The coronary grove is situated in the coronary body which is a half round fibro-cartilaginous roll, this gives some flexibility and also absorbs some concussive forces in the coronary band area, it also reduces in thickness towards the heels as does the thickness of horn.

 

The coronary corium is covered in long papillae which grow distally. This corium supplies the papillae with nutrition so the horn can be produced. From around the base of the papillae tubular horn is made which grow distally to the grounds surface.

Figure 1: Showing the coronary cushion, perioplic corium and the long papillae.

 

Tubular Horn

These grow distally in a multi layered, alternating spiral structure. This structure gives great strength, good shock absorbency and resists wear reasonably well.

 

Inter tubular horn

This grows from the germative layer of the epidermis within the coronary corium from the hollows between the papillae; it acts like cement and totally encases the tubular horn.

 

Intra tubular horn

This grows from the tip of the papillae; they act as moisture conveyers maintaining the flexibility of the horn.

 

The horn tubules are spaced further apart on the more internal area of the hoof wall becoming more closely packed towards the external part of the wall. This is due to the way the hoof transfers weight. Tubular horn resists compressive forces effectively whilst inter tubular horn is more effective dealing with tensile forces.

For more information on this please look at the bio-mechanical considerations for laminitis section of the website.

Figure 2: Cross section of the dorsal wall including the laminae and distal phalanx.

 

Laminae

 

There are 2 types of laminae: Primary and Secondary.

 

Primary Laminae

There are 2 types of primary laminae:

1. Dermal (sensitive) laminae - this is produced from the laminar corium and surrounds the parietal surface of the distal phalanx to which it is attached to via a modified periosteum. The sensitive laminae also contain a network of blood vessels which supply the insensitive laminae.

2. Epidermal (insensitive) laminae - this is produced from the coronary corium and grow distally with and at the same rate as the horny wall, it detaches and reattaches to the dermal laminae in a ratchet like motion as the horn grows down.

 

Secondary Laminae

There are about 500 to 600 primary laminae leaves which each have 100 to 200 secondary laminae leaves interlocking both the dermal and epidermal laminae together. This is known as interdigitation between the two laminae.

 

Blood Supply

 

Blood travels down the limb around the circumflex artery at the distal phalanx, up the sensitive laminae where it is fed to the laminae corium and the insensitive laminae. The blood continues proximally to the coronary band where it is fed to the papillae which produce the horn cells.

 

Figure 3: The hoof wall from a shire horse. Shire horses are well known for the quantity and quality of hoof they produce.

 

Growth of the horny wall

by

Paul Conroy BSc(Hons) AWCF &

Sam Ratcliffe Dip WCF

The wall grows from the dermis of the coronary corium, which is situated in the coronary grove on the internal proximal boarder of the hoof wall.

>Tubular Horn

>Laminae

>Blood Supply