Coriums are the vascular tissue of the foot that provides nutrition to specific parts of the hoof and is responsible for keeping the pedal bone floating in place.
Here is a picture of the sole corium to give you an idea of how thin the actual corium is.
We tend to only think of the front (maybe the quarters sometimes) area when we talk about Laminitis and Founder, but please remember that the hoof is attached to the inner structures in all-around (see all the coriums underneath), not just in the front.
Jamie Jackson has a good point when he says that Laminitis (defined as inflammation of the laminae) happens in ALL the coriums, not just the Lamellar Corium. The notion that it is only in the Lamellar Corium stems from the P3-Rotation thinking.
Therefore, hoof slough (where the horse throws off the entire capsule…in some cases including the sole and frog), is in fact a severe case of laminitis where ALL the laminae are inflamed and let go of their connections.
There are actually five Coriums.
- The Perioplic Corium that feeds the Periople (Stratum Externa or Outer hoof wall)
- The Coronary Corium that feeds the Hoof wall (Stratum Medium or Inner hoof wall)
- The Lamellar Corium that feeds the Dermal Laminae (Stratum Internum – the leaflike connections you see in the pictures on the Laminae page)
- The Sole Corium that feeds the Sole
- The Frog Corium that feeds the Frog.
All coriums have a two-sided attachment. On the one side, it is attached to the bone and on the other side, it is attached to the outer structures which it nourishes.
Suffice to say that this is a very big topic. If you are interested in studying deeper into it, I attach a paper written by Jamie Jackson on the Coriums. You can download the pdf by clicking this link.