(Folia Morphol 2014; 73, 1: 30-36)

This study aimed to examine the incidence and contribution to the innervation of the larynx from Galen's "Anastomosis" (GA), which is the direct connection between the dorsal branches of the internal laryngeal nerve (ILN) and the recurrent laryngeal nerve (RLN). Fifty adult laryngeal specimens were micro-dissected. The diameter of the ILN and RLN were measured immediately after each had given off their muscular branches to form GA. The incidence of GA was 81%. The average diameter of the ILN after giving off muscular branches to form GA was 1.28 mm (right) and 1.27 mm (left) while the average diameter of the RLN after giving off muscular branches to form GA was 0.65 mm (right) and 0.68 mm (left). The weighted mean incidence of GA (77.3%) calculated from a review of the literature concurred with the present finding of 81%. The ILN and RLN supplied the laryngeal musculature. According to the results obtained; it appears that the ILN may provide a greater contribution to the connection between the ILN and RLN as the morphometric contribution from the ILN was larger in comparison to the RLN. In addition, the authors propose a suitable term viz. the "communicating branch" as opposed to the commonly used misnomer GA to describe the connection between the dorsal branch of the RLN and the ILN, based on the definition that an "Anastomosis" refers to blood vessels and that a single connection exists between the dorsal branch of the RLN and ILN.

Purpose The anterior ethmoidal artery is a major surgical landmark that is susceptible to iatrogenic injury during surgery of the anterior ethmoidal sinus, frontal sinus, and skull base. The present study aimed to define the location of the anterior ethmoidal artery in relation to specific anatomical landmarks using radiological imaging and endoscopic dissection. Methods Eighty-six anterior ethmoidal arteries were assessed using computed tomography scans (bilateral analyses) and forty anterior ethmoidal arteries were assessed using cadaveric specimens (bilateral analyses). The skull base, anterior nasal spine, anterior axilla of the middle turbinate, and nasal axilla were morphometrically analysed to determine their reliability as anterior ethmoidal artery landmarks. Results Distances to the skull base, anterior nasal spine, and nasal axilla displayed statistically significant differences between sexes and sides (p < 0.05). All landmarks demonstrated excellent reliability as anatomical landmarks for the localisation of the anterior ethmoidal artery, radiologically and endoscopically (ICC values ranged from 0.94 to 0.99). Conclusion The middle turbinate axilla was the most reliable landmark, due to the lack of statistically significant differences according to sex and laterality, and the high inter-rater agreement between measurements. Anatomical knowledge of variations and relationships observed in the present study can be applied to surgeries of the anterior ethmoidal sinus, frontal sinus, and skull base to improve localisation of the anterior ethmoidal artery, preoperatively and intraoperatively, and avoid iatrogenic injury of the vessel.

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