Henri M. Duvernoy

Anatomy of the Hippocampus

Hippocampal anatomy is so complex that its description will be comprehensible only with the aid of the figures grouped at the end of this book.

A practical guide for the identification of major sulcogyral structures of the human cortex.

The precise sulcogyral localization of cortical lesions is mandatory to improve communication between practitioners and to predict and prevent post-operative deficits. This process, which assumes a good knowledge of the cortex anatomy and a systematic analysis of images, is, nevertheless, sometimes neglected in the neurological and neurosurgical training. This didactic paper proposes a brief overview of the sulcogyral anatomy, using conventional MR-slices, and also reconstructions of the cortical surface after a more or less extended inflation process. This method simplifies the cortical anatomy by removing part of the cortical complexity induced by the folding process, and makes it more understandable. We then reviewed several methods for localizing cortical structures, and proposed a three-step identification: after localizing the lateral, medial or ventro-basal aspect of the hemisphere (step 1), the main interlobar sulci were located to limit the lobes (step 2). Finally, intralobar sulci and gyri were identified (step 3) thanks to the same set of rules. This paper does not propose any new identification method but should be regarded as a set of practical guidelines, useful in daily clinical practice, for detecting the main sulci and gyri of the human cortex.

Comments on the Microvascularization of the Brain

Microvascularization refers to the network of vessels that irrigates the nervous tissue of the brain and that is derived from the main macroscopic arteries and veins. Our knowledge of the fi ne vascular network of the brain is rather limited and leaves many questions unanswered. Two examples: (1) What is the precise vascular supply to different regions of the brain? (2) What is the architecture of the vascular capillary network in relation to known cerebral structures? For normal functional understanding as well as surgical and pathological considerations, it would be interesting to know the organization of the arterial supply ( fi g. 1 , A) and venous drainage ( fi g. 1 , V) of each and all brain structures both of gray or white matter. Indeed, if the principal arteries and veins have a well-known mapping on the brain surface, this is not the case regarding their deep branching network supplying specifi c brain structures. It would be possible to follow and trace these vessels to their fi nal ramifi cations using tridimensional reconstructions of serial sections after injection of the main vascular tree with colored liquids such as India ink, or plastics such as methyl metacrylate, or equivalents. The second point concerns the specifi c vascular architecture of specifi c brain structures. Indeed, many so-called nuclei have a specifi c and characteristic capillary vascular network. Figure 1 shows that the hypothalamic paraventricular nucleus can be identifi ed by its fi ne and dense capillary network when compared with nearby tissue. Figure 2 shows that the dorsal motor vagal nucleus, the nucleus of the solitary tractus and the area postrema can be identifi ed by the unusual appearance of their vascular network, again when compared with surrounding tissue.

Structure, Functions, and Connections

The hippocampus bulges into the temporal horn of the lateral ventricle, and its general appearance does indeed resemble a sea horse. It is arched around the mesencephalon and divided into three segments: A body, or middle segment, which is sagittally oriented A head, or anterior segment, which is transversely oriented and which shows elevations, the digitationes hippocampi A tail, or posterior segment, which is also oriented transversely and which narrows, disappearing beneath the splenium

Vascularization of the cerebellum and the brain stem

The vascularization of the cerebellum is not the topic of this work (except for the study of the vascular architecture of the cerebellar cortex and deep nuclei, Figs. 57–67). Thus, the reader will find here only an overview and is referred to [5, 14, 62, 75, 85, 109, 110, 111, 115, 122, 152, 160, 165, 166, 169, 180, 206, 222, 229, 243, 256, 257] for further details.

Structure and functions of the brain stem

The structure of the brain stem is first explained from a general view (Fig. 36), principal pathways (Figs. 37 and 38), cranial nerve nuclei (Fig. 39), and reticular formation (Fig. 40), then through a series of 16 axial (horizontal) sections (Figs. 41 to 56) parallel to the bicommissural plane and which can be compared to the axial sections in Figs. 99–127.

Sectional Anatomy and Magnetic Resonance Imaging

Coronal, sagittal, and axial sections according to the bicommissural plane will be successively studied in 20 plates each composed of 4 pages, showing the plane of the section, details about structures, MRI views, and head section.

A Survey of the Brain Stem Morphology

This overview of the brain stem surface and division is essential to a good understanding of its vascularization. To simplify the description, the anatomy of the brain stem will be presented in several drawings and dissections with comments, based on a previous work (Duvernoy 1995) (Figs. 1–14).

Superficial Path and Internal Territories of Arteries and Veins of Medulla, Pons and Mesencephalon

The superficial arteries and veins of the medulla can be divided into three groups: anterior (subdivided into anteromedial and anterolateral), lateral and posterior, corresponding to the anterior, lateral and posterior surfaces of the medulla (see Figs. 2–4).

Structure, Connexions and Functions of the Hippocampus

The hippocampus belongs to the limbic lobe which is on the medial aspect of the hemisphere, separated from adjoining cortex by the limbic fissure. This fissure is a discontinuous sulcus composed successively of the cingulate, subparietal, anterior calcarine, collateral and rhinal sulci. Broca (1878) divided the limbic area into the limbic and intralimbic gyri, a persistant tradition.