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Topic

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Posterior superior alveolar nerve

The posterior superior alveolar (PSA) nerve is a sensory branch of the maxillary nerve (V2), itself a division of the trigeminal nerve (cranial nerve V). It originates in the pterygopalatine fossa, travels through small foramina on the posterior surface of the maxilla, and enters the posterior superior alveolar canals to supply the maxillary molar teeth, adjacent gingiva, and the maxillary sinus mucosa. The nerve typically divides into two to three terminal branches before entering the bone. It is crucial for dental anesthesia, sinus surgery, and maxillofacial procedures.

Synonyms

  • Posterior superior dental nerve

  • Maxillary posterior alveolar branch

  • PSA nerve of V2

Function

  • Provides sensory innervation to maxillary molar teeth (except occasionally the mesiobuccal root of the first molar, which may receive innervation from the middle superior alveolar nerve)

  • Supplies the buccal gingiva over maxillary molars

  • Innervates the maxillary sinus mucosa

  • Transmits tactile, pain, and temperature sensations from its area of distribution

MRI Appearance
T1-weighted images:

  • The PSA nerve appears as a small, linear low-to-intermediate signal structure within the fatty tissue of the posterior maxilla

  • Surrounding high-signal fat in the pterygopalatine fossa provides contrast

  • Pathology such as neuroma or inflammation may appear hyperintense after contrast administration

T2-weighted images:

  • Nerve signal remains low-to-intermediate, while surrounding fat appears hyperintense

  • Edema, inflammation, or nerve compression may appear as focal hyperintensity along the nerve course

STIR (Short Tau Inversion Recovery):

  • Fat suppression highlights edema, inflammation, or nerve pathology

  • Normal nerve is low signal, while pathological changes appear bright hyperintense

CT Appearance

  • The PSA nerve itself is not directly visible, but its course is inferred from the posterior superior alveolar foramina and canals

MRI images

Posterior superior alveolar nerve mri sagittal image -img-00000-00000