- Indications: surgery on the hand and fingers
- Nerves: radial, ulnar, median
- Local anesthetic: 5 mL for median and ulnar nerve, 10 mL for radial nerve
- Never use an epinephrine-containing local anesthetic
(A) Technique to accomplish a wrist block. (B) Median nerve block. Needle is inserted medial or lateral to the flexor palmaris longus tendon and carefully advanced to avoid paresthesia. Then 5 mL of local anesthetic is injected.
A wrist block consists of anesthetizing the terminal branches of the ulnar, median, and radial nerves at the level of the wrist. It is an infiltration technique that is simple to perform, essentially devoid of systemic complications, and highly effective for a variety of procedures on the hand and fingers. The relative simplicity, low risk of complications, and high efficacy of the procedure mandates this block to be a standard part of the armamentarium of an anesthesiologist. Several different techniques of wrist blockade and their modifications are in clinical use; in this chapter, however, we describe the one most commonly used at our institution. Wrist blocks are used often for carpal tunnel and hand and finger surgery.
Innervation of the hand is shared by the ulnar, median, and radial nerves (Figure 16-2 and 16-3). The ulnar nerve provides sensory innervation to the skin of the fifth digit and the medial half of the fourth digit, and to the corresponding area of the palm. The same area is covered on the corresponding dorsal side of the hand. Motor branches innervate the three hypothenar muscles, the medial two lumbrical muscles, the palmaris brevis muscle, all the interossei, and the adductor pollicis muscle. The median nerve traverses the carpal tunnel and terminates as digital and recurrent branches. The digital branches supply the skin of the lateral three and a half digits and the corresponding area of the palm. Motor branches supply the two lateral lumbricals and the three thenar muscles (recurrent median branch).
(A) Anatomy of the right wrist.
flexor palmaris longus.
flexor carpi radialis.
radial artery &circle7; flexor carpi ulnaris. (B) Anatomy of the right superficial radial nerve.
superficial radial nerve.
flexor carpi radialis tendon.
Cutaneous innervation of the left hand.
Although there is significant variability in the innervation of the ring and middle fingers, the skin on the anterior surface of the thumb is always supplied by the median nerve and that of the 5th finger by the ulnar nerve. The palmar digital branches of the median and ulnar nerves also innervate the ...