Clinical anatomy of the superior orbital fissure
There are discrepancies between authors as far as topography of superior ophthalmic vein in the orbital apex is concerned.
The aim was to determine the location of the structures within the posterior part of the orbit and in the superior orbital fissure.
One hundred preparations of orbits were derived from the corpses sectioned in Forensic Medicine Department, University Medical School in Warsaw, Poland.
Anatomical preparation was performed with use of standard set of microsurgical equipment and operating microscope.
Nine various morphological types of the superior orbital fissure were distinguished. Among those were two main categories: type "a" characterised by a clear narrowing within the fissure and type "b" which lacked such narrowing. The type "a" and "b" fissures were also different in length whereby type "b" fissure was significantly shorter. A diversity of positioning of the soft structures within those types was successfully noted. In type "a" the superior ophthalmic vein was located typically, however in type "b" fissures it was significantly more often the lowest structure in the posterior part of the orbital apex (except for muscles and orbital fat). A short case report of patient with superior orbital syndrome was added.
Position of soft tissue structures in superior orbital fissure depended on its morphological type.
Available from: Stanisław Nitek
- "While operating within the orbit surgeon must cope with number of important structures located in a small area, in a nontransparent environment. Position of the soft tissue structures in reference to the easily identifiable bony points is helpful and could prevent serious complications      . "
[Show abstract] [Hide abstract]
ABSTRACT: Objectives. To determine safe distances within the orbit outlining reliable operative area on the basis of multislice computed tomography (MSCT) scans. Patients and Methods. MSCT of orbits of 50 Caucasian patients (26 males and 24 females, mean age 56) were analysed. Native scans resolutions were in all cases 0.625 mm. Measurements were done in postprocessing workstation with 2D and 3D reconstructions. The safe distances values were calculated by subtracting three standard deviations from the arithmetical average (í µí± = AVG − 3 STD). This method was chosen because this range covers 99.86% of every population. Results. The results of the measurements in men and women, respectively, are as follows (1) distance from optic canal to supraorbital foramen, mean 46,49 mm and 43,29 mm, (2) distance from the optic canal to maxillozygomatic suture at the inferior margin of the orbit mean 45,24 mm and 42,8 mm, (3) distance from the optic canal to frontozygomatic suture 46,15 mm and 43,58 mm, (4) distance from the optic canal to anterior lacrimal crest 40,40 mm and 38,39 mm, (5) distance from superior orbital fissure to the frontozygomatic suture 34,06 mm and 32,62 mm, and (6) distance from supraorbital foramen to the superior orbital fissure 42,32 mm and 39,39 mm. Conclusion. The most probable safe distances calculated by adopted formula were for the superior orbital fissure 23,39–30,58 mm and for the orbital opening of the optic canal 31,9–38,0 mm from the bony structures of the orbital entrance depending on the orbital quadrant.
09/2015; vol. 2015(ID 101438):10 pages. DOI:10.1155/2015/101438
Available from: Giulio Ruffini
- "In Mimics, small irregularities in the CSF outer surface were smoothed out. Also, two cylindrical plugs with a cross-section of 100 mm 2 each were cut out from the skull near the apexes of the orbits to represent the superior orbital fissures and the optic foramina (Chen and Chen, 2010; Fujiwara et al., 2009; Reymond et al., 2008). It was not possible to segment these apertures from the images. "
[Show abstract] [Hide abstract]
ABSTRACT: The electric field in the cortex during transcranial current stimulation was calculated based on a realistic head model derived from structural MR images. The aim of this study was to investigate the effect of tissue heterogeneity and of the complex cortical geometry on the electric field distribution. To this end, the surfaces separating the different tissues were represented as accurately as possible, particularly the cortical surfaces. Our main finding was that the complex cortical geometry combined with the high conductivity of the CSF which covers the cortex and fills its sulci gives rise to a very distinctive electric field distribution in the cortex, with a strong normal component confined to the bottom of sulci under or near the electrodes and a weaker tangential component that covers large areas of the gyri that lie near each electrode in the direction of the other electrode. These general features are shaped by the details of the sulcal and gyral geometry under and between the electrodes. Smaller electrodes resulted in a significant improvement in the focality of the tangential component but not of the normal component, when focality is defined in terms of percentages of the maximum values in the cortex. Experimental validation of these predictions could provide a better understanding of the mechanisms underlying the acute effects of tCS.
NeuroImage 12/2012; 70. DOI:10.1016/j.neuroimage.2012.12.034 · 6.36 Impact Factor
Available from: Abeye Mekonnen
- "The shape and surface area of the orbital fissures vary considerably among individuals (). The total area of the superior orbital fissure and optic foramen is approximately 1 cm 2 (, ). We used a realistic human head model based on the finite element method to simulate tCs in order to investigate the effect of skull openings on the electric field in the cortex. "
[Show abstract] [Hide abstract]
ABSTRACT: Due to its low electric conductivity, the skull has a major impact on the electric field distribution in the brain in transcranial current stimulation (tCS). However, the skull has several openings that are filled with higher conductivity soft tissues, and through which a significant fraction of the injected current may pass. We show that current entering the brain via the orbital openings increases the electric field intensity in the cortical regions near the orbit. Furthermore, this depends on the how far electrodes are placed from the orbital openings.
Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 08/2012; 2012:831-4. DOI:10.1109/EMBC.2012.6346060
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.