HIPPOCAMPUS ANATOMY GYRI FULL

Removing the вЂњlittle lidвЂќ would expose the underlying insular gyri ( в–¶ Fig. Accordingly, the three segments are called the frontal operculum, temporal operculum, and frontoparietal operculum. The three segments of the frontal, parietal, and temporal lobes that cover the insula make up the operculum (Latin: вЂњlittle lidвЂќ). Not visible on the lateral surface is the insula, which consists of three short and two long gyri, predominantly vertically directed (insular gyri, в–¶ Fig. By contrast, the frontal and temporal lobes are clearly separated from each other by the large sylvian fissure.

An imaginary curved line drawn upward and backward from a small notch at the inferior edge of the inferior temporal gyrus, the temporo-occipital incisure, will roughly define the boundary of the occipital lobe. It is more difficult to locate the boundary between the occipital and temporal lobes on the lateral cerebral surface because they are not separated by a sulcus. The boundary between the occipital lobe and parietal lobe is clearly marked by the parieto-occipital sulcus ( в–¶ Fig. Thus, the precentral gyrus is part of the frontal lobe while the postcentral gyrus is part of the parietal lobe. The central sulcus, for example, divides the frontal lobe from the parietal lobe ( в–¶ Fig. Most of the cerebral lobes are delineated by sulci. The cerebrum is subdivided into the following lobes: We shall also explore the anatomy of the 12 pairs of cranial nerves and anatomic variants without pathologic significance, relying mainly on standard MRI sequences-mostly T1-weighted (T1w) images-owing to their importance in routine clinical imaging. We shall describe landmarks and key structures that facilitate orientation in the superficial and deep regions of the brain. This chapter is intended to aid in that process. The outstanding ability of MRI to reveal structural details obliges the radiologist to be at least as good as the technology and to name and classify all brain structures that are visible on the images and can be identified by their location. The accurate localization of a lesion is the first step on the road to diagnosis. The precise description of a lesion must be accompanied by accurate localization, which often opens the way to making a diagnosis and determining the functional significance of a lesion and the best surgical approach. We do not need radiologists to tell us that MRI shows вЂњa massвЂќ or вЂњa hemorrhageвЂќ located вЂњin the region of the posterior cranial fossa,вЂќ for example. Radiologists whose oral or written report shows that they are not thoroughly familiar with the region that they are describing and evaluating for pathologic changes do not really justify their existence as a profession. Findings that are cloaked in generalities with frequent use of the word вЂњregionвЂќ will not be taken seriously by the referring neurologist, and rightly so. With magnetic resonance imaging (MRI), this difficulty is compounded by the fact that different sequences produce different tissue contrast, and the selection of the imaging plane is a key factor in determining whether or not an anatomic structure or lesion can be localized.Д«ut that is precisely what is expected of radiologists. This makes it difficult to appreciate the three-dimensional anatomy of brain structures on sectional images. Usually they are visible only in a sectional view, occasionally appearing at multiple sites within the same image.

HIPPOCAMPUS ANATOMY GYRI FULL

When these structures are examined using a sectional imaging modality, they are rarely shown to their full extent. The interior of the brain is composed of structures with a high cellular density (gray matter) in addition to structures with a high fiber density (white matter). The brain is an extremely complex structure with a seemingly random arrangement of ridges (gyri) separated by grooves (sulci).

Hippocampus anatomy gyri