Median Wrist

In addition, clay wedging, throwing, and building can cause hand and wrist injuries, including median nerve damage resulting in carpal tunnel syndrome (identified by numbness in the thumb and first three fingers). 

To minimize clay dust inhalation, it is best to buy premixed clay. Potters should change clothes before leaving their work area. Fresh clay should be used to minimize bacteria and mold growth. To avoid median nerve damage and resulting carpal tunnel syndrome, the potter s wrist should be unflexed frequently. A face mask can be worn when clay dust is present. 

Injection of a local anesthetic into or around individual peripheral nerves or nerve plexuses produces even greater areas of anesthesia than do the techniques described above. Blockade of mixed peripheral nerves and nerve plexuses also usually anesthetizes somatic motor nerves, producing skeletal muscle relaxation, which is essential for some surgical procedures. The areas of sensory and motor block usually start several centimeters distal to the site of injection. Brachial plexus blocks are particularly useful for procedures on the upper extremity and shoulder. Intercostal nerve blocks are effective for anesthesia and relaxation of the anterior abdominal wall. Cervical plexus block is appropriate for surgery of the neck. Sciatic and femoral nerve blocks are useful for surgery distal to the knee. Other useful nerve blocks prior to surgical procedures include blocks of individual nerves at the wrist and at the ankle, blocks of individual nerves such as the median or ulnar at the elbow, and blocks of sensory cranial nerves. 

Carpal tunnel syndrome (CTS) The result of compression of the median nerve in the carpal tunnel of the wrist. 

Carpal mnnel syndrome A common affliction caused by the compression of the median nerve in the carpal tunnel. It is often characterized by tingling, pain, or numbness in the thumb and first three fingers. It is often associated with repeated wrist flexion. 

An anatomic feature in the wrist formed by the wrist bones and the transcarpal ligament through which the median nerve and the nine digital flexor tendons pass. 

A repetitive motion injury caused by the compression and entrapment of the median nerve where it passes through the wrist into the hand—in the carpal tunnel. 

Carpal T mnel An internal passage in the wrist between the extensor retinaculum and the carpal bones through which the median nerve, finger flexor tendons, and blood vessels pass from the arm to the hand. 

Examination She is moderately obese, 90 kg, and has osteoarthritis affecting the wrists. There is decreased sensitivity to pinprick and touch in the median nerve distribution of both hands, i.e., the lateral half of the palm and the ventral thumb, and index and middle fingers. TineTs and Phalen s are positive. There is moderate weakness of the oppo-nens and flexor muscles of the both thumbs. There was no weakness proximal to the wrists or in the lower Umbs. Tendon reflexes were normal, plantar reflexes were flexor. 

Studies Blood chemistries including thyroid and parathyroid tests are normal. Nerve conductions showed severe bilateral dyssdiwannian neuropathy of the median nerves, with prominent conduction block across both wrists. Nerve conductions across the elbow and elsewhere were normal. BMG showed, in both hands, slight-moderate recent denervation in the opponens pollicis and abductor pollicis brevis. Nerve conductions and BMG in the lower limbs were normal. 

Scatterplot of the sensory amplitudes and latencies of the monkey median nerve repaired by either large pore conduit (Tube 85A) or nerve autograft obtained by stimulating the index finger and recording the evoked potential at the level of the wrist (A) evoked sensory amplitudes (B) latencies of the sensory potentials. 

Although the soft tissue anatomy of the forearm is complex due to the high number of muscles involved in the spectrum of wrist and fingers movements, musculoskeletal pathology amenable to US examination is relatively uncommon in this area. Only a few specific conditions affecting the median nerve proximal to the carpal tunnel level merit separate consideration. 

Fig. 103 a,b. a Photograph of the anterior aspect of the wrist with b cadaveric correlation shows the flexor carpi radialis tendon (black arrow) which serves as a guide to the radial artery (a) which lies just lateral to it. The long lean tendon of the pahnaris longus (arrowhead) is a landmark for the median nerve (MN) which is deep and frequently lateral to it. More medially, the flexor carpi ulna-ris tendon (open arrow) is seen moving down to the pisiform (P). This tendon may be used as a key reference for the ulnar artery and nerve which lie lateral to it... 

The wrist is crossed by the median nerve, the ulnar nerve and the superficial cutaneous branch of the radial nerve. In the wrist area, the ulnar nerve is accompanied by the ulnar artery and the median nerve gives off a sensory branch, the palmar cutaneous branch. 

Fig. 10.10 a,b. Clinical tests for evaluation of carpal tunnel syndrome, a The Tinel sign elicits paresthesias by tapping the median nerve at the palmar crease, b The Phalen sign provokes paresthesias at the end of the range of flexion of the wrist... 

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