384 THE ARTICULATIONS. 



They are strengthened by the processes given off from the tendon of the Tibialis 

 posticus. 



The Interosseous Ligaments consist of strong transverse fibres which pass 

 between the rough non-articular portions of the lateral surfaces of the adjacent 

 cuneiform bones. 



The Synovial Membrane of these joints is part of the great tarsal synovial 

 membrane. 



Actions. 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. 



These bones are connected together by 



Dorsal, Plantar, and Interosseous ligaments. 



The Dorsal Ligament consists of a band of fibrous tissue which passes trans- 

 versely between these two bones. 



The Plantar Ligament has a similar arrangement. It is strengthened by a 

 process given off from the tendon of the Tibialis posticus. 



The Interosseous Ligament 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. 



The Synovial Membrane of this joint is part of the great tarsal synovial 

 membrane. 



Actions. 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. 



Surgical Anatomy. In spite of the great strength of the ligaments which connect the 

 tarsal bones together, dislocation at some of the tarsal joints does occasionally occur; though, on 

 account of the spongy character of the bones, they are more frequently broken than dislocated, 

 as the result of violence. 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 tibio-fibular 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 navicular 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 down- 

 ward, so that the trochlear surface faces to one or the other side. Finally, dislocation may 

 occur at the medio-tarsal 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. 



VI. Tarso-metatarsal Articulations. 



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, resting against the 

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

 bones ; the third metatarsal articulates with the extremity of the external cunei- 

 form ; the fourth with the cuboid and external cuneiform ; and the fifth, with the 

 cuboid. The articular surfaces are covered with cartilage, lined by synovial 

 membrane, and connected together by the following ligaments : 



Dorsal. Plantar. Interosseous. 



The Dorsal Ligaments consist of strong, flat, fibrous bands, which connect the 

 tarsal with the metatarsal bones. The first metatarsal is connected to the internal 

 cuneiform by a single broad, thin, fibrous band; the second has three dorsal 



