Morton's neuroma is an inflammation of the nerves in the foot that go to the toes. Although the name includes the word “neuroma,” it is not really a tumor. It can affect any of the toes in the foot. However, it most often affects the nerves that run between the third and fourth or second and third toes.

Nerves of the Foot
Foot Anatomy Nerve and muscle
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Morton's neuroma is an inflammation caused by a buildup of fibrous tissue on the outer coating of nerves. This fibrous buildup is a reaction to the irritation resulting from nearby bones and ligaments rubbing against the nerves.

Irritation can be caused by:

  • Wearing shoes that are too tight
  • Wearing shoes that place the foot in an awkward position, such as high heels
  • A foot that is mechanically unstable
  • Repetitive trauma to the foot such as from sports activities like tennis, basketball, and running
  • Trauma to the foot caused by an injury such as a sprain or fracture

It is unusual for more than one Morton's neuroma to occur on one foot at the same time. It is rare for Morton's neuroma to occur on both feet at the same time.