ObjectiveTo master the morphological characteristics of the recurrent laryngeal nerve (RLN) and extra-laryngeal branching (ELB) in dogs, and to provide an anatomical basis for the establishment of an animal model of injury to the ELB in dogs as well as for functional studies. MethodsSix adult healthy Beagles were selected, completely dissected the thyroid gland, the full length of the cervical segment of the RLN and the ELB. Then, the location, size and morphology of the thyroid gland and the morphological features of the RLN and ELB were observed. The length of the RLN and its ELB were measured. The incidence and number of ELB and their relationship with trachea, esophagus and peripheral blood vessels were recorded. ResultsSix Beagles (12 sides) all had ELB. In 9 sides the main trunk of the RLN divided into internal and external branches on its way up into the larynx and converged before them entering the larynx. The total number of ELB was 48, and the number of branches on each side were ranging from 1 to 7. There were 38 ELB were located below the lowest level of the thyroid gland. ConclusionsThe Beagles included in this study all have ELB. The ELB were widely distributed in the cervical trachea and esophagus after branching from the internal branch of RLN. It is speculated that the ELB may be involved in the function of the cervical esophagus and trachea. In thyroid surgery, the tracheal branch and esophageal branch of the ELB should be preserved as much as possible.
