172 



THE SKEJ.KTOX 



Blood-supply.— The nutrient artery of the shaft enters on the inner (tibial) 

 side and runs towards tlie base. 



The FIFTH METATARSAL has on the iibular side of its base a large ni})ple- 

 shaped tuberosity, to wliieh the tendon of the pewneuj^ brevu is inserted. Its 

 oblique ti-rniinal facet articulates with the cuboid, and on the tibial side it has a 

 large facet for the fourth metatarsal. The plantar aspect of the base has a shallow 

 groove whicli lodges the abductor minimi digiti. 



Muscles : — 



Tliird plantar interosseous. 

 P'ourth dorsal interosseous. 

 Poroneus brevis. 



Peroneus tertius. 



Abductor ossis metatarsi quinti. 



Flexor brevis minimi digiti. 



FxG. 187.— The Fifth (Left) Metataksal. 



TIBIAL 

 OR 

 INNER SIDE 



FOURTH METATARSAL 



FIBULAR 



OR 



OUTER SIDE 



Blood-supply. — Tlie nutrient artery enters on the tibial side of the shaft and 

 runs towards the Ijase. 



Ossification. — Each metatarsal ossifies from two centres. The j^riniary nucleus 

 for the diaphysis appears in the eighth week of embryonic life in the middle of the 

 cartilaginous metatarsal. At birth, each extremity is represented by cartilage, and 

 that at the ])roximal end is ossified by extension from the primary nucleus, except 

 in the case of the first metatarsal. For this, a nucleus appears in the third year. 



The distal ends of the four outer metatarsals are ossified by secondary nuclei 

 which make tht-ir appearance about the third year. Very frequently an epiphysis 

 is found at the distal end of the first metatarsal as well as at its base. The shafts 

 and epiphyses consolidate at the twentieth year. The sesamoids belonging to the 

 flexor brecia hallucis begin to ossify about the fifth year. 



THE PHALANGES 



There are fourteen phalanges to each foot. The hallux has two, and the 

 remaining toes three each. They are usually distinguished as fir.st, second, and 

 third. The la.st are sometimes called the ungual i)halanges, because they su]i]wrt 

 the nail. 



The i)halangesof the first row have narrow laterally compressed shafts, rounded 

 on the dorsal and concave on the i»lantar aspects. The base of each has a deep 



