Unit:
Faculty of MedicineLibrary of the School of Health Sciences
Author:
Koutsarnakis Christos
Dissertation committee:
Πιάγκου Μαρία, Αναπληρώτρια Καθηγήτρια , Ιατρική Σχολή, ΕΚΠΑ
Στράντζαλης Γεώργιος, Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Τρουπής Θεόδωρος, Καθηγήτης, Ιατρική Σχολή, ΕΚΠΑ
Πρωτογέρου Βασίλειος, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Δεμέστιχα Θεανώ, Αναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Γούτας Νικόλαος, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Βλαχοδημητρόπουλος Δημήτριος, Αναπληρωτής Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Original Title:
Επιφανειακή ανατομία και υποφλοιώδης αρχιτεκτονική του ινιακού λοβού
Translated title:
Surface anatomy and subcortical architecture of the occipital lobe
Summary:
OBJECTIVE
To study and record the surface anatomy and subcortical architecture of the occipital lobe, since detailed knowledge of its axonal connectivity is still vague. Regarding the surface anatomy, the morphological pattern of the lateral, medial and basal occipital sulci has been studied whereas in regard to the subcortical architecture the morphology, spatial relationship and axonal connectivity of the fiber tracts residing in the occipital lobe have been meticulously explored.
MATERIALS & METHODS
Thirty –three (33) adult, cadaveric hemispheres fixed in a 10-15% formalin solution for a period of at least 8 weeks were studied. The arachnoid membrane and vessels of the area of the occipital lobe were cautiously removed and the sulcal morphology was systematically recorded. Following the removal of the arachnoid membrane and vessels, all specimens underwent the Klingler’s procedure (freeze–thaw process) and were subsequently investigated using the fiber dissection technique and the microscope (Carl Zeiss OPMI). The dissection tools used consisted of fine metallic periosteal elevators, various sized anatomical forceps, and micro-scissors. Numerous photographs were obtained during cadaveric dissections to illustrate the regional cortical and subcortical anatomy of interest.
RESUL TS
With regard to the surface anatomy of the occipital lobe we recorded the lateral occipital sulcus and the intraoccipital sulcus in 100% of the specimens whereas the anterior occipital sulcus in 24%, and the inferior occipital sulcus in 15%of cases. In the medial occipital surface, the calcarine fissure and parieto- occipital sulcus were always present. Finally, the basal occipital surface was always indented by the posterior occipitotemporal and posterior collateral sulci. A sulcus not previously described in the literature was identified on the supero-lateral aspect of the occipital surface in 85% of cases. We named this sulcus “marginal occipital sulcus” after its specific topography.
With respect to the subcortical architecture of the occipital lobe, special attention has been given to the detailed description of a novel fasciculus named as the “sledge runner fasciculus” after its peculiar shape. This tract was consistently identified as a distinct white matter pathway lying under the U fibers of the medial occipital lobe, exhibiting an oblique dorsomedial–ventrolateral direction and connecting the areas of the anterior cuneus, anterior lingula, isthmus of the cingulum and posterior parahippocampal gyrus. To our knowledge this is the first study in the pertinent literature to describe the morphology, correlative anatomy and axonal connectivity of this fiber pathway.
Furthermore, emphasis was placed to the anatomy, morphology and axonal connectivity of the middle longitudinal fasciculus. This white matter tract has been consistently identified as a discrete group of fibers travelling medial to the fibers of the arcuate fasciculus and found to participate in the connectivity of the temporal pole to the parietal and occipital lobes. The tract was further subdivided into three segments according to their special axonal connectivity.
CONCLUSION
By using the white matter dissection technique – Klingler preparation, we were able to provide a detailed description of the white matter tracts that traverse the occipital lobe and indeed participate in the axonal connectivity and functional integration of the human brain. Hence, the sledge runner fasciculus is consistently involved in the axonal connectivity of cerebral areas that are believed to be strongly implicated in the cognitive ability of spatial navigation and visuospatial imagery whereas the middle longitudinal fasciculus seems to participate in the connectivity of functional hubs sub serving the integration of acoustic information.
Main subject category:
Health Sciences
Keywords:
Fiber tracts, Occipital lobe, White Matter, Connectivity
Number of references:
247
