A brachial plexus block can be supplemented or "rescued" with an ulnar nerve block for surgeries in the distribution of the ulnar nerve or in the instance when a brachial plexus block may have spared the ulnar nerve distribution. Fibers from the spinal roots of C6-T1 form the ulnar nerve. The ulnar nerve is inferior and anterior to the axillary artery above the axilla and exits the axilla along with the brachial artery. At the level of the elbow, the ulnar nerve lies between the medial epicondyle of the humerus and the olecranon process, before continuing downward between the heads of the flexor carpi ulnaris and further downward along with the ulnar artery. It divides into a dorsal and palmar branch at a point approximately 1 in. proximal to the crease of the wrist. Sensation to the dorsum of the hand, the dorsum of the little finger, and the ulnar half of the ring finger is provided by the dorsal branch. The sensation to the ulnar aspect of the palm of the hand, the ulnar half of the ring finger, and the palmar aspect of the little finger is provided by the palmar branch of the ulnar nerve.
Arrange sterile towels, sterile gloves, gauze pads, marking pen, antiseptic solution, peripheral nerve stimulator, syringes, and needles for local infiltration and nerve block placement.
5-10 ml syringes of local anesthetic. Needles
25 g 1.5 in. needle for skin infiltration.
3% chloroprocaine, 2% lidocaine, 0.5% ropivacaine, 0.5% bupivacaine.
Surface Anatomy and Landmarks Landmarks
Basic considerations for the ulnar nerve block at the elbow (A) and ulnar nerve block at the wrist (B) are discussed below:
A. The arm is abducted to 85-90° with the patient in a supine position. The landmarks identified are the medial epicondyle of the humerus and the olecranon process, in between which lies the ulnar nerve sulcus. In an aseptic fashion a 25 g 1 in. needle is inserted in a slightly cephalad direction to elicit paresthesia, which is usually observed at a depth of 0.5 in. After negative aspiration and in the absence of persistent paresthesia, a total of 5-7 ml of local anesthetic is slowly.
B. Ulnar nerve block at the wrist is usually performed in the supine position with the arm fully adducted and the wrist slightly flexed. The flexi carpi ulnaris tendon is identified and in an aseptic fashion, a 25 g 1 in. needle is inserted at the level ofthe styloid process on the radial side of the tendon in a slightly cephalad direction. A paresthesia is usually elicited at a depth of about half an inch and after negative aspiration (in the absence of persistent paresthesia), a total of 3-5 cc of local anesthetic is injected.
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