Which muscle action includes ankle extension, foot inversion, and knee flexion?

Which muscle action includes ankle extension, foot inversion, and knee flexion?

• A. Gracilis
• B. Gastrocnemius
• C. Soleus
• D. Tibialis Anterior

Answer: (B)

The key idea here is a muscle that can affect two joints at once. The gastrocnemius spans both the knee and the ankle, so when it contracts it can bend the knee and push the foot downward (ankle plantarflexion, i.e., ankle extension). That combination matches the requested actions across the two joints more completely than the other muscles listed. The gracilis mainly acts on the knee and hip without plantarflexing the ankle; the soleus plantarflexes the ankle but does not cross the knee to influence knee flexion; the tibialis anterior inverts and dorsiflexes rather than plantarflexing the ankle. So the gastrocnemius is the best fit for producing knee flexion together with ankle extension.

The key idea here is a muscle that can affect two joints at once. The gastrocnemius spans both the knee and the ankle, so when it contracts it can bend the knee and push the foot downward (ankle plantarflexion, i.e., ankle extension). That combination matches the requested actions across the two joints more completely than the other muscles listed. The gracilis mainly acts on the knee and hip without plantarflexing the ankle; the soleus plantarflexes the ankle but does not cross the knee to influence knee flexion; the tibialis anterior inverts and dorsiflexes rather than plantarflexing the ankle. So the gastrocnemius is the best fit for producing knee flexion together with ankle extension.