Ethmoid Artery Anatomy (Cadaver)
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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.
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Citations
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- Naidu L, Sibiya LA, Aladeyelu OS, Rennie CO. Anatomical landmarks for localisation of the anterior ethmoidal artery: a combined radiological and cadaveric (endoscopic) study. Surg Radiol Anat. 2023;45(5). doi:10.1007/s00276-023-03122-x.
- Guarnizo A, Nguyen TB, Glikstein R, Zakhari N. Computed tomography assessment of anterior ethmoidal canal dehiscence: an interobserver agreement study and review of the literature. Neuroradiol J. 2020;33(2). doi:10.1177/1971400920908524.
- Abdullah B, Lim EH, Mohamad H, et al. Anatomical variations of anterior ethmoidal artery at the ethmoidal roof and anterior skull base in Asians. Surg Radiol Anat. 2019;41(5). doi:10.1007/s00276-018-2157-3.
- El-Anwar MW, Khazbak AO, Eldib DB, Algazzar HY. Anterior ethmoidal artery: a computed tomography analysis and new classifications. J Neurol Surg B Skull Base. 2021;82. doi:10.1055/s-0039-3400225.
- Rudmik L, Smith TL. Management of intractable spontaneous epistaxis. Am J Rhinol Allergy. 2012;26(1). doi:10.2500/ajra.2012.26.3696.
- Sah BP, Chettri S, Gupta MK, Shah SP, Poudel D, Manandhar S. Radiological correlation between the anterior ethmoidal artery and the supraorbital ethmoid cell in relation to skull base. Ann Adv Med Sci. 2018;2(1). doi:10.21276/aams.1892.
- Cascio F, Cacciola A, Portaro S, et al. In vivo computed tomography direct volume rendering of the anterior ethmoidal artery: a descriptive anatomical study. Int Arch Otorhinolaryngol. 2020;24(1). doi:10.1055/s-0039-1698776.
- Kharoubi S. Posterior Ethmoidal Artery: Surgical Anatomy and Variations. In: Paranasal Sinuses Anatomy and Conditions. ; 2022. doi:10.5772/intechopen.99152.
- Shorr N, Baylis HI, Goldberg RA, Perry JD. Transcaruncular approach to the medial orbit and orbital apex. Ophthalmol. 2000;107(8). doi:10.1016/S0161-6420(00)00241-4.
Cite this article
Brown CS, Ramakrishnan JB. Ethmoid artery anatomy (cadaver). J Med Insight. 2024;2024(161.2). doi:10.24296/jomi/161.2.
Procedure Outline
Table of Contents
- Identify Frontal Recess
- Identify Posterior Ethmoid Artery
- External Approach
Transcription
CHAPTER 1
So the anterior ethmoid artery - obviously, the most important reason that you talk about it or think about it is in surgical preparation, when you're doing your preoperative CT scan analysis. That's one of the things on the checklist to check for - where that artery is and is it hanging down from the skull base or not because it can be injured during your anterior ethmoidectomy, and it - in about 20% of cases, it's - it's dehiscent or hanging down below the skull base, so most of the time, it's going to be within your skull base. The other reason that it's important is if - again, intractable - intractable epistaxis patient that you feel like the bleeding is coming from this area as opposed to posteriorly, you can do an anterior ethmoid artery ligation, and then sometimes you'll have malignancies in this area where, again, you're going to need to get control of this artery to devascularize that tumor. So David, again, has done the ethmoidectomy for the most part here.
This is the frontal recess here, which I'm going to leave alone, but - oh, the other reason that the artery’s important is because that's going to be one of your boundaries for the frontal recess dissection. And so - and it's going to be the posterior boundary. And so, again, David's kind of done the dissection here already - so pretty easy to see that artery right there, but when you're doing surgery, you've done your - your sphenoidotomy back here, and you're working from posterior to anterior, and you're using your curette and up-angled instruments to take down these ethmoid cell partitions and - and identifying your orbit and making this look nice and pretty, as you start to come to this area and approaching the frontal recess, that's where you need to look for the artery. And a mentor had told me at one time: one way you can think about this artery is like the facial nerve when you're doing a parotid. And so obviously, you don't want to injure it, but you - don't be afraid of it. It's a good landmark. Identify it, and use that to help you identify that posterior border of the - of your frontal dissection. And so there it is right there, and the - let's look at the posterior ethmoid artery real quick.
Posterior ethmoid artery is rarely an issue in - just endoscopic sinus surgery. It can be - it is another artery that you're going to want to get control of if you're doing a skull base resection or a malignancy back in this area. Rarely, if you have a patient who has extremely hyperaerated sinuses, rarely, you - this artery can be dehiscent and hang down in the sinus and could be injured, but typically, it's going to be essentially, in front of the sphenoidotomy. So here's the face of the sphenoid plane right here, and right in front of that, you’re probably - this mucosa was up here - you’re prob - in order to see it, you’ll probably need to take that mucosa down, and you'll be able to see that running through the posterior ethmoid right there. If you want, you can kind of take the lamina down and expose this more intranasally. If you have an epistaxis patient where you're trying to control this artery - that is a procedure that's been described to do this endoscopically - is essentially identify the artery here, open the lamina here, and actually cauterize the artery on the orbital side, which I've never done that before because I think it's - it's a little crazy to do because of the risk of CSF leak. And usually, the shape of that person's nose when you get them into the operating room is not good, and so this is a lot easier because there's no bleeding right now. But basically, take down this part of the lamina, and isolate that artery - and you can clip it or cauterize it as the endoscopic way.
To me the more effective and pragmatic way is with an external approach, and it's a lot quicker, a lot safer, and you can do that with either using the old school Lynch incision, you can do an upper lid bleph approach, or you can do a transcaruncular approach. I don't do this often, but I prefer the upper lid bleph approach, which heals very well. So here, what I've done is I've just made an incision probably a little bit longer and - and higher than I normally would, but just - just cut into the upper lid. You're going to go through the skin. You're going to go through the orbicularis and the orbital septum. You’re going to get to this medial fat pad, and you're just going to reflect the fat pad medially. And you're going to identify the medial orbital wall here, and we're going to be behind - this is the level of the lacrimal sac here. So we're going to go in behind that posterior lacrimal crest, and we're going to get underneath the periosteum. We're going to elevate that back and get the same view of the artery but from - from laterally, and you can see, you know, it's a - it's a little bit easier to expose than endoscopically. There's going to be less bleeding. And so here you can put that artery on a stretch and clip it or cauterize it, so I prefer that approach for that. And then of course, you can elevate this all the way back and find that posterior ethmoid artery, optic nerve, and optic canal.