Clinical anatomy : official journal of the American Association of Clinical Anatomists & the British Association of Clinical Anatomists
-
The purpose of this study was to determine if various lithotomy positions increase strain on the obturator and lateral femoral cutaneous nerves in fresh adult cadavers. A static load cell was used to record strain changes of the obturator and lateral femoral cutaneous nerves in the pelvis and anterior thigh when the lower limbs were placed in three sets of positions of varying hip abduction and flexion. The means of the strain measurements, which were measured in grams in all positioning angles were compared to the baseline 0 degrees measurements. ⋯ The addition of 45 degrees or more of flexion to abduction negated the strain increase on the obturator nerves seen with abduction alone. Nerve strain >30 g has been associated consistently with nerve dysfunction, disrupting axonal transmission, and causing structural neural damage. Our findings suggest that concomitant hip flexion should be used when placing anesthetized patients in a lithotomy position that includes abduction of the lower limbs to >30 degrees to decrease the risk for perioperative neuropathy of the obturator nerve.
-
The radial nerve penetrates the lateral intermuscular septum of the arm before dividing into deep and superficial branches. It may be encountered in both anterior and posterior approaches to the humerus. An ability to accurately predict the point at which the nerve pierces the septum would be valuable during surgery in the arm, and would facilitate planning an approach to exploring the radial nerve after fractures of the distal humeral shaft. ⋯ We dissected 20 cadaver upper limbs to establish whether the radial nerve enters the anterior compartment of the arm at a predictable level. We found that in almost every case the radial nerve entered the anterior compartment at a point within 5 mm of the junction of the distal and middle thirds of a line joining the lateral epicondyle of the humerus to the most lateral point of the acromion process of the scapula. This has not previously been described, and we believe is a useful aide-de-memoir to predicting the level at which the radial nerve penetrates the lateral intermuscular septum.
-
Common anatomical structures that can lead to radial nerve entrapment in the radial tunnel (radial tunnel syndrome) were studied in 46 embalmed cadaveric upper limbs. After dissecting the radial tunnel, we investigated: the radial nerve and its division into superficial and deep (DBRN) branches; the course of the DBRN in relation to the extensor carpi radialis brevis (ECRB) muscle; the presence of fat; fibrous adhesions between the anterior radiohumeral joint capsule and the DBRN; the nature of the superomedial margin of the ECRB; vascular arcades of the radial recurrent vessels; and the superior and inferior borders of the superficial layer of the supinator muscle. ⋯ Near the radiohumeral joint, fibrous adhesions were observed between the DBRN and underlying capsule in 23/46 (50%) cases; vascular arcades of the radial recurrent vessels were found in 33/46 (72%) cases; the superomedial margin of the ECRB was tendinous in 36/46 (78%) instances; the superior border of the superficial layer of the supinator muscle was noted to be tendinous (arcade of Frohse) in 40/46 (87%) specimens, and the inferior border of the superficial layer of the supinator muscle was tendinous in 30/46 (65%) cases. These anatomical features in the radial tunnel are significant enough to lead to entrapment neuropathy of the radial nerve.