What is the anatomy of the deep peroneal nerve in nerve entrapment syndromes of the lower extremity?

Updated: Oct 15, 2019
  • Author: Minoo Hadjari Hollis, MD; Chief Editor: Thomas M DeBerardino, MD  more...
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The deep peroneal nerve, the other branch of the common peroneal nerve, originates just distal to the fibular head, [14] entering the anterior compartment in front of the interosseous membrane. It courses lateral to the anterior tibial muscle, traveling along with the anterior tibial artery and vein. In the proximal third of the leg, the nerve courses between the anterior tibial muscle and the extensor digitorum longus; in the middle third, it runs between the anterior tibial muscle and the extensor hallucis longus anterior to the anterior tibial vessels.

At approximately 3-5 cm proximal to the ankle mortise, the extensor hallucis longus crosses over the deep peroneal nerve, and the nerve is then seen between the extensor hallucis longus and the extensor digitorum longus in the distal part of the leg, at an average of 1.25 cm above the ankle joint. Occasionally, the nerve does not enter this interval until just distal to the mortise. At this level, it is about 3 mm in size and may be under the extensor retinaculum, because the inferior extensor retinaculum can be at, above, or below the ankle mortise level.

At approximately 1 cm distal to the ankle mortise, the nerve divides into lateral and medial branches. The terminal lateral branch curves laterally and supplies the extensor digitorum brevis, the extensor hallucis brevis, the adjacent tarsal and tarsometatarsal joints (including two to four branches innervating the anterolateral part of the subtalar joint), and, occasionally, the second and third dorsal interosseous muscles.

The terminal medial branch is just medial to the dorsalis pedis artery and just lateral to the first tarsometatarsal joint. It travels between extensor hallucis longus tendon and extensor hallucis brevis muscle on the dorsum of the foot. At approximately the metatarsophalangeal (MTP) joint level, the extensor hallucis brevis crosses over the nerve, and the nerve is then between the extensor hallucis brevis and the extensor digitorum longus to the second toe.

This nerve then divides into the dorsolateral cutaneous nerve of the great toe and the dorsomedial cutaneous nerve of the second toe. It supplies sensation to the web between the first and second toes, the dorsalis pedis artery, and the adjacent MTP and interphalangeal (IP) joints. Usually, it supplies the first dorsal interosseous muscle; occasionally, it supplies the second and third interosseous muscles.

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