Eur J Anat, 17 (1): 53-58 (2013)

Near complete tracheal rings in an adult male cadaver associated with variation in V2 and V3 segments of vertebral artery

Lakshmi T. Anantharaman¹, Jagdish Chaturvedi², Anne DSouza¹, Nachiket Shankar¹, Roopa Ravindranath¹, Ravi C. Nair²

¹Department of Anatomy, St. Johnâ??s Medical College, Bangalore, India, ²Department of ENT, St. Johnâ??s Medical College, Bangalore, India

ABSTRACT During routine dissection in an adult male cadaver, the presence of long segment nearcomplete tracheal rings associated with variation in the second (V2) of right vertebral artery (VA) and third (V3) segments of the left VA was encountered. This case report highlights the normal lifespan of an individual despite anatomical variations that are reported to be incompatible with life.Congenital complete and near-complete tracheal rings are extremely rare tracheal deformities, and long-segment occurrences of these variations are usually incompatible with life. They are reported to be associated with cervical chondrogenic anomalies and craniosynostotic syndromes.In the same cadaver the left VA entered the foramen transversarium (FT) of C6 vertebra and exited through the FT of the axis. It formed a loop below the arch of atlas and entered the vertebral canal between the atlas and axis, completely bypassing the FT of the atlas. A branch from the loop divided into two branches, one of which supplied the dorsal ramus of C1, the other ending in the surrounding neck musculature. The right VA was normal, except that it entered the FT of C5 vertebra bypassing C6 vertebra. It was noted that the calibre of the VA on the left side was considerably more than that on the right. Variations in the vertebrobasilar system have a potential clinical impact, since they are the feed arteries of the brain.

Keywords: Near complete tracheal rings, Vertebral artery, Foramen tranversarium, Atlas vertebra, Tortuosity