Rom J Leg Med [27] 95-102 [2019] DOI: 10.4323/rjlm.2019.95 © 2019 Romanian Society of Legal Medicine FUNDAMENTAL RESEARCH Anatomic enigmas of the olfactory neuronal system structures in man. Implications in psychopathology Gheorghe S.Drăgoi1,2,*, Elena Pătrașcu3, Ileana Marinescu4 _________________________________________________________________________________________ Abstract: The anatomic enigmas of the olfactory neuronal system have blocked the real denominations and their systemic integration for a long time. They were finally understood as a result of anatomic and physiological studies on the dynamics of their ontogenesis and phylogeny. In the present paper we aim at bringing to light the issues associated with the anatomic enigmas of the olfactory neuronal structures in man. The object of the present paper is to report an ample anatomic study on extracerebral olfactory neuronal structures in man. The anatomic evaluation was carried out on 18 human encephala free of acute or chronic lesions taken from 8 adults (between 40 and 62 years of age), 6 feti (aged between 3 and 7 months antepartum life), and 4 embryos (30 to 36 mm long from vertex to coccigis). Prelevation, conservation and processing of the encephala was carried out on the basis of protocols worked out by the authors. Three olfactory neuronal structures in man were anatomically analyzed: the olfactory bulb, the olfactory peduncle and the olfactory tubercle. The morphogenesis of these structures was microanatomically evaluated on serial sections of embryo encephala, as well as macroanatomically on fetal samples. We encountered difficulties in denomination criteria, classification of topographic locations of chain stations and interconnective pathways. The elucidation of these issues opens up new integrative potentials of olfactory neuronal structures within the neuronal system of behavior and cognition with further implications in psychopathology. Key Words: olfactory neuronal structures, olfactory bulb, olfactory peduncle and olfactory tubercle. INTRODUCTION issues connected to the macroscopic anatomy and the morphogenesis of these structures. Our main object is to The olfactory neuronal system structures achieve the anatomic analysis of the following structures: in man has generated a score of problems regarding the olfactory bulb as a first extracerebral synaptic chain denomination, anatomic evaluation and integration in station, the olfactory peduncle as an interconnective the neuronal system the process behavior and cognition. structure and the olfactory tubercle as a first synaptic Localization and characteristics of interconnection station of the cortical chain. require the mastering of encephalon dissection methods which enable the access paths to these structures situated MATERIALS AND METHOD at the border between neocortex and archicortex. Anatomically speaking, they are forms of relief that Materials can be grouped in: synaptic stations of extracerebral The anatomic study was carried out on 18 human chains; interconnective structures and synaptic stations encephala free of acute or chronic lesions taken from of cortical integration. The present paper raises current 8 adults (between 40 and 62 years of age), 6 feti (aged 1) University of Medicine and Pharmacy of Craiova, Doctoral School, Craiova, Romania 2) Romanian Academy of Medical Sciences, Bucharest, Romania * Corresponding author: E-mail: [email protected] 3) University of Medicine and Pharmacy of Craiova, Department of Anatomy, Craiova, Romania 4) University of Medicine and Pharmacy of Craiova, 5th Department, Craiova, Romania 95 Drăgoi G.S. et al. Anatomic enigmas of the olfactory neuronal system structures in man. Implications in psychopathology between 3 and 7 months antepartum life), and 4 embryos of the peduncle. It is oval in form, surrounded by the (30, 32, 34 and 36 mm long) from vertex to coccigis. arachnoid that forms a full sleeve. It lies on the olfactory sulcus above the cribriform plate. The longitudinal Methods antero-posterior axis is oblique regarding the olfactory Prelevation and preservation of encephala was peduncle which, in turn, makes an obtuse angle, laterally done in accordance with the protocols set up by the open, of about 165 degrees. The medial margin is convex, authors of the paper (Drăgoi et al., 2019). Variability while the lateral margin is a straight line. A circular of locations, relations, connexions and morphogenesis groove is seen at the borderline of the olfactory peduncle of olfactory neuronal structures in man required the (Fig. 1B). selection of adequate anatomic methods for the two The olfactory peduncle was visualized in the anatomic entities under study: two rostral olfactory olfactory sulcus, in direct continuation of the olfactory neuronal structures and a caudal olfactory neuronal bulb. Its form is a triangular prism. The inferior face has structure. a longitudinal groove that divides it into two tracts: the Rostral olfactory structures – the olfactory bulb olfactory medial tract and the olfactory lateral tract; they and the olfactory peduncle – that can be seen on the are more distanced in the lower third and become the inferior face of the frontal lobe were individualized by olfactory medial stria and the olfactory lateral stria that dissecting the subarachnoidian space after inflating it participate in the delimitation of the olfactory trigone with air through the chiasmatic cistern situated ventrally (Fig. 1B and Fig. 2B). The apex of this triangle is in the and rostrally as reported to the optic chiasm. A large terminal part of the olfactory peduncle, while the basis number of arachnoidian trabeculae were split open in lies against the anterior perforated substance. We followed order to individualize the structural characteristics of the the routes of the two olfactory striae. The lateral olfactory form. stria is continuous, from the lateral angle of the olfactory The caudal olfactory structure – the olfactory trigone to the posterior and the lateral parts, and reaches tubercle in the anterior perforated substance – was the anterior border of the temporal lobe. The olfactory identified as the Sylvius’ valley after cutting a frontal medial stria goes from the margin of the medial angle of plane in the anterior extremity of the temporal lobe and the olfactory trigone to the medial and disappears in the pulling the optic chiasm towards the posterior. Following antero-medial of the anterior perforated substance (Fig. the opening up of the chiasmatic cistern by sectioning the 1C and Fig. 2B). arachnoid, we identified the rostral components of the The anterior perforated substance was visualized internal carotid system: the anterior cerebral artery and the as a small rectangular space, its long axis parallel to the middle cerebral artery. The former, as the terminal branch optic tract that makes up its posterior part. The medial of the internal carotid artery, passes medially and rostrally part is formed, towards the inferior, by a blunt crease that between the optic nerve and the anterior perforated is situated at the junction of medial and inferior faces of substance, further penetrating the longitudinal cerebral the frontal lobe. The lateral segment of the anterior face fissure where it comes into anastomoses with the collateral displays a prominent crease – the falciform crease – that homonymous artery through the anterior communicating separates the Sylvius’ valley from the lateral cerebral fossa artery (Fig.1A and 1B). The latter passes laterally and (Sylvius). The posterior face is made up of the optic tract rostrally between the temporal lobe and the frontal lobe which, from the optic chiasm, moves obliquely outwardly in the direction of the lateral cerebral fossae. We have also and to the posterior. identified the perforating branches of striate arteries that The anterior of the optic tract, the diagonal band enter the anterior perforated substance (Fig. 1A and 1C). (Broca) can easily be seen. The surface of the anterior perforated substance is smooth, grey in color and marked RESULTS by many orifices that make it look like a sieve because of the arterioles and venules of the corpus striatum. These The evaluation of the olfactory neuronal orifices are co-linear and make up spaced regular rows. In structures in man is based on the macroscopic anatomic each of these rows the diameter of the orifices increases analysis and on the study regarding the formation from medial towards lateral. The orifices that are situated processes and their evolution in ontogenesis. on a tract parallel to the posterior border are oval in shape and their larger diameter is oriented transversally. A. Macroscopic anatomic analysis In the anterior part of the perforated space, but Three extracerebral olfactory neuronal structures posteriorly to the bifurcation of the olfactory peduncle, were macroscopically analyzed: the olfactory bulb, the we noticed a small oval prominence generated by olfactory peduncle and the olfactory tubercle in the the olfactory tubercle that had the larger diameter anterior perforated substance. transversally oriented. It is surrounded by a large number The olfactory bulb was identified on the inferior of orifices that correspond, in the deep structure, to the faces of the frontal lobe, looking like an anterior dilatation ventral striatum (Fig. 1C and Fig. 2B). 96 Romanian Journal of Legal Medicine Vol. XXVII, No 2(2019) Figure 1. Presentation of olfactory structures in pars basalis telencephali. 1. Olfactory sulcus. 2. Olfactory bulb.