Tendon of fibularis brevis

The tendon of the fibularis brevis (Peroneus brevis tendon; FB) originates from the fibularis brevis muscle in the distal third of the leg, and then passes posterior to the lateral malleolus within the retromalleolar groove of the fibula, sharing a common synovial sheath with the fibularis longus tendon. The tendon is held in place by the superior peroneal retinaculum as it courses through the superior peroneal tunnel, with the retromalleolar groove forming the osseous floor and the retinaculum forming the roof.

Distally, the tendon inserts onto the tuberosity at the base of the fifth metatarsal.

Anatomical studies have demonstrated significant variability in the number of tendon slips and insertion sites, with accessory bands sometimes inserting onto the dorsal digital expansion of the fifth toe or adjacent metatarsals, and the presence of accessory muscles such as the fibularis digiti quinti can further alter the insertion pattern.

Common mnemonics

• “Brevis before Longus” A simple phrase to recall that the brevis tendon lies in front of the longus as they pass behind the lateral malleolus.

• “B over L” (Brevis over Longus) Reinforces the vertical relationship: brevis is superficial/anterior, longus is deep/posterior.

• Bruce Lee

• “BLT – Brevis Longus Tendons” Some use this food-related mnemonic (like a BLT sandwich) to remember the brevis comes first, then longus.