THE METATARSUS. 243 
tion with the base of the fourth metatarsal, more or less conical in outline, and 
having its lower edge sharply defined by a narrow groove which underlies it. 
The fourth metatarsal has a base more cubical in shape. Its proximal ae 
articulates with the cuboid, whilst internally an elongated oval facet, divided by a 
Il. METATARSAL 
INTERNAL 
Basr / CUNEIFORM 
Heap SHAFT 
EXTERNAL 
CUNEIFORM 
MIDDLE 
CUNEIFORM 
: Ill. MeraTARsAL 
. Ill. METATARSAL 
EXTERNAL 
CUNEIFORM 
EXTERNAL 
CUNEIFORM 
[V. MeraTaARsSAL 
IV. METATARSAL 
y EXTERNAL CUNEIFORM 
III, MreTaTARSAL V. METATARSAL 
A, Inner sides. B, Outer sides. 
Fic. 190.—ViIEW OF THE BASES AND SHAFTS OF THE SECOND, THIRD, AND FouRTH METATARSAL BONES 
OF THE RicHt Foor. 
slight vertical ridge, provides surfaces for articulation with the third metatarsal in 
front and the outer side of the internal cuneiform behind. On the outer side there 
is a demi-oval facet, bearing a slightly saddle-shaped surface, for articulation with 
the inner side of the base of the fifth metatarsal, 
The fifth metatarsal can be readily recognised by the peculiar shape of its 
base, from the outer side of which there projects backwards and outwards a pro- 
minent tubercle (tuberositas oss. metacarpi V.). To the 
hinder extremity of this is attached the tendon of the peroneus 
brevis muscle. To its upper surface the tendon of the peroneus 
_tertius is inserted, whilst its under surface provides an origin 
"for the flexor brevis minimi digiti muscle. The inner surface 
of the base is provided with a demi- oval, slightly concave 
facet, for the outer side of the base of the fourth metatarsal, 
whilst proximally it articulates with the cuboid by means of 
a semi-circular facet. 
Vascular Foramina.—The canals for the nutrient vessels open, as 
a rule, on the plantar aspects of the middle of the shafts. Those of the 
outer metatarsals are directed towards the bases of the bones, whilst 
that for the metatarsal of the great toe passes towards its head. 
Architecture.—In structure and the arrangement of their lamellee 
the metatarsal bones agree with the metacarpus. 
Variations—Several instances of separation of the tuberosity of 
the fifth metatarsal (os Vesaleanum) have been recorded, whilst 
numerous examples of an os intermetatarsum between the bases of the 
first and second metatarsal bones have been recorded by Gruber and 
others. The tubercle on the base of the first metatarsal for the attach- 
ment of the peroneus longus tendon is occasionally met with as a Peroneus brevis 
separate ossicle. 
; 
| 
‘ 
, 
METATARSAL 
TV 
Fig. 191.—FirraH Ricut 
Ossification.—In correspondence with the mode of ossification ee 
which maintains in the metacarpus, the primary centres for the (Sorell asb°cH: 
-metatarsus appear as early as the third month of foetal life. In the case of the second, 
third, fourth, and fifth, these centres furnish the bases and shafts of the bones, the heads 
