Anatomical variation

n (%)

Laterality left/right n(%)/n(%)

Type I (extralaryngeal divergence)

376 (11.5)

205 (13.0)/171 (10.1)

Type II (fan-shaped divergence)

234 (7.2)

61 (3.9)/173 (10.2)

Type III (laryngeal entry > 5 mm

distant to the cricothyroid joint)

37 (1.1)

25 (1.6)/12 (0.7)

Type IV (degenerated recurrent larynx nerve in the elderly)

17 (0.5)

11 (0.7)/6 (0.4)

Type V (non-recurrent larynx nerve)

15 (0.5)

0 (0.0)/15 (0.9)

Type VI (intracranial branch)

7 (0.2)

0 (0.0)/7 (0.4)

Type VII (tortuous upward-leading

recurrent larynx nerve )

4 (0.1)

3 (0.2)/1 (0.06)