Pharynx: Anatomy & Function

• The presentation is about the pharynx.
• The lecture will be given by Dr. Ramya Rathan, Assistant Professor of anatomy on March 1, 2025.
• Objectives include describing the site, extension, and muscular wall of the pharynx.

Extent and Function

• The pharynx extends from the base of the skull to vertebra C6.
• It functions as a common channel for both food and air.

Measurements

• Length: 12-14 cm.
• Width of nasopharynx: 3.5 cm.
• Width at pharyngo-oesophageal junction: 1.5 cm.

Pharynx Parts

• Nasopharynx lies behind the nose.
• Oropharynx lies behind the oral cavity.
• Laryngopharynx lies behind the larynx.

Nasopharynx

• The nasopharynx is the upper part of the pharynx.
• It communicates with the nasal cavity anteriorly.
• The nasopharynx communicates with the oropharynx inferiorly.
• Its roof and posterior wall are continuous, opposite the body of the sphenoid, the basiocciput, and the anterior arch of the atlas, featuring the pharyngeal or nasopharyngeal tonsil.

Lateral Wall of Nasopharynx

• The lateral wall has a pharyngeal opening of the auditory tube, with the elevated ridge called the tubal elevation.
• Salpingopharyngeal fold: vertical fold of mucous membrane covering the salpingopharyngeus muscle.
• Also present are levator veli palatine and the Pharyngeal recess (fossa of Rosenmuller), a depression behind the tubal elevation.

Nasopharyngeal Tonsil

• The nasopharyngeal tonsil is formed by an aggregation of lymphoid tissue beneath the mucous membrane.
• Location: internal aspect of roof & posterior wall
• More prominent in children, atrophies in adults.
• Enlargement due to infection results in adenoids, obstructing nasal respiration.

Oropharynx

• The oropharynx extends from the soft palate to the upper border of the epiglottis.
• Superiorly, it presents the nasopharyngeal isthmus.
• Anteriorly, it presents the oropharyngeal isthmus.
• Inferiorly, it continues with the laryngopharynx.
• Posteriorly, it is related to the axis & C3 vertebra.
• The lateral wall presents the tonsillar fossa, lodging the palatine tonsil.

Tonsillar Fossa

• The tonsillar fossa is anteriorly bound by the palatoglossal arch containing the corresponding muscle.
• Posteriorly bound by the palatopharyngeal arch containing the corresponding muscle.
• Function: Lodges the palatine tonsil.

Laryngopharynx

• The laryngopharynx runs from the upper border of the epiglottis to the lower border of the cricoid cartilage.
• The anterior wall has the inlet of Larynx.
• Posterior wall related to C3, C4, C5, and C6 vertebrae.
• The lateral wall presents the piriform fossa.

Piriform Fossa

• The piriform fossa is present in the lateral wall of the laryngopharynx.
• Its medial boundary is the Aryepiglottic fold.
• Lateral boundary: thyrohyoid membrane & thyroid cartilage
• Its floor is related to the internal laryngeal nerve.
• Lodges foreign bodies like fish bones, removal attempts may damage the internal laryngeal nerve, leading to anesthesia of the upper larynx.

The Palatine Tonsils

• The palatine tonsils are two masses of lymphoid tissue in the depression on the lateral wall of the oral part of the pharynx, between the palatoglossal and palatopharyngeal arches.
• Each tonsil lies in a triangular tonsillar sinus.
• Position: In front- palato-glossal arch, Behind, palato-pharyngeal arch
• Apex: soft palate where both arches meet.
• Base: dorsal surface of the posterior one-third of the tongue.

Waldeyer's Ring of Lymphoid Tissue

• Waldeyer's ring of lymphoid tissue: palatine tonsils and tubal tonsils form the lateral part of the ring.
• Pharyngeal tonsil: roofs nasopharynx (upper part).
• Lingual tonsil: posterior third of tongue (lower part).