THE DIAGNOSTIC NERVE BLOCK OF THE SESAMOIDEAN NERVE - DESENSITIZED STRUCTURES AND POSSIBLE CLINICAL-APPLICATIONS

The sesamoidean nerve branches from the palmar nerve and runs towards the proximal sesamoid bone, To study the structures innervated by this nerve, a technique for blocking it was developed, The effect of this nerve block was determined in ponies with an induced lameness located ip the lateral proximal sesamoid bone (5 ponies) or in the distal part of the lateral branch of the suspensory ligament (5 ponies), and in 1 0 horses with clinical sesamoidosis. A lameness provoked by the implan tation of an expansion plug in the proximal sesamoid bone could, to a large extent, be anaesthetized by a sesamoidean nerve block, However, lameness due to a local tendonitis in the lateral branch of the suspen sory ligament, was only partially eliminated by a sesamoidean nerve bl ock In horses with sesamoidosis the lameness improved, on average, by about 30%, It is concluded that the sesamoidean nerve contains sensory fibres that innervate the proximal sesamoid bone, The sesamoidean ner ve block is highly specific for pain originating from the proximal ses amoid bone including the adjacent distal part of the extensor branch o f the suspensory ligament, In horses suffering from sesamoidosis the m ain source of pain appears not to be located in the proximal sesamoid bone. The specificity of the sesamoidean nerve block makes it a useful technique for differentiating the site of a lameness located in the f etlock area.