**Core Concept:** Ankle sprain is a traumatic injury to the ligaments of the ankle joint, causing pain, swelling, and limited mobility. Plantar Hexed foot is a term used to describe a specific position of the foot where the plantar aspect (bottom) of the foot is flexed and the dorsal aspect is extended. Forced inversion of this foot position can lead to an increased risk of ankle sprain.

**Why the Correct Answer is Right:** An ankle sprain due to forced inversion of a plantar Hexed foot is mainly caused by injury to the anterior talofibular ligament (ATFL) and calcaneofibular ligament (CFL). These ligaments are responsible for maintaining the stability of the ankle joint and preventing excessive inversion (side-to-side movement) of the foot. When the foot is placed in a plantar Hexed position and forcefully inverted, the ATFL and CFL are stretched or torn, leading to the characteristic symptoms of an ankle sprain.

**Why Each Wrong Option is Incorrect:**

A. This option refers to the deltoid ligament, which is located on the medial side of the ankle and plays a role in maintaining stability in eversion (turning outwards) of the ankle. Injuries to the deltoid ligament are not directly associated with ankle sprains due to forced inversion of a plantar Hexed foot.

B. This option also refers to the deltoid ligament, which is incorrect for the same reason as option A.

C. This option incorrectly refers to the syndesmosis ligaments, which are located between the tibia and fibula and stabilize the ankle joint during dorsiflexion (toe-upwards) movement. These ligaments are not directly involved in maintaining ankle stability during inversion of a plantar Hexed foot.

D. This option refers to the peroneal muscles, which are responsible for dorsiflexion and eversion of the ankle. Injuries to these muscles are not directly associated with ankle sprains due to forced inversion of a plantar Hexed foot.

**Clinical Pearl:** Understanding the anatomy and biomechanics of the ankle joint is essential when assessing and managing patients with ankle injuries. Recognizing the specific structures involved in maintaining ankle stability in different directions can help in formulating an accurate diagnosis and appropriate treatment plan for patients presenting with ankle sprain symptoms.