Ponticulus posticus incidence in Brazilian Atlas vertebrae: a cadaveric study

ABSTRACT

The suboccipital segment of the vertebral artery (VA) passes around the lateral mass of atlas (C1). It is located in a groove on the superior surface of the arch of C1, the so-called vertebral artery sulcus (VAS). Occasionally, a small bony arch is found to connect the retroglenoid tubercle with the posterior arch of C1. This anatomical structure is known as ponticulus posticus (PP). The partial or total incidence of PP reported in the literature ranges from 5.14 percent to 51 percent. The clinical implication of PP includes the cervicogenic migraine, vertigo, and the Barre-Lieou syndrome. The scope of this paper is to determine the incidence of PP in isolated cadaveric vertebrae in the Brazilian population. The cervical vertebrae C1 from thirty not identified adult cadavers were examined at the Laboratory of Anatomy of the Federal University of Sergipe, Brazil. PP was present in 40 percent of evaluated C1 and it involved a complete bony arch in 42 percent of the cases. In 58 percent of the cases, PP was observed bilaterally. In the cases where the presence of PP was unilateral, this structure was situated exclusively on the right, even though a bigger incidence on the left side has been described for the majority of right-handed people. PP was a frequent finding in our study and its presence always must be suspected while setting the diagnosis of cervicogenic chronic headache and cervical pain without radiation to upper limbs.