**Core Concept**
The pterygomandibular raphe is an anatomical landmark that represents the intersection of the buccinator and superior constrictor muscles with the inferior alveolar nerve and the pterygomandibular fold. The posterior part of this raphe is a significant site for the attachment of certain muscles.

**Why the Correct Answer is Right**
The muscle attached to the posterior part of the pterygomandibular raphe is the **superior constrictor muscle**. This muscle is one of the three constrictor muscles of the pharynx and plays a crucial role in the swallowing process. The superior constrictor muscle is innervated by the pharyngeal plexus, which is formed by the pharyngeal branches of the glossopharyngeal nerve (cranial nerve IX) and the vagus nerve (cranial nerve X). The attachment of the superior constrictor muscle to the posterior part of the pterygomandibular raphe allows for the coordination of swallowing movements with the opening of the jaw.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the **buccinator muscle** is primarily attached to the anterior part of the pterygomandibular raphe, not the posterior part.

**Option B:** This option is incorrect because the **inferior constrictor muscle** is attached to the lateral surface of the thyroid cartilage and the midline of the cricoid cartilage, not the posterior part of the pterygomandibular raphe.

**Option D:** This option is incorrect because the **mylohyoid muscle** is attached to the mylohyoid line of the mandible and the hyoid bone, not the posterior part of the pterygomandibular raphe.

**Clinical Pearl / High-Yield Fact**
The pterygomandibular raphe is a significant landmark for the administration of local anesthesia, particularly for the inferior alveolar nerve block. The raphe is a common site for the insertion of the needle for this block, which is used to anesthetize the lower teeth and surrounding tissues.

**Correct Answer:** C.