TIBIAL ARTERIES.) II. lirgion tf the toes.—In the natural state the toes are covered by a skin, soft and pliable, except the extreme phalanx, the dorsal surface of which is defended by the nail, for the struc ture and arrangement of which we refer to the article TEGUAIENTARY SYSTEM. Under the skin and subcutaneous tissue we find the tendon of the long extensor, lying close upon the bone adhering to it and to the synovial membranes of the joints, by short but free cellular tissue, sufficiently loose to allow of the free movements of the subjacent joints. We observe that the length of the toes, by the construction of the bones, much shorter and smaller than the fingers, appears shorter still in the metatarsal phalanx by the greater depth of the integumental web between the toes. The operator will do well to remember this in amputating at the metatarso-phalangeal joint, or he ‘vill surely be foiled in his attempt to open it, particularly as this joint, lying deeper and being composed of smaller bones than the corresponding joint of the hand, is much less readily perceptible, even to the touch. Lastly, these organs, the toes, more universally, and in greater degree perhaps than any other part of the body, pay the penalty of hyper-refinement and civilization in the distortion and disfigurement of their entire structure from pressure. The skin suffers most acutely ; it becomes entirely altered in struc ture. The soft cuticle which covered it is, by the irritation of pressure, increased in thick ness by successive additional layers. This increase is greatest just at the point where there is most pressure, namely, at the upper and lateral parts of the projecting joints; nature thus providing a defence for the tender cutis, pressed between the bone and the shoe. The cause of irritation being still continued, the defence itself is converted into an ad ditional enemy ; the accumulated layers of hardened cuticle form a hard corn, and irritate and inflame the subjacent cutis. Another effort of nature is made to relieve the suffering parts ; a small bursa is formed under the most prominent part of the corn, and this again is made an additional cause of suffering by this part also becoming inflamed, the original source of evil not being removed. The same process taking place between the toes by the pressure of one toe against the other, produces the soft corn by the moisture of this part not allowing the thickened cuticle to become hard and dry. The same process on a larger scale over the joints of the great toe occasions the bunion,* the bursal cysts of which form a beautiful illustration of the powers of nature in accommodating herself to accidental circum stances.
Nor is the mischief arising from this oppo sition to nature confined to the results now mentioned. The toes, from being constantly kept in a distorted position, acquire perma nently an unnatural form, sometimes being bent laterally under or over each other, the ligaments become stretched, the articular car tilages absorbed, the ends of the bones altered in form, and anchylosis is not unfrequcntly the result. If the shoe be too short, a per manent contraction of the joint of the toe is produced, which is sometimes so distressing in walking as to be a serious impediment to this exercise, and even to demand amputation of the toe as the only means of deliverance.
This, when it does occur, is almost always found in the second toe, because it projects beyond the others.
Plantar region.—The plantar region, like the dorsal, may be divided into the plantar region, strictly so called, and the region of the toes.
I. Proper plantar region.—The skin upon the sole of the foot is covered by a cuticle remarkable both for its general density and for the great difference of its density in different parts. In the hollow of the sole it is thinnest, next along the outer side, and thickest of all under the heel and heads of the metatarsal bones. This great thickness of the cuticle, though partly arising from pressure, is yet partly natural, being found in sonic degree even in the fetus, and is one of those marks of Provident Wisdom of which every part of our structure furnishes instances. The cutis itself is still more striking for the strength and density of its structure, which we observe particularly in dissecting this part. The scal pel must be sharp indeed to cut through it with case. This, in fact, with its horny cuticle is nature's provision against the injuries to which the important parts of the sole are exposed, and the only defence, the only sandal worn to this day by multitudes. Its structure, as shewn by removing carefully the cellular tissue from its inner surface, is composed of a number of whitish glistening fibres crossing each other in every .direction, and enclosing in their meshes portions of that granular fat which forms the layer immediately subjacent to the skin. These meshes are closer and smaller as we approach the outer surface, where the cells entirely disappear. \\len the cuticle is separated from it, the cutis exhibits a vast number of exhalent pores, the source of that profuse perspiration which is given off from this part of the feet under exercise; these are pretty equally distributed over the sole, but the great thickness of the epidermis at the heel must impede the transpiration through it to a considerable degree. The sensibility of this part of the integuments is not at all in relation to its apparent want of delicacy in structure ; no part of the body possesses a covering more acutely sensitive. The effects of pricking, of titillation, of cold or heat applied to the sole of the foot, exemplify this. Its sympathies also are as remarkable for their liveliness as for their extent. Not even the arm-pits or sides of the ribs are at all equal to it in this respect. The bladder, the urethra, the stomach and intestines, in fact almost all the mucous membranes, together with the whole voluntary system of nerves, and through them the whole system of voluntary muscles, may be said especially to sympathize with and to be influenced by this one part. Of this no one can doubt when we see the effects of sudden cold applied to it in relaxing spasm of the urethra or bowels, in checking vomiting, or in rousing the whole nervous and muscular system during fainting, &c. The effect also of hot applications of stimulants and irritants applied to this part familiarly illustrate its ex tensive sympathies. The most sensitive part of the sole is the hollow, that part where the cuticle is least dense.