A Scalable Histological Method to Embed and Section Multiple Brains Simultaneously.

The preparation and processing of rodent brains for evaluation by immunohistochemistry is time-consuming. A large number of mouse brains are routinely used in experiments in neuroscience laboratories to evaluate several models of human diseases. Thus, methods are needed to reduce the time associated with processing brains for histology. A scalable method was developed to embed, section, and stain multiple mouse brains using supplies found in any common histology laboratory. Section collection schemes can be scaled to provide identical bregma locations between adjacent sections for immunohistochemistry, facilitating comprehensive, high-quality immunohistochemistry. As a result, sectioning and staining times are considerably reduced as sections from multiple blocks are stained simultaneously. This method improves on previous procedures and allows multiple embedding and subsequent immunostaining of brains easily with a dramatically reduced time requirement. Furthermore, we expand this method for use in numerous mouse tissues, rat brain tissue, and post-mortem human brain and arterial tissues. In summary, this procedure allows the processing of many rodent or human tissues from perfusion through microscopy in 10 days or less.

Optic Canal Size is an Indicator for the Accessory Optic Canal: Applications for Anterior Clinoidectomy.

BACKGROUND: The ophthalmic artery normally travels with the optic nerve through the optic canal. However, sometimes, the ophthalmic artery travels through a foramen within the optic strut named an accessory optic canal, double optic canal, or ophthalmic canal. This variant puts individuals at an increased risk for blindness or death during anterior clinoidectomy due to unforeseen hemorrhage of the ophthalmic artery or internal carotid artery when the optic strut is separated from the body of the sphenoid bone. Several features make the accessory optic canal difficult to recognize on imaging: its variant nature, small size, and ability to masquerade as a caroticoclinoid foramen or a pneumatized sphenoidal structure. Hence, improved methods of presurgical identification are warranted. The aim of this study was to assess the size and shape of the optic canal, with and without a concomitant accessory optic canal, to determine whether measurement of the optic canal may provide useful information regarding the presence of an accessory optic canal. METHODS: In 191 dry crania, optic canals with and without concomitant accessory optic canals were assessed for the following parameters: canal area, canal perimeter, circularity, solidity, the axes and aspect ratio of a best-fit ellipse, and roundness. RESULTS: Normal optic canals were found to have a larger area (P = 0.036), perimeter (P = 0.043), and minor axis of a best-fit ellipse (P = 0.031) than the optic canals that occurred alongside accessory optic canals. CONCLUSIONS: Asymmetry in optic canal size can help indicate the presence of a unilateral accessory optic canal before surgery.

Online interactive medical neuroimaging exercise to identify human brain structures.

A persisting need remains for developing methods for inspiring and teaching undergraduate medical students to quickly learn to identify the hundreds of human brain structures, tracts and spaces that are clinically relevant (viewed as three-dimensional volumes or two-dimensional neuroimages), and to accomplish this with the option of virtual on-line methods. This notably includes teaching the essentials of recommended diagnostic radiology to allow students to be familiar with patient neuroimages routinely acquired using magnetic resonance imaging (MRI) and computed tomography (CT). The present article includes a brief example video plus details a clinically oriented interactive neuroimaging exercise for first year medical students (MS1s) in small groups, conducted with instructors either in-person or as an entirely online virtual event. This "find-the-brain-structure" (FBS) event included teaching students to identify brain structures and other regions of interest in the central nervous system (and potentially in head and neck gross anatomy), which are traditionally taught using brain anatomy atlases and anatomical specimens. The interactive, small group exercise can be conducted in person or virtually on-line in as little as 30 min depending on the scope of objectives being covered. The learning exercise involves coordinated interaction between MS1s with one or several non-clinical faculty and may include one or several physicians (clinical faculty and/or qualified residents). It further allows for varying degrees of instructor interaction online and is easy to convey to instructors who do not have expertise in neuroimaging. Anonymous pre-event survey (n = 113, 100% response rate) versus post-event surveys (n = 92, 81% response rate) were attained from a cohort of MS1s in a neurobiology course. Results showed multiple statistically significant group-level shifts in response to several of the questions, showing an increase in MS1 confidence with reading MRI images (12% increase shift in mean, p < 0.001), confidence in their approaching physicians for medical training (9%, p < 0.01), and comfort levels in working online with virtual team-based peers and with team-based faculty (6%, p < 0.05). Qualitative student feedback revealed highly positive comments regarding the experience overall, encouraging this virtual medium as a desirable educational approach.

Cribra orbitalia is correlated with the meningo-orbital foramen and is vascular and developmental in nature.

Cribra orbitalia is a phenomenon with interdisciplinary interest. However, the etiology of cribra orbitalia remains unclear. Recently, the appearance of cribra orbitalia was identified as vascular in nature. This study assessed the relationship between anatomical variation of vasculature, as determined by the presence of meningo-orbital foramina, and the presence of cribra orbitalia in 178 orbits. Cribra orbitalia was identified in 27.5% (49:178) of orbits (22.7%, 35:154 adult orbits and 58.3%, 14:24 subadult orbits) and meningo-orbital foramina were identified in 65.8% (100:152) of orbits. Among the 150 total intact adult orbits (i.e., orbital roof and posterior orbits both intact), cribra orbitalia was found in 35 (23.3%). Of these 35 occurrences of cribra orbitalia, 32 (91.4%) had the concurrent finding of a meningo-orbital foramen. However, in the absence of the meningo-orbital foramen, cribra orbitalia was only found in three sides out of the total sample of intact orbits (3:150; 2.0%). Fisher's exact test revealed that the presence of cribra orbitalia and the meningo-orbital foramen were statistically dependent variables (p = .0002). Visual evidence corroborated statistical findings-vascular impressions joined cribra orbitalia to meningo-orbital foramina. This study identifies that individuals who possess a meningo-orbital foramen are anatomically predisposed to developing cribra orbitalia. Conversely, cribra orbitalia is unlikely to occur in an individual who does not possess a meningo-orbital foramen. Thus, the antecedent of cribra orbitalia is both vascular and developmental in nature. This report represents an important advancement in the understanding of cribra orbitalia-there is an anatomical predisposition to the development of cribra orbitalia.

Cribra orbitalia is a vascular phenomenon unrelated to marrow hyperplasia or anemia: Paradigm shift for cribra orbitalia.

The orbital phenomenon, cribra orbitalia, has long been a source of controversy, especially with regard to its nature, derivation, and relationship to anemia. Therefore, the external surfaces of orbital roofs were systematically examined microscopically in human skulls from historical collections. Superior orbital surfaces of 278 individual crania within the Hamann-Todd collection were assessed at various magnifications using epi-illumination microscopy to identify the presence of cribra orbitalia and characterize its nature. Also, 12 additional individuals with diagnosed anemia in the Hamann-Todd collection were evaluated. Orbital roof alterations, present in one-third of examined crania, had two discrete appearances: Vascular grooves (45%) and application of new bone in a vascular branching pattern on the orbit surface (55%). Porosity of the orbit was not observed. Evaluation of the orbits of 12 individuals with diagnosed anemia revealed one with a single deep defect, suggesting a space-occupying phenomenon, but no evidence of bone accretion, vascular grooves, or porosity. Cribra orbitalia has often been lumped indiscriminately as an indicator of organismal stress, rather than identified as a indicating a specific etiology. Neither that perspective nor porosity are supported by high resolution examination of orbital roof changes. Recognition of the blood vessel imprint pattern falsifies previous speculations and provides a new paradigm. The actual character of cribra orbitalia is documented and new hypotheses generated. While population prevalence of cribra orbitalia seems excessive for explanation on the basis of these hypotheses, the imprints are clearly vascular in origin.

Clinical Implications of the Submental and Sublingual Arteries in Relation to the Mylohyoid Boutonnière.

OBJECTIVE: Mylohyoid musculature may be included in the submental artery flap to protect perforators. However, blood vessels may pass through the mylohyoid muscle and therefore cause bleeding and risk to pedicle or perforator injury when a mylohyoid-containing flap is lifted. The objectives of this study were to identify the prevalence of the submental and sublingual arteries that traverse the mylohyoid and to assess relationships between vasculature transmitted through mylohyoid muscles and mylohyoid boutonnières. STUDY DESIGN: Cross-sectional human cadaveric study. SETTING: The West Virginia University School of Medicine human gross anatomic laboratories. SUBJECTS AND METHODS: A total of 43 intact mylohyoid muscles from 22 cadavers were dissected. The prevalence of submental vasculature perforating the mylohyoid was recorded in addition to the prevalence and contents of mylohyoid boutonnières. RESULTS: Of 43 mylohyoid muscles, 21 (48.8%) transmitted the submental or sublingual arteries, and 30 (69.1%) possessed boutonnières. One muscle had 2 boutonnières. Of 31 mylohyoid boutonnières, 21 transmitted blood vessels (67.7%). Specifically, 9 transmitted an artery and a vein (29.0%), and 12 transmitted an artery (38.7%). Ten boutonnières (32.3%) were exclusively occupied by fascia. CONCLUSION: This report identifies the importance of identifying and carefully ligating branches of the submental artery that pierce the mylohyoid during elevation of the submental island flap. This report also identifies that a boutonnière is often present where a submental or sublingual artery is traversing the mylohyoid to supply sublingual glands, tongue, and anterior mandible.

Transoral Chondrolaryngoplasty: Scarless Reduction of the Adam's Apple.

The purpose of our study is to test the feasibility of transoral thyroid chondrolaryngoplasty using a similar approach to transoral thyroidectomy. This approach would allow for gender-affirming surgery while avoiding an external neck scar. We carried out our cadaveric feasibility study in an anatomy laboratory at an academic center. Five fresh cadavers were used for this study. We used a lower oral vestibular incision, along with retractors and an endoscope to dissect and gain access to the laryngeal prominence of the thyroid cartilage. Portions of the laryngeal prominence were then removed using scissors to achieve a satisfactory neck contour. Endoscopic as well as extracorporeal photographs were taken to demonstrate the approach. We were able to remove the laryngeal prominence successfully in all of our cadaveric specimens with this transoral approach.

Improving exposure for transoral oropharyngeal surgery with the floor of mouth window: a cadaveric feasibility study.

BACKGROUND: Transoral robotic and laser surgery is rising in popularity due to the increasing incidence of Human Papilloma Virus (HPV) related oropharyngeal cancer. However, adequate exposure of the tongue base remains a major hurdle in many cases. This study introduces a novel surgical technique called the Floor of Mouth Window, which can be used to improve tongue base exposure at the time of transoral surgery. METHODS: This is a preclinical anatomic cadaver study. Seven fresh cadavers were used for this study. Exposure of the tongue base was compared between conventional mouth gags - the Feyh-Kastenbauer and McIvor - and our novel procedure, the Floor of Mouth Window. Exposure was compared subjectively using endoscopic and extracorporeal photographs, as well as objective measurements of inter-incisor distance, and oral cavity volume. RESULTS: The exposure achieved by the Floor of Mouth Window technique was superior to the mouth gags. Inter-incisor distance and oral cavity volume measurements were all more favorable with the Floor of Mouth Window. This technique allowed for successful transoral laser tongue base and tonsil resection without the use of gags or scopes. CONCLUSION: The Floor of Mouth Window is an adjunctive procedure that simply and reliably improved exposure for transoral oropharyngeal surgery in this cadaveric feasibility study. This improved exposure may help increase the adoption of transoral surgery and reduce the number of aborted cases due to anatomic limitations.

Troisier sign and Virchow node: the anatomy and pathology of pulmonary adenocarcinoma metastasis to a supraclavicular lymph node.

Metastatic spread of cancer via the thoracic duct may lead to an enlargement of the left supraclavicular node, known as the Virchow node (VN), leading to an appreciable mass that can be recognized clinically - a Troisier sign. The VN is of profound clinical importance; however, there have been few studies of its regional anatomical relationships. Our report presents a case of a Troisier sign/VN discovered during cadaveric dissection in an individual whose cause of death was, reportedly, chronic obstructive pulmonary disease. The VN was found to arise from an antecedent pulmonary adenocarcinoma. Our report includes a regional study of the anatomy as well as relevant gross pathology and histopathology. Our anatomical findings suggest that the VN may contribute to vascular thoracic outlet syndrome as well as the brachial plexopathy of neurogenic thoracic outlet syndrome. Further, the VN has the potential to cause compression of the phrenic nerve, contributing to unilateral phrenic neuropathy and subsequent dyspnea. Recognition of the Troisier sign/VN is of great clinical importance. Similarly, an appreciation of the anatomy surrounding the VN, and the potential for the enlarged node to encroach on neurovascular structures, is also important in the study of a patient. The presence of a Troisier sign/VN should be assessed when thoracic outlet syndrome and phrenic neuropathy are suspected. Conversely, when a VN is identified, the possibility of concomitant or subsequent thoracic outlet syndrome and phrenic neuropathy should be considered.

Troisier sign and Virchow node: the anatomy and pathology of pulmonary adenocarcinoma metastasis to a supraclavicular lymph node

ABSTRACT: Metastatic spread of cancer via the thoracic duct may lead to an enlargement of the left supraclavicular node, known as the Virchow node (VN), leading to an appreciable mass that can be recognized clinically ­ a Troisier sign. The VN is of profound clinical importance; however, there have been few studies of its regional anatomical relationships. Our report presents a case of a Troisier sign/VN discovered during cadaveric dissection in an individual whose cause of death was, reportedly, chronic obstructive pulmonary disease. The VN was found to arise from an antecedent pulmonary adenocarcinoma. Our report includes a regional study of the anatomy as well as relevant gross pathology and histopathology. Our anatomical findings suggest that the VN may contribute to vascular thoracic outlet syndrome as well as the brachial plexopathy of neurogenic thoracic outlet syndrome. Further, the VN has the potential to cause compression of the phrenic nerve, contributing to unilateral phrenic neuropathy and subsequent dyspnea. Recognition of the Troisier sign/VN is of great clinical importance. Similarly, an appreciation of the anatomy surrounding the VN, and the potential for the enlarged node to encroach on neurovascular structures, is also important in the study of a patient. The presence of a Troisier sign/VN should be assessed when thoracic outlet syndrome and phrenic neuropathy are suspected. Conversely, when a VN is identified, the possibility of concomitant or subsequent thoracic outlet syndrome and phrenic neuropathy should be considered.

A Gantzer muscle arising from the brachialis and flexor digitorum superficialis: embryological considerations and implications for median nerve entrapment.

Gantzer muscles are variant muscles in the anterior forearm inserting into the flexor pollicis longus or, less often, the flexor digitorum profundus. The presence of Gantzer muscles can cause a compressive neuropathy affecting the anterior interosseous nerve (Kiloh-Nevin syndrome). These muscles must also be considered when anterior forearm fasciotomies are performed for the management of acute compartment syndrome. In this case report, a novel Gantzer muscle originated from the flexor digitorum superficialis as well as the investing fascia of the brachialis muscle; the latter site is a novel proximal attachment not previously reported. In addition, the Gantzer muscle possessed rare characteristics because it (1) possessed a split tendinous distal insertion into both the flexor pollicis longus and flexor digitorum profundus, (2) exhibited a triangular morphology, and (3) was innervated by the median nerve. Most importantly, the dual origin of this Gantzer muscle formed a tunnel containing branches of the median nerve; therefore, this report documents a unique anatomical scenario in which the Gantzer muscle may compress and cause entrapment of aspects of the median nerve.

The submental arrowhead variation of the mylohyoid and anterior belly of the digastric muscles.

PURPOSE: Submental anatomical variation is of clinical importance with regard to head and neck surgeries. One such anatomical variation is that of additional musculature joining the intermediate tendon of the digastric muscle to the midline of the mylohyoid musculature-a variation which this report refers to, accordingly, as an arrowhead variation. Though the arrowhead variation has been described in several case reports, it has not been subject to cross-sectional study. The purpose of this study is to determine the prevalence of the arrowhead variation. METHODS: Prevalence of the arrowhead variation was assessed in 19 cadavers via gross dissection. RESULTS: Two of the 19 cadavers (10.5%) were found to have arrowhead variations. The arrowhead variation was found in one male (1:11; 9.1%) and one female (1:8; 12.5%), respectively. CONCLUSIONS: This report demonstrates that the submental arrowhead variation of the anterior digastric and mylohyoid musculature has been reported in isolated case reports since the nineteenth century. This report is the first cross-sectional study of the arrowhead variant, identifying it in approximately one in ten individuals and in both sexes. Therefore, the presence of an arrowhead variation should be regularly considered with regard to diagnosis of submental masses. Likewise, the arrowhead variation should be considered in the preoperative planning of the myriad operations performed in the submental region.

A Review of Extensor Hallucis Longus Variants Featuring a Novel Extensor Primi Internodii Hallucis Muscle Merging With Extensor Hallucis Brevis.

The extensor hallucis longus (EHL) muscle/tendon complex has been used in a variety of tendon transfer and tenodesis surgeries to correct iatrogenic hallux varus deformity, equinovarus foot deformity, clawed hallux associated with a cavus foot, and dynamic hyperextension of the hallux and, even, to prevent pedal imbalance after transmetatarsal amputation. Although it is usually considered a unipennate muscle inserting into the dorsum of the base of the distal phalanx of the hallux, a vast majority of EHL muscles possess ≥1 accessory tendinous slips that insert into other neighboring bones, muscles, or tendons, which can complicate these surgeries. The present report reviewed the reported data on EHL variants and describe a new variant, in which the tendons of the extensor primi internodii hallucis muscle of Wood and extensor hallucis brevis muscle merged together proximal to the tarsometatarsal (Lisfranc) joint, a site of rupture for extensor tendons of the foot. The reported variant might have contributed to the development of the clawed hallux seen in our patient and could complicate its operative management by mimicking the normal extensor digitorum longus tendon. Knowledge of the EHL variants and the particular muscular pattern described in the present review could improve the diagnosis and tendon transfer and tenodesis operative planning and outcomes.

Morphological Spectra of Adult Human Stellate Ganglia: Implications for Thoracic Sympathetic Denervation.

Cardiac sympathetic denervation (CSD) to treat ventricular arrhythmias (VAs) requires transection at the middle or lower third of stellate (cervicothoracic) ganglia (SG). However, the morphological appearance of the adult SG and distribution of neuronal somata within it are not well described. To determine the morphology of left and right SG (LSG and RSG) and the distribution of somata within. LSG and RSG (n = 28) from 14 embalmed adult cadavers were dissected intact. Weight, volume, height, morphologic appearance, relationship between C8 and T1 ganglia (which form the SG) were determined, along with histology. Demographics, history of cardiac disease, and cause of death were also reviewed. Mean age of the subjects was 76 ± 13 years, and 5/14 were male. Three distinct morphologies of SG were identified: fusiform-rounded; fusiform-elongated; and bilobed. RSG and LSG did not differ in weight or volume. RSG were longer than LSG (2.05 ± 0.28 cm vs. 1.66 ± 0.47 cm, P = 0.024). Bilobed morphology was most common in RSGs (8/14), while fused, elongated was most common in LSG (8/14). RSGs lacked fused, rounded appearance, while 28.6% of LSG appeared as such. Histologically, one focus of somata was seen in fused rounded ganglia, while fused elongated SG had somata distributed throughout. Bilobed SG demonstrated two foci of somata, with the interconnecting stalk containing sparse somata. SG appears in three major forms and contains varying distributions of somata. Larger studies are warranted to define the relationship between gross anatomy and distribution of neuronal somata to improve the efficacy of CSD in treating VAs. Anat Rec, 301:1244-1250, 2018. © 2018 Wiley Periodicals, Inc.

The Use of Ultrasonography to Identify the Intersection of the Dorsomedial Cutaneous Nerve of the Hallux and the Extensor Hallucis Longus Tendon: A Cadaveric Study.

Terminal branches of the superficial fibular nerve are at risk of iatrogenic damage during foot surgery, including hallux valgus rigidus correction, bunionectomy, cheilectomy, and extensor hallucis longus tendon transfer. One terminal branch, the dorsomedial cutaneous nerve of the hallux, is particularly at risk of injury at its intersection with the extensor hallucis longus tendon. Iatrogenic injuries of the dorsomedial cutaneous nerve of the hallux can result in sensory loss, neuroma formation, and/or debilitating causalgia. Therefore, preoperative identification of the nerve is of great clinical importance. The present study used ultrasonography to identify the intersection between the dorsomedial cutaneous nerve of the hallux and the extensor hallucis longus tendon in cadavers. On ultrasound identification of the intersection, dissection was performed to assess the accuracy of the ultrasound screening. The method successfully pinpointed the nerve in 21 of 28 feet (75%). The sensitivity, positive likelihood ratio, and positive and negative predictive values of ultrasound identification of the junction of the dorsomedial cutaneous nerve and the extensor hallucis longus tendon were 75%, 75%, 100%, and 0%, respectively. We have described an ultrasound protocol that allows for the preoperative identification of the dorsomedial cutaneous nerve of the hallux as it crosses the extensor hallucis longus tendon. The technique could potentially be used to prevent the debilitating iatrogenic injuries known to occur in association with many common foot surgeries.

The Retaining Ligament of the Anterior Digastric Muscle.

The anterior belly of the digastric muscle (ABDM) is important in numerous esthetic surgeries including rhytidectomy, alteration of the cervicomental angle via partial resection of the ABDM muscle belly, and suprahyoid muscular medialization and suspension. Recently, the connection between the ABDM and the mylohyoid muscle (MH) has been proposed as important for the mechanism of the digastric corset procedure. This report refers to the connection between the ABDM and the MH as a type of retaining ligament of the anterior digastric muscle (RLAD). This report is the first to directly demonstrate the existence of the RLAD, via photograph and video, and document variation in its attachment sites, its composition, and its behavior when traction forces are applied. In addition to the importance of the RLAD in plastic surgery, the RLAD may affect neurovascular structures between the ABDM and MH and serve as a physical barrier separating the submental fascial space from the submandibular fascial space and, therefore, influence the spread of infection.

Morphometrics of the Anterior Belly and Intermediate Tendon of the Digastric Muscle: Sexual Dimorphism and Implications for Surgery.

The anterior belly of the digastric muscle (ABDM) is important in a variety of surgeries including submental lipectomy, rhytidectomy, alteration of the cervicomental angle via muscle resection, the "digastric corset" procedure for submental rejuvenation, the submental artery flap, and reanimation of the mouth after facial nerve palsy. Despite its clinical significance, little information exists regarding the morphometrics of the ABDM or its associated intermediate tendon. This study analyzed a total of 35 intact ABDMs and 43 intact intermediate tendons from 23 cadavers. Measurements were taken of the following parameters: muscle belly area, muscle belly length, intermediate tendon length, and intermediate tendon width at mid-tendon. Normative descriptive statistics are included within the report. Males were found to have significantly longer left-sided muscle bellies than right-sided bellies from males (U = 23.0; P = 0.044), left-sided bellies from females (U = 19.0; P = 0.020), and right-sided bellies from females (U = 12.0; P = 0.035). The morphometry, including sexual dimorphism, presented in this report can aid in the surgical planning and execution of numerous operations performed in head and neck, especially digastric muscle transfer surgery.

Circularity, Solidity, Axes of a Best Fit Ellipse, Aspect Ratio, and Roundness of the Foramen Ovale: A Morphometric Analysis With Neurosurgical Considerations.

The structure of the foramen ovale of the sphenoid bone is clinically important, particularly with regard to surgical procedures that cannulate the foramen such as percutaneous trigeminal rhizotomy for the treatment of trigeminal neuralgia, percutaneous biopsy of parasellar lesions, and electroencephalographic analysis of the temporal lobe among patients undergoing selective amygdalohippocampectomy. Differences in the morphology of the foramen ovale (FO) have been reported to contribute to difficulties in the cannulation of the FO. Reports regarding the structure of the FO, however, use subjective and ambiguous descriptions of morphology, including "oval," "truly oval," "elongated oval," "elongated," "semicircular," "almond," "round," "rounded," "slit," "irregular," "D shape," and "pear." Therefore, it is necessary to describe the structure of the FO with reproducible objective morphometric data. This study analyzed 169 foramina to determine normative morphometric shape descriptions of the following: area, perimeter, circularity, solidity, axes of a best fit ellipse, aspect ratio, and roundness. The shape descriptors reported herein may aid in identification and description of structural variation in FO including bony projections encroaching upon the foramina and may improve surgical approaches to transovale cannulation.