SUMMARY:The recognition of emissary foramens is important not only for understanding the regional neurovascular anatomy, but also to distinguish normal from potentially abnormal structures. Thus, the aim of this study was to review the literature on anatomical and clinical aspects of the mastoid, parietal and sphenoid emissary foramens. It was found that the emissary foramen presents importance in clinical practice because it acts as a route of spread of extracranial infection to the intracranial structures and also possible complications in neurosurgery, due to its influence in the performance of techniques such as radiofrequency rhizotomy for treatment of trigeminal neuralgia. The anatomical knowledge of the emissary foramens is important due to variability in their incidence in the human skull and its relation to the dura mater sinuses. KEYWORDS: Emissary foramens 288less studied by clinical, needs a through approach to avoid interpretation errors during procedures in neurosurgery and clinical dentistry (Sicher & DuBrul, 1977;Gupta et al., 2005;Louis Jr. et al., 2009;Rossi et al., 2010).Considering the importance of knowing the implications of the anatomical variations of the human skull can generate during clinical procedures, the aim of this study was to review the literature on anatomical and clinical aspects of the mastoid, parietal and sphenoid emissary foramens. Literature ReviewMastoid Foramen. The emissary mastoid foramen is located at the mastoid portion of the temporal bone, near to occipitomastoid suture (Fig. 1). This foramen can also appear on the occipitomastoid suture and, if present, transmits an emissary vein to sigmoid sinus. It can occur in single or multiple (Sicher & DuBrul).The mastoid emissary vein may act as another route of spread of infection or tumors originated in the face and infratemporal fossa (Sicher & DuBrul).In addition, the mastoid foramen is considered an anatomical landmark that helps in the differentiation of species and, thus, was verified their importance in forensic anthropology (Reis et al.). It is believed that the adaptation of a bipedal hominid position was associated with anatomical and physiological changes in the venous system of the skull base to adapt to the concomitant changes in intracranial venous blood flow. The pattern of venous drainage of the Australopithecus was based on the occipital vein. In homo sapiens, the volume of this drainage was reduced occurring, thus, the development of new veins. Among these new veins, the emissary mastoid vein led to the emergence of the mastoid foramen in the modern human skull (Falk, 1986).These evolutionary changes have shown that the sigmoid sinus drains into the vertebral venous plexus when is in the upright position and drains into the internal jugular vein when is in the supine position (Goucha et al., 2002). Boyd (1930) found an incidence of 68% of the mastoid foramen in a sample of 1478 skulls of modern human, while Falk obtained a 90% incidence in a sample of 51 skulls of early human. Reis et al., found an inci...