RESUMO
Background: Vertebral artery is a medium sized artery which has long, tortuous course through neck and cranium.It is highly protected by bony and muscular structures because it provides the vascularization to importantintracranial structures. During cervical spine movements, it is exposed to large shear and tensile forces at theexit from second cervical vertebra. A reduction in blood flow in vertebral artery may occur due to many congenitaland structural factors which will cause ischemia and various neurological symptoms. Vertebral artery tearsafter blows to the head and neck are usually associated with basal subarachnoid haemorrhage with a rapidlyfatal outcome. Aim of study was to study histomorphometric variations in four segments of vertebral artery.Material and methods: All four segments of vertebral arteries each having 0.5 cm long of both sides werecollected from 30 cadavers. Outer and inner diameters were measured. Tissues were processed and stained byVerhoeff’s Van Geison and Masson Trichrome. Slides were scanned by “IS capture software” under 10 Xmagnifications.Results: Outer diameter of left vertebral artery was 3.598± 0.32mm and that of right was 3.286± 0.33mm. Innerdiameter of left vertebral artery was 3.19± 0.30 mm and right was 2.86± 0.26mm. Diameter of 1st and 3rd part ofvertebral artery was more than 2nd and 4th part. Internal elastic lamina was thick and prominent in 4th part.External elastic membrane was prominent in 1st, 2nd, and 3rd part, but it is completely absent or represented bysparse fibrils in 4th part of vertebral artery.Conclusion: Left vertebral artery was found to be dominant than the right.Internal elastic lamina was mainelastic constituent of 4th part of vertebral artery, so damage to it may cause vascular pathologies likeatherosclerosis, aneurysm etc.