Surgical and radiologic anatomy : SRA
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The presence of enlarged optic nerve sheaths (ONS) suggests that raised intracranial pressure is transmitted to the perineural subarachnoid space (SAS). This phenomenon has gained interest because ultrasound methods are able to quantify the optic nerve sheath diameter (ONSD) in-vivo non-invasively with a resolution below 0.5 mm. In order to study the normal variation and distensibility of the human ONS. ⋯ The different extent of pressure-induced sheath expansion along the nerve may be partly due to the non-uniform distribution of subarachnoid trabecular fibers between nerve and sheath. In conclusion, measurements of the ONSD for clinical purposes should be targeted to the region immediately behind the globe. Under conditions of raised pressure around the intraorbital optic n., bilateral ONSD measurements should give comparable findings.
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The authors report the results of the dissection of the superficial peroneal nerves of 30 adult cadavers, from its emergence through the deep sural fascia up to its terminal branches. Its emergence was located, on average, 11 cm from the lower end of the lateral malleolus (min: 9 cm, max: 11.5 cm). The division of the nerve into the medial dorsal cutaneous n. and the intermediate dorsal cutaneous n. was found in 29 cases after its emergence from the sural fascia and before its passage on the proximal edge of the extensor retinaculum. ⋯ It divided into two branches at a variable distance from the fourth interdigital space (4 to 6 cm). According to Kosinski's classification, we found 24 cases of type I (80%), three cases of type II (10%) and three cases of type IV (10%). The authors stress the numerous topographic variations and the multiple anatomical types.
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Ten anatomical preparations and 15 MRI scans (Magnetic Resonance Imaging) performed on healthy subjects were used to define accurately the lateral attachments and anatomical boundaries of the supraspinatus m. Using 5 frozen specimens sectioned in the plane corresponding to the sagittal oblique MRI plane, it was possible to calculate quantitatively the ratio between the bony contours (O) and muscles (M) of the supraspinous fossa. ⋯ This observation was confirmed in the 15 MRI subjects which showed that the supraspinatus m. may arise as far laterally as the "Y" section on MRI in 53% of cases. A quantitative evaluation of atrophy of the supraspinatus m. using MRI is possible with a knowledge of these two parameters.