Oropharynx

The oropharynx is the middle part of the pharynx located posterior to the oral cavity. It serves as a common passageway for both air and food.

Boundaries

Oropharyngeal Isthmus

The communication between the oral cavity and oropharynx is called the oropharyngeal isthmus (fauces). It is bounded:

• Superiorly by: Soft palate and uvula

• Inferiorly by: Dorsum of tongue

• Laterally by: Palatoglossal arches

Important Structures

1. Palatine Tonsils

• Located in the tonsillar fossa between the palatoglossal arch (anteriorly) and the palatopharyngeal arch (posteriorly).

• Form part of the Waldeyer's ring and function in immune surveillance

2. Base of Tongue

• Forms the anterior wall of the lower oropharynx

• Contains lingual tonsils

• Separated from the oral part of the tongue by the sulcus terminalis

3. Soft Palate

• Forms the roof of the oropharynx

• Prevents nasopharyngeal reflux during swallowing

Muscles

The wall of the oropharynx contains several muscles, including:

• Superior pharyngeal constrictor

• Middle pharyngeal constrictor

• Palatopharyngeus

• Stylopharyngeus

• Salpingopharyngeus

Blood Supply

Primarily from branches of:

• Facial artery (tonsillar and ascending palatine branches)

• Ascending pharyngeal artery

• Lingual artery

• Maxillary artery

Venous Drainage

• Pharyngeal venous plexus, which drains into the internal jugular vein

Lymphatic Drainage

• Mainly to jugulodigastric (tonsillar) lymph nodes, which drain into the deep cervical lymph nodes

Innervation

• Sensory: via glossopharyngeal nerve (CN IX)

• Motor: Pharyngeal plexus via vagus nerve (CN X) - exception is stylopharyngeus, which is innervated by CN IX

Clinical Correlates

• Tonsillitis can occur due to infection and inflammation of the palatine tonsils, leading to enlarged jugulodigastric lymph nodes.

• Peritonsillar abscess (Quinsy) can result from collection of pus around the tonsil, causing severe sore throat, dysphagia, and uvular deviation.

• Oropharyngeal carcinoma commonly involves the tonsil, base of tongue, and soft palate.

• Gag Reflex can be checked as part of the neurological examination in this region, where in the afferent limb is via the Glossopharyngeal nerve (CN IX), and efferent limb via the vagus nerve (CN X)