**Core Concept**
The deltoid ligament, also known as the medial ligament of the ankle, is a strong, fan-shaped ligament that provides medial stability to the ankle joint. It is composed of four distinct bands and plays a crucial role in preventing excessive inversion of the ankle.

**Why the Correct Answer is Right**
The deltoid ligament is attached to the medial aspect of the talus, the medial malleolus, and the spring ligament. The medial cuneiform, however, is an osseous structure in the midfoot that forms part of the medial arch. It does not have any direct attachments to the deltoid ligament. The correct attachments of the deltoid ligament are to the medial malleolus, the spring ligament, the talus, and the sustentaculum tali.

**Why Each Wrong Option is Incorrect**
**Option A:** The medial malleolus is indeed attached to the deltoid ligament, serving as its origin.
**Option C:** The spring ligament is also attached to the deltoid ligament, providing additional support to the medial arch of the foot.
**Option D:** The sustentaculum tali is a bony projection of the calcaneus that attaches to the deltoid ligament, contributing to its medial stability.

**Clinical Pearl / High-Yield Fact**
The deltoid ligament is a critical structure in ankle stability, and its integrity is essential for preventing medial ankle instability and related injuries, such as medial malleolar fractures.

**✓ Correct Answer: B. Medial cuneiform. The medial cuneiform does not have any direct attachments to the deltoid ligament.**