FOOT, REGIONS OF TI1E.—The sur gical anatomy of the ankle having already been given, (see ANKLE, REGIONS or,) it remains for us, in this article, to describe the foot pro perly so called, that is, all of the lower extremity beyond the ankle. This part comprises much that is practically interesting and important, both in its pathology and surgery, which must be evident when we consider the vast number of ills which are endured in the feet. The foot, considered as an entire region, is na turally and obviously subdivided into dorsal and plantar regions. In the first of these we observe, 1st, the dorsum, or instep, ex tending from the front of the ankle to the heads of the metatarsal bones ; 2d, the toes themselves.
I. Region of the dorsum.—We see the instep falling, with a gentle curve, forwards from the ankle, and forming the anterior portion of that arch, which posteriorly runs through the ankle joint to the heel, and the crown of which, formed by the astragalus, bears the weight of the whole body. This most remarkable provision for the safety and efficiency of the body is well deserving of particular examination, and we shall return to it when describing the plantar region. The curve of the dorsum just men tioned is running forwards to the head of the metatarsal bone of the great toe; there is another arch, a lateral one, running across the foot, of which the inner end is abrupt, as it bends over the inner side of the ossa naviculare and cuneiforme interim ; the outer end slopes off more gradually to the os cuboides and metatarsal bone of the little toe. The use of this arch is best seen also in the sole, though it presents itself to the view most strikingly on the dorsum.
The principal points which claim our atten tion in this region are :— t. The integuments, which are here rather thinner and softer than in other parts of the limb, but varying considerably in texture ac cording to age, sex, and habit : they are also rather thinner on the outer than on the inner side. 2. The subeutuneous cellular tissue. This is rather loose, and freer from fat than in other parts of the body, permitting free movement of the superficial parts upon those beneath. This laxity of the cellular tissue is
greatest on the middle of the instep ; and accordingly we see in children and females, where there is a large quantity of superficial fat, and in effusions of water or other fluids, that the skin of this part rises most, while across the ankle and the roots of the toes there is an appearance like a ligature arising from the comparative closeness and shortness of this cellular web. In this layer also we find several large veins and some branches of nerves. The dorsal veins of the foot run in very irregular directions, varying in size in different subjects, but mostly collected into two plexuses, which form in front of the inner and outer ankles, the sap/Iola major and minor veins. The course of these veins, though various, is generally as follows :—The saphenu major begins to shew itself pretty conspicuously on the middle and inner side of the instep, and running to the inner ankle receives in its course numerous additions, and then passes over the internal malleolus. The supheria minor is seldom found in a notable trunk on the foot ; we see only on the outer side of the dorsum several small branches commu nicating with the inner plexus, and taking their course towards the outer ankle ; there they form sometimes one, but generally two branches, which pass sometimes over, generally behind the outer malleolus. It is the first of these veins that is principally im portant in surgery, as it occasionally, and we think it might with advantage be more fre quently, opened for the detraction of blood. It is immediately brought into view by a ligature placed above the ankle, and in opening it we must bear in mind that, from its super ficial situation, from the looseness of the en veloping tissue, and from the greater distance of the ligature from the point to be punctured, the vein is much more liable to roll and to foil our attempts than the vein at the elbow : we must, therefore, take the precaution of putting the fore-finger above, and the thumb below the spot where the lancet is to enter, which will retain with facility the vein in its place.