What Is the Extensor Digitorum Brevis?

One of the deep muscles of the forearm posterior group of brachialis extensors. There are abductor hallucis longus lateralis and extensor hallucis longus medial. It starts from the radius, the back of the ulna, and the interosseous membrane, and ends at the base of the phalanx of the first phalanx of the thumb. Its function is to stretch the thumb. Dominated by radial nerves (necks 6-8).

One of the deep muscles of the forearm posterior group of brachialis extensors. There are abductor hallucis longus lateralis and extensor hallucis longus medial. It starts from the radius, the back of the ulna, and the interosseous membrane, and ends at the base of the phalanx of the first phalanx of the thumb. Its function is to stretch the thumb. Dominated by radial nerves (necks 6-8).

Chinese name

Extensor hallucis

Foreign name

Shortextensor

Brachial extensor related diseases and treatment

1. Mild hallux valgus, using Mcbride and its various improved techniques. The advantage of the modified Mcbride procedure is that except for the removal of the medial osteophytes, it is all directed to the soft tissue surgery on both sides of the first metatarsophalangeal joint. The disadvantage is that there will still be relapses. Based on Mcbride's technique, the researchers moved the distal end of the brachial extensor tendon inward to enhance its correction effect. The intention is to improve the success rate of the operation without disturbing the bone structure through simple operation steps. Reduce the recurrence rate.

2. In addition to shortening the hallux extensor, the abductor can also be abducted. In the pathological evolution of hallux valgus, with the gradual increase of the degree of valgus, subluxation of the first metatarsophalangeal joint will occur. It is not clear what role the short extensor hallucis plays. When the deformity is already present, the extensor hallucis extensor can definitely promote the abduction of the toe and shift outward.

3. Some researchers believe that after the short extensor hallucis muscle is moved inward, reconstruction of the dead center on the medial base of the proximal toe of the thumb has the following advantages: First, the force of adduction and inward movement of the thumb can be strengthened and the metatarsophalangeal joint can be antagonized. The lateral subluxation; the second allows the valgus toe to gain partial external rotation power against its internal rotation stress; the third retains its toe extension function; the fourth does not interfere with the metatarsophalangeal joint and does not change the first sequence length. Some experimental results show that the excellent rate is simple, easy to implement, and worthy of promotion.

Brachial extensor related clinical techniques

1. Based on the research of applied anatomy, the operation of reconstructing the function of the thumb and the palm using the direct displacement of the short extensor hallucis was designed, and all achieved good results. This method has the advantages of constant dynamic tendon position, less variation, simple operation and satisfactory curative effect, and small damage to the donor site.

2. Surgery method: Make a horizontal incision on the dorsal side of the thumb metacarpophalangeal joint, exposing the short hallux extensor tendon stop. In the radial dorsal incision of the wrist, the abdomen and muscle cavity of the brachialis extensor muscle are exposed and freed up to the radial base stop of the thumb base. In the "S" incision in the distal forearm, cut off the distal end of the long palmar tendon, move the free brachial extensor tendon to the palm side through the subcutaneous tunnel from the back of the wrist to the palmar side, and use the distal end of the long palmar tendon on the wrist Rebuilding the tackle. At this time, the proximal and distal ends of the tendon are on the palm side of the great intermuscular muscle, and they are inclined straight. The displacement of the short extensor hallucis muscle is consistent with the direction of action of the short abductor hallucis, so it does not move its stop. When rebuilding the block during the operation, pay attention to adjust the tension so that the thumb is in the opposite palm position. After the operation, the cast was fixed for 3 weeks. After the cast was removed, active and passive exercise activities were performed.

3. Improvement of the operation method: The thumb extensor muscle reconstructs the thumb palm. There are many operation methods abroad. There are professional literature records that this muscle stop is cut off. After being pulled out from the wrist, it bypasses the radial wrist flexor tendon or through the interosseous membrane as a pulley, and then sutures the original stop through a subcutaneous tunnel. Although Matve directly shifts without stopping the stop, but uses nearly 1/3 of the transverse carpal ligament for the tackle. We use the palmar long muscle as a pulley to avoid damage to the carpal tunnel. The palmar long muscle cavity is longer and it is easy to adjust the tension. At the time of surgery, neither the tendon tissue of the two tendons is damaged, so the blood supply is good, and the friction between the pulley and the tendon is small, which is conducive to movement.

Choice of dynamic tendon: There are many methods for reconstruction of thumb to palm function, and there are many alternative dynamic tendons. Choosing the short extensor hallucis muscle as the dynamic tendon has the following advantages: (1) The short extensor hallucis muscle is adjacent to the short hallux abductor and is a synergistic muscle. Therefore, the dead point can be completely reconstructed without being cut. (2) The rate of absent muscle cavity is small, and because of its superficial location, the presence or absence can be determined by inspection before surgery. (3) After the tendon is displaced, its original function can be compensated by the extensor hallucis longus muscle, which has little effect on the function of the donor site. 4) For those with hallux-palm loss, brachial plexus injury, median nerve, and ulnar nerve joint injury are common. When the available tendon on the palm side is insufficient, it is reasonable to select the short hallux extensor muscle innervated by the radial nerve. select.