RT Journal Article T1 Origin, communication and course of the vagus nerve auricular branch with special references to the mastoid canaliculus for the nerve: A study using human fetus histological sections A1 Rodríguez Vázquez, José Francisco A1 Verdugo López, Samuel A1 Kim, Ji Hyun A1 Hirano-Kawamoto, Ai A1 Murakami, Gen A1 Yamamoto, Masahito AB BackgroundThe vagus nerve auricular branch (Xab) is a well-known sensory nerve and it communicates with the facial and glossopharyngeal nerves. Xab passes through the so-called mastoid canaliculus of the temporal bone (TB) to reach the facial nerve. We aimed to examine the nerve origin, communication and course of Xab as well as bone components along the nerve.MethodsWe observed serial histological sections of 13 embryos (6–8 weeks of gestation) and 31 midterm fetuses (9–17 weeks) as well as semiserial sections of 11 late-term fetuses (25–32 weeks).ResultsThe initial Xab originated from both the glossopharyngeal and vagus nerves and these two roots were joined at six weeks. Soon later, Xab ran laterally along the anteromedial aspect of the internal jugular vein to reach the facial nerve. Communication with the sympathetic trunk appeared by nine weeks. By 12 weeks, variations became evident in the nerve course, communication and terminal. A microganglion sometimes accompanied Xab. The early Xab ran through a relatively large space between the future occipital condyle and Reichert’s cartilage. Depending on a delayed growth of the otic capsule precondylar process, the nerve became to pass through a narrow space between the otic capsule (or Rechert’s cartilage) and occipital. At late-term, Xab passed through a canaliculus between the occipital and TB or within the TB.ConclusionsXab had two roots, ran along the anterior wall of the bony jugular fossa and, penetrated the TB or passed between the occipital and TB to reach the facial nerve descending portion. PB Elsevier SN 0940-9602 YR 2025 FD 2025-04 LK https://hdl.handle.net/20.500.14352/120940 UL https://hdl.handle.net/20.500.14352/120940 LA eng NO Rodríguez-Vázquez JF, Verdugo-López S, Kim JH, Hirano-Kawamoto A, Murakami G, Yamamoto M. Origin, communication and course of the vagus nerve auricular branch with special references to the mastoid canaliculus for the nerve: A study using human fetus histological sections. Ann Anat. 2025 Apr;259:152389. doi: 10.1016/j.aanat.2025.152389 DS Docta Complutense RD 24 dic 2025