Middle superior alveolar artery

The middle superior alveolar artery (MSAA) is a small and inconstant branch of the infraorbital artery (itself a terminal branch of the maxillary artery) that supplies the premolar region of the upper jaw. It accompanies the middle superior alveolar nerve and is notable for its anatomical variability it is not present in all individuals.

Origin and Course

The MSAA arises from the infraorbital artery as it courses through the infraorbital canal on the floor of the orbit. From its origin, the artery descends along the lateral wall of the maxillary sinus within a bony canal (the middle alveolar canal), running downward from the upper part of the sinus to ultimately join the anterior superior alveolar canal.

Territory of Supply

The MSAA provides blood supply to:

• The maxillary premolar teeth (first and second premolars) and their periodontal ligaments

• The adjacent buccal gingiva and alveolar bone in the premolar region

• A portion of the mucous membrane (Schneiderian membrane) lining the maxillary sinus

Anatomical Variability

The MSAA is one of the most variable vessels in the maxillary region. Cadaveric dissection studies have found a middle superior alveolar nerve (and its accompanying artery) in only about 37% of specimens (7 of 19 dissections). When the MSAA is absent, the premolar territory is supplied by overlapping branches of the posterior superior alveolar artery (PSAA) and the anterior superior alveolar artery (ASA), which form an extensive anastomotic network within the lateral wall of the maxillary sinus. This intraosseous anastomosis also called the alveolar antral artery is present in virtually 100% of cases and courses through the lateral sinus wall approximately 15.920.4 mm from the alveolar crest.

Relationship to the Maxillary Arterial Network

The MSAA is one of three superior alveolar arteries (posterior, middle, and anterior) that collectively supply the maxillary teeth, alveolar bone, and sinus lining. All three arise ultimately from the maxillary artery. The blood supply of the maxillary sinus is primarily provided by the PSAA and the infraorbital artery, which form both intraosseous (present in 100% of cases) and extraosseous (present in ~44% of cases) anastomoses along the lateral antral wall.