Posterior Ethmoidal Foramen Research Articles

Morphometry of the Bony Orbit and Periorbital Structures: Personal Perspectives From Decades of Related Research.

The author introduces his personal perspectives on the bony orbit, nerves, arteries, and ligaments relating to orbital re- construction surgery. A supraorbital fissure was 40.0 ± 2.5 mm from the supraorbital notch. Posterior ethmoidal foramen was 31.7 ± 3.0 mm from the anterior lacrimal crest. The infraorbital fissure, where the infraorbital groove started, was 26.4 ± 2.6 mm from the infraorbital foramen. The supraorbital fissure was 34.3 ± 2.7 mm from the frontozygomatic suture. The medial palpebral ligament consisted of 2 layers. The superficial layer of the palpebral ligament (SMPL) was from the anterior lacrimal crest to the upper and lower tarsal plates. The deep layer of the palpebral ligament (DMPL) lay from the anterior lacrimal crest to the posterior lacrimal crest, covering the lacrimal sac. Horner muscle was at the posterior lacrimal crest just lateral to the attachment of the DLPL and ran laterally to the tarsal plate deep to the SLPL. Three components of the lateral canthal area are: (1) lateral palpebral raphe, (2) superficial lateral palpebral ligament (SLPL), and (3) deep lateral palpebral ligament (DLPL). The lateral ends of superior and inferior orbicularis oculi muscles interlaced at the lateral commissure and formed the lateral palpebral raphe. The superficial lateral palpebral ligament extended from the lateral ends of the tarsal plate to the periosteum of the lateral orbital rim. The lateral palpebral ligament extended from the lateral ends of the tarsal plate deep to the origin of SLPL to the Whitnall tu- bercle on the zygomatic bone. The palpebral branch of the in- fraorbital artery emerged from the infraorbital foramen and ran superior and lateral to the orbital septum. After passing through the orbital septum, distributed to the orbital fat.

MORPHOMETRIC ANALYSIS OF ETHMOIDAL FORAMEN IN ADULT DRY INDIAN SKULL

Ethmoid bone is located in the anterior part of the base of the cranium between the orbits. The medial orbital wall separates the content of the orbit from the ethmoidal air sinuses. The anatomical landmarks of orbital cavities are very much important during orbital surgeries which includes surgery of anterior cranial fossa and endonasal microsurgeries of ethmoidal region. On this medial orbital wall, the anterior and the posterior ethmoidal foramina are located along the frontoethmoidal suture and more anteriorly to the optic canal and these are very much important in orbital surgeries. This prospective observational study was undertaken to study the morphology of Ethmoidal foramen in adult dry Indian skull and to study the clinical implications of ethmoid foramen. A total 50 dry adult skulls were measured for the ethmoidal foramen. It was reported that the mean of posterior ethmoidal canal right and left was 2.09±0.75mm and 2.31±0.132mm respectively. The study concluded that to ensure the safety of surgical procedures to be performed among ethmoid foramen it is very important to measure the various landmarks; as the anatomical variations can cause problems and leads to surgery related complications.

Are the Ethmoidal Foramina Through the Frontal Bone, Ethmoid Bone, or Frontoethmoidal Suture?

To investigate the locations of the anterior, middle, and posterior ethmoidal foramina and their relationships to the frontoethmoidal suture. One hundred twenty sides from sixty adult human skulls were used. Specimens with significant damage to the medial orbit wall were excluded. The number of ethmoidal foramina (anterior, middle, and posterior) on the medial orbital wall and the relationship of each foramen to the frontoethmoidal suture were recorded and classified as follows: Type I: superior to the frontoethmoidal suture; Type II: on the frontoethmoidal suture; Type III: inferior to the frontoethmoidal suture. Of the ninety-four sides, fourteen (14.9%) had one foramen, sixty-two (66.0%) had two , and eighteen (19.1%) had three. In total, 192 ethmoidal foramina were observed. Among the fourteen sides with one foramen, eight foramina were anterior and six were posterior. Among the 192 ethmoidal foramina, 162 were eligible for fur ther classification (74 anterior, 14 middle, and 74 posterior). Types I, II, and III ethmoidal foramina were found in 38.3% (62/162), 61.7% (100/162), and 0% (0/162), respectively. Our current study found a higher incidence of type I than previously reported. It is important to be aware of the significant incidence of foramen variations when the medial orbit wall is manipulated during surgery. Unless caution is observed, an inadvertent surgical injury can occur and lead to life-threatening complications. Therefore, a good understanding of orbital anatomy and its potential variations is critical for improving patient out comes.

Radiologic Evaluation of the Anterior and Posterior Ethmoidal Foramen and Optic Canal by Paranasal Sinus Computed Tomography Scan among Adult Filipinos

ABSTRACT Objective: To measure the average distances from anterior lacrimal crest (ALC) to anterior ethmoidal foramen (AEF), anterior ethmoidal foramen to posterior ethmoidal foramen (PEF) and posterior ethmoidal foramen to optic canal (OC) using plain paranasal sinus (PNS) computed tomography (CT) scans of adults in a tertiary private hospital in the Philippines. Methods: Design: Retrospective review of plain PNS CT scans Setting: Tertiary Private Teaching Hospital Participants: One hundred four (104) plain PNS CT scans from January 2018 to December 2020 were considered for inclusion. Results: Of the 104 PNS CT scans, 35 were excluded - seven for age less than eighteen, six for undistinguishable PEF and twenty-two for chronic rhinosinusitis. The remaining 69 PNS CT scans demonstrated identifiable structures, with overall average distances from ALC to AEF of 23.71 ± 2.43 mm, AEF to PEF of 10.87 ± 2.39 mm and PEF to OC of 7.39 ± 2.28 mm. Conclusion: Our study suggests average distances for localization of vital structures such as the anterior ethmoidal artery, posterior ethmoidal artery and optic nerve among Filipinos. Because of considerable variation between and within sexes, individual measurements should still be obtained for each patient in performing endonasal, skull base and orbital surgery.

The relationship between ethmoidal foramina and orbital fat herniation.

The aims of this study are to determine the incidence and more frequent localizations of orbital fat tissue herniation accompanying dehiscences in the medial orbital wall and to investigate the relationship between orbital fat tissue herniations and the anterior and posterior ethmoidal foramina. One thousand two hundred patients who had undergone computed tomography with a preliminary diagnosis of sinusitis and who had no previous facial, orbital, paranasal sinus surgeries or history of trauma were retrospectively analyzed. The localization of the ethmoidal foramina and orbital fat tissue herniations were marked. In patients with orbital fat tissue herniation, the relationship between the localization of orbital fat tissue herniation and the anterior and posterior ethmoidal foramina was investigated. The incidence of orbital adipose tissue herniation in our study was 7.9%. Of the 98 herniations on the bilateral medial orbital wall, 60 were in zone 3, and the most common herniation site was zone 3. A statistically significant difference was noted between the localization zone of the anterior ethmoidal foramen and the localization zones of orbital fat tissue herniations (Fisher's exact test, p < 0.001). Zone 3 is the weakest area of the medial orbital wall, and zone 3 is the most prone to herniation of fat tissue. The association of orbital fat tissue herniations with the anterior ethmoidal foramen is extremely common. Being cognizant of this finding may help a surgeon better estimate the anatomical view to be met before functional endoscopic sinus surgery as well as to minimize the risk of possible orbital complications, especially anterior ethmoidal artery injury.

A cadaveric study investigating the anatomy of the medial orbital wall.

The purpose of this study is to investigate the applicability of the current surgical guideline, known as ‘24-12-6’ surgical guideline, in the Hispanic and European populations. This guideline is used during numerous orbital surgeries and states that the distance between the anterior lacrimal crest (ALC) to the anterior ethmoidal foramen (AEF) (24 mm), the AEF to the posterior ethmoidal foramen (PEF) (12 mm), and the PEF to the optic canal (OC) (6 mm) follows a Rule of Halves. Previous studies suggest this surgical guideline is not applicable for all ethnicities; however, to our knowledge, no data has been published regarding the accuracy of this guideline pertaining to the Hispanic population. An experimental study was performed on 79 orbits (52 cadavers) donated to the Human Anatomy Program at UT Health San Antonio. The ALC, AEF, posterior ethmoidal foramen, and OC were identified; the orbit was enucleated and all remaining soft tissue removed. The distance between each landmark was recorded using a digital caliper. For all cadavers studied, the distances between the ALC, AEF, posterior ethmoidal foramen, and OC were 24.76 mm, 13.89 mm, and 7.61 mm, respectively. Thus, the ‘24-12-6’ surgical guideline was not applicable to the sample studied. Based on ethnicity data, these relationships were also not true for the European or the Hispanic populations. Therefore, significant anatomical variations exist in the current surgical guideline. Clinicians may need to adjust their methodology during surgical procedures in order to optimize patient care.

The relationship between ethmoidal foramina and orbital fat herniation.

The aims of this study are to determine the incidence and more frequent localizations of orbital fat tissue herniation accompanying dehiscences in the medial orbital wall and to investigate the relationship between orbital fat tissue herniations and the anterior and posterior ethmoidal foramina. One thousand two hundred patients who had undergone computed tomography with a preliminary diagnosis of sinusitis and who had no previous facial, orbital, paranasal sinus surgeries or history of trauma were retrospectively analyzed. The localization of the ethmoidal foramina and orbital fat tissue herniations were marked. In patients with orbital fat tissue herniation, the relationship between the localization of orbital fat tissue herniation and the anterior and posterior ethmoidal foramina was investigated. The incidence of orbital adipose tissue herniation in our study was 7.9%. Of the 98 herniations on the bilateral medial orbital wall, 60 were in zone 3, and the most common herniation site was zone 3. A statistically significant difference was noted between the localization zone of the anterior ethmoidal foramen and the localization zones of orbital fat tissue herniations (Fisher's exact test, p < 0.001). Zone 3 is the weakest area of the medial orbital wall, and zone 3 is the most prone to herniation of fat tissue. The association of orbital fat tissue herniations with the anterior ethmoidal foramen is extremely common. Being cognizant of this finding may help a surgeon better estimate the anatomical view to be met before functional endoscopic sinus surgery as well as to minimize the risk of possible orbital complications, especially anterior ethmoidal artery injury.

A Cadaveric Study of Skeletal Facial Foramina in the Hispanic/Latino Population

Clinicians currently follow two surgical guidelines involving skeletal features of the orbit and face to optimize patient care. The first guideline states that along the medial wall of the orbit, the distances between the anterior lacrimal crest, anterior ethmoidal foramen, posterior ethmoidal foramen, and optic canal, follow a “24‐12‐6”mm guideline. The second guideline states that the supraorbital foramen/notch, infraorbital foramen, and mental foramen are equidistant from the midline. Previous studies suggest these two surgical guidelines are not applicable for all ethnicities; however, to our knowledge, no data has been published regarding the accuracy of these guidelines pertaining to the Hispanic/Latino population. A cadaveric study was performed to investigate these skeletal guidelines in the Hispanic/Latino population. Adult male and female cadavers, with no evidence of trauma to the orbit and face, donated to the Human Anatomy Program at UT Health San Antonio were used for this study. To investigate the medial orbital wall “24‐12‐6” guideline, distances between four orbital landmarks (anterior lacrimal crest, anterior and posterior ethmoidal foramina, and optic canal) were measured using a 26‐gauge wire and a Vernier caliper. To investigate whether the supraorbital, infraorbital, and mental foramen, lie within the same sagittal plane, we used a Vernier caliper to measure the distance between each foramen to midline. Our preliminary findings suggest these surgical guidelines may not accurately describe the morphologic characteristics of the Hispanic/Latino bony orbit and face. Preliminary results to date indicate the average distances from the anterior lacrimal crest to the anterior ethmoidal foramen, the anterior ethmoidal foramen to the posterior ethmoidal foramen, and the posterior ethmoidal foramen to the optic canal for Hispanic/Latino orbits (n =5) were 24.4 mm (± 0.686), 16.2 mm (± 2.190), 7.4 mm (± 0.661) respectively. This suggests the anatomy of the Hispanic/Latino boney orbit may differ from the currently accepted “24‐12‐6” surgical guideline. Meanwhile, preliminary data also indicates the average distances from the midline to the supraorbital foramen/notch, infraorbital foramen, and mental foramen for all cadavers studied (94 hemifaces, 47 cadavers) were 26.07 mm (± 3.88), 29.12 mm (± 4.30), 25.46 mm (± 3.15) respectively. This also suggests the currently practiced guideline may not apply to the Hispanic/Latino population. To optimize patient care, it is critical clinicians are aware of ethnic difference between anatomical structures. Our preliminary data is the first to report specific anatomical relationships in the medial orbital wall and facial foramina in the Hispanic/Latino population.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

An Applied Anatomical Study of the Ethmoidal Arteries: Computed Tomographic and Direct Measurements in Human Cadavers.

Computed tomography (CT) images have been used in very few studies on distances to the ethmoidal arteries in the orbit. Most other studies have included direct measurements on cadavers and frequently quote the 24-12-6 mm rule to describe distances from the anterior lacrimal crest to the anterior and posterior ethmoidal foramina (AEF and PEF), optic canal (OC), respectively. However, the large interindividual variation of distances renders absolute values less applicable in a clinical setting. Preoperative measurements on CT images may provide more precise distances than absolute rules and thus lead to safer orbital surgery. The authors hypothesize that the distances to the ethmoidal arteries and the length of the medial wall are positively correlated and that measurements of the distances from the posterior lacrimal crest (PLC) on CT images are feasible with a low intra- and interobserver variability.Fifty intact orbits from 25 Caucasian cadavers were exenterated and examined. In additional, high-resolution CT scans of 48 orbits from 24 other Caucasian nonexenterated cadavers were examined. Distances were measured from 4 different anterior landmarks to the AEF and PEF and the OC.Distances from the most anterior landmarks to the arteries were positively correlated with the length of the medial wall. Measurements of the distances from the PLC to the ethmoidal arteries on CT images were feasible with a low intra- and interobserver variability. In conclusion, iatrogenic damage to the ethmoidal arteries in the orbit may be best avoided by using CT measurements in presurgical planning.

Orbital Morphometry: A Computed Tomography Analysis.

The human orbit is a complex anatomic region, which plays predominant role in the evaluation of craniofacial complex. A thorough understanding of the relationship of the distance from orbital rim to the important vital structures of the orbital apex is required for the surgeon to perform safe and effective surgery. To evaluate and compare the depth and distances from various points of the orbital rim to the fissures and foramina of the orbital apex between genders in the local population. Linear measurements were conducted on 60 orbits from 30 patients who had undergone head computed tomography scan. These measurements were done utilizing the multiplanar reconstruction modes on computed tomography images with minimum slice thickness of 1 mm. Males have statistically significant larger orbits than females with higher mean measurements in all parameters, except for the distance from posterior ethmoidal foramen to the optic canal which was the same. However, there were no significant differences in all parameters between the right and left orbits. This study provides the absolute limit of safe internal orbital dissection in respect to the local population. Despite males having larger orbits than females, it is clinically negligible.

Predictability of Optic Foramen Location From a Ray Through the Ethmoidal Foramina.

To determine how accurately a ray through the anterior and posterior ethmoidal foramina predicts the location of the optic foramen. Dried, well-preserved, complete human skulls without bony defects belonging to the Hamann-Todd osteological collection of the Cleveland Museum of Natural History were examined. Photography was performed and a ray was drawn on orbit photographs extending through the center of the anterior and posterior ethmoidal foramina toward the optic canal. The location of the ray at the anterior aspect of the optic canal was recorded. Sixty-six total orbits were examined from 36 skulls with 6 skulls with only unilateral data. Thirty-eight orbits were of African descent and 28 were of European descent with an average age 45.25 years (range = 19-89 years). The anterior-posterior ethmoidal foramen ray extended superior (12/66), through (53/66), and inferior (1/66) to the optic canal. Of those rays passing through the optic canal, 32/53 (60%) passed through the upper one-third, 19/53 (36%) passed through the middle one-third, and 2/53 (4%) passed through the lower one-third of the optic canal. The anterior-posterior ethmoidal foramen ray highly predicts the superior aspect of the optic canal. This information can guide medial orbital wall surgery.

Positional Relationship of Ethmoidal Foramens With Reference to the Nasion and Its Significance in Orbital Surgery.

The aim of the study was to elucidate the positional relationship of the ethmoidal foramens (EFs) with reference to the nasion to facilitate prediction of the exact location of EFs, the optic canal (OC), and the frontoethmoidal suture (FS), and thereby avoid complications during complex surgery involving the medial wall of the orbit. One hundred two intact orbits of 57 embalmed cadavers were dissected in this observational anatomic study. Nasion' (N') was defined as the intersection point of the medial orbit margin with the horizontal line through the nasion, and this was used as a reference point. N'-OC was defined as the straight line joining N' and OC. The locations of the anterior ethmoidal foramen (AEF), posterior ethmoidal foramen (PEF), and OC were determined with reference to N'. The vertical distances from N'-OC to EFs and to FS were also determined. The N'-AEF, AEF-PEF, and PEF-OC distances were 18.4, 15.3, and 8.3 mm, respectively. Vertically, AEF and PEF were situated at 0.2 mm below and 0.4 mm above N'-OC, respectively. At the same reference points, N'-OC was situated at 0.4 and 0.6 mm above FS, respectively. N', AEF, PEF, and OC were considered to be situated on the same straight line, and N'-OC could be regarded as coinciding with FS. This means that N' is an easily identifiable and reliable landmark for identifying EFs, OC, and FS. Our navigational parameters with reference to N' will help surgeons to enhance the safety of orbital surgery.

The orbit: A re-appraisal of the surgical landmarks of the medial and lateral walls.

The anterior ethmoidal foramen (AEF) and posterior ethmoidal foramina (AEF and PEF, respectively) on the medial wall and the cranio-orbital foramen (COF) on the lateral wall are used as landmarks in orbital surgeries. In surgery these foramina, the neurovascular structures they transmit and other orbital structures in close proximity need to be identified to minimise their risk of damage. Despite the clinical importance, the current understandings lack consistency in the precise location, microanatomy and morphology of the foramina. This study therefore aimed to document and analyze the microanatomy, location, and morphometric relations of the EF and COF to determine a standardized guideline to accessing the foramina. One hundred dry orbits were morphometrically analyzed, and a further six orbits were micro-dissected to determine the locations of the EF and COF. The orbital size dimensions were measured for each dry orbit and correlated with the morphometric distances. A complete morphometric and quantitative analysis showed the distances of the EF and COF to be variable, with greater variations observed in the incidence of the accessory EF and PEF distances in the medial wall, and in the presence of the COF and the accessory COF in the lateral orbital wall. Significant correlations were observed between the length of the medial orbital wall and some EF distances. This study is the first to suggest a standardized method of locating these foramina in the orbit irrespective of population and sex differences, in order to help improve clinical applications in crucial orbital surgeries. Clin. Anat. 29:998-1010, 2016. © 2016 Wiley Periodicals, Inc.

An osteologic study of human ethmoidal foramina with special reference to their classification and symmetry.

The present investigation was designed to study the anatomy of the ethmoidal foramina in adult human dry skulls. In addition to investigate the number of ethmoidal foramina that can be found on the orbital wall, we also addressed their classification and symmetry. The analy- sis of 1089 orbits demonstrated that the average number of ethmoidal foramina/orbit was 2.07 (range 0 to 4). As for their classification, we devised the relative depth index (RDI) to differenti- ate the anterior from the posterior ethmoidal foramina. The index represents the ratio "distance of the foramen from the anterior lacrimal crest/length of the medial orbital wall". The average index of the anterior and posterior ethmoidal foramina were 0.53±0.04 and 0.84±0.06 respective- ly. As the mean of the two indexes was 0.685, we used the latter value as a sort of numerical watershed to define the domains of the anterior and of the posterior ethmoidal foramina on the orbital wall. Thus all ethmoidal foramina with an RDI : 0.68 were considered anterior ethmoi- dal foramina and all ethmoidal foramina with an RDI 0.69 were considered posterior ethmoi- dal foramina. In this way it is possible to properly classify foramina on orbits with 1,.3 or 4 ethmoidal foramina. As for their symmetry, in contrast to what had been previously reported, we observed that in most cases ethmoidal foramina have a highly symmetric arrangement both in terms of number of foramina on fellow orbits and of position along the orbital wall.

The Surgical Relevance of a Histological Investigation into the Accessory Ethmoidal Foramina and their Contents in a Caucasian Population

Aims: It is the objective of this article to investigate the accessory ethmoidal foramina, located in the medial wall of the orbit, adjacent to the anterior and posterior ethmoidal foramina. Previous studies have shown that there is significant variation in the number and location of the fronto-ethmoidal foramina, causing potential complications during surgery. This study aims to identify accessory foramina in cadaveric orbits, and, using histological staining, further identify any structures passing through the foramina. Methods: Thirty cadaveric orbits from Caucasians were dissected. The number and locations of the accessory foramina in the medial wall were noted. All orbits containing accessory foramina in the medial wall were stained with Sudan black dye, micro-dissected, and microscopically analysed. Results: Accessory foramina were found in twelve orbits. All accessory foramina showed evidence of vasculature. Three orbits had less than five accessory foramina, four orbits presented with five accessory foramina, six accessory foramina presented in four cases, and in one case eight accessory foramina were present. Underdocumented vasculature was found traversing these foramina. Conclusion: This study highlights the occurrence and variations of accessory ethmoidal foramina in a Caucasian population, and presents their vascular contents. Ophthalmic and ENT surgeons operating on, or in proximity to, the medial wall must be aware of these communicating blood vessels when operating on Caucasian patients. This aims to reduce the risk of intra-operative or post-operative complications, especially in anti-coagulated patients or those with bleeding disorders.

Clinical and surgical implications regarding morphometric variations of the medial wall of the orbit in relation to age and gender.

The ethmoidal foramens are located on the medial wall of the orbit and are key reference points for intraoperative orientation. Detailed knowledge of the anatomy, bony landmarks and morphometric characteristics of the medial wall of the orbit is essential for various surgical procedures. The aim of this study was to determine the morphometric variations in the medial wall of the orbit and establish significant variations regarding age and gender. A total of 110 orbits were analyzed and subdivided by age (over or under 40years) and gender. The distances of the medial wall of the orbit between the anterior lacrimal crest, the ethmoidal foramen, the optic canal and the interforamina were determined. Safe surgical areas were sought. Statistical tests were used to determine the differences between groups. In men, there is a safe surgical area proximal to the anterior and posterior ethmoidal foramen. In women, this area is in the posterior third of the medial wall of the orbit between the posterior ethmoidal foramen and the optic canal. Regarding variation according to age, the results of this study suggested that the anteroposterior diameter of the medial wall increases with age. This study showed that the anteroposterior total length of the medial orbit wall is similar between genders of similar age, increases with age, and has significant variations in the distances between the various structures that make up the medial orbit wall with regard to gender and age.

Medial Orbital Wall Landmarks in Three Different North American Populations

Purpose: We sought to measure the medial orbital wall foramina distances in two previously unstudied populations, to describe a new bony medial wall feature, and to validate the accuracy of a new coordinate measurement device within the orbit.Methods: Dried, well-preserved, complete human skulls without orbital defects were studied. Age, gender, birthplace, ethnicity, and laterality of the orbit were recorded for each skull. Supranumerary ethmoidal foramina were recorded, and the fronto-ethmoidal groove depth was measured. The distances between the anterior lacrimal crest (ALC) – anterior ethmoidal foramen (AEF), AEF – posterior ethmoidal foramen (PEF), and PEF – optic canal (OC) were measured first by surgical ruler and wire and then by the Microscribe coordinate measurement device.Results: One hundred and forty-six orbits were studied. Fifty-seven orbits were of European or Caucasian descent, 68 orbits of African American descent, 2 orbits of West African descent, 11 orbits of Eskimo descent, and 8 orbits of unknown origin. No significant differences existed between the manual and Microscribe measurements for the ALC-AEF, AEF-PEF, and PEF-OF distances (p < 0.0001). A significant frontoethmoidal groove was observed in 27/146 (19%) orbits, in 6/57 (11%) Caucasian orbits, in 17/70 (24%) African American orbits, and in 4/11 (36%) Eskimo orbits. Supranumerary ethmoidal foramina were found in 50/146 orbits (34.2%) and in 17/27 (63%) orbits with a significant frontoethmoidal grooves.Conclusions: No significant differences in medial wall foramina distances exist between African American and Caucasian orbits; however, a frontoethmoidal groove occurs more commonly in African American orbits. This groove often occurs in the presence of supernumerary ethmoidal foramina. The Microscribe coordinate measurement system represents a valid tool to measure distances within the orbit.

Three-dimensional evaluation of the danger zone of ethmoidal foramens on the frontoethmoidal suture line on the medial orbital wall.

It is clear that the importance of the ethmoidal foramen (EF) is based on its vascular contents. The frontoethmoidal suture (FS) line is recommended as more reliable navigational landmark for identifying the EF. The vertical orientation between the EF and the FS line was studied in 188 orbits using a computer software program. 146 anterior EFs (77.7 %) and 42 anterior EFs (22.3 %) were situated in the FS line as intrasutural and extrasutural, respectively. 146 posterior EFs (77.25 %) and 8 posterior EFs (4.25 %) were presented as intrasutural and extrasutural, respectively. Although accessory EFs were detected in 25.5 % specimen exhibited an extrasutural location. Majority of the EFs (1-4 EFs) were situated on the FS line. The mean distances from the FS and the anterior EF, the posterior EF and the accessory EF were measured as 2.1 ± 0.5, 2.0 ± 1.5 and 2.3 ± 1.2 mm, respectively. The range of the distances from the FS to the anterior EF, posterior EF and accessory EF were -1.2 to 3.32 , -1.02 to 5.76 and -1.1 to 3.65 mm, respectively. The ranges of EF changed within 1-6 mm. As the FS is not a single point, it is more suitable to make the incision 7 mm above the suture line. The data from this study to help the orbital surgeons explain and avoid unexpected hemorrhage during the orbital procedures such as posttraumatic orbital reconstruction, orbital tumor resections, anterior skull base reconstruction, and orbital decompression surgery.

Morphometric study of the medial orbital wall emphasizing the ethmoidal foramina.

Ethmoidal foramina on the medial orbital wall show a higher incidence of variation. Surgeons performing endonasal, anterior cranial fossa and medial orbital wall surgeries must be aware of these variations as they are a source of hemorrhage and also serve as landmark in proximity to the orbital apex. The present study aims to describe the morphometric distances of various ethmoidal foramina between anterior lacrimal crest to optic canal in south Indian dry human skulls. The study was done on 44 adult dry human skulls. The occurrence of Ethmoidal foramina was noted by direct inspection. The distance of Ethmoidal foramina from anterior lacrimal crest to optic canal was measured with the help of ruler, probe and magnifying glass. The Posterior ethmoidal foramina were found in all 44 skulls bilaterally. Middle ethmoidal foramen was present in 12 and 13 skulls on right and left, respectively. Anterior ethmoidal foramen was found in 38 and 37 skulls on right and left, respectively. The distance between anterior lacrimal crest (ALC) and posterior lacrimal crest (PLC) was in the range of 3-8 mm and that of ALC to anterior ethmoidal foramen was in the range of 24-30 mm. The range of distance between anterior ethmoidal foramen to posterior ethmoidal foramen was 9-17 mm and that between posterior ethmoidal foramen to optic canal was 5-13 mm. These observations would help to predict the anatomical variations in the position of ethmoidal foramina with respect to anterior and posterior lacrimal crest and ensure the safe and precise performance of medial orbital wall surgeries to avoid injuries to the important neurovascular bundles passing through various foramina and fissures.

Computer-assisted analysis of anatomical relationships of the ethmoidal foramina and optic canal along the medial orbital wall

Typically, the medial orbital wall contains an anterior ethmoidal foramen (EF) and a posterior EF, but may also have multiple EFs transmitting the arteries and nerves between the orbit and the anterior cranial fossa. The aim of this study is to determine a patient-friendly landmark of the medial orbital wall and to specify a precise location of the ethmoidal foramens (EF) in order to standardize certain anatomical marks as safe ethmoidal arteries. Orientation points on the anterior ethmoidal foramen (AEF), posterior ethmoidal foramen (PEF) and middle ethmoidal foramen (MEF) were investigated in 262 orbits. Using a software program, distances between each foramen and the midpoint of the anterior lacrimal crest (ALC), the optic canal (OC), and some important angles were measured. The EFs were identified as single in 0.8%, double in 73.7%, triple 24,4% and quadruple in 1.1% specimens. The mean distances between ALC and AEF, ALC and PEF and ALC and MEF were 27.7, 10.6, and 12.95 mm, respectively. The distances from ALC-AEF, AEF-PEF, and PEF-OC were 27.7 ± 2.8, 10.6 ± 3.3, 5.4 ± 1 mm. The angles from the plane of the EF to the medial border of the OC were calculated as 13.2° and 153°, respectively. The angle from the AEF to the medial border of the OC was based on the plane between the ALC and AEF was 132°. The occurrence of multiple EF with an incidence of 25% narrows the borders of the safe region in the medial orbital wall. Safe distance of the ALC-EF was measured as 22.1 mm on medial wall. The line of the location of the EF was calculated 16.2 mm. In this study, it was possible to investigate the variability of the orbital orifice of the EF and the feasibility of the EA, to observe various angles of the orbital wall bones and to calculate the lengths of some parameters with the help of certain software.