Abstract
When making sonographic measurements of peripheral nerves, either for research or clinical purposes, it is important to have established that the measurements are valid. This study compared sonographic measurements and appearances of the ulnar nerve at the elbow with anatomic measurements of the nerve and with histologic findings. The results demonstrated that the anatomic measurements were very similar to the sonographic measurements of the nerve, when the nerve was imaged postdissection. However, the in situ sonographic measurements of the nerve were discrepant with the anatomic measurements of the nerve. This discrepancy occurred because the predissection sonographic measurement did not include the echogenic border surrounding the hypoechoic nerve. Histologic correlation demonstrated that the hypoechoic structure on the sonogram probably represented the major fascicle(s) of the nerve rather than the complete nerve and that the surrounding echogenic tissue represents the epineurial connective tissues of the nerve.