THe characteristics and the topographic anatomy of the extracranial part of the vertebral artery; its importance in anterior and antero-lateral cervical surgery approaches

2. SUMMARY The Characteristics and the Topographic Anatomy of the Extracranial Part of the Vertebral Artery; Its Importance in Anterior and Anterolateral Cervical Surgery Approaches. Mustafa GÜVENÇER In this study, the extracranial part of the vertebral artery (VA), its relation with the surrounding anatomic structures and its characteristics, in terms of anterior and anterolateral approaches, were evaluated directly and morphometrically with radiographic method. On 24 cadavers, direct measurements and evaluations were done. On 12 of these cadavers which were decapitated, the VA's were filled with silicone+barium sulphade mixture and angiographic examination was done in order to provide a better evaluation of the V2 segment of the VA that was in the bone channel. Morphometric measurements were done related with the surrounding bone structures of the V2 segment. The distances between the VA and the structures such as the proc. uncinatus, the midline of the vertebral body and medial side of the longus colli muscle that provide orientation and form security border for surgical interventions were measured at the C2- C7 vertebra levels. The distance between the medial side of the longus colli muscle and the medial side of the VA was measured at the C3 vertebral body level as 10.36±2.65 mm., at the C4 as 9.38±1.90 mm., at the C5 as 9.21±2.59 mm., at the C6 as 12.29±3.74 mm. on the average. The distance between the VA and the vertebral body was measured at the C2 as 16.15±4.66 mm., at the C3 as 14.80±4.06 mm., at the C4 as 15.26±2.99 mm., at the C5 as 16.03±3.38 mm., at the C6 as 17.19 ±4.09 mm. The angle between the medial side of the vertebra corpus and the VA axis was measured at three levels: 1 -Between the origin and the transverse foramen (the V1 segment), 2- At the C3-C6 vertebral level. 3-At the C2-C3 vertebral level. These values were 26.20±5.53°, 3.13±1.86°, and 11.33±6.58° respectively. The distances between the V1 segment and the surrounding neurovascular structures such as the n.phrenicus, the truncus symphaticus, the ganglion stellata, 2