Melon and rostral muscle morphology of Gervais' beaked whale (Mesoplodon europaeus): Alternating patterns of bilateral asymmetry.

Toothed whales utilize specialized nasal structures such as the lipid-rich melon to produce sound and propagate it into the aquatic environment. Very little nasal morphology of mesoplodont beaked whales has been described in the literature, and the anatomy of the melon and associated musculature of Gervais' beaked whale (Mesoplodon europaeus) remains undescribed. Heads of three (n = 3) Gervais' beaked whales were examined in detail via dissection as well as computed tomography (CT) and magnetic resonance imaging (MRI). Two additional Gervais' beaked whale individuals (n = 2) were studied via archived CT and MRI scans. Representative transverse dissection sections of the melon were processed for polarized light imaging to verify the presence of tendons inserting into the melon tissue. Three-dimensional (3D) CT reconstructions of the melon, rostral muscles, and associated structures were performed to assess morphology and spatial relationships. In all individuals, the melon's main body demonstrated a bilaterally asymmetrical, curvilinear geometry. This curvilinear shape was defined by a pattern of alternating asymmetry in the medial rostral muscles that projected into the melon's tissue. In transverse polarized light imaging, a network of tendons originating from these asymmetrical rostral muscle projections was observed permeating the melon's lipid tissue. This curvilinear melon morphology and associated asymmetrical musculature suggest a means of lengthening the lipid pathway within a relatively short dimensional footprint. In addition, the species-specific arrangement of muscular projections suggests complex fine-tuning of the melon's geometry during echolocation. Further studies may lend additional insight into the function of this unusual melon morphology.

Methods and outcomes of teaching functional anatomy of the musculoskeletal system: A scoping review.

PURPOSE: Although musculoskeletal anatomy is inherently related to motion, there is a lack of evidence review about the best teaching practices for the locomotor apparatus functional anatomy. We aimed to detect the strategies that have been implemented for functional musculoskeletal anatomy education, and their outcomes, with the ultimate purpose of suggesting the most effective teaching methods. METHODS: The databases PubMed, Scopus, ERIC, and Cochrane Library were searched for papers with the purpose of exploring the outcomes (participants' perceptions and/or examination performance) of teaching functional musculoskeletal anatomy. From each study, the following information was extracted: author(s), number of participants, implementation method, participants' perceptions and/or examination performance after the educational intervention, and classification of the outcomes according to the Kirkpatrick hierarchy. RESULTS: Seven papers were included. Six of them involved active learning strategies (other than seeing, listening, and taking notes). Several specific teaching methods were implemented, including physical activities, lectures, textbooks, atlases, prosected specimens, near-peer teaching, and digital and physical models. Overall, methods that involved active learning, especially some form of physical activity, had the best educational outcomes, while passive learning was not found to be significantly more effective in any case. The role of modern anatomy education technologies has been inadequately explored. CONCLUSIONS: It appears that teaching functional musculoskeletal anatomy is more successful when using active learning methods, especially involving some form of physical activity. More research is necessary to determine the best environment for these methods and investigate the role of modern technologies in functional musculoskeletal anatomy education.

When the central integrator disintegrates: A review of the role of the thalamus in cognition and dementia.

The thalamus is a complex neural structure with numerous anatomical subdivisions and intricate connectivity patterns. In recent decades, the traditional view of the thalamus as a relay station and "gateway to the cortex" has expanded in recognition of its role as a central integrator of inputs from sensory systems, cortex, basal ganglia, limbic systems, brain stem nuclei, and cerebellum. As such, the thalamus is critical for numerous aspects of human cognition, mood, and behavior, as well as serving sensory processing and motor functions. Thalamus pathology is an important contributor to cognitive and functional decline, and it might be argued that the thalamus has been somewhat overlooked as an important player in dementia. In this review, we provide a comprehensive overview of thalamus anatomy and function, with an emphasis on human cognition and behavior, and discuss emerging insights on the role of thalamus pathology in dementia.

Making a Stand.

OBJECTIVE: This is a review of the advertisements for basic surgical training course on social media and a comment on the ergonomics of the training. DESIGN: The author examined social media advertisements (Twitter and Instagram) over 4 months with a focus on stitching courses. No computer algorithm was available or could be made to ensure a comprehensive inclusion of all courses. RESULTS: One hundred nine basic surgical skills courses were identified, and 102 out of 109 (94%) courses are conducted sitting down. Courses were run in regular rooms or lecture theatres at regular table and using ordinary chairs. CONCLUSION: The practice and acquisition of basic surgical skills needs to address correctness of the technique and ergonomics especially with regards to posture. This influences not only muscle memory and musculoskeletal health but also the position of the needle and potential trauma to the tissues.

Validating osteological correlates for the hepatic piston in the American alligator (Alligator mississippiensis).

Unlike the majority of sauropsids, which breathe primarily through costal and abdominal muscle contractions, extant crocodilians have evolved the hepatic piston pump, a unique additional ventilatory mechanism powered by the diaphragmaticus muscle. This muscle originates from the bony pelvis, wrapping around the abdominal viscera, extending cranially to the liver. The liver then attaches to the caudal margin of the lungs, resulting in a sub-fusiform morphology for the entire "pulmo-hepatic-diaphragmatic" structure. When the diaphragmaticus muscle contracts during inspiration, the liver is pulled caudally, lowering pressure in the thoracolumbar cavity, and inflating the lungs. It has been established that the hepatic piston pump requires the liver to be displaced to ventilate the lungs, but it has not been determined if the lungs are freely mobile or if the pleural tissues stretch ventrally. It has been hypothesized that the lungs are able to slide craniocaudally with the liver due to the smooth internal ceiling of the thoracolumbar cavity. We assess this through ultrasound video and demonstrate quantitatively and qualitatively that the pulmonary tissues are sliding craniocaudally across the interior thoracolumbar ceiling in actively ventilating live juvenile, sub-adult, and adult individuals (n = 7) of the American alligator (Alligator mississippiensis) during both natural and induced ventilation. The hepatic piston is a novel ventilatory mechanism with a relatively unknown evolutionary history. Questions related to when and under what conditions the hepatic piston first evolved have previously been left unanswered due to a lack fossilized evidence for its presence or absence. By functionally correlating specific characters in the axial skeleton to the hepatic piston, these osteological correlates can be applied to fossil taxa to reconstruct the evolution of the hepatic piston in extinct crocodylomorph archosaurs.

Current State of Functional MRI in the Presurgical Planning of Brain Tumors.

Surgical resection of brain tumors is challenging because of the delicate balance between maximizing tumor removal and preserving vital brain functions. Functional MRI (fMRI) offers noninvasive preoperative mapping of widely distributed brain areas and is increasingly used in presurgical functional mapping. However, its impact on survival and functional outcomes is still not well-supported by evidence. Task-based fMRI (tb-fMRI) maps blood oxygen level-dependent (BOLD) signal changes during specific tasks, while resting-state fMRI (rs-fMRI) examines spontaneous brain activity. rs-fMRI may be useful for patients who cannot perform tasks, but its reliability is affected by tumor-induced changes, challenges in data processing, and noise. Validation studies comparing fMRI with direct cortical stimulation (DCS) show variable concordance, particularly for cognitive functions such as language; however, concordance for tb-fMRI is generally greater than that for rs-fMRI. Preoperative fMRI, in combination with MRI tractography and intraoperative DCS, may result in improved survival and extent of resection and reduced functional deficits. fMRI has the potential to guide surgical planning and help identify targets for intraoperative mapping, but there is currently limited prospective evidence of its impact on patient outcomes. This review describes the current state of fMRI for preoperative assessment in patients undergoing brain tumor resection. Keywords: MR-Functional Imaging, CNS, Brain/Brain Stem, Anatomy, Oncology, Functional MRI, Functional Anatomy, Task-based, Resting State, Surgical Planning, Brain Tumor © RSNA, 2023.

A Unique Arc of Bühler Variant Connecting the Arteries of the Foregut, Midgut, and Hindgut and Its Surgical Significance.

This case report presents a rare variation of the arc of Bühler (AOB) in a cadaver during the abdominal dissection assignment in the Ross Anatomy Lab at William Carey University College of Osteopathic Medicine. The AOB is a patent anastomotic channel between the celiac trunk and the superior mesenteric artery independent of the gastroduodenal artery and dorsal pancreatic artery. This report describes in detail a complex and extensive branching pattern of a unique AOB variant. Our findings contribute to the limited literature on this condition and emphasize the importance of thorough knowledge of vascular variations to avoid potential complications during surgical procedures.

Functional anatomy of the worker honeybee stinger (Apis mellifera).

The honeybee stinger is a powerful defense mechanism that combines painful venom, a subcutaneous delivery system, and the ability to autotomize. It is a complex organ and to function autonomously it must carry with it all the anatomical components required to operate. In this study, we combined high-speed filming, SEM imagery, and micro-CT for volumetric rendering of the stinger with a synthesis of existing literature. We present a comprehensive description of all components, including cuticular elements, musculature, nervous and glandular tissue using updated imagery. We draw from the Hymenoptera literature to make interspecific comparisons where relevant. The use of 3D reconstruction allows us to separate stinger components and present the first 3D renders of the bee stinger including the terminal abdominal ganglion and its projections. It also clarifies the in-situ geometry of the valves within the bulb and the spatial relationships among the accessory plates and accompanying musculature.

Functional traits and water-transport strategies of woody species in an insular environment in a tropical forest.

PREMISE: Plants survive in habitats with limited resource availability and contrasting environments by responding to variation in environmental factors through morphophysiological traits related to species performance in different ecosystems. However, how different plant strategies influence the megadiversity of tropical species has remained a knowledge gap. METHODS: We analyzed variations in 27 morphophysiological traits of leaves and secondary xylem in Erythroxylum pulchrum and Tapirira guianensis, which have the highest absolute dominance in these physiognomies and occur together in areas of restinga and dense ombrophilous forest to infer water-transport strategies of Atlantic Forest woody plants. RESULTS: The two species presented different sets of morphophysiological traits, strategies to avoid embolism and ensure water transport, in different phytophysiognomies. Tapirira guianensis showed possible adaptations influenced by phytophysiognomy, while E. pulchrum showed less variation in the set of characteristics between different phytophysiognomies. CONCLUSIONS: Our results provide essential tools to understand how the environment can modulate morphofunctional traits and how each species adjusts differently to adapt to different phytophysiognomies. In this sense, the results for these species reveal new species-specific responses in the tropical forest. Such knowledge is a prerequisite to predict future development of the most vulnerable forests as climate changes.

Symptomatic responses elicited by electrical stimulation of the cingulate cortex: Study of a cohort of epileptic patients and literature review.

Our understanding of cingulate cortex function is limited. As a method for locating the epileptogenic zone, direct electrical cortical stimulation (ECS) provides an opportunity to understand the functional localization of the cingulate cortex. This study aimed to learn more about the function of the cingulate cortex by analyzing a large body of data from our center and by reviewing existing literature on cortical mapping. We retrospectively analyzed the ECS data of 124 patients with drug-resistant epilepsy who had undergone electrode implantation in the cingulate cortex. The standard stimulation parameters included a biphasic pulse and bipolar stimulation at 50 Hz. Furthermore, we reviewed existing studies on cingulate responses elicited by the ECS and compared them with our results. A total of 329 responses were evoked in 276 contacts using ECS. Of these, 196 were physiological functional responses, which included sensory, affective, autonomic, language, visual, vestibular, and motor responses, along with a few other sensations. Sensory, motor, vestibular, and visual responses were concentrated in the cingulate sulcus visual area (CSv). Furthermore, 133 epilepsy-related responses were evoked, most of which were concentrated in the ventral cingulate cortex. No responses were evoked by 498 contacts. Furthermore, the comparison of our ECS results with those reported in 11 comprehensive reviews revealed that the cingulate cortex is involved in complicated functions. The cingulate cortex is involved in sensory, affective, autonomic, language, visual, vestibular, and motor functions. The CSv is an integrating node of sensory, motor, vestibular, and visual systems.

Larval anatomy of the digestive and excretory systems of the pharyngeal bot fly, Pharyngomyia picta (Diptera: Oestridae).

Oestrid flies (Diptera: Oestridae) are obligate parasites of mammals during their larval stage and show anatomical adaptations for the infestation of host tissues. Unlike the species that parasitize domestic mammals, those oestrid species that infest wild mammal hosts remain poorly known. With the use of x-ray micro-computed tomography, we describe for the first time the anatomy of the digestive and excretory systems of the second and third larval instars of Pharyngomyia picta (Meigen), a parasite of cervids that, like other species within the subfamily Oestrinae, causes nasopharyngeal myiasis. Both larval instars of P. picta show a pair of remarkably large salivary glands arranged in a characteristic 'glandular band', a convoluted and thickly uniform midgut and a greatly enlarged distal region of the anterior pair of Malpighian tubules. These anatomical features also have been described in other species within the subfamily Oestrinae, whereas they differ from the observations in other oestrid subfamilies. We discuss the potential functional significance of the anatomy of the digestive and excretory systems of Oestrinae larvae as specific adaptations to parasitize the nasopharyngeal cavities of mammal hosts.

Knuckle-walking in Sahelanthropus? Locomotor inferences from the ulnae of fossil hominins and other hominoids.

Because the ulna supports and transmits forces during movement, its morphology can signal aspects of functional adaptation. To test whether, like extant apes, some hominins habitually recruit the forelimb in locomotion, we separate the ulna shaft and ulna proximal complex for independent shape analyses via elliptical Fourier methods to identify functional signals. We examine the relative influence of locomotion, taxonomy, and body mass on ulna contours in Homo sapiens (n = 22), five species of extant apes (n = 33), two Miocene apes (Hispanopithecus and Danuvius), and 17 fossil hominin specimens including Sahelanthropus, Ardipithecus, Australopithecus, Paranthropus, and early Homo. Ulna proximal complex contours correlate with body mass but not locomotor patterns, while ulna shafts significantly correlate with locomotion. African apes' ulna shafts are more robust and curved than Asian apes and are unlike other terrestrial mammals (including other primates), curving ventrally rather than dorsally. Because this distinctive curvature is absent in orangutans and hylobatids, it is likely a function of powerful flexors engaged in wrist and hand stabilization during knuckle-walking, and not an adaptation to climbing or suspensory behavior. The OH 36 (purported Paranthropus boisei) and TM 266 (assigned to Sahelanthropus tchadensis) fossils differ from other hominins by falling within the knuckle-walking morphospace, and thus appear to show forelimb morphology consistent with terrestrial locomotion. Discriminant function analysis classifies both OH 36 and TM 266 with Pan and Gorilla with high posterior probability. Along with its associated femur, the TM 266 ulna shaft contours and its deep, keeled trochlear notch comprise a suite of traits signaling African ape-like quadrupedalism. While implications for the phylogenetic position and hominin status of S. tchadensis remain equivocal, this study supports the growing body of evidence indicating that S. tchadensis was not an obligate biped, but instead represents a late Miocene hominid with knuckle-walking adaptations.

Exploring the impact of interactive movement-based anatomy learning in real classroom setting among kinesiology students.

Descriptive and functional anatomy is one of the most important sciences for kinesiology students. Anatomy learning requires spatial and motor imagery abilities. Learning anatomy is complex when teaching methods and instructional tools do not appropriately develop spatial and motor imagery abilities. Recent technological developments such as three-dimensional (3D) digital tools allow to overcome those difficulties, especially when 3D tools require strong interactions with the learners. Besides interactive digital tools, embodied learning or learning in motion is an effective method for a wide variety of sciences including anatomy. The aim of this study was to explore the impact of combining movement execution with 3D animation visualization on anatomy learning in a real classroom teaching context. To do so, the results of two groups of kinesiology students during three official assessments were compared. The experimental group (n = 60) learned functional anatomy by combining movement execution with traditional knowledge acquisition (e.g., 3D animations visualization, problem-based learning exercises). The control group (n = 61) had the same material but did not execute the movements during problem-solving exercises. Although no differences were found between both groups on early and mid-semester examinations, significant difference appeared at the end of the semester with an advantage for the experimental group. This exploratory study suggests that embodied learning is beneficial in improving functional anatomy learning. Therefore, it would be interesting to integrate such type of pedagogical approach within the kinesiology curriculum.

Do we understand the prefrontal cortex?

Many suggestions have been made as to the functions of the prefrontal (PF) cortex. However, they involve labelling areas using psychological terminology. But what we need to know is how the PF cortex operates. We argue that understanding this must start with describing the flow of information. We illustrate this argument by considering three PF areas. Each has a unique pattern of inputs and outputs, and we suggest that the implication is that each performs a unique transformation from the inputs to the outputs. The caudal PF cortex transforms input that is maintained by attention or short-term memory into the target of the appropriate eye movement. The mid-dorsal PF cortex transforms input concerning the order of objects or actions into the target of the appropriate eye and hand movements, thus supporting sequences of action. The ventral PF cortex transforms input concerning an object or sound into prospective activity that encodes the associated object or sound. However, it is important to appreciate that the mid-dorsal and ventral PF cortex are specialized for encoding abstract transformations, irrespective of the specific actions or objects. The advantage is that this enables generalization to novel problems that have the same underlying logic. We account for the difference between fast learning and slow learning in this way. The human brain has co-opted these mechanisms so as to support intelligence. Non-verbal tests of IQ typically use sequences of letters, numbers or designs. These test the ability to understand the abstract rules that apply. Here the activations lie in the mid-dorsal PF cortex. Verbal tests typically assess the ability to understand semantic associations. These can be presented either in pictorial or verbal form. Here the activations lie in the ventral PF cortex.

Technical, functional, and oncological validity of robot-assisted total-intersphincteric resection (T-ISR) for lower rectal cancer.

BACKGROUND: Few studies fairly compared anorectal function and prognostic outcomes between patients undergoing abdominoperineal resection (APR) and anorectal-function-saving operations (ASO) under the equivalent conditions. By contrast, surgeons used to be somewhat hesitant to conduct total intersphincteric resection (T-ISR) as maximal ASO, due to its technical complexity and potential anorectal dysfunction. METHODS: Propensity-score matched cohorts undergoing robot-assisted R0 surgery [T-ISR vs APR vs partial-subtotal ISR (PS-ISR)/lower anterior resection (LAR)] for rectal cancer (n = 1361) were included. Operative outcomes, recurrence, and disease-free/overall survival (DFS/OS) were analyzed. Anorectal function was evaluated based on fecal incontinence score and high-resolution manometry between the T-ISR and other ASO groups. RESULTS: Few differences were detected between the T-ISR and APR groups. More patients undergoing APR had T4 stage disease, while the lowest tumor margin was the same in both groups (mean, 1.5 cm from anal verge). Prognostic outcomes did not differ between the T-ISR and APR groups, including local (5.1% vs 7.7%, p = 1) or systemic (15.4% vs 25.6%, p = 0.401) recurrence, and 5-year DFS (78.7% vs 61.5%, p = 0.1) and OS (89% vs 82.1%, p = 0.434) rates, nor were there differences between the T-ISR and PS-ISR/LAR groups. The PS-ISR group generally showed less anorectal dysfunction than the T-ISR group, but maximal tolerance volume did not differ between these two groups and was within the range for the healthy population. CONCLUSIONS: T-ISR can replace most traditional APR, except for advanced T4 disease with aggressive infiltration into the levator-sphincters, and can provide tolerable anorectal dysfunction.

Depiction of detailed surgical anatomy and CSF flow information using a single MRI technique.

We describe a novel MRI sequence (T2 SPACE) capable of demonstrating detailed structural anatomy and functional CSF flow information simultaneously. While traditionally, a variety of sequences are utilised for this purpose, we have highlighted the advantages of this technique over traditional approaches, using example of a patient with CSF loculation in prepontine/suprasellar cistern, causing third ventricular compression and hydrocephalus. The sequence depicted the surgical anatomy by showing the web/cyst wall as well as CSF flow entering the cyst potentially causing increased pressure.

Study of the functional relationships between the buccinator muscle and the connective tissue of the cheek in humans.

BACKGROUND: The buccinator muscle derives from the mesenchyme of the second pharyngeal arch. In adults, it has a quadrilateral shape, occupying the deepest part of the cheek region. Its function is complex, being active during swallowing, chewing, and sucking. To our knowledge, there are no studies that have specifically analyzed the relationship of the buccinator muscle fibers and neighboring connective tissue of the cheek in humans, neither during development nor in adults. Such relationships are fundamental to understand its function. Thus, in this study the relations of the buccinator muscle with associated connective tissue were investigated. METHODS: The buccinator muscle region was investigated bilaterally in 41 human specimens of 8-17 weeks of development. Moreover, four complete adult tissue blocks from human cadavers (including mucosa and skin) were obtained from the cheek region (between the anterior border of the masseter muscle and the nasolabial fold). All samples were processed with standard histological techniques. In addition, subsets of sections were stained with picrosirius red (PSR). Furthermore, immunoreactivity against type I and III collagen was also studied in adult tissues. RESULTS: The buccinator muscle showed direct relationships with its connective tissue from 8 to 17 weeks of development. Collagen fibers were arranged in septa from the submucosa to the skin through the muscle. These septa were positive for type I collagen and presented elastic fibers. Fibrous septa that were positive for type III collagen were arranged from the lateral side of the muscle to the skin. CONCLUSIONS: The intimate relationship between buccinator muscle fibers and cheek connective tissue may explain the complex functions of this muscle.

An early snapshot of plant-herbivore interactions: Psilophyton diakanthon sp. nov. from the Early Devonian of Gaspé (Quebec, Canada).

PREMISE: Trimerophytes are a plexus of early tracheophytes that form the base of the euphyllophyte clade and, thus, represent the link between the earliest land plants and modern-day ferns, sphenophytes, and seed plants. As the best-characterized trimerophyte, the genus Psilophyton occupies a key position in the euphyllophyte fossil record. We describe a new Psilophyton species that has implications for the evolution of plant-animal interactions. METHODS: The fossil material is preserved by permineralization in the Lower Devonian (Emsian) Battery Point Formation (Québec, Canada) and was studied in serial sections using the cellulose acetate peel technique. RESULTS: Psilophyton diakanthon sp. nov. differs from other Psilophyton species in possessing fibers that form a discontinuous layer in the inner cortex and two distinct types of spinescent emergences whose anatomy and morphology are consistent with roles in anti-herbivore defense. CONCLUSIONS: Psilophyton diakanthon adds another species to an already diverse genus. Its two morphologically distinct types of spinescence suggest that herbivory was rampant in plant-animal interactions and demonstrate that anti-herbivory defenses had reached a previously unrecognized level of sophistication by 400 million years ago, in the Early Devonian.

A method to establish functional vagus nerve topography from electro-neurographic spontaneous activity.

Bioelectronic medicine is an emerging approach to treat many types of diseases via electrical stimulation of the autonomic nervous system (ANS). Because the vagus nerve (VN) is one of the most important nerves controlling several ANS functions, stimulation protocols based on knowledge of the functional organization of the VN are particularly interesting. Here, we proposed a method to localize different physiological VN functions by exploiting electro-neurographic signals recorded during spontaneous VN fibers activity. We tested our method on a realistic human cervical VN model geometry implanted via epineural or intraneural electrodes. We considered in silico ground truth scenarios of functional topography generated via different functional neural fibers activities covered by background noise. Our method accurately estimated the underlying functional VN topography by outperforming state-of-the-art methods. Our work paves the way for development of spatially selective stimulation protocols targeting multiple VN bodily functions.

Cricotracheal Adenoid Cystic Carcinoma: Insights Into the Diagnosis and Management of an Uncommon Anatomic Variant.

Adenoid cystic carcinoma (ACC) is the second most common malignant salivary gland tumor and accounts for 30% of minor salivary gland tumors. Its location in the larynx and trachea are rare. We present the case of a 45-year-old healthy male whose MRI revealed a posterior endoluminal tumor that invaded the posteroinferior perichondrium of the cricoid lamina and displaced the hypopharynx and esophagus. A left-limited cervical surgical exploration and an intraluminal incisional biopsy through the tracheostomy space were performed by another surgical team. The pathological study reported an ACC, T4aN0M0, stage IVA tumor. Then, a circular tracheal resection and an excision of the inferior part of the posterior cricoid lamina were carried out. The macroscopic study showed a lesion, 3cm long, 2.2cm wide, and 1cm thick, located at the posterior wall of the cricoid cartilage and proximal trachea. Only the upper margin was compromised. Microscopically, the tumor showed tubular, solid, cribriform, and trabecular patterns. One and a half years after surgery, the patient still has bilateral vocal cord mobility and normal speech. It is clear that a contrast-enhanced CT scan is useful to assess tumor extent and growth pattern in these rare variants. Among treatment alternatives, surgery sometimes complemented with radiotherapy is essential; constant follow-up is mandatory.