title: Innervation of the human cricopharyngeal muscle by the recurrent laryngeal nerve and external branch of the superior laryngeal nerve.
abstract: OBJECTIVE
  The major component of the upper esophageal sphincter is the cricopharyngeal muscle (CPM). We assessed the contribution of the laryngeal nerves to motor innervation of the CPM.
  
  
  METHODS
  We performed an intraoperative electromyographic study of 27 patients. The recurrent laryngeal nerve (RLN), vagus nerve, external branch of the superior laryngeal nerve (EBSLN), and pharyngeal plexus (PP) were stimulated. Responses were evaluated by visual observation of CPM contractions and electromyographic examination via insertion of needle electrodes into the CPM.
  
  
  RESULTS
  In total, 46 CPMs (24 right, 22 left) were evaluated. PP stimulation produced both positive visual contractions and electromyographic (EMG) responses in 42 CPMs (2080 ± 1583 μV). EBSLN stimulation produced visual contractions of 28 CPMs and positive EMG responses in 35 CPMs (686 ± 630 μV). Stimulation of 45 RLNs produced visible contractions of 37 CPMs and positive EMG activity in 41 CPMs (337 ± 280 μV). Stimulation of 42 vagal nerves resulted in visible contractions of 36 CPMs and positive EMG responses in 37 CPMs (292 ± 229 μV). Motor activity was noted in 32 CPMs by both RLN and EBSLN stimulation, 9 CPMs by RLN stimulation, and 3 CPMs by EBSLN stimulation; 2 CPMs exhibited no response.
  
  
  CONCLUSIONS
  This is the first study to show that the EBSLN contributes to motor innervation of the human CPM. The RLN, EBSLN, or both of the nerves innervate the 90, 75, and 70 % of the CPMs ipsilaterally, respectively.
authors: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Department of General Surgery, Istanbul, Turkey. drmuludag@hotmail.com.
authors: Mehmet
authors: M
authors: Uludag
authors: General Surgery, Sisli Hamidiye Etfal Training and Research Hospital, Department of General Surgery, Istanbul, Turkey.
authors: Nurcihan
authors: N
authors: Aygun
authors: General Surgery, Bahcesehir University Medical Faculty, Department of General Surgery, Istanbul, Turkey.
authors: Adnan
authors: A
authors: Isgor
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D007823:Laryngeal Nerves / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D037981:Neck Dissection; D010609:Pharyngeal Muscles / Q000294:innervation*; D013959:Thyroid Diseases / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D013965:Thyroidectomy
keywords: Cricopharyngeal muscle; External branch of the superior laryngeal nerve; Pharyngeal plexus; Recurrent laryngeal nerve