Septal branches of posterior ethmoidal artery

The septal branches of the posterior ethmoidal artery are small terminal arterial branches that arise from the posterior ethmoidal artery (PEA) after it exits the posterior ethmoidal canal and enters the nasal cavity. They supply the posterosuperior portion of the nasal septum and the upper nasal mucosa.

Origin and course

The posterior ethmoidal artery originates from the third segment of the ophthalmic artery (internal carotid system), courses through the medial orbit between the superior oblique and superior rectus muscles, and traverses the posterior ethmoidal canal to enter the posterior ethmoid sinus and then the nasal cavity. It is typically smaller in caliber than the anterior ethmoidal artery, measuring less than 1 mm in diameter, and may be absent in up to 19% of individuals. Once the PEA reaches the nasal cavity, it gives off septal branches that descend along the posterosuperior nasal septum to supply the mucosa of this region.

Territory and anastomoses

The septal branches of the PEA supply the upper posterior nasal septum and contribute to the rich anastomotic vascular network of the septum. Specifically, they anastomose posterosuperiorly with the posterior septal artery (a branch of the sphenopalatine artery from the external carotid system). They also participate in forming the arterial arches surrounding the S-point (the medial projection of the middle turbinate axilla on the superior septum), where branches of both the anterior and posterior ethmoidal arteries converge superiorly with the posterior septal artery inferiorly to create single or multiple anastomotic arches. These arches are clinically significant as a common source of severe epistaxis. Anteriorly, the septal branches of the PEA contribute along with the anterior ethmoidal artery, the posterior septal artery (sphenopalatine), the greater palatine artery, and the superior labial artery to Kiesselbach's plexus (Little's area) on the anteroinferior septum, the most common site of epistaxis.