The Lower Extremity and Pelvis 



185 



Fourth Metatarsal. Notice the very oblique plane of the base, the heaviness of 

 this end of the bone, with the appearance of a notch and twist in it ; this, with the 

 fact that its basal facet is not triangular but rather four-sided, is enough to distinguish 

 the bone. There is a small marginal facet internally for the outer cuneiform, because 

 this bone projects very slightly beyond the cuboid, and this facet is continuous with 

 that for the third metatarsal. A single facet externally for the fifth metatarsal : 

 just in front of this is the notch or pit that gives the crooked appearance to the proximal 

 part of the bone, for the strong interosseous ligament which connects it with the last 

 bone of the series. 



Fifth Metatarsal. The proximal end has a very oblique tarsal facet, a slightly 

 concave metatarsal facet, and a prominent 

 styloid process : to this are fastened the 

 Peroneus brevis at the point and, on the dorsal 

 side of its base, the Peroneus tertius. This 

 latter muscle has usually a fairly extensive 

 aponeurotic insertion spreading along the 

 dorsal border of the bone, where there is a 

 sharp ridge that marks its attachment and 

 that of the dorsal fascia with which it is 

 blended. 



The Abductor metatarsi quinti, deep fibres 

 of the abductor of the little toe, is attached, 

 with much ligamentous tissue, to the outer and 

 under part of the process, and the Flexor brevis 

 has a part of its origin from the plantar surface 

 further in. 



The strong base and styloid process may 

 support some weight when the outer arch is Fj<J 

 sufficiently flattened to bring them to the 

 ground ; this probably occurs when any 

 pressure is made on the arch beyond that 

 supported in balancing the body, and thus 

 there is no extra strain thrown on the shaft 

 or small head. The whole of the dorsal and 



outer surface of the bone can be palpated, but its lower aspect is covered by the 

 marginal musculature. 



The heads of the four metatarsals are comparable with those of the metacarpals 

 (see pp. 105 etseq.}, and the same may be said about the structure of the metatarso- 

 phalangeal joints, save that the transverse metatarsal ligament extends to the capsule 

 of the great toe and has an Adductor muscle arising from it. 



The shafts, however, differ from those in the hand in that the markings for inter- 

 osseous muscles, being arranged on a slightly different plan, do not render each shaft 

 distinguishable. 



PHALANGES. 



Compared with those in the hand, the phalanges of the foot in general are recognised 

 at once (Fig. 85) by their thin and rounded shafts and large extremities : in the big 

 toe they are broad and strong, but short for their size, and the first shows an obliquity 

 of its base (Fig. 138), which enables one to place it at once on its proper side. 



Irtvit 



156. Left fifth metatarsal. Dorsa 

 and plantar aspects. A. is the sub- 

 cutaneous surface outside the dorsal 

 ridge for Peroneus tertius ; a tendinous 

 slip from Peroneus brevis passes on to 

 this surface along the groove B., covered 

 by ligamentous fibres attached to the 

 margins of the groove. 



