A STUDY OF THE FORMATION OF THE ANSAHYPOGLOSSI AND ITS VARIATIONS / 解剖学报

ABSTRACT

The form and position of the ansa hypoglossi and the course of its com-ponents, the descending branch of the hypoglossal nerve and the communicatingbranches of the cervical nerves, were studied in 128 Chinese cadavers. It wasfound that only in half of the cases (55.7%) the ansa showed loop formationwhile in the other half the component nerves either joined each other at anacute angle or came together more gradually. The ansa may be found on thesurface of the carotid sheath or inside it. The point of union in percentageswas 48.2 half way between the mandible and the clavicle and 32.7 below thatlevel. In the majority of the cases (80.3%) the descending branch of thehypoglossal nerve ran down on the antero-lateral surface of the internal carotidartery, while in the rest it appeared in between the internal carotid artery andthe internal jugular vein.