Typically to supplement proximal block when one (or more) branch is not blocked.
Significant neuropathy (risk of “double-crush” injury with block at two levels).
- Median nerve:
- Elbow: immediately medial to the brachial artery in the elbow crease. Elicit appropriate response (flexor carpi radialis, flexor digitorum, pronator quadratus, opponens, abductor brevis) and inject 5–7 mL of LA (Figure 137-1)
- Wrist: between tendons of flexor carpi radialis and palmaris longus. Elicit appropriate response (opponens, abductor brevis) and inject 5 mL of LA Median and ulnar nerve blocks at wrist
- Flexor carpi
- radialis tendon
- carpi ulnaris
- Ulnar a.
- Ulnar n.
- longusRadial nerve:
- Elbow: lateral to the tendon of the biceps in the elbow crease; alternatively, the radial nerve can be located above the elbow joint, on the lateral aspect of the arm, in the crease between biceps and triceps. Elicit appropriate response (brachioradialis, extensor carpi radialis/ulnaris, extensor pollicis, extensor digitorum) and inject 5–7 mL of LA. NB: The dorsal aspect of the forearm is typically not anesthetized with the block in the elbow crease, as the posterior cutaneous nerve of the forearm will be missed (Figure 137-1)
- Wrist: the radial nerve has only sensory rami at this level; they are blocked by infiltrating subcutaneously the skin on the lateral aspect of the wrist (from the midpoint of the dorsum to the midpoint of the volar aspect of the wrist) with 7–10 mL of LA. Pay attention not to lacerate the basilic vein (Figure 137-3)
- Ulnar nerve:
- Elbow: the nerve goes through the ulnar groove, posterior to the medial epicondyle. Do not block the nerve in the tunnel, as there is a risk of compression. Locate the nerve slightly more proximal, on the medial aspect of the arm, between biceps and triceps. Elicit appropriate response (flexor carpi ulnaris, hypothenar muscles, adductor pollicis, interossei, and lumbricals) and inject 5–7 mL of LA
- Wrist: the nerve courses medial to the ulnar artery and deep to the tendon of the flexor carpi ulnaris. Ask the patient to flex the wrist to locate the tendon, and insert needle from the medial side, deep to the tendon. Inject 3–5 mL of LA when an ulnar response is elicited (hypothenar muscles, adductor pollicis, interossei, and lumbricals) (Figure 137-2)
Figure 137-1. Median and Radial Nerve Blocks at the Elbow
Reproduced with permission from Miller RD, ed. Miller's Anesthesia. 6th ed. New York: Churchill Livingstone; 2005:1693. © Elsevier.
Figure 137-2. Median and Ulnar Nerve Blocks at Wrist