Surgical and radiologic anatomy : SRA
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Sciatic nerve block is a commonly used technique for providing anesthesia and analgesia to the lower extremity. It is classically performed through posterior or lateral approaches. However, an anterior approach should be considered in certain conditions where patient positioning would be complicated. The success rate of the sciatic nerve block with previously defined approaches has been reported to be low, however, the complication rate with such approaches has been found to be high. Therefore, we aimed to conduct an anatomical study defining a new anterior approach to block the sciatic nerve and also to examine if the femoral nerve can be blocked via the same approach. ⋯ The technique described herein appears anatomically safe with a lower risk of damage to major neurovascular structures. Additionally, the femoral nerve can be blocked simultaneously to obtain a larger area of anesthesia of the lower limb.
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Variant brachial plexus formation with two trunks and two cords is uncommon and has clinical implications as it may result in failure of regional brachial or axillary block. During routine anatomical dissection, unilateral variation in the formation of brachial plexus accompanied by unusual positional relationship with axillary artery was discovered in the left upper extremity of a 52-year-old Indian male cadaver. Brachial plexus showed two trunks formed by ventral rami of C5, C6 and C7, C8, T1 spinal nerves, respectively, which first split and then reunited in an unusual manner to form two cords: posterior and lateral instead of three. ⋯ Median nerve was observed to be formed from a single root, instead of usual two roots. Embryologically, this rare variation may be due to the development of axillary artery from ninth segmental artery instead of usual seventh cervical intersegmental artery. Such rare variation is clinically important as this knowledge may help the anesthesiologists and the surgeons to avoid any inadvertent damage to nerves and axillary artery during blocks and surgical interventions.