A—Relevant ultrasound anatomy pertinent to the radial, ulnar, musculocutaneous, and median nerve block. The marker (green circle) is oriented cranially. The radial nerve can be observed in between the brachialis, lateral, accessory, and medial heads of the triceps. The goal is to first advance the needle into the medial aspect of the radial nerve and administer the first aliquot of local anesthetic. Secondly, the needle should be redirected and advanced towards the brachial neurovascular sheath where the brachial vessels, musculocutaneous, median, and ulnar nerves can be found. Following verification of a negative aspiration test, a second aliquot of local anesthetic should be administered in this location. Expansion of the neurovascular sheath should be observed during the injection. B—Ultrasound-guided radial, ulnar, musculocutaneous, and median nerve block being carried out on a Beagle dog. The dog is positioned in lateral recumbency with the limb to be blocked positioned uppermost. A high-frequency, linear array ultrasound transducer should be positioned on the lateral aspect of the brachial area, over the triceps muscle, in a transverse orientation related to the ipsilateral humerus and with the marker (green circle) oriented cranially. The needle should be advanced in plane. brachial artery. BM = biceps femoris muscle. H = humerus. MCN = musculocutaneous nerve. MN = median nerve. RN = radial nerve. TAH = triceps muscle accessory head. TLH = triceps muscle lateral head. TMH = triceps muscle medial head. UN = ulnar nerve. lake Figure 2 for remainder of key.
Citation: Journal of the American Veterinary Medical Association 2022; 10.2460/javma.22.08.0354