The so-called Dorello's canal was studied in 32 specimens (16 human cadaver heads) injected with colored latex and fixed in formalin (28 specimens) or studied with microscopic and ultrastructural methods (four specimens). To avoid the differences usually encountered in the description of this area, the authors preferred to consider a larger space that they have named the petroclival venous confluence (PVC). It was located between two dural layers: inner (or cerebral) and outer (or osteoperiosteal). The PVC was quadrangular on transverse section. The posterior petroclinoid fold and the axial plane below the dural foramen of the abducent nerve (sixth cranial nerve) limited the PVC at the top and bottom, respectively. Its anteroinferior limit was the posterosuperior aspect of the upper clivus and outer layer of the dura mater. Its anterior limit was the vertical plane containing the posterior petroclinoid fold, and its posterior limit was the inner layer of the dura. The PVC was limited laterally by the medial aspect of the petrous bone apex and medially by the virtual sagittal plane extending the medial limit of the inferior petrosal sinus upward. The PVC was a venous space bordered by endothelium and continuous with the cavernous sinus, the basal sinus of the clivus, and the inferior petrosal sinus. There were trabeculations between the two dural layers. The petrosphenoidal ligament of Gruber may be regarded as a larger trabeculation, and it divided the PVC into a superior and an inferior compartment. The abducent nerve generally ran through the inferior compartment, where it was fixed to the surrounding dura mater. This nerve was only separated from venous blood by a meningeal sheath of varying thinness lined with endothelium. The clinical implications of these findings are discussed.
Various practical surgical approaches are discussed. The knowledge gained by studying this particular anatomy will help prevent injury to the optic radiations during neurosurgery.
The persistence of a left superior vena cava (LSVC) is an intrinsically cardiac anomaly, which can lead to serious complications during catheterization via the subclavian or internal jugular vein. We found this anomaly during dissection associated with an abnormal origin of the vertebral artery originating from the aortic arch between the left common carotid and subclavian arteries. The LSVC coursed towards the right atrium through a very dilated coronary sinus ostium. No abnormality of the azygos system was found. A thorough anatomic description was then made with external and internal morphology. The embryonic development and variations are described. Radiological and clinical implications are discussed.
The accumbofrontal fasciculus is an elective and specific projection from the orbitoprefrontal cortex. This fasciculus is part of a corticostriatothalamocortical loop and a putative target for deep-brain stimulation in the treatment of obsessive-compulsive disorder and major depression. The analysis of in vivo diffusion tractography, used today as a standard in the investigation of many brain disorders, could potentially take advantage of complementary anatomic correlations and functional extrapolations, as described in this study.
The objective of this study is to explore histological and ultrastructural changes induced by Klingler's method. Five human brains were prepared. First, the effects of freezing-defrosting on white matter were explored with optical microscopy on corpus callosum samples of two brains; one prepared in accordance with the description of Klingler (1956) and the other without freezing-defrosting. Then, the combined effect of formalin fixation and freezing-defrosting was explored with transmission electron microscopy (EM) on samples of cingulum from one brain: samples from one hemisphere were fixed in paraformaldehyde-glutaraldehyde (para/gluta), other samples from the other hemisphere were fixed in formalin; once fixed, half of the samples were frozen-defrosted. Finally, the effect of dissection was explored from three formalin-fixed brains: one hemisphere of each brain was frozen-defrosted; samples of the corpus callosum were dissected before preparation for scanning EM. Optical microscopy showed enlarged extracellular space on frozen samples. Transmission EM showed no significant alteration of white matter ultrastructure after formalin or para/gluta fixation. Freezing-defrosting created extra-axonal lacunas, larger on formalin-fixed than on para/gluta-fixed samples. In all cases, myelin sheaths were preserved, allowing maintenance of axonal integrity. Scanning EM showed the destruction of most of the extra-axonal structures after freezing-defrosting and the preservation of most of the axons after dissection. Our results are the first to highlight the effects of Klingler's preparation and dissection on white matter ultrastructure. Preservation of myelinated axons is a strong argument to support the reliability of Klingler's dissection to explore the structure of human white matter.
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