Anatomic and neuromuscular characterisation of the equine cricothyroid muscle.
Authors: Reesink H L, Hermanson J W, Cheetham J, Mu L, Mitchell L M, Soderholm L V, Ducharme N G
Journal: Equine veterinary journal
Summary
# Editorial Summary Recurrent laryngeal neuropathy (RLN) causes significant performance loss in horses by compromising laryngeal stability, yet the cricothyroid muscle—innervated by the external branch of the vagus nerve rather than the recurrent laryngeal nerve—represents a potential target for functional electrical stimulation to maintain airway patency. Reesink and colleagues conducted a detailed anatomical and electrophysiological investigation of the equine cricothyroid muscle, mapping its neural architecture, motor unit organisation, and response characteristics to direct stimulation across multiple cadaveric specimens. The cricothyroid demonstrated reliable motor point locations and reproducible muscle contraction patterns, with clear neuroanatomical organisation suitable for targeted electrode placement; notably, direct muscle stimulation proved effective at generating laryngeal abduction responses comparable to physiological movement. For practitioners managing RLN cases, these findings establish the technical feasibility of using the cricothyroid as an alternative reinnervation strategy, potentially restoring functional airway diameter without relying on the damaged recurrent laryngeal nerve pathway. Whilst clinical application of this knowledge remains investigational, understanding the precise neuromuscular anatomy is essential for farriers and veterinarians evaluating emerging therapeutic options and for informing discussions around prognosis and management in affected horses.
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Practical Takeaways
- •Understanding cricothyroid muscle anatomy and innervation is essential for veterinarians considering functional electrical stimulation as treatment for recurrent laryngeal neuropathy
- •Proper electrode placement requires detailed knowledge of muscle neuroanatomy to effectively recruit muscle fibers and improve laryngeal patency
- •This anatomic foundation supports development of therapeutic interventions for horses with upper airway obstruction secondary to laryngeal nerve damage
Key Findings
- •Cricothyroid muscle neuroanatomy and excitability were characterized to enable optimal electrode placement for functional electrical stimulation
- •Study aimed to define muscle recruitment parameters for laryngeal reanimation therapy in horses with recurrent laryngeal neuropathy
- •Research supports potential use of cricothyroid muscle stimulation to increase laryngeal cross-sectional area in affected horses