A previously healthy 8-year-old boy is brought to the emergency department by his parents because of fever and progressively worsening sore throat and dysphagia Physical examination shows pharyngeal erythema with painful left and right cervical lymphadenopathy. Contrast-enhanced computed tomography (CT) shows fluid accumulation in the retropharyngeal space. A diagnosis of retropharyngeal abscess is suspected. Which of the following fasciae is most likely involved in this process?