Occipital lobe morphological anatomy: anatomical and surgical aspects

BACKGROUND: The occipital lobe is an important region of the central nervous system and site of a wide variety of lesions. Different from others regions of the brain, whose anatomy has been already meticulously detailed, controversies about occipital lobe morphology can occasionally hinder the surgical approaches to it. METHOD: Twenty-six hemispheres were dissected, examining the distances of the medial structures of the posterior interhemispheric fissure region; identifying the sulci and gyri more frequently found in the lateral surface; and detailing the anatomy of the occipital horn of the lateral ventricle. Also, anatomical details of structures such as the calcarine sulcus and preoccipital notch were evaluated. RESULTS: Twenty-four hemispheres (92%) showed sulci with evident transverse trajectories in the lateral surface, and it was possible to identify marked longitudinal sulci in 16 (61%). All of the specimen presented a transverse sulcus in the inferior third of the lobe - labeled in this paper as Inferior Transverse Occipital - and 69% of the cases showed a transverse sulcus in the superior third - labeled as Superior Transverse Occipital. The occipital horn was present in 53% of the cases at level of the anterior boundary of the lobe. It was a half moon shaped cavity, whose the medial wall was formed by the calcar avis and the lateral wall, roof and floor formed by fibers of the tapetum. CONCLUSION: The occipital lobe presents parameters that are often recognized in most of the dissected brain and can be useful for the planning and performance of surgery in this area of the brain.