**Core Concept**
Thyroplasty type 2 is a surgical procedure used to medialize a paralyzed vocal cord, thereby improving voice quality and preventing aspiration. This procedure involves the injection of a material into the vocal cord to shift its position medially.

**Why the Correct Answer is Right**
In thyroplasty type 2, the vocal cord is medialized by injecting a material, such as silicone or Gore-Tex, into the vocal cord. This injection causes the vocal cord to move medially, thereby improving voice quality and preventing aspiration. The material is typically injected into the vocal process of the arytenoid cartilage or the vocal cord itself, using a small incision in the neck.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because thyroplasty type 2 involves medialization of the vocal cord, not lateralization.
**Option B:** This option is incorrect because thyroplasty type 1 involves lateralization of the vocal cord, not medialization.
**Option C:** This option is incorrect because the material injected in thyroplasty type 2 is not a muscle, but rather a synthetic material such as silicone or Gore-Tex.

**Clinical Pearl / High-Yield Fact**
Thyroplasty type 2 is a valuable procedure for patients with vocal cord paralysis, particularly those with a significant impact on voice quality or aspiration. It is essential to carefully evaluate the patient's anatomy and function before performing the procedure to ensure optimal outcomes.

**Correct Answer:** C. The vocal cord is medialized by injection of a material.