Origin and Course
The nasopalatine nerve originates from the pterygopalatine ganglion (gangl. pterygopalatinum), which receives sensory fibers from the maxillary nerve (n. maxillaris — CN V2).
Topography and course of the nerve:
- Entry into the nasal cavity: The nerve enters the nasal cavity from the pterygopalatine fossa via the sphenopalatine foramen (foramen sphenopalatinum).
- Course along the septum: It runs between the periosteum and the mucous membrane of the nasal septum, coursing downward and forward.
- Emergence onto the palate: It reaches the incisive canal (canalis incisivus), traverses it, and emerges onto the hard palate through the incisive foramen (foramen incisivum).
Innervation Targets
As a sensory nerve, it innervates the following structures:
- Nasal septum: Mucous membrane of the superior part of the nasal septum.
- Hard palate: A triangular area of mucosa in the anterior hard palate between the canines.
- Palatine tonsil (tonsilla palatina): Participates in its innervation along with the palatine nerves and pharyngeal plexus.
Anastomoses: The nasopalatine nerve anastomoses with its counterpart from the opposite side. Additionally, within or just before entering the incisive canal, it gives off anastomotic branches to the anterior part of the superior dental plexus (plexus dentalis).
Topography and Neighboring Structures
On the hard palate within the oral cavity, the nasopalatine nerve is located near the incisive papilla (papilla incisiva), situated anterior to the palatine raphe.
In this anatomical region, it is closely related to:
- Arteries: Posterior septal branch of the sphenopalatine artery (a. nasalis posterior septi).
- Other palatine nerves: Greater palatine nerve (n. palatinus major) and lesser palatine nerves (nn. palatini minores).
- Tissues: Palatine glands (gll. palatinae).
Clinical Significance: Incisive Nerve Block
To anesthetize the area supplied by the nasopalatine nerve in dentistry, incisive nerve block (nasopalatine block) is performed. The anatomical landmark is the incisive foramen, located 7–8 mm posterior to the gingival margin between the central incisors, just behind the incisive papilla.
Techniques:
- Intraoral approach: The patient's head is tilted backward. After topical anesthesia, the needle is inserted into the mucosa of the incisive papilla slightly anterior to the foramen opening. Inserting the needle directly perpendicular to the foramen prevents alignment with the axis of the incisive canal due to obstruction by the mandible. The anesthetic is injected via diffusion until bone is contacted or intra-anally, advancing the needle 0.5–0.75 cm into the canal to block the anastomotic branch to the superior dental plexus.
- Intranasal approach (extraoral/nasal access): Needle insertion and drug administration are performed at the base of the nasal septum bilaterally. This is used when the intraoral approach is not feasible or when a combination of bilateral infraorbital block and intraoral nasopalatine block fails to fully control pain in the central incisor region.