Lateral Plantar Nerve

Original Editor - Elena Ferrero Vila Top Contributors - Elena Ferrero Vila, Leana Louw and Wendy Snyders

Original Editor - name here

Top Contributors - Elena Ferrero Vila, Leana Louw and Wendy Snyders

References

The lateral plantar nerve or the external plantar nerve (latin: nervus plantaris lateralis) is a terminal branch of the tibial nerve. The lateral plantar nerve enters the sole of the foot by passing deep to the proximal insertion of the abductor hallucis muscle. It continues across the sole anteriorly and laterally, between the digitorum brevis and quadratus plantae muscles inervating both of this muscles. Then, close to the 5th metatarsal head it will divide into the deep and superficial branches:

• Superficial branch of the lateral plantar nerve splits into:
  • The lateral proper plantar digital nerve, which inervates the skin of the lateral aspects of the 5th toe and a branch for inervating the flexor digiti quinti brevis.
  • The common plantar digital nerve which communicates with the 3rd common branch of the medial plantar nerve and divides into the two proper digital nerves of the 4th and 5th toe.
• Deep branch of the lateral plantar nerve; is a motor branch and it inervates from the second to the fourth lumbricales, the adductor hallucis, and supplies all the interossei (appart from the ones on the 4th metatarsal space inervated by the superficial branch).

It provides sensory information from the two anterior thirds of the lateral sole of the foot, as well as the plantar surfaces for the 5th and half of the 4th toe.

It is also a motor nerve which inervates all the intrinsic muscles from the sole with the exception of abductor hallucis, flexor digitorum brevis, the flexor hallucis brevis and the first lumbrical muscle inervated by the medial plantar nerve.

The clinical relevance, the entrapement of the lateral plantar nerve first branch, also known as Baxter's nerve has symptoms similar to plantar fasciitis and tarsal tunnel syndrome including pain at the inside of the ankle and heel. Baxter's Neuropathy,is the entrapement of the first branch of the lateral plantar nerve, which inervates the abductor digiti quinti muscle. The Baxter's Neuropathty is a painful condition that can lead to chronic heel pain.

Assessment:

Baxter's Neruopathy:

• The symptoms are usually pain at the medial aspect of the heel that exponentially increases with loadberaing.
• Symptoms tend to get worse as the day goes on , or appering after prolonged activity.
• A radiating pain may be present when the nerve is palpated.
• There is maximal tenderness at the medial border of the heel where the entrapment occurs – usually around the origin and deep to the abductor hallucis. This may create radiating and/or burning pain laterally across the plantar foot.
• There is a positive Phalen’s test (invert and plantarflex the foot passively). This compresses the nerve due to narrowing of the porta pedis
• There may be weak abduction of the fifth toe. This is due to the abductor digiti minimi muscle.
• There may be a positive Tinel’s sign. Paresthesias may be reproduced with tapping over the nerve beneath the abductor hallucis muscle.
• In chronic cases, patients may have diminished sensation in the lateral plantar foot.

Treatment:

• Conservative treatment includes

1. Taping and/or orthotics to control overpronation.
2. Stretching of the soleus and gastrocnemius muscles.
3. Soft tissue therapy to the plantar fascia and foot intrinsic.
4. No steroidal anti-inflammatory medication (NSAIDS).
5. Strengthening exercises for the foot intrinsics.

• Non-conservative treatment:

Endoscopic decompression of the first branch of the lateral plantar nerve

References