A 30-year-old male underwent tooth extraction for dental caries. Now he presents with fever and trismus. Oropharyngeal examination is revealing that the tonsils are pushed medially. There is also a swelling in the neck at the upper border of sternocleidomastoid muscle. Most likely diagnosis is:

(d) Parapharyngeal abscess(Ref. Scott Brown, 8th ed., Vol 3; 550)Ludwig's angina is cellulitis of the submandibular space. Its most common underlying cause is dental caries. The patient has fever and trismus. Here the floor of mouth is raised pushing the tongue up and also there is swelling in the neck below the mandible on both sides. The tonsils are not pushed medially here.Peritonsillar abscess or Quinsy can also follow dental caries. The patient here presents with fever and trismus. On examination, the tonsils are pushed medially but external swelling at the upper border of sternocleidomastoid is not seen here.Parapharyngeal abscess can also follow dental infection. The patient presents with fever and trismus.On examination, the tonsils are pushed medially, because of the lateral pharyngeal wall being pushed medially.Since the lower boundary of the parapharyngeal space is hyoid, here external swelling at the upper border of sternocleidomastoid will also be seen.In retropharyngeal abscess a unilateral para-median bulge of the posterior pharyngeal wall is seen, the tonsil is not displaced here.