A callus crash course…

Have you ever had a thick patch of skin in the palm of your hand after lifting weights for a day at the jump or after trying to do some pull-ups? The first time this develops is after stress and it may mimic an injury with pain and peeling of the skin. But this is actually the start of the callus formation, more like a trigger. But the difference is that this is not a one time trigger and the trigger has to be constant for the callus to take shape and form. Lets take a look at foot callus…

foot callus


A foot callus basically is an area of thickened skin. This area mainly consists of an accumulation or increase in the amount of dead skin cells, that, in the normal counterpart usually shed off from the surface.

So, a person who keeps going to the gym and lifting weights will find the skin at the base of his fingers thickened and hardened, basically much more tough and strong as compared to the surrounding areas. This is a callus or a callosity.

The same principle is the one that applies to the development of most callosities, however, there can be more specific causes. A constant pressure beyond the normal limits constantly applied to an area that will finally result in the thickening of the skin and a callus.

When it comes to our area, the foot…we have to consider the fact our feet are actually supporting our body as we walk or stand, which is why the sole of our feet is generally thicker compared to other areas.

But in certain instances when this is not enough or when due to some anatomic abnormality or other causes such as improper footwear, there is constant increased pressure or friction then this leads to the thickening of the skin.

foot callus

Scientifically seeing, our skin is made up of minute cells that are packed together and held by means of intercellular bonds, but this is constantly replenishing. The bottom-most layer of cells gradually move to the top and then die and are finally shed off.

And the thickening that we are referring to here is nothing but these cells accumulating and not shedding off as they normally should. This can also be considered as a protective mechanism of the body to protect the underlying delicate soft tissues from the increased amount of forces that are being applied there.

Callus treatment is most commonly the removal of the dead skin by products that are commercially available. But this is not the full treatment. A callus must always be controlled at the cause. Only if the cause is identified and negated the callus will not keep recurring. Or else you the callus will keep forming and you will keep removing it in a vicious cycle.

But why are they there? Why do foot calluses form?

First, let us look at one of the functions of the skin.

The human body has loads of defense mechanisms against harmful agents in the environment, one of them being the skin. The skin is a physical barrier. Imagine your body without its skin, the outer covering. All the inner important organs in the body would just be exposed to the environment. The bacteria would have an all you could eat buffet!!

But another important defense mechanism or function of the skin is the resistance it provides against external forces, pressures, and stresses.

foot callus

The callus or more specifically here, the foot callus, is an adaptation to the increased stresses or forces that act from outside. On long-term application of an increased or higher than normal pressure on a particular area of the foot signals the body that this area requires more defense or a kind of cushioning effect to prevent any injury to internal structures.

Hence, the body has this adaptive mechanism to increase the amount of skin in this area to provide the necessary defense against these forces to withstand them. Thus resulting in the formation of a callus on the foot.

The same when it comes to the surface of the foot that faces the floor or the sole of the foot, this kind of callus is referred to as a plantar callus.


So how does callus formation take place?

The epidermis or the outermost layer of the skin consists of five layers: (From down upwards)

  1. Stratum Basale
  2. Stratum Spinosum
  3. Stratum Corneum
  4. Stratum Lucidum
  5. Stratum Corneum

foot callus

The stratum corneum is the layer that consists of dead cells that provide a good deal of resistance to outside forces.

In microscopic studies, it has been found that foot calluses formed due to various reasons mainly consist of an increase in the thickness of the stratum  corneum.

The increased force in a particular area seems to jam pack the cells of the epidermis together and thus also prevent the normal shedding off of cells that takes place at regular intervals.

Thus an increase in the thickness or the number of dead cells forms, namely the stratum corneum. And hence a callus is formed.

This callus area is referred to as hyperkeratosis and can also be seen as an additional feature in many conditions such as leukoplakia, etc.

Next up : How to identify a callus

Leave a Comment