Ethmoid Artery Anatomy (Cadaver)

The ethmoid arteries, comprising the anterior and posterior branches, are integral vascular structures that hold immense significance in the realm of sinus and skull base surgery. Originating from the third segment of the ophthalmic artery, these arteries traverse through the medial orbit before passing through the respective ethmoidal canals and entering the ethmoid air cells. Although there is a degree of variability in the existence of the posterior ethmoidal artery (PEA), with studies reporting its absence in up to 19% of cases, in the majority of individuals, it is found running between the superior oblique and rectus superior muscles, ultimately entering the posterior ethmoidal canal to supply the posterior ethmoid sinus, the anterior cranial fossa meninges, and the upper nasal mucosa.¹ Notably, the PEA is often smaller in caliber, typically measuring less than 1 mm in diameter.² In contrast, the anterior ethmoidal artery (AEA) is more consistent in its anatomical course, traversing between the superior oblique and medial rectus muscles before passing through the anterior ethmoidal canal. This artery plays a crucial role in supplying blood to the anterior and middle ethmoidal sinuses, the frontal sinus, the nasal septum, and the lateral wall of the nose. A thorough understanding of the anatomy and clinical implications of these vascular structures is essential for ensuring safe and effective surgical planning and execution.

The AEA is a particularly important landmark in the context of preoperative surgical preparation.³ During the analysis of preoperative CT scans, identifying the precise location of this artery is crucial, as it allows surgeons to assess its potential vulnerability during anterior ethmoidectomy procedures. Interestingly, studies have revealed that approximately 20% of cases exhibit a dehiscent or downward extension of the AEA below the skull base, highlighting the need for careful surgical management to prevent inadvertent injury to this structure.⁴

The AEA serves as a valuable landmark during functional endoscopic sinus surgery (FESS). The advancements in endoscopic technologies, equipment, and imaging modalities have expanded the use of FESS, allowing it to be utilized for the orbit and skull base. The identification of the AEA aids surgeons in precisely locating the frontal sinus, frontal recess, and anterior skull base.^5,6

During surgical procedures, the AEA serves as a crucial landmark, particularly delineating the posterior boundary of the frontal recess dissection.⁹ Its identification aids in guiding surgical maneuvers, ensuring precision and minimizing the risk of inadvertent injury.

While the PEA is generally less problematic in routine endoscopic sinus surgery, it assumes significance in contexts such as skull base meningioma interventions.¹⁰ Although rare, instances of its dehiscence may necessitate attention, particularly in cases of hyperaerated sinuses where it may protrude into the sinus cavity.

An endoscopic approach to addressing the PEA involves careful identification and subsequent cauterization or clipping. However, concerns regarding the risk of cerebrospinal fluid (CSF) leakage and technical complexity warrant consideration of alternative approaches, such as external methods. The transcaruncular approach is favored for its efficacy, safety, and expedited procedure duration. This method offers improved exposure of the artery with reduced bleeding, facilitating precise arterial manipulation.¹¹

Furthermore, the AEA assumes clinical importance in the management of severe and intractable epistaxis, a condition characterized by persistent and uncontrolled nosebleeds. In cases where the bleeding is suspected to originate from the AEA region, the ligation of this artery serves as an effective therapeutic intervention to address the refractory bleeding that is unresponsive to conventional treatment modalities.⁷ Additionally, the identification of this artery helps in the endoscopic drainage of orbital abscesses and the evacuation of orbital hematomas.⁸

In summary, understanding the anatomical significance and clinical implications of the anterior and posterior ethmoid arteries is paramount in ensuring safe and effective management of sinus pathologies and associated complications. Accurate preoperative assessment, appropriate surgical techniques, and a thorough knowledge of these vascular structures are essential for optimizing patient outcomes and minimizing the risk of adverse events during surgical interventions.

Check out the rest of the series below:

1. Functional Endoscopic Sinus Surgery: Maxillary, Ethmoid, Sphenoid (Cadaver)
2. Ethmoid Artery Anatomy (Cadaver)
3. Frontal Sinus Dissection (Cadaver)
4. DCR and Nasolacrimal System (Cadaver)
5. Parotid Dissection (Cadaver)
6. Thyroidectomy (Cadaver)