Peroneus Longus   

- Anatomy:
    - lateral compartment
    - plantar muscles of the foot:
    - origin:
         - lateral condyle of tibia, head and proximal 2/3 of lateral surface of fibula, intermuscular septa and adjacent fascia;
    - course:
         - peroneus longus courses posteiror to the brevis tendon, and then both tendons pass thru the common peroneal synovial sheath, 
                about 4 cm proximal to the lateral malleolus;
         - synovial sheath passess through a fibro-osseous tunnel that is stabilized by the superior peroneal retinaculum and by the calcaneofibular 
         - after the peroneus longus emerges from its sheath and passes inferior to the cuboid on its way to its insertion;
         - os peroneum is an accessory bone which is located within the peroneus longus tendon in about 20% of feet;
                - typically this is located plantar to the cuboid, near the calcaneo-cuboid articulation;
                - this accessory ossicle may be associated with peroneus longus tenosynovitis;
    - insertion:
         - lateral margin of plantar surface of 1st cuniform and proximal end of 1st metatarsal.
    - action:
         - primary action is to plantar flex the first ray of the foot;
         - plantar flexion and eversion of the foot at the ankle;
         - primarily active during the stance phase of gait;
         - gives lateral stability to the ankle;
         - synergists: gastrocnemius, soleus;
    - nerve supply:
         - peroneal, S1 > L5, L4; (see innervation)

Pathologic Conditions:
    - peroneal tendon subluxation:
    - peroneal tendon disruption:
         - persistent swelling along the peroneal tendon sheath is a reliable sign for peroneus brevis tendon tear;
    - peroneal muscle spasm:
         - may occur w/ tarsal coalition, but may also occur w/ rheumatoid arthritis, osteochondral frx, & infection in subtalar joint or 
                neoplasm (osteoid osteoma, fibrosarc)
    - Charcot Marie Tooth:
         - when there is loss of the tibialis anterior and peroneus brevis (which is common in CMT), the peroneus longus will cause flexion 
                of the first ray, which subsequently leads to a cavus foot deformity;
    - polio:
         - in polio syndrome, transfer of the peroneus longus in the presence of strong tibialis anterior results in a dorsal bunion as the 
                forefoot supinates;
         - it must be combined with lateral transfer of the tibialis anterior to the base of the second metatarsal bone

Peroneal tendon injuries.


Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, April 11, 2012 10:42 am