Since the ethmoid bone forms part of the orbit, it is associated with seven extraocular muscles. All but the inferior oblique arise from the orbital apex. The inferior oblique arises from the orbit floor near the orbital rim while the rectus muscles arise from the annulus of Zinn. All of the extraocular muscles have an insertion to the globe apart from the levator palpebrae superioris, which expands to form the levator aponeurosis.[8] 

Of all the paranasal sinuses, the ethmoid sinus is the most complex and most variable. The roof of the ethmoid bone labyrinth consists of the fovea ethmoidalis, and the olfactory fossae are grooves on the cribriform plate within the ethmoid bone.[9] Keros categorized the depth of the olfactory fossa into three types: Type I, which has a depth of 1 to 3 mm, Type II, which has a depth of 4 to 7 mm and Type III, which has a depth of 8 to 16 mm.[10] The greater the height of the lateral lamella, the greater the risk of its perforation into the anterior cranial fossa.[10] The ethmoid roof also varies in different populations. For instance, Alazzawi et al. found that, among 150 cases from Malaysia, China, and India, 80% of the specimens were Keros Type I and 20% of were Keros Type II. Keros Type II was also more common in males than in females.[11] However, Solares et al. discovered, among 50 CT scans in the United States, 83% of the specimens were Keros Type I, 15% were Type II, and 2% were Type III.[12]

The depth of the cribriform plate has also shown to be different in various ethnic groups. For instance, Meloni et al. found that the cribriform plate has an average depth of 5.9 mm among Italian subjects.[13] Alazzawi et al. discovered the left lateral cribriform plate has an average height of 2.64 mm among three ethnic groups in Malaysia.[11] Kaplanoglu et al. found, among 500 CT scans from Turkish patients, the left lateral cribriform plate has an average height of 4.92mm.[9]

The uncinate process, which is the sickle-shaped portion of the ethmoid bone, also has multiple variations among different patients. Its superior attachment has three major variants[14]:

1. The uncinate process could extend laterally to the lamina papyracea or ethmoid bulla to generate a nook at the end of the infundibulum; this is the most common variation found in patients.
2. The uncinate process could extend medially to the lateral region of the middle turbinate, with the frontal recess going into the infundibulum.
3. The uncinate process could extend medially and superiorly to the base of the skull, with the frontal recess going into the infundibulum.

Knowledge of the anatomic structures and variations of the ethmoid bone and paranasal sinuses is critical for avoiding complications during endoscopic sinus surgery.[9] Complications may occur in endoscopic sinus surgeries because it is a complex procedure. Minor complications can include hemorrhage, infection, cohesion, obstruction/narrowness of the ostium, topognosis/insensitivity in the teeth or lips, and disease relapse.[9] Major complications include cerebrospinal fluid leakage, ocular traumatization, meningitis, and intracranial vascular traumatization.[9] Surgeons should investigate anatomic variations among their patients using preoperative CT examination. In addition to the anatomic variations mentioned previously, some other variations may involve areas around the ethmoid bone, such as the supraorbital recess, concha bullosa, Haller cells, Onodi cells, and pneumatization of the uncinate process.[15]

The ethmoid bone is important in the structural formation of the skull and has a protective role in the human body. The cribriform plate allows the olfactory nerve to pass through from the nasal chamber into the skull. Pneumatized ethmoid air cells ensure structural stability, resist fractures within the medial wall of the orbit, and protect the eyeball during trauma.[16] Orbital fractures are associated with many aesthetic defects, such as enophthalmos, diplopia, facial asymmetry, hypertelorism, and dystopia. Enophthalmos, which is the backward and downward displacement of the globe into the bony orbit, happens more commonly when the lamina papyracea is fractured and when there is herniation of the orbital content in the ethmoid.[17] Since the naso-orbital-ethmoid (NOE) complex is a delicate anatomic structure, clinical examination and radiographic analysis are critical to assess the position of the globe relative to the orbital rim, eyelid rim, and other facial structures.[18] NOE injuries may originate from direct blows during altercations or motor vehicle accidents, and pupillary discrepancies, retrobulbar hematoma, and optic nerve damage must be ruled out in such injuries.[18] 

Ethmoid fractures may result in delayed complications even years after trauma; however, such cases are relatively rare. These complications include meningitis, recurrence of cerebrospinal fluid rhinorrhea, and delayed cerebrospinal fluid rhinorrhea onset. A previous study found that patients with these complications often have large ethmoid bone defects and often have normal radiological assessments after trauma. With successful surgical repair, these patients were well after follow-up.[19]  

Patients with inflammation of the ethmoid bone may have osteitis of the ethmoid bone and chronic rhinosinusitis. Chronic rhinosinusitis occurs when the nasal and paranasal sinus mucosa becomes inflamed for longer than three months without complete symptom resolution, and functional endoscopic sinus surgery (FESS) is the treatment for this condition.[20] The purpose of FESS is to open up the sinus air cells and sinus ostia with an endoscope.[21] CT scans of patients with chronic rhinosinusitis have shown to have areas of increased bone density and irregular thickening of the sinus walls, which could result in recurrence of the disease after surgical treatment and serve as sources of chronic inflammation.[22][23][24] Previous studies suggested patients undergoing endoscopic sinus surgery for chronic rhinosinusitis may have osteitis of the ethmoid bone, and the prevalence could be as high as 64%.[25][26][27] Meningitis or abscess related to osteomyelitis with the ethmoid bone may also result in anosmia or taste disturbances.[28]