The innervation of the posterior cricoarytenoid muscle: exploring clinical possibilities.

Manipulation of the nerve supply to the posterior cricoarytenoid (PCA) muscle has potential for ameliorating the symptoms of some neurologic conditions such as abductor spasmodic dysphonia. The anatomy of the nerve supply to the PCA is better understood than in previous eras, but the anatomical understanding has not translated to clinical application yet. Microscopic dissection allowed the identification and measurement of the branches from the recurrent laryngeal nerves (RLNs) to the PCA in 43 human cadaver larynges. The cricothyroid (CT) joint was the primary landmark for measurement. Other structural measurements were also made on the larynges. All of the PCA muscles received innervation from the anterior division of the RLN. The number of direct branches from the RLN ranged from 1 to 5 (average 2.3) More than 70% of PCA muscles also received 1-3 branches off of the branch to the interarytenoid (IA) muscle. Less than half of PCA muscles received any kind of nerve branches from the posterior division of the RLN. Branches to the PCA most commonly departed the main RLN in its vertical segment and all entered the muscle from its deep surface. All branches departed the RLN within an average of 9.5mm from the CT joint; the branch to the IA occurs distal to this point. The innervation to the PCA is complex and redundant, and the segment of the RLN supplying those branches is difficult to expose safely. For these reasons, selective denervation or reinnervation procedures limited to the nerve branches may be technically difficult. When needing only to denervate the PCA, this can be accomplished by removing a portion of the PCA and the underlying nerve supply. Surgical technique should be based upon the understanding of the anatomy of the PCA muscle and its nerve supply.