OSTEOLOGY AND SYNDESMOLOGY. 39 



4. The Foot is composed of twenty-six bones, which are arranged in 

 three parts, the tarsus, metatarsus, and toes. The bones of the tarsus {pi. 

 122, firjs. 28, 29, 3'°; pL US, ßfjs. 48 and 49) are seven: astragalus, 

 calcaneum, navicular, cuboid, and three cuneiform (internal, middle, and 

 external). These are arranged in two rows, the first embracing the astra- 

 galus, OS calcis, or calcaneum ; the second row consists of five bones : the 

 cuboid bone forms it externally alone, but on the inner side it presents two 

 short transverse rows, the navicular forming the posterior, and the three 

 cuneiform bones the anterior. 



The astragalus {pi 123, fig. 48') comes next to the calcaneum in point 

 of size, and is situated at the upper and middle part of the tarsus, where it 

 is wedged between the two malleoli ; superiorly it articulates with the tibia, 

 inferiorly with the calcaneum, anteriorly with the scaphoid, and externally 

 with the fibula. 



The calcaneum or os calcis {fig. 49 ^ ) is the largest bone in the tarsus, at 

 the lower and posterior part of which it is placed : it is elongated posteriorly 

 into a process called the heel ; its upper surface presents two articulating 

 surfaces, the support of the astragalus ; the anterior extremity presents an 

 articular surface for the cuboid bone ; the posterior extremity is roughened 

 below, for the attachment of the tendo Achillis ; the inferior surface presents 

 two tubercles, for the attachment of muscles and ligaments : externally it is 

 flat, and marked with two shallow grooves, separated by a spine ; internally 

 it is broad, and hollowed out into an arch, through which pass various 

 nerves, vessels, and tendons. 



The navicular or scaphoid hone {fig. 48 ') is situated about the middle of 

 the tarsus, and at its upper and internal part ; of an oval form, its long axis 

 directed downwards and forwards : the posterior surface forms a superficial 

 glenoid cavity, for the head of the astragalus ; the anterior surface is convex, 

 and divided by two vertical ridges into three surfaces, for the three cunei- 

 form bones ; on the external side there is usually a small flat articular sur- 

 face, for the cuboid bone ; the scaphoid is connected to the calcaneum by a 

 strong ligament. 



The cuboid hone {fi^. 48 ') is situated at the outer and anterior j^art 

 of the tarsus, external to the navicular, and anterior to the calcaneum ; 

 it articulates posteriorly with the calcaneum, internally with the scaphoid 

 and the external cuneiform, and anteriorly with the fourth and fifth, or the 

 two external metatarsal bones. 



The three wedge-shaped cuneiform hones {fig. 48 *• "■ °) are situated at the 

 anterior part of the tarsus, between the scaphoid and the three internal 

 metatarsal bones : the first or internal is the largest, and the middle the 

 smallest ; the first articulates with the scaphoid, the second metatarsal, and 

 the second cuneiform ; the second also articulates behind with the scaphoid, 

 before with the second metatarsal ; the third articulates anteriorly with the 

 third metatarsal, posteriorly with the scaphoid, internally with the middle 

 cuneiform and with the second metatarsal, and externally with the cuboid 

 and with the fourth metatarsal. 



The metatarsus {fig. 48 '') consists of five long bones, parallel, and sepa- 



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