|Microsurgery: Transplantation and Replantation by Harry J. Buncke, MD, et al.|
| The body of the extensor digitorum muscle is made up of four muscle slips. They originate from the lateral talocalcaneal ligament and the inferior and lateral surfaces of the calcaneus. The extensor hallucis brevis muscle is the most medial slip and inserts at the base of the proximal phalanx of the big toe. It can be isolated on its own neurovascular pedicle and transplanted as a single muscle slip. The lateral three slips insert laterally on the long extensors of the second through fourth toes. The muscle lies deep to the extensor hallucis longus tendon and the extensor digitorum longus tendons. Above these tendons lie the superficial peroneal nerve and the superficial saphenous venous system on the dorsum of the foot. All four muscle slips, which measure 4.5 cm x 6.0 cm, are harvested together.
Exposure of the muscle is carried out under tourniquet control through an S-shaped incision over the lateral foot. The use of T-shaped incisions has led to tip necrosis and has delayed healing. The incision should be designed to provide exposure of the muscle belly and allow extension proximally for the nutrient vessels.
The following structures are important in the dissection.
1. The dorsalis pedis artery should be marked preoperatively. The muscle belly will lie lateral to the vascular axis and can be mapped by palpation or by Doppler probe.
2. The extensor hallucis longus tendon and extensor digitorum longus tendons can be palpated when the patient extends against resistance. These tendons require medial and lateral retraction respectively to expose the extensor digitorum brevis muscle.
3. The extensor hallucis brevis muscle lies lateral to the extensor hallucis longus tendon. It is the most medial of the four muscle slips that make up the extensor digitorum brevis muscle. It is an important landmark, crossing the first metatarsal space and covering the dorsalis pedis artery and venae comitantes.
4. The motor nerve is a branch of the deep peroneal nerve. It passes deep to the extensor digitorum brevis muscle with the lateral tarsal vessels. The neurovascular pedicle crosses the junction between the proximal and middle thirds of the muscle.
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