Posterior atlanto-occipital and atlanto-axial area and its surgical interest.

UNLABELLED Classic anatomical studies describe two membranes - atlanto-occipital and atlanto-axial in the posterior aspect of the craniocervical region. During many surgical procedures in this area, however, we have not found such membranes. OBJECTIVE To clarify the anatomical aspects and structures taking part of the posterior atlanto-occipital and atlanto-axial area. METHOD Analysis of histological cuts of three human fetuses and anatomical studies of 8 adult human cadavers. RESULTS In both atlanto-occipital and atlanto-axial areas, we have observed attachment between suboccipital deep muscles and the spinal cervical dura. However, anatomical description of such attachments could not be found in textbooks of anatomy. CONCLUSION Our study shows the absence of the classical atlanto-occipital and atlanto-axial membranes; the occipito-C1 and C1-C2 posterior intervals are an open area, allowing aponeurotic attachment among cervical dura mater and posterior cervical muscles.