Histological study of the innervation of the suspensory ligament of the forelimb of the horse.

The research article examines the nerve supply to the suspensory ligament of the horse’s forelimb, revealing that a typical ulnar nerve block would not fully numb this ligament.

Overview of the Study

• The study looked at the innervation, or nerve supply, of the interosseus muscle of the forelimb in four equine subjects – two ponies and two horses.
• The researchers investigated the nerve supply specifically in the suspensory ligament – a band of fibrous tissue that supports the digit in ungulates, which includes horses and ponies.
• This investigation was carried out through histological examinations, a microscopic study of tissue structure, following neurectomy (surgical removal or destruction of a nerve) of the ulnar and median nerve branches near the carpal joint.

Key Findings

• The findings revealed that the interosseus muscle is primarily innervated by the deep branch of the lateral palmar nerve, which emerges around the midcarpal region.
• This deep branch of the lateral palmar nerve receives fibres from both the ulnar and median nerves.
• This suggests a more complex nerve supply to the interosseus muscle than perhaps previously thought.

Implications of the Research

• The main implication from these findings is that a traditional ulnar nerve block – that is, an anaesthetic procedure to numb the area by blocking the ulnar nerve – administered near the accessory bone, would not adequately anaesthetise the entire suspensory ligament.
• This is because the suspensory ligament also receives innervation from the median nerve.
• Therefore, when dealing with procedures that require the anaesthetisation of the suspensory ligament, such as certain surgical interventions, alternative or additional methods may be necessary to give full analgesia.