Surgical and radiologic anatomy : SRA
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Ten normal human volunteers and 44 patients with pathology of the brainstem or cranial nerves were scanned using a. 3 Tesla permanent MR imaging system. MR images were obtained of the cranial nerves and brainstem using various spin-echo pulse sequences and scanning planes. 4 mm thick sections with .75 mm pixels on a 256 display matrix were used whenever possible. The normal MR images were correlated with thin section cryodissection specimens of fresh human cadavers. ⋯ Unlike CT, there is no beam hardening artifact from bone. T1 weighted images maximize brainstem-CSF contrast and are useful for demonstrating the external anatomy of the brainstem and cranial nerves. The T2 weighted images show internal brainstem anatomy, CSF within neural foramina, and highlight many pathological conditions.
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On the supposition that some "pseudocoxalgias" might be due to a neuralgia of the lateral rami leaving the subcostal and iliohypogastric nerves above the lateral edge of the iliac crest, the authors undertook an anatomic study of their pathways and pattern of distribution. These rami supplying the skin below the iliac crest, which they cross close together, the ramus arising from the subcostal nerve by perforating the internal and external oblique abdominal muscles, that arising from the iliohypogastric nerve a little lower, creating a bony groove palpable in thin subjects and transformed into an osseomembranous tunnel by the aponeurosis of these muscles. This arrangement may give rise to an entrapment syndrome. ⋯ That arising from the iliohypogastric nerve descends further, passing 3 to 5 cm anterior to the great trochanter. It ends either at this level or 8 to 10 cm below. This accounts for the distribution of the pain felt when there is irritation of this ramus.