Name

# Peroneus Longus

Pronunciation

(per-o-NE-us LONG-gus)

Origin/Proximal Attachment

Head of fibula

proximal two 3rd‘s of lateral surface of fibula

deep surface of the fascia cruris

the adjacent anterior & posterior crural intermuscular septa

occasionally by a few fibres from the lateral condyle of the tibia

Insertion/Distal Attachment

Plantar surface of cuboid

base of 1st (& 2nd) metatarsal

medial cuneiform (plantar surface)

Action/Relevance

Abducts & everts foot

Weakly plantar-flexes foot

Could possibly act on the leg from its distal attachment

The oblique direction of its tendon across the sole would also enable it to support the longitudinal & transverse arches of the foot

Peroneus longus & brevis come strongly into action to maintain the concavity of the foot during toe-off & tip-toeing.

Innervation

Superficial peroneal nerve (L4, 5,S1)

Notes

Superficial to Peroneus brevis

Narrow

Between its attachments to the head & shaft of the fibula there is a gap through which the common peroneal nerve passes.

The muscle belly ends in a long tendon running distally behind the lateral malleolus in a groove shared with the tendon of peroneus brevis (which lies behind it).

The groove is converted into a canal by the superior peroneal retinaculum, so that the tendons are contained in a common sheath.

The tendon runs obliquely forwards across the lateral side of the calcaneus, below the peroneal trochlea & the tendon of peroneus brevis, & beneath the inferior peroneal retinaculum.

It crosses the lateral side of the cuboid & then runs under it in a groove converted into a canal by the long plantar ligament.

It crosses the sole of the foot obliquely, & is attached by two slips to the lateral side of the base of the first metatarsal bone & the medial cuneiform.

Occassionally a third slip is extended to the base of the second metatarsal bone.

The tendon changes position at two points: below the lateral malleolus & on the cuboid bone. At both sites it is thickened & at the second a sesamoid fibrocartilage (or sometimes bone) usually develops within it.

A 2nd synovial sheath invests the tendon as it crosses the sole of the foot.