Abstract: Objective    To observe the morphological characteristics of the communicating branches between accessory nerve, vagus nerve, and cervical nerve roots, as well as the adjacent position of accessory nerve at the jugular foramen.    Methods   The specimens of head and neck were dissected to observe the adjacent structures in the jugular foremen, the communicating branches between accessory nerve and vagus nerve below the jugular foramen, and the communicating branches between the spinal root of accessory nerve and the cervical nerve root.    Results    The area of the left vagal tract was (6.99±0.74) mm2, and the area of the right vagal tract was (5.02±0.37) mm2 at the jugular foramen, with significant difference statistically (P<0.05). Under the jugular foramen, 29 sides (76.3%) had communicating branches between the vagus nerve and accessory nerve. There were four types of communicating branches, with the length of the left communicating branch was (5.82±1.18) mm and the length of the right communicating branch was (6.60±1.17) mm. There was no statistical difference between the left and right sides. There were 17 sides (77.27%, 17/22) to be observed to have communicating branches between the spinal root of accessory nerve and the posterior branch of the cervical nerve (C1 and C2).    Conclusions    Accessory nerve and vagus nerve have communicating branches below the jugular foramen, which provides anatomical basis for avoiding damage to accessory nerve in clinical practice. The presence of communicating branches between accessory nerve and the posterior root of the cervical nerve indicates that accessory nerve contains sensory fibers, which may originate from posterior root of cervical nerve, and its function may be related to the maintenance of the head posture.

Key words: Accessory nerve; ,  , Jugular foremen; ,  , Vagus nerve; ,  , Cervical nerve