Final answer:
In the early stages of Achilles tendonitis, the inflammation occurs around the calcaneus or heel bone, where the Achilles tendon attaches to the gastrocnemius and soleus muscles.
Step-by-step explanation:
At the beginning stages of Achilles tendonitis, the tissue surrounding the calcaneus gets inflamed. Achilles tendonitis is a condition where the Achilles tendon, which serves to attach the plantaris, gastrocnemius, and soleus muscles to the calcaneus bone, becomes inflamed.
The calcaneus, also known as the heel bone, is where the Achilles tendon anchors. Other structures such as the medial malleolus, lateral malleolus, and tibia, while important to ankle structure and function, are not directly related to the inflammation in Achilles tendonitis.