is lengthened and broadened. Deformity is increased when standing. In severe cases the 

 patient walks on the inner side of the foot. The condition is due to weakness of the Tibialis 

 posticus muscle, with a consequent yielding of the tarsal ligaments. Abduction is permitted 

 by yielding of the internal lateral and calcaneo-astragaloid ligaments. Yielding of the calcaneo- 

 scaphoid ligament permits the head of the astragalus to pass downward and forward, and the 

 entire arch falls. 



VI. The Tarsometatarsal Articulations (Articulationes Tarsometatarseae 

 [Lisfranci] ) (Figs. 276, 277). 



These are arthrodial joints. The bones entering into their formation are four 

 tarsal bones viz., the internal, middle, and external cuneiform and the cuboid 

 which articulate with the metatarsal bones of the five toes. The metatarsal 

 bone of the great toe articulates with the internal cuneiform; that of the second 

 is deeply wedged in between the internal and external cuneiform, rests against 

 the middle cuneiform, and is the most strongly articulated of all the metatarsal 



