Ethmoidal Foramen Research Articles

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.

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.

The forgotten foramina: a study of the anterior cribriform plate.

The olfactory cleft has garnered interest since the advent of endoscopic skull base surgery. Its precise anatomy, however, is still partially unknown. According to Rouvière, an "ethmoidal foramen" is located in its antero-medial part and contains a process of the dura mater. In a more lateral and anterior location, a second foramen, the "cribroethmoidal foramen", contains the anterior ethmoidal nerve. The aim of this study was to verify the existence of these elements and to establish landmarks for surgery. We performed an anatomical and histological study of eight olfactory clefts in four cadavers using both endonasal endoscopic and endocranial dissection. An ethmoidal and a cribroethmoidal foramen were found in, respectively, 100 and 75% of cases. Their mean length was, respectively, 4.1 and 1.8 mm. They were located, respectively, in mean at 5.3 and 5.8 mm from the anterior ethmoidal artery. Our anatomical study demonstrates the existence of both foramina. The ethmoidal foramen clearly represents an area of least resistance in the anterior part of the olfactory cleft, which could predispose to anterior skull base cerebrospinal fluid leaks and meningoceles.

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.

Anatomy of anterior ethmoidal foramen, medial canthal tendon, and lacrimal fossa for transcutaneous anterior ethmoidal nerve block in Japanese individuals.

To examine the anatomical relationships of the anterior ethmoidal foramen (AEF), medial canthal tendon (MCT), and lacrimal fossa (LF) in Japanese individuals. Thirty-eight orbits from 19 Japanese cadavers (7 men and 12 women; average age at death, 89.3 years) were used in this experimental anatomical study. The AEF, MCT, and superior border of the LF were exposed. The following distances were then measured: 1) from the point at the medial orbital rim directly anterior to the AEF to the superior border of the MCT (AEF-MCT), and 2) from the superior border of the LF to the superior border of the MCT (LF-MCT). (AEF-MCT) and (LF-MCT) distances were 9.40±1.92 (mean±standard deviation) and 4.21±1.18 mm, respectively. No values of (LF-MCT) exceeded the mean (AEF-MCT) (9.40 mm). The transcutaneous anterior ethmoidal nerve block can be reliably performed without injury to the lacrimal sac by inserting a needle approximately 9 mm superior to the superior border of the MCT.

The superior ophthalmic vein: delineation with high-resolution magnetic resonance imaging.

To delineate the superior ophthalmic vein (SOV) with high-resolution magnetic resonance (MR) imaging. This retrospective study enrolled 302 consecutive outpatients, 101 patients, 51 males and 50 females, who underwent coronal T2-weighted imaging and 201 patients, 99 males and 102 females, who underwent three-dimensional (3D) phase-contrast (PC) MR angiography. Coronal T2-weighted imaging clearly delineated the intraorbital course of SOV on serial images in all 101 subjects. The SOV could be topographically divided into three segments in relation to the superior rectus muscle. The SOV crossed over the optic nerve at the level of the anterior ethmoidal foramina in 87% of right orbits and 71% of left orbits. The mean outer diameter of the SOV at the crossing point was 1.7 mm on both sides, but the SOVs were asymmetric in the same individual in 75% of the subjects. 3D PC MR angiography showed that the bilateral SOVs were symmetrical in 16% of subjects, larger in the right orbit in 18%, and larger in the left orbit in 13%, and were unidentified in 52%. The SOV showed a consistent lateral course to the ophthalmic artery. The SOV consistently courses lateral to the ophthalmic artery, but tends to show bilateral asymmetry in the outer diameter. The superior rectus muscle, anterior ethmoidal foramen, and anterior ethmoidal artery are valuable landmarks to identify the SOV during transcranial orbital surgery. Combination of high-resolution MR imaging and 3D PC MR angiography is useful for delineating the SOV.

The Nerve Supply to the Eye of the Yak (Bos Grunniens) in the Qinghai-Tibetan Plateau

Fifteen head specimens of the yak (Bos grunniens) were dissected to study the anatomical characteristics of the nerves supplied to a yak's eye. In the orbit, the optic nerve was “S” shaped and received 1–2 twigs from the ciliary ganglion. The ciliary ganglion was a grayish fusiform structure, located between the ventral branch of oculomotor nerve and retractor bulbi muscle, which gave off 2–3 long ciliary nerves—one penetrated the sclera, and the others penetrated into the optic nerve. In addition, there were 3–4 communicating branches from the nasociliary nerve and the ventral branch of the oculomotor nerve. The oculomotor nerve divided into dorsal and ventral branches; the dorsal branch divided into 4–6 twigs, two of which supplied the rectus dorsalis muscle and the others supplied levator palpebra superioris. The ventral branch furnished 3–5 twigs to the rectus medialis and ventralis muscles. After it received a branch from the maxillary nerve, it finally supplied the obliquus ventralis muscle. The trochlear nerve supplied the obliquus dorsalis muscle. The ophthalmic nerve divided into zygomaticotemporal, frontal sinus, and nasociliary nerves. After the zygomaticotemporal branch received a branch of maxillary nerve, it supplied the skin of the temporal region, the lacrimal gland and the upper eyelid; the frontal nerve supplied the lateral portion of upper eyelid; the nasociliary nerve divided into ethmoidal and infratrochlear nerves. The ethmoidal nerve penetrated the ethmoidal foramen, and the infratrochlear nerve supplied the upper eyelid and skin of the frontal region. The abducent nerve supplied the rectus lateral and retractor bulbi muscles. Therefore, the yak does not have accessory ciliary ganglion.

An Anatomical Study of the Positional Relationship Between the Ethmoidal Foramina and the Frontoethmoidal Suture

To examine the positional relationship between the ethmoidal foramina and the frontoethmoidal suture. Eighty-four orbits of 42 Japanese cadavers (24 male and 18 female cadavers; average age at death, 81.0 years; range, 61-101 years), fixed in 10% buffered formalin, were used for investigation. The most anterior or posterior ethmoidal foramen was defined as the anterior or posterior ethmoidal foramen, respectively. All the intermediate foramina were determined as the accessory foramina. The vertical distances from the frontoethmoidal suture to the anterior, posterior, and accessory ethmoidal foramina were examined. Seventeen anterior ethmoidal foramina (20.2%) were situated above the frontoethmoidal suture (mean distance, 1.8 mm), and 2 posterior ethmoidal foramina (2.3%) were situated at 1.0 mm and 1.5 mm above the suture. Although accessory ethmoidal foramina were detected in 32 orbits (38.1%), one accessory foramen (middle ethmoidal foramen) was identified in 30 orbits, and 2 foramina (additional deep-middle ethmoidal foramina), in 2 orbits. One middle ethmoidal foramen (3.1%) and 1 deep-middle ethmoidal foramen (50.0%) were located at 1.5 mm above the suture. In total, 2 of the 34 accessory ethmoidal foramina (5.9%) exhibited the extrasutural location. Several ethmoidal foramina were situated above the frontoethmoidal suture. The anterior ethmoidal foramen most frequently showed the situation, followed by the accessory and posterior foramina, in order. Our findings help predict the anatomical variations in the location of the ethmoidal foramina in relation to the frontoethmoidal suture, thereby enhancing safety for medial orbital wall surgery.

Is there any relationship between the frontal cell and the Agger nasi cell and the localization of the anterior ethmoid artery?

In this article, we examined the effect of the presence or absence of a frontal cell or an Agger nasi cell on the localization of the anterior ethmoid artery. Coronal paranasal sinus computed tomography scans on 110 sides of 61 patients (35 males, 26 females; mean age 35.6 ± 12.7 years; range 15 to 72 years) who underwent surgery for septal deviation, concha bullosa, antrochoanal polyp between September 2006 and February 2008 were retrospectively evaluated and the anterior ethmoid foramen localization was measured according to the anterior nasal spine. The correlations of these measurements with the presence and absence of a frontal cell and an Agger nasi cell were investigated. The measurement of the anterior ethmoidal foramen according to anterior nasal spine was 18.2 ± 8.8 mm in the absence of an Agger nasi cell and was 20.3 ± 6.6 mm in the presence of an Agger nasi cell. This distance was measured as 20.0 ± 7.3 mm when the frontal cell was not determined. This measurement was 20.2 ± 6.5 mm in the presence of a frontal cell. According to the frontal cell types the results of the measurements were 20.5 ± 5.9 mm, 18.9 ± 8 mm, 20.6 ± 7.3 mm, for type 1, type 2 and type 3, respectively. Our results revealed that there were no significant relationship between the presence or absence of a frontal cell and an Agger nasi cell and the localization of the anterior ethmoidal foramen. The results of this study showed that the presence or absence of these cells does not affect localization of the anterior ethmoid artery.

Level I to III craniofacial approaches based on Barrow classification for treatment of skull base meningiomas: surgical technique, microsurgical anatomy, and case illustrations

Although craniofacial approaches to the midline skull base have been defined and surgical results have been published, clear descriptions of these complex approaches in a step-wise manner are lacking. The objective of this study is to demonstrate the surgical technique of craniofacial approaches based on Barrow classification (Levels I-III) and to study the microsurgical anatomy pertinent to these complex craniofacial approaches. Ten adult cadaveric heads perfused with colored silicone and 24 dry human skulls were used to study the microsurgical anatomy and to demonstrate craniofacial approaches in a step-wise manner. In addition to cadaveric studies, case illustrations of anterior skull base meningiomas were presented to demonstrate the clinical application of the first 3 (Levels I-III) approaches. Cadaveric head dissection was performed in 10 heads using craniofacial approaches. Ethmoid and sphenoid sinuses, cribriform plate, orbit, planum sphenoidale, clivus, sellar, and parasellar regions were shown at Levels I, II, and III. In 24 human dry skulls (48 sides), a supraorbital notch (85.4%) was observed more frequently than the supraorbital foramen (14.6%). The mean distance between the supraorbital foramen notch to the midline was 21.9 mm on the right side and 21.8 mm on the left. By accepting the middle point of the nasofrontal suture as a landmark, the mean distances to the anterior ethmoidal foramen from the middle point of this suture were 32 mm on the right side and 34 mm on the left. The mean distance between the anterior and posterior ethmoidal foramina was 12.3 mm on both sides; the mean distance between the posterior ethmoidal foramen and distal opening of the optic canal was 7.1 mm on the right side and 7.3 mm on the left. Barrow classification is a simple and stepwise system to better understand the surgical anatomy and refine the techniques in performing these complex craniofacial approaches. On the other hand, thorough anatomical knowledge of the midline skull base and variations of the neurovascular structures is crucial to perform successful craniofacial approaches.

A cadaveric study of ethmoidal foramina variation and its surgical significance in Caucasians

AimsTo describe the morphometric and geometric relationships of the medial orbital wall ethmoidal foramina and the orbital apex in a Caucasian population.Methods47 orbits from 24 formalin-fixed cadavers were exenterated. Morphometric...

Accessory Ethmoidal Foramina: An Anatomical Study

To examine the distances between the anterior lacrimal crest and the anterior, posterior, and accessory ethmoidal foramina and the optic canal in adult cadavers. Fifty-four orbits from 27 Japanese cadavers (17 male and 10 female; average age at death, 79.7 years; range, 61-96 years) had previously been fixed in 10% buffered formalin before use. The shallowest and deepest ethmoidal foramina were defined as the anterior and posterior ethmoidal foramina, respectively, and all intermediate foramina were defined as accessory foramina. The distances from the anterior lacrimal crest to the accessory, anterior, and posterior ethmoidal foramina and to the optic canal were examined. Accessory ethmoidal foramina were detected in 18 orbits (33.3%) from 11 cadavers; one accessory foramen (middle ethmoidal foramen) was identified in 17 orbits and 2 foramina (additional deep middle ethmoidal foramen) in one orbit. The middle and deep middle ethmoidal foramina were located 29.8 mm and 32.0 mm posterior to the anterior lacrimal crest, respectively. There were no significant side- or gender-related differences in distances from the anterior lacrimal crest to the middle ethmoidal foramen (p > 0.05, Mann-Whitney U test). The mean distances from the anterior lacrimal crest to the anterior and posterior ethmoidal foramina and the optic canal were 19.6 mm, 33.5 mm, and 41.9 mm, respectively. The authors demonstrated the locations of the accessory ethmoidal foramina in adult cadavers. These observations may help to ensure the safe and precise performance of medial orbital wall surgeries.

A Cadaveric Study of the Morphometric and Geometric Relationships of the Orbital Apex

Introduction: To define the morphometric and geometric relationships which exist at the orbital apex.Materials and Methods: Forty-seven orbits from twenty-four formalin-fixed Caucasian cadavers were exenterated and the relevant sutures, fissures and foramina identified. Measurements were taken from the optic canal to anatomical landmarks located along the medial wall, inferior wall and lateral wall of each orbit. Based on the mean results the geometric angles between the different anatomical structures were calculated and used to create three-dimensional models.Results: The mean distances from the midpoint of the optic canal to the superior orbital fissure, inferior orbital fissure and anterior ethmoidal foramen were 10.22 mm, 29.56 mm and 21.65 mm, respectively. The mean distances from the anterior ethmoidal foramen to the superior and inferior orbital fissures were 24.27 mm and 31.93 mm, respectively. The mean distance between the tips of the superior and inferior orbital fissures was 27.70 mm. The mean distances directly from the tips of the superior and inferior orbital fissures and the anterior ethmoidal foramen to the orbital rim were 39.23 mm, 17.11 mm and 18.94 mm, respectively. These values were used to calculate geometric values and create three-dimensional models.Discussion: The orbital apex is a congested structure and the practicing orbital surgeon must have an intimate knowledge of its contents. We have presented novel data, which in conjunction with radiology may be used as both a navigational aid to plan orbital surgery and to guide the surgeon intraoperatively to assess proximity to key anatomical structures.

Inlay Implanting Technique for the Correction of Medial Orbital Wall Fracture

For blowout fractures of the medial orbital wall, the goals of treatment are complete reduction of the herniated soft tissue and anatomical restoration of the orbital wall without surgical complications. Surgeons frequently worry about damage to the optic nerve caused by dissection when the part over the posterior ethmoidal foramen is fractured. The authors performed small incision and inlay implantation of porous polyethylene for reconstruction of medial orbital wall fractures. Between January of 2007 and December of 2009, 55 patients were included in an analysis of the outcome of corrected medial orbital wall fractures. For 55 patients with posterior comminuted fractures of the medial orbital wall, insertion of porous polyethylene into the ethmoid sinus was performed in multiple layers, through the transconjunctival approach. In all cases, the orbital cavity was restored to its normal anatomical shape. The associated ocular problems disappeared except for mild enophthalmos in three patients and diplopia in one patient. There were no serious surgical complications associated with inlay implantation. The advantages of the inlay technique include the anatomical reconstruction of the orbital wall, the avoidance of optic nerve injury, the simplicity of the procedure, and consequently the absence of surgery-related complications. This technique is presented as one of the preferred treatments for posterior comminuted fractures of the medial orbital wall.