ACSM Personal Trainer Certification Practice Exam

Which muscle assists the tibialis anterior in dorsiflexion at the ankle?

1. Peroneus longus

2. Gastrocnemius

3. Peroneus tertius

4. Iliopsoas

The correct answer is: Peroneus tertius

The tibialis anterior is the primary muscle responsible for dorsiflexion at the ankle, which involves raising the foot upwards. The peroneus tertius assists this movement by helping to lift the foot while also providing some degree of eversion. This makes the peroneus tertius particularly relevant in activities requiring dorsiflexion and lateral stability. Other muscles mentioned have different primary functions. For instance, the peroneus longus primarily aids in eversion and plantarflexion, the gastrocnemius is mainly responsible for plantarflexion when the knee is extended, and the iliopsoas primarily functions in hip flexion rather than ankle movements. Therefore, peroneus tertius is the correct choice because it specifically collaborates with tibialis anterior in the dorsiflexion of the ankle.