208 



THE SKELETON. 



surface upward, the prolonged edge backward; the separate articular facet for the 

 cuboid will point to the proper side. 



Articulations. With six bones : the riavicular, middle cuneiform, cuboid, and 

 second, third, and fourth metatarsal bones. 



Attachment of Muscles. To two : part of the Tibialis posticus, and Flexor 

 brevis hallucis. 



The number of tarsal bones may be reduced owing to congenital ankylosis, 

 which may occur between the os calcis and cuboid, the os calcis and navicular, the 

 os calcis and astragalus, or the astragalus and navicular. 



The Metatarsal Bones. 



The Metatarsal Bones are five in number, and are numbered one to five, in 

 accordance with their position from within outward; they are long bones, and 

 present for examination a shaft and two extremities. 



Common Characters. The shaft is prismoid in form, tapers gradually from the 

 tarsal to the phalangeal extremity, and is slightly curved longitudinally, so as to 

 be concave below, slightly convex above. The posterior extremity, or base, is 

 wedge-shaped, articulating by its terminal surface with the tarsal bones, and by 

 its lateral surfaces with the contiguous metatarsal bones, its dorsal and plantar 

 surfaces being rough for the attachment of ligaments. The anterior extremity, 

 or head, presents a terminal rounded articular surface, oblong from above 

 downward, and extending farther backward below than above. Its sides are 

 flattened and present a depression, surmounted by a tubercle, for ligamentous 

 attachment. Its under surface is grooved in the middle line for the passage 

 of the Flexor tendon, and marked on each side by an articular eminence 

 continuous with the terminal articular surface. 



Peculiar Characters. The First 

 (Fig. 146) is remarkable for its 

 great thickness, but is the shortest 

 of all the metatarsal bones. The 

 shaft is strong and of well-marked 

 prismoid form. The posterior ex- 

 tremity presents, as a rule, no lateral 

 articular facet, but occasionally on 

 the outer side there is an oval facet 

 by which it articulates with the 

 second metatarsal bones. Its ter- 

 minal articular surface is of large 

 size, kidney-shaped; its circumfer- 

 ence is grooved, for the tarso-meta- 

 tarsal ligaments, and internally 

 gives attachment to part of the 

 tendon of the Tibidis anticus: its 

 inferior angle presents a rough 

 oval prominence for the insertion 

 of the tendon of the Peroneus 

 longus. The head is of large size ; 

 on its plantar surface are two grooved facets, over which glide sesamoid bones ; 

 the facets are separated by a smooth elevated ridge. 



This bone is known by the single kidney-shaped articular surface on its base, 

 the deeply grooved appearance of ^the plantar surface of its head, and its great 

 thickness relatively to its length. When it is placed in its natural position", the 

 concave border of the kidney-shaped articular surface on its base points to the 

 side to which the bone belongs. 



Attachment of Muscles. To three : part of the Tibialis anticus, the Peroneus 

 longus, and the First dorsal interosseous. 



Occasional facet foi 



For internal cuneiform. second metatarsal. 



FIG. 146. The first metatarsal. (Left.) 



