1. DENTAL GROSS ANATOMY CASE 4.2 (POSTERIOR SUPERIOR ALVEOLAR
NERVE BLOCK)

2. HISTORY
A 52 yo man, Francis McKean, went to his dentist because of severe pain
in his left maxillary molars.
The dentist found that the 2nd and 3rd maxillary molars had fractured crowns
and thought that the remaining root portions should be extracted.
A posterior superior alveolar nerve block was administered. The needle was
placed just distal to the maxillary 3rd molar and was advanced superiorly
and posteriorly ~ 2cm into the infratemporal region.
Immediately after deposition of the anesthetic Mr. McKean felt the left side of
his face swell up. The dentist realized what had happened and explained
that he had probably penetrated a venous structure causing a hematoma.
This complication might have been avoided by using an aspirating technique.
No extractions were attempted because of the facial swelling. Mr. McKean
was prescribed antibiotics and asked to return in one week to re-attempt
extraction.

3. Would a posterior superior alveolar nerve
block be suitable for extraction of other
upper teeth?
1. Would a posterior superior alveolar nerve block be suitable for extraction of other upper teeth?
No. The maxillary incisors and canine are innervated by the anterior superior alveolar nerve and the premolars by the middle superior alveolar nerve.

4. INNERVATION OF MAXILLARY TEETH
Anterior superior alveolar n.
Mucosa of maxillary sinus
Dental and gingival branches
Middle superior alveolar n.
Posterior superior alveolar n.

5. 2. Where does the posterior superior alveolar
nerve arise from and where does it enter
the maxilla?
2. Where does the posterior superior alveolar nerve arise from and where does it enter the maxilla?
The posterior superior alveolar nerve arises from V2 in the pterygopalatine fossa. It enters the posterior (infratemporal) aspect of the maxilla through the posterior superior alveolar foramen (foramina).

6. INNERVATION OF MAXILLARY TEETH
V ganglion
Sensory root of V
Infraorbital n.
Anterior superior alveolar n. V3 V2
Mucosa of maxillary sinus
Dental and gingival branches
Middle superior alveolar n.
Posterior superior alveolar n.

7. What venous structure was penetrated by the needle?
Pterygoid plexus of veins.

8. POSTERIOR SUPERIOR ALVEOLAR NERVE BLOCK
Pterygoid plexus
Maxillary a.
PSA nerve and
foramina
Maxillary 2nd molar

9. 4. Are there any special concerns about
infection of this venous structure?
4. Are there any special concerns about infection of this venous structure?
Yes. The pterygoid plexus communicates with the cavernous sinus in the cranial cavity via an emissary vein through the foramen ovale, and with the inferior ophthalmic vein in the orbit through the inferior orbital fissure. Infection could therefore spread into the cranial cavity or orbit via these routes.

10. Emissary vein communicating
with cavernous sinus through
foramen ovale
Posterior superior alveolar v.
Pterygoid plexus
Inferior alveolar v.

11. 5. What important structure is related to
the roots of the maxillary molars and
must be taken into consideration when
performing their extraction?
What important structure is related to the roots of the maxillary molars and must be taken into consideration when performing their extraction?
Maxillary sinus. (Note: The teeth related to the floor of the sinus vary from the three molars to the molars, premolars and canine.)

12. Opening into middle nasal meatus
Maxillary sinus
Roots of teeth

13. END OF CASE 4.2