The Lower Extremity and Pelvis 



171 



TubtrctfS 



fhorfpknCar, 

 lig 1 



peronrJl 

 groove 



outer cuneiform has an oblong shape when seen from the top, and this difference enables 

 one to distinguish the two bones at once when they are loose. 



Notice also how the depth of the cuboid is much less in the outer part, -both from 

 above downwards and from before backwards in conformity with the oblique line of 

 the tarso-metatarsal joint. Finally, look at the line of this joint more closely and 

 observe that it is irregular, for the inner and outer cuneiforms project forward beyond 

 the line, so that the bases of the first and third metacarpals are in front of the levels of 

 the second and fourth ; or, to call attention to the most noticeable feature, the base of 

 the second metatarsal projects beyond the line of the others in conformity with the 

 small size of the middle cuneiform. 



Now examine the lower or plantar surface of the skeleton of the foot. There is 

 a marked concavity on this aspect that is bounded behind by (Fig. 140) the prominent 

 tuberosity of the os calcis : this gives attach- 

 ment to the superficial muscles of the sole, and 

 the strong plantar fascia, so that an over- 

 hanging lip is seen on it, and inner and outer 

 tubercles, the former being the larger. On its 

 inner side, between the tuberosity and the 

 sustentaculum tali, the bone is concave and 

 gives origin to the inner head of Flexor acces- 

 sorius. 



The sustentaculum is seen to have a broad 

 groove on its lower aspect, and this is con- 

 tinuous behind with a groove on the back and 

 inner part of the astragalus, and is for the 

 tendon of the Flexor longus hallucis. 



The head of the astragalus is visible, in 

 front of the sustentaculum, between it and 

 the scaphoid. The inner part of the scaphoid 

 is prolonged downwards as the tubercle of 

 scaphoid. In front of this the inner cuneiform 

 is seen to have a thick and strong base, whereas 

 the other two cuneiform bones have their broad 

 bases uppermost and consequently do not show 

 very well on the plantar surface ; moreover, they 



are rather hidden in the deep concavity of the sole. The cuboid forms a prominent 

 mass outside the cuneiforms, and has a deep groove crossing it obliquely just behind 

 its metatarsal border ; this is for the tendon of Peroneus longus, and is therefore 

 directed towards the proximal end of the first metatarsal, on which bone and the 

 internal cuneiform the tendon is inserted. This groove commences in a deep notch, 

 on the outer border, for the tendon as it comes round from the outer side of the os 

 calcis, and here there is a facet for a nbro-cartilaginous sesamoid thickening in the 

 tendon. A prominent ridge crosses the cuboid behind the groove, and behind the ridge 

 is a ligamentous hollow that is immediately in front of a corresponding hollow on the 

 os calcis and is filled by the " short plantar ligament," a mass of fibres connecting the 

 two bones here. 



Now compare the skeleton with the living foot, and endeavour to recognise some of 

 the bony points ; these can be felt even through the boot as a rule. 



On the inner side the malleolus of the tibia is, of course, recognised at once ; about 

 three-quarters of an inch below this the sustentaculum can be felt by fairly deep 



FIG. 140. Plantar aspect of right foot. 

 Semidiagrammatic. 



