Anatomical observation on relationship of the second segment of vertebral artery (V2) with its surrounding structures

Objective To explicit the anatomical mechanism of extracerebral vertebral artery insufficiency on the basis of studying the relationship of the second segment of vertebral artery (V2) with its surrounding structures.Methods Twenty preserved head neck specimens were used to observe V2 and its relation to surrounding structures macroscopically.Among them,seventeen were made into dry cervical vertebrae including C3 C7.and transverse foramens were measured.Another two fresh cadavers were used to observe the surrounding structures of vertebral artery microscopically.Results The fibrous sheath like structures derived from periosteal tissues of cervical vertebra,transverse process and uncus process were observed to enwrap vertebral artery,vein and spinal nerve root.The V2 vertebral artery was fixed by the fibrous tissue connecting vertebral artery adventitia to uncus.No obvious transverse foramen narrowing was found during this specimen observation.Conclusion The vertebral artery is fixed and tethered by its surrounding structures including bony and soft tissues.The vertebral artery is susceptible to be affected in case of cervical motion or instability.The tethering mechanism of vertebral artery may play an important role in the etiology of vertebral artery insufficiency.