SOME ABNORMALITIES OF THE VERTEBRAL ARTERY » 



By Miguel Can iz ares 

 Of the Department of Anatomy, University of the Philippines, Manila 



ONE PLATE AND FIVE TEXT FIGURES 



The considerable number of marked abnormalities of the ver- 

 tebral artery met with in the department of anatomy in the 

 course of our dissections there within the last two years, and 

 their apparent practical importance and embryological signifi- 

 cance, suggested the preparation of this report on the subject. 



The observations were made on forty cadavers used in the 

 dissecting rooms of the College of Medicine and Surgery, Uni- 

 versity of the Philippines. The cases were numbered from 1 

 to 40. 



It is well known that the vertebral artery is one of the largest 

 and most constant branches of the first portion of the subclavian, 

 and that it has a different origin on each side. On the right 

 side the artery arises from the subclavian about 2 centimeters 

 from the origin of the latter from the innominate. On the left 

 side, it arises from the most prominent part of the arch of the 

 subclavian, close to the medial edge of the scalenus anterior 

 muscle. On both sides it first ascends to the foramen transversa- 

 rium of the sixth cervical vertebra and, having passed that fora- 

 men and the foramina of the succeeding cervical vertebrae as high 

 as the epistropheus, it turns laterally and ascends to the foramen 

 of the transverse process of the atlas. From that point it turns 

 backward behind the articular process and, after piercing the 

 posterior occipito-atlantoid membrane and the dura mater, enters 

 the cranium through the foramen magnum. Both vertebral ar- 

 teries terminate at the lower portion of the pons varolii by 

 anastomosing to form the basilar artery. 



While numerous observations on variations in the entrance 

 of the vertebral artery to the foramen transversarium have been 

 recorded, only a few reports on the abnormalities of its origin 

 have been found by me. 



Bean, (2) in one hundred twenty-nine cases studied, found only 



1 Read before the IV Asamblea Regional de Medicos y Farmaceuticos 

 de Filipinas, February 5, 1918. 



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