Dress and care of the feet /

by John Lord Peck

We come now to another class of difficulties to which the foot is subject, though they affect the outside mainly, not its structure, and which appropriately call for a notice here, and for some hints concerning their nature and treatment. Almost every one, at some period in a lifetime, forms their unpleasant acquaintance; and to know how to avoid them entirely, or to destroy and remove them at pleasure, may be considered information worth possessing. Although we lack the familiar practical knowledge of the man who makes corns his profession, the reader shall have the benefit of as much as we are able to supply.

A common corn is caused by friction or irritation of the skin—the chafing and pressure of the foot against the leather of the boot, or the crowding of the toes against each other. The skin thickens and hardens to protect itself in the same way that it does upon the hands or other parts of the body exposed to rough contact, the fact and law of which are familiar to everybody. As the irritation is continued the skin continues growing harder and thicker, until a large and ugly corn is produced. To understand its nature more fully, and why it assumes a sharp point, thus turning its protection into a torture, it will be necessary to explain something more of the nature of the skin itself.

There are two layers of membrane composing the skin—the cutis vera, dermis, or true skin, which is the inner portion; and the cuticle, epidermis, or scarf-skin, which is the outside layer. The dermis, or true skin, consists mainly of a net-work or web of fibrous material, having outside of this a net-work of capillary blood-vessels and lymphatics, interwoven with still another net-work, of nerves, both blood-vessels and nerves terminating in projecting or upright loops, each loop formed of a blood-vessel and a nerve-cord, the two being together side by side. These loops, which are the most extremely sensitive portion of the skin, are called papillæ, and they form the projecting fine ridges that are seen on the palm of the hand, where their abundance gives the hand its superior sense of feeling or touch. All these parts—the fibrous meshes, the blood-vessels, nerves, and loops of papillæ—are microscopically minute.

The outside skin or cuticle has no blood-vessels or nerves, and hence no life or sensation, but seems to be a covering to protect the true skin, and to modify or diminish its otherwise too extreme sensitiveness; besides being of use in other ways to the general system. It is that part which is raised up when a blister is produced; and the sensitiveness of the papillæ under it, where it is taken off, shows its necessity. The matter of which it is formed is secreted or poured out by the true skin, and is the same matter which, when dried and hardened in various degrees, becomes the thick skin on the sole of the foot, the callous place on the hand or elsewhere, the dandruff of the head, the hair on any part of the body, the nails of fingers and toes, the hard portion of warts, and the hard or soft corn. All these are essentially the same thing under different modifications. It is constantly worn off from the external surface, and as constantly added to at the under side.

This internal or under-side layer of the cuticle is commonly distinguished as the rete mucosum, and contains a colouring matter secreted from the true skin, which, as it is greater or less in quantity gives the different shades of complexion; the semi-transparent nature of the matter outside allowing it to show through. The oil tubes and perspiratory ducts take their rise immediately under the skin, and find their way to the surface, while nerves and blood-vessels traverse it forth and back.

Some further idea of the nature of the skin may be gained by observing a piece of thick sole-leather in which that part called the grain is the cuticle or epidermis, and the thicker portion is the dermis, or cutis vera.

Now, when any portion of these sensitive loops is injuriously irritated by pressure or friction, they sometimes push entirely through the cuticle, growing large and covering themselves with hard cuticular matter, thus forming the warts that appear on the hands and other parts of the body. Some corns, we believe, are produced in a similar way—a larger number of the papillæ projecting and being covered completely and thickly with epidermis, which, becoming dry and hard, still further pains the sore and sensitive papillæ as it is pressed upon by the boot. This kind of corn can be cured only as a wart is removed—by burning the papillæ, or, as they are called in the wart, the roots; thus changing the structure of the skin, or, in other words, making a scar.

Ordinarily a hard corn commences at a point, or by the irritation of a small surface of the skin, or only a few of the papillæ. From this point an increased supply of the cuticular matter is pushed out in every direction to protect them, growing harder as the process advances, and being more pressed against by the shoe, while the increasing external pressure incites the foot to push out a still larger corn. Thus it grows; and as the matter first thrown out is the first to become hardened, a point is formed, and the pressure forces it into the flesh, which is compelled to retire before it. The longer this is continued the larger the surface of skin that is made sore, the larger and more conical in shape the corn becomes, and the farther its point is forced into the flesh.

This description is more especially true of the smaller corns; those which extend over a large surface being, probably, originated by a slighter irritation of a larger portion of the skin; hence they have less of a point and penetrate less deeply.

Soft corns appear between the toes, and are soft for the reason that, so situated, they are kept moist by perspiration. Some of them are secretions of epidermis having no centre or point, but thrown out from the foot at the bottom and sides of the spade between the toes, and giving a sensation as of some foreign body, like a pea or a gravel stone, confined there. There may be others that are accompanied by projections of the papillæ.