The inferocentral whorl region and its directional patterns in the corneal sub-basal nerve plexus: A review.

There has been a growing application of in vivo confocal microscopy (IVCM) in the examination of corneal microstructure, including different corneal layers and corneal nerve fibers in health and in pathological conditions. Corneal nerves forming the sub-basal nerve plexus (SBNP) beneath the corneal basal epithelial cell layer in particular have been intensively researched in health and disease as a marker for corneal neurophysioanatomical and degenerative changes. One intriguing feature in the SBNP that is found inferior to the corneal apex, is a whorl-like pattern (or vortex) of nerves, which represents an anatomical landmark. Evidence has indicated that the architecture of this 'whorl region' is dynamic, changing with time in healthy individuals but also in disease conditions such as in diabetic neuropathy and keratoconus. This review summarizes the known information regarding the characteristics and significance of the whorl region of nerves in the corneal SBNP, as a potential area of high relevance for future disease monitoring and diagnostics.

Anatomic Variations of the Lateral Branch of the Supraorbital Nerve Observed in Endoscopic Forehead Surgery.

Surgeons dissect carefully in the medial third of the supraorbital rim to preserve the supraorbital nerve (SON) during surgical forehead rejuvenation. However, the anatomic variations of SON exit from the frontal bone have been researched in cadaver or imaging studies. In this study, we report a variation in the lateral branch of SON observed in an endoscopic view during forehead lifts. A retrospective review of 462 patients who underwent endoscopy-assisted forehead lifts between January 2013 and April 2020 was performed. Data, including the location, number, and form of the exit point and thickness of SON and its lateral branch variant, were recorded and reviewed intraoperatively, utilizing high-definition endoscopic assistance. Thirty-nine patients and 51 sides were included, and all patients were female, with a mean age of 44.53 (18-75) years. This nerve exited a foramen in the frontal bone ~8.82 ± 2.79 mm lateral to SON and ~1.89 ± 1.34 mm from the supraorbital margin vertically. Observed thickness variations of the lateral branch of SON included 20 small, 25 medium, and 6 large nerves. This study revealed various positional and morphologic variations of the lateral branch of SON in an endoscopic view. Thus, surgeons can be alerted of the anatomic variations of SON and establish careful dissection during procedures. In addition, the findings of this study will be useful in planning nerve blocks, filler injections, and migraine treatments in the supraorbital region.

A whole-mount immunohistochemistry protocol for detection of mouse corneal nerves.

A cornea is innervated by sensory nerves, which branch into thick trunks, subbasal plexuses, and sensory endings. Appropriate assessment of nerve structure in a tissue provides a more complete understanding of the role of nerves in health and disease. Here, we present a whole-mount immunohistochemistry protocol that facilitates evaluation of nerve architecture throughout the mouse cornea. The fixation step in this protocol allows for reliable detection of nerve structures within the cornea and likely other tissues. For complete details on the use and execution of this protocol, please refer to Yun et al, (2020).

Corneal Health during Three Months of Scleral Lens Wear.

SIGNIFICANCE: This study evaluated the effects scleral lens wear has on corneal health using fluorometry and in vivo confocal microscopy. No subclinical changes on healthy corneas of young subjects were observed during 3 months of scleral lens wear. PURPOSE: This study aimed to evaluate the effects 3 months of scleral lens wear has on the corneal epithelial barrier function, dendritic cell density, and nerve fiber morphology. METHODS: Twenty-seven neophytes (mean [standard deviation] age, 21.4 [3.9] years) wore scleral lenses of a fluorosilicone acrylate material bilaterally (97 Dk, 15.6 to 16.0-mm diameter) for 3 months without overnight wear. Subjects were randomized to use either Addipak (n = 12) or PuriLens Plus (n = 15) during lens insertion. Measurements of corneal epithelial permeability to fluorescein were performed with automated scanning fluorophotometer (Fluorotron Master; Ocumetrics, Mountain View, CA) on the central cornea of the right eye and the temporal corneal periphery of the left eye. Images of the distributions of corneal nerve fibers and dendritic cells and nerve fibers were captured in vivo with a confocal laser scanning microscope (Heidelberg Retina Tomograph, Rostock Cornea Module; Heidelberg Engineering, Heidelberg, Germany) on the central and inferior peripheral cornea of the left eye. Corneal measurements and imaging were performed at baseline and after 1 and 3 months of lens wear. RESULTS: The corneal permeability values in natural log, dendritic cell densities, and nerve fiber morphology did not significantly change from baseline to 1 and 3 months of lens wear, for both central and peripheral corneal regions (P > .05). Dendritic cell density at the inferior cornea was higher than the central cornea throughout the study (P < .001). No relationships were observed between each outcome measurements and the saline solution groups (P > .05). CONCLUSIONS: Scleral lens wear for 3 months on healthy cornea of young subjects did not affect corneal epithelial barrier function, nerve fiber, and dendritic cell densities. Buffered and nonbuffered saline solutions impacted the corneal health in similar ways.

Anatomical study of the supraorbital and supratrochlear nerves: A new classification and application to understanding some migraine headaches.

The frontal nerve is the largest branch of the ophthalmic nerve. This nerve gives rise to two terminal branches, the supraorbital (SON) and supratrochlear nerves (STN). To the best of our knowledge, there are no reports describing the detailed proximal course of these nerves while inside the orbit. Therefore, the goal of this study was to clarify the anatomy of the SON and STN inside and at their exit from the orbit. Twenty sides from ten fresh-frozen cadavers were used in this study. Intra and extra orbital dissections were performed to observe the course of the SON and STN. Additionally, measurements of the nerves were made at these locations. The course of the SON and STN inside the orbit was classified into three groups depending on the STN branching pattern from the SON. The group without any branch from the SON and STN inside the orbit was the most common. The exit points of these nerves were via the supraorbital notch, foramen, or neither a notch nor foramen. A distinct fibrous band was consistently found tethering the nerve except in specimens with nerves traversing a bony foramen. The mean diameters of the SON and STN were 1.3 ± 0.2 and 0.7 ± 0.1 mm, respectively. The results of this study further our knowledge of the course and morphology of the SON and STN and might be useful for better understanding and potentially treating some forms of migraine headache due to SON or STN compression/entrapment. Clin. Anat. 33:332-337, 2020. © 2019 Wiley Periodicals, Inc.

Comparative Anatomy of the Mammalian Corneal Subbasal Nerve Plexus.

Purpose: The subbasal nerve plexus (SNP) is the densest and most recognizable component of the mammalian corneal innervation; however, the anatomical configuration of the SNP in most animal models remains incompletely described. The purpose of the current study is to describe in detail the SNP architecture in eight different mammals, including several popular animal models used in cornea research. Methods: Corneal nerves in mouse, rat, guinea pig, rabbit, dog, macaque, domestic pig, and cow eyes were stained immunohistochemically with antiserum directed against neurotubulin. SNP architecture was documented by digital photomicrography and large-scale reconstructions, that is, corneal nerve maps, using a drawing tube attached to a light microscope. Results: Subbasal nerve fibers (SNFs) in mice, rats, guinea pigs, dogs, and macaques radiated centrally from the corneoscleral limbus toward the corneal apex in a whorl-like or spiraling pattern. SNFs in rabbit and bovine corneas swept horizontally across the ocular surface in a temporal-to-nasal direction and converged on the inferonasal limbus without forming a spiral. SNFs in the pig cornea radiated centrifugally in all directions, like a starburst, from a focal point located equidistant between the corneal apex and the superior pole. Conclusions: The results of the present study have demonstrated for the first time substantial interspecies differences in the architectural organization of the mammalian SNP. The physiological significance of these different patterns and the mechanisms that regulate SNP pattern formation in the mammalian cornea remain incompletely understood and warrant additional investigation.

A Relationship Between the Supratrochlear Nerve and Trochlea: Anatomical Study and Application to Migraine Headaches.

Supratrochlear nerve (STN) is a terminal branch of the frontal nerve arising from the ophthalmic nerve (V1). Compression of the STN by adjacent structures might result in migraine headaches. The aim of this study was to explore the relationship of the STN and trochlea for a better understanding of potential entrapment of the STN. Nineteen orbits from ten fresh-frozen cadaveric heads were dissected. The relationship of the STN and the trochlea was classified into three types: In type I, the STN passed lateral to the trochlea; In type II, the STN passed through the trochlea; In type III, the STN passed medial to the trochlea. Type I was found in 52.6% (10/19 sides), type II was found in 42.1% (8/19 sides), and type III was seen in 3.4% (1/19 sides). In type III, both the STN and infratrochlear nerve were identified as separate branches. The authors propose a new classification of the pathway of the STN based on its relationship with the trochlea. This study might shed light on headaches emanating from this region.

Mapping the entire nerve architecture of the cat cornea.

OBJECTIVE: To provide a complete nerve architecture and neuropeptide distribution in the cat cornea. ANIMALS STUDIED: Two adult domestic cats. PROCEDURE: The cat corneas were stained with protein gene product (PGP) 9.5 antibody-a pan marker for nerve fibers-and then divided into four quarters and double labeled with calcitonin gene-related peptide (CGRP) or substance P (SP) antibodies. Relative corneal nerve fiber densities and nerve terminals were evaluated in whole mount images by computer-assisted analysis. RESULTS: An average of 21.5 ± 2.1 thick stromal nerves enters the cornea around the limbus where they split into many branches going up to the anterior stroma. Some branches link to each other, but most of them penetrate the basement membrane in the periphery to give origin to subbasal bundles, which run centripetally and merge to form a whirl-like structure (vortex) at the center. These nerve bundles send out many fine terminals that innervate the epithelial cells. Subbasal nerve density and nerve terminals were greater in the center than in the periphery of the cornea. Additionally, CGRP-positive central epithelial nerve fibers and terminals were more abundant than SP-positive nerves and terminals. CONCLUSION: The architecture of cat corneal nerves shows similarities to human and mouse cornea innervation. This study provides useful data for researchers who use the cat model to assess corneal nerve pathological alterations, as well as in the veterinary field where corneal opacities, ulcerations, and infections damage the nerves and decrease sensitivity.

Sensory Innervation of the Upper Eyelid.

The aim of this study was to elucidate the sensory territory of the trigeminal nerve on the upper eyelid.Eight hemifaces from Korean cadavers were dissected. The frontal nerve (FN), supraorbital nerve (SON), supratrochlear nerve (STN), infratrochlear nerve (ITN), and lacrimal nerve (LN) were traced.The terminal branches to the eyelid margin of FN were distributed between 1/6 and 2/5 of the palpebral fissure width lateral to the medial canthus and 1/6 of the eyebrow height from eyelid margin. The SON was distributed between 2/5 and 9/10 of the eye width lateral to the medial canthus, at 1/3 of the eyebrow height. The STN was distributed between -1/4 and -1/5 of the eye width medial to the medial canthus, at 1/5 of the eyebrow height. The ITN was distributed at -1/4 and 1/10 of the eye width medial to the medial canthus, and at 1/5 of the eyebrow height. The LN was distributed between approximately 3/5 and 13/10 of the eye width lateral to the medial canthus, and at 1/4 of the eyebrow height. The main branches of FN and SON ran deep to the orbicularis from the supraorbital notch to the upper border of the tarsal plate. In the pretarsal area, they were between the orbicularis and tarsal plate. The STN and ITN were between the orbicularis and the skin. The LN was observed between the orbicularis and the tarsal plate.Upper eyelid was mainly supplied by SON and FN. The medial extremity was supplied by STN and ITN, and the lateral extremity by LN.

Long-Term Impacts of Orthokeratology Treatment on Sub-Basal Nerve Plexus and Corneal Sensitivity Responses and Their Reversibility.

PURPOSE: To examine the effects of one year of overnight orthokeratology (OK) treatment on the sub-basal nerve plexus (SBNP) and corneal sensitivity and to assess the reversibility of these effects one month after treatment interruption. METHODS: Thirty-two subjects with low-moderate myopia underwent OK treatment for one year. Fifteen non-contact lens wearers served as controls. At the time points baseline, one year of treatment, and one month after removing the OK lenses, two tests were conducted: corneal sensitivity (Cochet-Bonnet esthesiometer) and SBNP imaging by in vivo confocal microscopy. RESULTS: In participants wearing OK lenses, significant reductions over the year were produced in SBNP nerve density (P=0.001 and P=0.006) and number of nerves (P<0.001 and P=0.001) in the central and mid-peripheral cornea, respectively. Differences over the year were also detected in central objective tortuosity (P=0.002). After lens removal, baseline values of nerve density (P=0.024 and P=0.001) and number of nerves (P=0.021 and P<0.001) for the central and mid-peripheral cornea, respectively, were not recovered. At one month post-treatment, a difference was observed from one-year values in central corneal sensitivity (P=0.045) and mid-peripheral Langerhans cell density (P=0.033), and from baseline in mid-peripheral objective tortuosity (P=0.049). Direct correlation was detected at one year between nerve density and tortuosity both in the central (P<0.01; r=0.69) and mid-peripheral cornea (P<0.01; r=0.76). CONCLUSIONS: Long-term OK treatment led to reduced SBNP nerve density and this was directly correlated with corneal tortuosity. After one month of treatment interruption, nerve density was still reduced.

Short-Term Effects of Overnight Orthokeratology on Corneal Sub-basal Nerve Plexus Morphology and Corneal Sensitivity.

OBJECTIVE: To assess the effects of a short period of orthokeratology (OK) on corneal sub-basal nerve plexus (SBNP) morphology and corneal sensitivity. METHODS: Measurements were made in 56 right eyes of 56 subjects with low-to-moderate myopia who wore 2 OK lens designs (Group CRT: HDS 100 Paragon CRT, n=35; Group SF: Seefree; n=21) for a period of 1 month and in 15 right eyes of noncontact lens wearers as controls. The variables determined in each participant were corneal sensitivity using a Cochet-Bonnet esthesiometer and 12 SBNP variables determined on laser scanning confocal microscopy images using 3 different software packages. Correlation between SBNP architecture and corneal sensitivity was also examined. RESULTS: Few changes were observed over the 1-month period in the variables examined in the OK treatment and control groups. However, significant reductions were detected over time in the number of nerves in the central cornea in the groups CRT (P=0.029) and SF (P=0.043) and in central corneal sensitivity in CRT (P=0.047) along with significant increases in central and midperipheral corneal Langerhans cell counts in SF (P=0.001 and 0.048, respectively). CONCLUSIONS: This study provides useful data to better understand the anatomical changes induced by OK in corneal SBNP. The different response observed to the 2 OK lens designs requires further investigation.

Laser scanning in vivo confocal microscopy (IVCM) for evaluating human corneal sub-basal nerve plexus parameters: protocol for a systematic review.

INTRODUCTION: Laser scanning in vivo confocal microscopy (IVCM) enables non-invasive, high-resolution imaging of the cornea. In recent years, there has been a vast increase in researchers using laser scanning IVCM to image and quantify corneal nerve parameters. However, a range of methodological approaches have been adopted. The primary aim of this systematic review is to critically appraise the reported method(s) of primary research studies that have used laser scanning IVCM to quantify corneal sub-basal nerve plexus (SBNP) parameters in humans, and to examine corneal nerve parameters in healthy individuals. METHODS AND ANALYSIS: A systematic review of primary studies that have used laser scanning IVCM to quantify SBNP parameters in humans will be conducted. Comprehensive electronic searches will be performed in Ovid MedLine, Embase and the Cochrane Library. Two reviewers will independently assess titles and abstracts, and exclude studies not meeting the inclusion criteria. For studies judged eligible or potentially eligible, full texts will be independently assessed by two reviewers to determine eligibility. A third reviewer will resolve any discrepancies in judgement. Risk of bias will be assessed using a custom tool, covering five methodological domains: participant selection, method of image capture, method of image analysis, data reporting and other sources of bias. A systematic narrative synthesis of findings will be provided. A multilevel random-effects meta-analysis will be performed for corneal nerve parameters derived from healthy participants. This review will be reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. ETHICS AND DISSEMINATION: As this review considers published data, ethical approval is not required. We foresee that this synthesis will serve as a reference for future studies, and can be used to inform best practice standards for using IVCM in clinical research. A manuscript reporting the results of the review will be published and may also be presented at scientific conferences.

Anatomy of the Corrugator Muscle.

The aim of this article is to systematically review the anatomy and action of the corrugator muscle. PubMed and Scopus were searched using the terms "corrugator" AND "anatomy." Among the 60 full texts from the 145 relevant abstracts, 34 articles without sufficient content were excluded and 4 articles drawn from the reference lists were added. Among the 30 articles analyzed (721 hemifaces), 28% classified by oblique head and transverse head, and 72% did not. Corrugator originated mostly from the medial supraorbital rim (45%), followed by the medial frontal bone (31%), the medial infraorbital rim (17%), and the upper nasal process (7%). Corrugator extended through the frontalis and orbicularis oculi (41%), only the frontalis (41%), or only the orbicularis oculi (18%). Corrugator ran superolaterally (59%), or laterally (41%). Corrugators inserted mostly to the middle of the eyebrow (57%), or the medial half of the eyebrow (36%), but also to the glabella region (7%). The length of the corrugator ranged 38 to 53 mm. The transverse head (23.38 mm) was longer than the oblique head (19.75 mm). Corrugator was thicker at the medial canthus than at the midpupillary line. Corrugator was innervated by the temporal branch of the facial nerve (66%), the zygomatic branch (17%), or the angular nerve (zygomatic branch and buccal branch, 17%). Supraorbital nerve (60%) or supratrochlear nerve (40%) penetrated the corrugator. The action was depressing, pulling the eyebrow medially (91%), or with medial eyebrow elevation and lateral eyebrow depression (9%). Surgeons must keep this anatomy in mind during surgical procedures.

Topography of the supraorbital nerve with reference to the lacrimal caruncle: danger zone for direct browplasty.

PURPOSE: To elucidate the course of the supraorbital nerve (SON) with reference to the lacrimal caruncle in order to facilitate safer direct browplasty by preventing nerve injury. METHODS: Thirty-four hemifaces from 18 embalmed Korean cadavers were dissected. A vertical line through the upmost point of the lacrimal caruncle and a horizontal line through the supraorbital margin were used as the horizontal and vertical reference positions, respectively. The course of the SON in the frontal view and the point at which it pierced the overlaying musculature were examined. RESULTS: The SON divides into a superficial branch and a deep branch just after exiting the orbit. In all cases, the deep SON remains in the subgaleal plane deep to the corrugator and frontalis muscles. The superficial SON travels under the corrugator muscle dividing into three branches (medial, intermediate and lateral) and pierced the frontalis muscle at 19-32 mm above the supraorbital margin. However, in 11 cases (32%) the medial branch of the superficial SON pierced the lower portion of the corrugator muscle at 3.6 mm above the supraorbital margin and ran in front of the muscle along with the vertical line through the upmost point of the lacrimal caruncle. CONCLUSIONS: One-third of the medial branch of the superficial SON without corrugator muscle protection is vulnerable to iatrogenic injury during direct browplasty. Therefore, the oculofacial surgeon must bring the dissection plane of the forehead tissue more superficially around the vertical line through the upmost point of the lacrimal caruncle in order to avoid nerve injury.

Age-Related Changes in Murine Corneal Nerves.

PURPOSE: The aim of this study is to determine age-related morphological changes in the corneal subbasal nerve plexus (SNP) in two inbred mouse strains. MATERIALS AND METHODS: The corneal SNP was investigated by in vivo confocal laser scanning microscopy (CLSM) in 0.5-, 1-, 1.5-, and 2-year-old C57BL/6J mice and in 0.5- and 1-year-old BALB/c mice (n = 4 per age category and strain; 10 images per mouse). Fixed corneal samples from C57BL/6J mice were also analyzed after PGP9.5 staining. Nerve fiber density (NFD) was determined using the semi-automated NeuronJ program. In addition, a new custom-designed, fully automated computerized technique based on oriented multiscale matched filtering was tested to objectify and accelerate image analysis. RESULTS: C57BL/6J mice showed low NFD (11.7 ± 0.5 mm/mm2). Aging from 0.5 to 1, 1.5, and 2 years resulted in significant reductions in subbasal NFD by 34%, 49%, and 66%, respectively. The decline in nerve fibers revealed by in vivo CLSM together with NeuronJ quantification was confirmed by ex vivo immunohistochemical analyses. Subbasal NFD in BALB/c mice (30.0 ± 1.4 mm/mm2) was 3-fold higher than in C57BL/6J mice. Aging from 0.5 to 1 year resulted in a significant 17% reduction in NFD. With the automated approach, NFD of 22.6 ± 2.9 mm/mm2 and a 45% reduction during aging was determined from the same images. CONCLUSIONS: An age-related reduction in subbasal corneal nerve fibers was observed. The differing extent of reduction in the two mouse strains may be accounted for by genetic factors. Automated NFD quantification of corneal nerve fibers in mice appears to be a useful, reliable, objective, and time-saving tool.

Compartmental Innervation of the Superior Oblique Muscle in Mammals.

PURPOSE: Intramuscular innervation of mammalian horizontal rectus extraocular muscles (EOMs) is compartmental. We sought evidence of similar compartmental innervation of the superior oblique (SO) muscle. METHODS: Three fresh bovine orbits and one human orbit were dissected to trace continuity of SO muscle and tendon fibers to the scleral insertions. Whole orbits were also obtained from four humans (two adults, a 17-month-old child, and a 33-week stillborn fetus), two rhesus monkeys, one rabbit, and one cow. Orbits were formalin fixed, embedded whole in paraffin, serially sectioned in the coronal plane at 10-µm thickness, and stained with Masson trichrome. Extraocular muscle fibers and branches of the trochlear nerve (CN4) were traced in serial sections and reconstructed in three dimensions. RESULTS: In the human, the lateral SO belly is in continuity with tendon fibers inserting more posteriorly on the sclera for infraducting mechanical advantage, while the medial belly is continuous with anteriorly inserting fibers having mechanical advantage for incycloduction. Fibers in the monkey superior SO insert more posteriorly on the sclera to favor infraduction, while the inferior portion inserts more anteriorly to favor incycloduction. In all species, CN4 bifurcates prior to penetrating the SO belly. Each branch innervates a nonoverlapping compartment of EOM fibers, consisting of medial and lateral compartments in humans and monkeys, and superior and inferior compartments in cows and rabbits. CONCLUSIONS: The SO muscle of humans and other mammals is compartmentally innervated in a manner that could permit separate CN4 branches to selectively influence vertical versus torsional action.

Comparison of Standard Versus Wide-Field Composite Images of the Corneal Subbasal Layer by In Vivo Confocal Microscopy.

PURPOSE: To evaluate whether the densities of corneal subbasal nerves and epithelial immune dendritiform cells (DCs) are comparable between a set of three representative standard images of in vivo confocal microscopy (IVCM) and the wide-field mapped composite IVCM images. METHODS: This prospective, cross-sectional, and masked study included 110 eyes of 58 patients seen in a neurology clinic who underwent laser-scanning IVCM (Heidelberg Retina Tomograph 3) of the central cornea. Densities of subbasal corneal nerves and DCs were compared between the average of three representative standard images and the wide-field mapped composite images, which were reconstructed by automated mapping. RESULTS: There were no statistically significant differences between the average of three representative standard images (0.16 mm2 each) and the wide-field composite images (1.29 ± 0.64 mm2) in terms of mean subbasal nerve density (17.10 ± 6.10 vs. 17.17 ± 5.60 mm/mm2, respectively, P = 0.87) and mean subbasal DC density (53.2 ± 67.8 vs. 49.0 ± 54.3 cells/mm2, respectively, P = 0.43). However, there were notable differences in subbasal nerve and DC densities between these two methods in eyes with very low nerve density or very high DC density. CONCLUSIONS: There are no significant differences in the mean subbasal nerve and DC densities between the average values of three representative standard IVCM images and wide-field mapped composite images. Therefore, these standard images can be used in clinical studies to accurately measure cellular structures in the subbasal layer.

Morphological Characteristics of the Sphenoid Sinus and Endoscopic Localization of the Cavernous Sinus.

The aim of this study was to investigate the relationship between the morphological characteristics of the sphenoid sinus and endoscopic localization of the cavernous sinus (CS) using an extended endoscopic endonasal transsphenoidal approach. Thirty sides of CS in 15 adult cadaver heads were dissected to simulate the extended endoscopic endonasal transsphenoidal approach, and the morphology of the sphenoid sinus and anatomic structures of CS were observed. The opticocarotid recess (OCR), ophthalmomaxillary recess (V1V2R), and maxillomandibular recess (V2V3R) in the lateral wall of the sphenoid sinus were presented in 16 sides (53.3%), 6 sides (20%), and 4 sides (13.3%) of the 30 sides, respectively. OCR is a constant anatomic landmark in endoscopy and coincides with the anterior portion of the clinoidal triangle. The C-shaped internal carotid artery (ICA) in the lateral wall of the sphenoid sinus was presented in 11 sides (36.7%), the upper one-third of which corresponds to the middle portion of the clinoidal triangle, and the lower two-thirds of which correlates to the supratrochlear triangle, infratrochlear triangle, and ophthalmic nerve in CS, around which the medial, lateral, and anteroinferior interspaces are distributed. From a front-to-behind perspective, the C-shaped ICA consists of inferior horizontal segment, anterior vertical segment, clinoidal segment as well as partial subarachnoid segment of the ICA. OCR and C-shaped ICA in the lateral wall of the sphenoid sinus are the 2 reliable anatomic landmarks in the intraoperative location of the parasellar region of CS.

Pain. Part 2a: Trigeminal Anatomy Related to Pain.

In order to understand the underlying principles of orofacial pain it is important to understand the corresponding anatomy and mechanisms. Paper 1 of this series explains the central nervous and peripheral nervous systems relating to pain. The trigeminal nerve is the 'great protector' of the most important region of our body. It is the largest sensory nerve of the body and over half of the sensory cortex is responsive to any stimulation within this system. This nerve is the main sensory system of the branchial arches and underpins the protection of the brain, sight, smell, airway, hearing and taste, underpinning our very existence. The brain reaction to pain within the trigeminal system has a significant and larger reaction to the threat of, and actual, pain compared with other sensory nerves. We are physiologically wired to run when threatened with pain in the trigeminal region and it is a 'miracle' that patients volunteer to sit in a dental chair and undergo dental treatment. Clinical Relevance: This paper aims to provide the dental and medical teams with a review of the trigeminal anatomy of pain and the principles of pain assessment.

Communications Between the Trigeminal Nerve and the Facial Nerve in the Face: A Systematic Review.

The aim of the article is to elucidate the communications between the trigeminal nerve and facial nerve in the face. In a PubMed search, 328 studies were found using the terms 'trigeminal nerve, facial nerve, and communication.' The abstracts were read and 39 full-text articles were reviewed. Among them, 11 articles were analyzed. In the studies using dissection, the maxillary branch (V2) had the highest frequency (95.0% ±â€Š8.0%) of communication with the facial nerve, followed by the mandibular branch (V3) (76.7% ±â€Š38.5%). The ophthalmic branch (V1) had the lowest frequency of communication (33.8% ±â€Š19.5%). In a Sihler stain, all of the maxillary branches and mandibular branches had communications with the facial nerve and 85.7% (12/14 hemifaces) of the ophthalmic branches had communications. The frequency of communications between the trigeminal nerve and facial nerve were significantly higher (P = 0.00, t-test) in the studies using a Sihler stain (94.7% ±â€Š1.1%) than the studies using dissection (76.9 ±â€Š35.8). The reason for the significantly higher frequency of trigeminal-facial communication in the studies using a Sihler stain is because of the limitation of the Sihler stain itself. This technique cannot differentiate the motor nerves from sensory nerves at the periphery, and a crossover can be misinterpreted as communication near to nerve terminal.