A constructivist approach to teach neuroanatomy lab: Students' perceptions of an active learning environment.

BACKGROUND: A recent trend in medical education is developing a more dynamic and integrated curriculum. Team-based learning (TBL) increases students' engagement and the active construction of anatomical knowledge. This initial study aimed to empirically observe medical students' perceptions of their achievement of learning outcomes and the construction of their neuroanatomy knowledge, critical thinking, and problem-solving using an interactive whiteboard (IWB) as a teaching strategy. METHODS: An independent neuroanatomy lab survey collected students' perceptions and comments about their learning experiences using the IWB on a questionnaire using a 5-point Likert scale. RESULTS: Student participants felt that using the IWB has facilitated their learning experience. 94.2% of student participants endorsed feelings that new technology has helped them achieve their learning outcomes, helped them integrate both their basic science and clinical science/skills knowledge (90.4%), enhanced their problem-solving skills (92.3%), facilitated their interaction with the neuroanatomy faculty (96.2%) and increase their critical thinking (88.4%). CONCLUSION: Collecting such empirical data about students' perceptions and their learning environment should help neurosciences faculty in medical schools better outline their activities to faculty at other medical institutions. Applying these methods may enhance the learning process, save time during neuroanatomy lab, and it could also help overcome the shortage of qualified neuroanatomy educators.

Defining the Morphology and Distribution of the Alar Fascia: A Sheet Plastination Investigation.

OBJECTIVES: This study aims to delineate the morphology, integrity, and distribution of the alar fascia using dissection and E12 sheet plastination. This is the first study that employs E12 sheet plastination to investigate the alar fascia and its adjacent potential spaces. METHODS: Twenty-nine manual dissections and 3 sets of E12 sheet plastinations were used to examine the posterior pharyngeal region for the architecture and distribution of the alar fascia. Specimens were examined from the inferior nuchal line to C6. RESULTS: The alar fascia originated as a well-defined midline structure at the level of C1 and could be identified down to C6. There was no evidence of the alar fascia between the inferior nuchal line and the base of the skull. Notably, the alar fascia permitted resistance to manual traction. CONCLUSIONS: E12 sheet plastination allowed for visualization of the alar fascia's superior attachments within the deep cervical region. Resistance to traction suggests that the alar fascia may be more than just a loose fibroareolar matrix. The findings in this study suggest an alternative point of entry into the danger space. Understanding the continuity of this fascial layer is critically important with regard to the pathophysiology of deep neck space infections.

The obliquus capitis inferior myodural bridge.

This study was designed to examine the obliquus capitis inferior (OCI) muscle from a gross anatomical perspective. The objective was to isolate and identify the OCI myodural bridge, while examining its course and contributing elements. An earlier study of the posterior cervical spine briefly reported a connection between the OCI and the cervical dura mater. To the best of our knowledge, a study has not yet been conducted specifically on this muscle and its relation to the dura mater. In this study, the suboccipital regions of nine embalmed cadavers were dissected. A total of 14 OCI muscles were isolated for examination. All findings were documented via photograph. Of the 14 OCI muscles isolated, all emitted fibrous tissue bands from the anterolateral portion of the muscular belly. These fibers attached to the posterolateral cervical dura mater by route of the atlantoaxial interspace. The OCI myodural bridge appeared to coalesce with the rectus capitis posterior major myodural bridge, giving the appearance of a single atlantoaxial structure that links these two muscles to the dura mater. In conclusion, the OCI was attached to the dura mater in all of the 14 muscle specimens. We hypothesize that the OCI myodural bridge may play a physiological role in monitoring dural tension and preventing dural infolding. It may also contribute to certain clinical symptoms manifesting from alterations in dural tone.

Magnetic resonance imaging investigation of the atlanto-axial interspace.

The objective of this study is to examine the anatomy of the atlanto-axial interspace using magnetic resonance (MR) imaging. Two hundred and forty MR images of living subjects were examined for the presence of a posterior dural prominence and oblique hypointense fibers between the first and second cervical neural arches. Of the 240 images analyzed, 64% revealed a posterior concavity of the cervical dura mater. Of this, 24% also revealed oblique, linear hypointense fibers that appeared to be in direct contact with the dura mater. Twenty-three percent of the 240 images revealed oblique, linear hypointense fibers. Of the 23% that exhibited these fibers, 76% had an associated posterior thecal concavity of the cervical dura mater. A posterior dural prominence and oblique hypointense fibers were present in the atlanto-axial interspace in a significant number of randomly selected magnetic resonance images. These findings may represent normal, nonpathological anatomy found on MR images and may be related to a recently reported anatomical structure.

The Posterior Atlantooccipital Membrane: The Anchor for the Myodural Bridge and Meningovertebral Structures.

INTRODUCTION: Sheet plastination has provided evidence that the posterior atlantooccipital membrane attaches to the dura's posterior sleeve at the cerebrospinal junction. These findings contradict the traditional anatomical description of this membrane extending from the atlas' posterior arch to the foramen magnum. METHODS: A total of 16 plastinated cadavers were studied to evaluate the in situ and gross configuration of the posterior atlantooccipital membrane. Fifteen cadavers underwent sheet plastination, and one head was hemisected and plastinated. In all specimens, stereomicroscopy was used to evaluate the posterior atlantooccipital membrane and related structures within the intervertebral and epidural spaces. RESULTS: In all 16 specimens, the posterior atlantooccipital membrane extending from the occiput, merged with the craniocervical dura mater, and formed a membrane-dura complex that ended at the level of the third cervical vertebra. The superior and inferior myodural bridge coalesced with their respective vertebrodural ligaments and fused with the posterior atlantooccipital membrane at their respective interspaces. CONCLUSION: The median aspect of the posterior atlantooccipital membrane does not directly communicate with the posterior arch of the atlas. Instead, the posterior atlantooccipital membrane converges with the craniocervical dura mater and terminates at the level of the third cervical vertebra. This membrane-dura complex serves as a common attachment site for the myodural and vertebrodural structures.

The Alar Fascia and Danger Space: A Modern Review.

PURPOSE: Given the advancements in dissection modalities over the last decade, what is the current understanding of the alar fascia and its clinical implications as an access point into the danger space (DS)? The aim of the study is to provide an updated review of the alar fascia and danger space. METHODS: A comprehensive search of the alar fascia and danger space was performed through PubMed databases up to August 2022. Thirty-two sagittal E12 sheet plastination slices of the head and neck were analyzed under a stereomicroscope to assess the morphology and continuity of the retropharyngeal, alar, and prevertebral fasciae (PVF and their respective potential spaces). RESULTS: Recent advancements have provided evidence that the alar fascia is a true fascial layer between the retropharyngeal and danger spaces within the deep cervical region. Although its composition, histological features, and borders remain topics of controversy, the alar fascia is comprised of dense connective tissue and may serve as a physical barrier to prevent the spread of infection into the danger space. Complications arising from deep neck infections that invade the danger space include mediastinitis, necrotizing fasciitis, and empyema. CONCLUSION: A proper understanding of the anatomy, structure, function, and potential spaces is crucial to assessing the alar fascia and danger space routinely in clinical practice, especially when imaging.

Quadrangular Space Syndrome: A Narrative Overview.

OBJECTIVE: The purpose of this narrative review of the literature is to provide an overview of quadrangular space syndrome with special attention to its clinical presentation, differential diagnosis, and treatment. METHODS: A narrative review of the English-language, peer-reviewed literature was performed using the key words "axillary nerve," "quadrangular space," "quadrilateral space," and "posterior humeral circumflex artery." Databases searched were Medline Complete, Cumulative Index to Nursing and Allied Health Literatures, and Index to Chiropractic Literature. The search period was from 1983 through January 2020. RESULTS: There were 85 articles selected for this review. A summary and overview are provided. CONCLUSION: Quadrangular space syndrome is an uncommon cause of shoulder pain. Clinicians should consider it as a diagnosis after ruling out more common shoulder conditions and examining other concurrent diseases.

Supernumerary Head of the Biceps Brachii Muscle: An Anatomic Variant With Clinical Implications.

OBJECTIVE: The purpose of this anatomic case report is to describe a variation of the biceps brachii muscle identified in an adult male cadaveric specimen and its potential clinical relevance. METHODS: A cadaveric specimen with a left supernumerary biceps brachii muscle was dissected. Adjacent neurovascular structures were isolated, and their pathways were observed for possible areas of compression. RESULTS: A tricipital supernumerary head of the biceps brachii muscle was noted on the left upper extremity in an embalmed human cadaveric specimen. The median nerve and brachial artery maintained their common neurovascular path. The musculocutaneous nerve passed deep to the third head of the anatomic variant before distributing its cutaneous branches as the lateral antebrachial cutaneous nerve. CONCLUSION: The presence of a supernumerary biceps brachii muscle may cause neurovascular compression of the median nerve, musculocutaneous nerve, or brachial artery, resulting in peripheral nerve deficits. When patient conditions are refractory to care, they may warrant careful evaluation of the anterior compartment of the arm for potential anomalous muscle variations.

Sonography of the normal greater occipital nerve and obliquus capitis inferior muscle.

BACKGROUND: To use sonography to measure the cross-sectional area (CSA) of the greater occipital nerve (GON) and the adjacent obliquus capitis inferior muscle (OCI) in normal subjects. METHODS: Data from 30 asymptomatic subjects between the ages of 22 and 35 were collected. CSA and circumference of the GON and CSA of OCI were measured using sonography. Interexaminer reliability analysis was performed using the intraclass correlation coefficient. RESULTS: The CSA of the GON and OCI were 2 mm2 +/- 1 mm2 and 1.86 cm2 +/- 0.51 cm2, respectively. The average circumference of the GON was 4.8 mm +/- 1.3 mm. The interexaminer reliability of the measurements was excellent with intraclass correlation coefficient coefficients of 0.91, 0.84, and 0.73 for the GON CSA, GON circumference, and OCI CSA, respectively. CONCLUSION: We report the normal values of the CSA of the GON and OCI. Knowledge of these normal values may facilitate the diagnosis of GON entrapment and provide outcome measures in therapeutic interventions.

Distal intersection syndrome progressing to extensor pollicis longus tendon rupture: a case report with sonographic findings.

The purpose of this case report is to describe the value of musculoskeletal ultrasound (US) in diagnosing both distal intersection syndrome (DIS) and rupture of the extensor pollicis longus (EPL) tendon in the same patient. A 38-year-old female presented for evaluation of a painful bump of unknown etiology on the dorsolateral aspect of her non-dominant wrist. US demonstrated tenosynovitis distal to Lister's tubercle of the EPL and extensor carpi radialis tendon sheaths, consistent with DIS. Immobilization therapy was employed, during which time the patient suffered rupture of the EPL tendon. Follow-up US examination confirmed this additional diagnosis. Characteristic US findings of DIS and EPL tendon rupture were observed. Surgical intervention was required and the patient recovered without complication. Although EPL rupture is relatively common in the literature, DIS is rare. This is the first known case of imaging-proven DIS progressing to EPL tendon rupture. This case underscores the value of US as a widely available, cost effective, and dynamic imaging modality for evaluation of wrist complaints.

Sonographic diagnosis of an acute Stener lesion: a case report.

This case report describes the use of diagnostic ultrasound to diagnose a Stener lesion in a patient who presented for conservative care of thumb pain following a fall on an outstretched hand. Conventional radiographic images demonstrated an avulsion fracture at the ulnar aspect of the base of the first proximal phalanx. Diagnostic ultrasound revealed a torn ulnar collateral ligament of the thumb that was displaced proximal to the adductor aponeurosis, consistent with a Stener lesion. Dynamic imaging with ultrasound confirmed displacement of the fully torn ligament. Surgical repair followed the diagnosis. Diagnostic ultrasound in this case provided an accurate diagnosis obviating further imaging. This allowed an optimal outcome due to early intervention.

Investigation of meningomyovertebral structures within the upper cervical epidural space: a sheet plastination study with clinical implications.

BACKGROUND CONTEXT: Over the past two decades, soft-tissue structures communicating with the dura mater within the epidural space have become the focus of many anatomical and histopathologic studies. The relationship between these bridging structures has yet to be evaluated in situ. PURPOSE: This is the first study that used E12 sheet plastination to investigate the epidural space of the upper cervical spine in situ and its associated bridging structures. Given the complexity of this space, this study may prove useful to clinical anatomists and surgeons who operate within this region. STUDY DESIGN: Anatomical and microscopic analyses of structures that communicate with the dura mater within the upper cervical region were carried out. METHODS: Gross dissection in conjunction with microscopy was used to evaluate bridging communications of the upper cervical spine in 10 cadavers. To evaluate the in situ arrangement of these structures, E12 sheet plastination was used on 13 cadavers. RESULTS: In all 23 specimens, suboccipital fascia coalesced with the dorsal meningovertebral ligament of the atlas, and inserted directly into the posterior surface of the dura as a single but separable laminar layer. At the level of the atlantoaxial interspace, suboccipital fasciae combined and coalesced with the dorsal meningovertebral ligament of the atlas and the axis. These structures inserted into the posterior surface of the dura mater as a single but separable layer. Microscopy validated these findings and E12 sheet plastination revealed the in situ organization of these soft-tissue structures. E12 sheet plastination also provided new information on dural arrangement at the craniocervical junction, which was observed to be composed of periosteum from the occiput but consisted mainly of deep fascia from the rectus capitis posterior minor. CONCLUSIONS: E12 sheet plastination has provided in situ visualization of bridging structures within the cervical epidural space and offers new insight into these structures, as well as the composition and arrangement of the posterior atlantooccipital membrane and cerebrospinal dura at the craniocervical junction. This study aims to expand on the anatomical understanding of the upper cervical region while defining structures that may reduce neurosurgical complications, and aid in the understanding of the pathophysiology of certain neurogenic disorders.

Management of Acute Patellar Dislocation: A Case Report.

OBJECTIVE: The purpose of this case study is to describe the evaluation and management of patellar dislocations and the different approaches used from providers in different countries. CLINICAL FEATURES: An individual dislocated her left patella while traveling abroad and received subsequent care in Thailand, China, and the United States. INTERVENTION AND OUTCOME: Nonoperative treatment protocols including manual closed reduction of the patella, casting of the leg, and rehabilitation exercises were employed. CONCLUSION: Receipt of care when abroad can be challenging. The patient's knee range of motion and pain continued to improve when she was diligent about performing the home exercise program. This case highlights the importance of a thorough examination, a proper regimen of care, and patient counseling to ensure a full recovery and minimize the chance of re-injury.

The cervical myodural bridge, a review of literature and clinical implications.

The role of posterior cervical musculature in sensorimotor control, cervicocephalic pain, and stabilization of the spinal cord has been recently described. Anatomical soft tissue connections which cross the cervical epidural space link suboccipital muscle fascia and dura. These myodural bridges provide passive and active anchoring of the spinal cord. They may also be involved in a dural tension monitoring system to prevent dural infolding, and maintain patency of the spinal cord. Modulation of dural tension may be initiated via a sensory reflex to muscular contractile tissues. Unanticipated movements such as hyperflexion extension injuries stimulate deep suboccipital muscles and transmit tensile forces through the bridge to the cervical dura. Due to its larger cross sectional area, the rectus capitis posterior major myodural bridge may exert greater mechanical traction on the dura than the rectus capitis posterior minor. University ethics committee approval and anatomical donor consent was obtained for this study.

Le rôle de la musculature cervicale postérieure dans le contrôle sensorimoteur, la douleur cervico-céphalique et la stabilisation de la moelle épinière n'a que récemment fait l'objet d'une description. Les connexions anatomiques des tissus mous qui traversent l'espace épidural cervical lient le fascia et la dure-mère des muscles sous-occipitaux. Ces ponts myoduraux offrent un point d'ancrage passif et actif à la moelle épinière. Ils peuvent aussi participer au système de contrôle de la tension durale afin de prévenir le repliement dural et de maintenir la perméabilité de la moelle épinière. Les modulations de la tension durale peuvent être provoquées par un réflexe sensoriel aux tissus musculaires contractiles. Les mouvements non anticipés comme les blessures résultant d'une hyperflexion-extension stimulent les muscles sous-occipitaux profonds et transmettent des efforts de traction par le pont sur la dure-mère cervicale. En raison de sa plus grande section transversale, le pont myodural grand droit postérieur peut exercer une plus grande traction mécanique sur la dure-mère que le muscle petit droit postérieur. L'approbation du comité d'éthique de l'université et le consentement du donneur anatomique ont été obtenus pour la présente étude.

Histological analysis of the rectus capitis posterior major's myodural bridge.

BACKGROUND CONTEXT: In recent literature, a soft-tissue communication between the rectus capitis posterior major (RCPma) muscle and the cervical dura mater has been identified. To the best of our knowledge, this communication has yet to be validated from a histological perspective nor has it been examined for neural tissue. PURPOSE: The purpose of this study was to examine the composition and true continuity of the communication between the RCPma and the dura mater at a microscopic level. The communication was also inspected for the presence of proprioceptive neurons. STUDY DESIGN: An anatomical and histological analysis of a novel structure in the atlantoaxial interspace. METHODS: Gross dissection was performed on 11 cadavers to remove the RCPma, the soft-tissue communication, and a section of posterior cervical dura mater as one continuous unit. Paraffin embedding and sectioning followed by hematoxylin and eosin staining was conducted to validate the connection. Staining with antineurofilament protein fluorescent antibodies was performed to identify proprioceptive neural tissue on one specimen, and all findings were recorded via photographic documentation. RESULTS: Histological investigation revealed a tendinous matrix inserting into both the RCPma and the posterior aspect of the cervical dura mater in all 11 specimens. In the one specimen examined for neural tissue, antineurofilament protein fluorescence revealed proprioceptive neurons within the communication. Immunoperoxidase staining demonstrated the insertion of these neurons into both the dura mater and the belly of the RCPma. CONCLUSIONS: The existence of a true connection between the RCPma and the cervical dura mater provides new insight in understanding the complex anatomy of the atlantoaxial interspace. The presence of a neural component within this connection suggests that it may serve another function aside from simply anchoring this muscle to the dura mater. Such a connection may be involved in monitoring dural tension and may also play a role in certain cervicogenic pathologies. This study also supports previous reports that no true membrane joins the posterior arch of the atlas to the laminae of the axis and contradicts the conventional belief that the ligamentum flavum joins these two structures.

Histological examination of the human obliquus capitis inferior myodural bridge.

This study was designed to examine the anatomical relationship between the obliquus capitis inferior (OCI) muscle and the cervical dura mater at the histological level. Eight human cadavers, with an average age of 65 ± 7.9 years were selected from a convenience sample for suboccipital dissection. Twelve OCI muscle specimens were excised, 100% of which emitted grossly visible soft tissue tracts that inserted into the posterolateral aspect of the cervical dura. These 12 myodural specimens were excised as single, continuous structures and sent for H&E staining. One sample also underwent immuno-peroxidase staining. Microscopic evaluation confirmed a connective tissue bridge emanating from the OCI muscular body and attaching to the posterolateral aspect of the cervical dura mater in 75% of the specimens. Microtome slices of the remaining 25% were not able to capture muscle, connective tissue and dura within the same plane and were therefore unable to be properly analyzed. The sample sent for neuro-analysis stained positively for several neuronal fascicles traveling within, and passing through the OCI myodural bridge. This study histologically confirms the presence of a connective tissue bridge that links the OCI muscle to the dura mater and the presence of neuronal tissue within this connection warrants further examination. This structure may represent a component of normal human anatomy. In addition to its hypothetical role in human homeostasis, it may contribute to certain neuropathological conditions, as well.

Co-presentation of unilateral femoral and bilateral sciatic nerve variants in one cadaver: A case report with clinical implications.

OBJECTIVE: To present a group of anatomical findings that may have clinical significance. DESIGN: This study is an anatomical case report of combined lumbo-pelvic peripheral nerve and muscular variants. SETTING: University anatomy laboratory. PARTICIPANTS: One cadaveric specimen. METHODS: During routine cadaveric dissection for a graduate teaching program, unilateral femoral and bilateral sciatic nerve variants were observed in relation to the iliacus and piriformis muscle, respectively. Further dissection of both the femoral nerve and accessory slip of iliacus muscle was performed to fully expose their anatomy. RESULTS: Piercing of the femoral nerve by an accessory iliacus muscle combined with wide variations in sciatic nerve and piriformis muscle presentations may have clinical significance. CONCLUSIONS: Combined femoral and sciatic nerve variants should be considered when treatment for a lumbar disc herniation is refractory to care despite positive orthopedic testing.

Anatomical connection between the rectus capitis posterior major and the dura mater.

STUDY DESIGN: Anatomic study performed on 13 cadaveric specimens focused on muscles of the suboccipital triangle, specifically, the rectus capitis posterior major (RCPma). OBJECTIVE: To investigate a connection between the RCPma and the cervical dura mater. SUMMARY OF BACKGROUND DATA: In a study of the posterior intervertebral spaces, a connection between the RCPma and the dura mater was briefly described. To the best of our knowledge, no study has been conducted specifically on this communication. METHODS: Anatomic dissections were performed in the suboccipital regions of 13 embalmed, adult cadaveric specimens. Findings were recorded via photographic documentation. RESULTS: In 11 of the 13 specimens, the RCPma attached to the spinous process of the axis and then continued to establish a gross anatomical connection with the dura mater in the atlantoaxial interspace. Manual traction of the RCPma resulted in gross dural movement from the spinal root level of the axis to the spinal root level of the first thoracic vertebra. CONCLUSION: A connection was found to exist between the RCPma and the cervical dura mater. Various clinical manifestations may be linked to this anatomical relationship.

Tumefactive multiple sclerosis: an uncommon diagnostic challenge.

OBJECTIVE: This case report describes a rare presentation of multiple sclerosis (MS) that was initially diagnosed as a peripheral nerve lesion in the emergency department. CLINICAL FEATURES: A 30-year-old woman presented to a chiropractic teaching clinic with a complaint of a sudden right foot drop. Magnetic resonance imaging of the brain revealed a large mass in the left parietal lobe with additional white matter lesions. The mass and smaller lesions were consistent with a rare presentation of demyelinating disease, tumefactive MS. INTERVENTION AND OUTCOME: The patient was referred to a neurologist for further evaluation and treatment. Her short-term clinical course was punctuated by recurrent myospasms and neurologic deficits. CONCLUSION: Tumefactive MS may mimic the clinical and magnetic resonance imaging characteristics of glioma or a cerebral abscess. The clinical presentation, pathophysiology, differential diagnosis, role of diagnostic imaging, and treatment options of MS are described. This case report illustrates that the timely diagnosis and optimal treatment of MS require recognition of its varied, sometimes atypical, and often nonspecific clinical and imaging manifestations.