The operculum is the cortical structure which forms the lid over the insular cortex, overlapping it and covering it from external view. More specifically it consists of the cortical areas adjacent to the insular lobe and its surrounding circular sulcus.
The operculum can be divided into three portions: the frontal, parietal and temporal operculum.
The frontal operculum begins at the anterior ramus of the lateral fissure and extends to the inferior portions of the precentral gyrus, encompassing the pars triangularis and opercularis of the inferior frontal gyrus. The parietal operculum is between the inferior portion of the postcentral gyrus and posterior rami of the lateral fissure. These two regions are often grouped together as the frontoparietal operculum.
Finally, the temporal operculum is inferior to the lateral fissure itself and is formed by the superior temporal and transverse temporal (Heschl's) gyri.
The function of the operculum depends primarily on the location of each of its segments. The frontal operculum rostral to the ascending ramus of the lateral fissure is associated with the pre-frontal association cortex and plays a role in thought, cognition and planning behaviour.
The frontoparietal operculum caudal to the ascending ramus is thought to contain the gustatory cortex and govern discrimination of various taste qualities. As the parietal operculum contains inferior portions of the precentral and postcentral gyrus, it also has a role in primary somatosensory and motor function.
The temporal operculum contains Heschl's gyrus which serves as the primary auditory complex. This is the termination of the afferent auditory pathway after receiving fibres from the medial geniculate nucleus.
History and etymology
Operculum is the Latin word meaning lid or cover.
After dissection of Albert Einstein's brain, there are claims that it was missing parietal opercula bilaterally allowing his inferior parietal lobe to grow 15% wider than normal. It was thought that this could explain his great mathematical and scientific abilities. However, the debate regarding the legitimacy of these variations continue.
- 1. Martin, J. (2003). Neuroanatomy: Text and Atlas, McGraw-Hill Companies Incorporated.
- 2. Standring, S. and N. R. Borley (2008). Gray's Anatomy: The Anatomical Basis of Clinical Practice, Churchill Livingstone/Elsevier.