Grossly simplified, tubular horn consists of tightly coiled strands of a special protein, keratin. Inside the horn tubes, there is a more loosely bound horn tissue, the intratubular horn. The horn tissue that runs between the horn tubes is called the intertubular horn. The horn is organized like a meshwork, where the horn tubuli grow from the coronary band and towards the distal tip of the hoof, and provides stability in this growth direction. The intertubular horn grows between the tubuli and provides stability in the depth of the hoof, that is from outside to inside. This arrangement of longitudinal and transversal growing horn gives the hoof great stability and flexibility to withstand the strains on the horn tissue when the horse is in motion.

It is also important to understand that this architecture allows the kinetic energy that arises when the hoof impacts on the ground during motion to effectively dissipate into this resistant tissue before the energy wave reaches the very sensitive lamellae close to the hoof wall. More than 90% of the energy generated by hoof impact is filtered away before reaching the lamellae – so in actual terms the meshwork of different types of horn provides optimal protection for the vulnerable lamellae where they fuse with the corium of the pedal bone. 

Looking at the figure below here, you will see that a transversal section of the hoof wall you may see that the number of horn tubes is at its highest at the external end of the hoof wall, and that gradually the number decreases  - in three distinct layers – as they approach the lamellae.  
 

This is another example of Nature’s fantastic engineering capacity; the external wall of the hoof is hard in order to resist direct trauma, but gradually becomes softer as it approaches the sensitive laminae, in order to facilitate and effectively dissipate the kintetic energy generated by the micro-movements in the hoof tissue.