Musculus extensor digitorum longus

The video tutorial covers the extensor digitorum longus muscle, one of the three extensors of the lower leg. It details the muscle's anatomy, including its origins on the tibial lateral condyle and other areas, and its tendon structure. The video also explains the muscle's innervation by the peroneal nerve and its functions, such as dorsal extension of the foot and pronation in the lower ankle joint. Additionally, it introduces the peronaeus tertius muscle, a variation found in some individuals.

Explain the role of the peroneal nerve in the innovation of the Extensor Digitorum Longus muscle.

What additional part is present in about 90% of the population regarding the Extensor Digitorum Longus muscle?