Anatomical Study Research Articles

Vascular supply of the radial nerve and its terminal branches: an anatomical study.

The aim of this cadaveric study was to further describe the vascular supply of the radial, posterior interosseous and superficial radial nerves. 11 cadaveric upper limbs, injected with colored latex, were dissected. Vascular afferents to the radial nerve, superficial radial nerve (SRN) and posterior interosseous nerve (PIN) were described and located. Their origin was identified and its distance to interepicondylar line was measured. The radial nerve had an average of 3 vascular afferents (1-5), of septomuscular origin in 54% of cases. 46% came from adjacent arteries. The PIN had an average of 8 vascular afferents (6-14), arising from septomuscular branches in 82% of cases. The PIN was vascularized in 100% of cases by a large arterial plexus originating from the supinator muscle between its two heads. The SRN had an average of 4 vascular afferents (3-7). Before crossing the septum of the brachioradialis, vascularization was predominantly septomuscular; after crossing the septum, the nerve was exclusively vascularized by septocutaneous arteries. This is the first study to describe the vascularization of the radial nerve and its terminal branches along their entire length. Our results are in line with the data available in the literature. An arterial plexus between the two heads of the supinator was surrounding the PIN in all cases. This vascular plexus might be involved in dynamic compression of the posterior interosseous nerve.

Anatomical Study of the Inferior Oblique Muscle and Its Innervation: Morphometric Characteristics, Anatomical Variations, and Histological Evaluation of the Nerve to the Inferior Oblique Muscle.

This report aims to supplement the existing knowledge on the inferior oblique muscle. In particular, this study presents detailed anatomical and histological data concerning the muscle's entry point (or entry zone) of the nerve to the inferior oblique muscle. Particular attention was paid to the topographical relationships of the nerve to the inferior oblique muscle (NTIO), including the location of its entry point to the muscle's belly and its anatomical variations. Sixty orbits from cadaveric hemi-heads fixed in 10% formalin were studied. The course of the NTIO was traced along the lateral border of the inferior rectus muscle as far as its entry point to the inferior oblique muscle. Particular attention was paid to the various ways in which the NTIO's muscular sub-branches penetrated between the fibers of the inferior oblique muscle. Three types of NTIO entries to the inferior oblique muscle's belly were distinguished. In the most common type (48.3%), the nerve entered the muscle's inferior (orbital) surface. In the next most common type (36.7%), terminal muscular sub-branches of the NTIO joined the superior (also referred to as ocular or global) surface of the inferior oblique muscle. In the remaining four cases (15%), the terminal sub-branches of the NTIO were divided into two main groups (superior and inferior) that joined both the superior and inferior surfaces of the muscle. Histological examination confirmed that the distal part of the NTIO shows a characteristic arcuate course (angulation) just before reaching the muscle's belly. The process for splitting and forming separate muscular sub-branches of the NTIO was observed for all the examined histological specimens at the level of the nerve's angulation. The presented findings enhance the understanding of the anatomical variations and precise distribution of motor sub-branches reaching the inferior oblique muscle, which may deepen anatomical knowledge and potentially enhance the management of ocular motor disorders.

Endoscopic transnasal prelacrimal recess approach via the orbital floor to the infraorbital region: an anatomical study.

The aim of this study is to describe the maximum exposure of the infraorbital region via the orbital floor using the transnasal prelacrimal recess approach (PLRA), and to provide an anatomical basis for treating lesions in the infraorbital region. Ten freshly injected frozen heads were dissected using the PLRA. The orbital floor was removed along the border of the medial infraorbital quadrangle, and the periorbita was opened to expose the infraorbital region. The areas of the medial infraorbital quadrangles were measured and analyzed. The PLRA was applied separately on the left and right sides of each cadaver head, resulting in a total of 20 prelacrimal recess approaches. The PLRA enabled visualization of the optic nerve and the central retinal artery through the orbital floor. By integrating both medial and lateral approaches in relation to the inferior rectus muscle, all crucial anatomical structures within the infraorbital region could be clearly identified. The area of the medial infraorbital quadrangle was 420.65 ± 24.03 mm2. The PLRA provides access through the orbital floor to the maximum boundary of the infraorbital region, including the lateral orbital wall at the outermost level, the superior rectus muscle at the topmost level, and the medial orbital wall at the innermost level.

Sonoanatomy of the Finger Synovio-Entheseal Complexes

ObjectivesThe objectives of this ultrasound and anatomical study were: (1) To evaluate the reliability of ultrasound identification of the enthesis of the central slip of the extensor digitorum tendon (CSET) using cadaver specimens; (2) To assess the concordance of the measurement of the CSET thickness by ultrasound and gross anatomy; (3) To evaluate the variation in ultrasound identification of the CSET enthesis in a cadaveric experimental model of PIP synovitis. MethodsFour rheumatologist ultrasonographers blindly and independently measured by ultrasound the CSET enthesis thickness in the second to fifth fingers of 8 hands from fresh-frozen human cadavers in two rounds. These fingers were dissected and the thickness of the CSET measured by the anatomist. In addition, an artificial synovitis was created in the proximal interphalangeal (PIP) joints of a different cadaveric hand. The ultrasonographic CSET enthesis thickness was measured by the four investigators before and after intra-articular ultrasound guided injection of material. ResultsIntra- and inter-observer reliability of CSET enthesis thickness measurement were good to excellent (ICC 0.93 for intra-observer agreement and 0.89–0.92 for inter-observer agreement). Ultrasound measurements were consistent and only slightly smaller than the anatomical ones (µ = -0.039 mm). The differences between the measurements of CSET enthesis thickness before and after the synovitis model were not statistically significant. ConclusionUltrasound demonstrated high multiobserver reliability and agreement with gross anatomy in identifying the CSET enthesis and discriminated it from the capsular tissue of the PIP. Furthermore, an experimental model of PIP synovitis did not interfere with its identification.

Does the calcar femorale affect the position of uncemented short stems?

Metaphyseal-stabilised short stems rely on sufficient metaphyseal fixation and are inserted by following the medial cortex. This type of stem is used extensively in our institution, and we observed on occasion unintended implant positioning with an increased distance between the implant and the medial cortex. A bony structure within the proximal femur which was first described in 1874 and named the calcar femorale, coincides with this phenomenon.The aim of this study was to investigate the impact of the calcar femorale on the position of a metaphyseal-stabilised short stem. The frequency of cases with an increased distance between medial cortex and the implanted short stem was analysed in 52 consecutive patients. Additionally, we performed an anatomical CT study with 60 cadaveric femora to obtain more detailed information on the anatomy of the calcar femorale. Detailed measurements regarding the calcar femorale and its relationship to the proximal femur were obtained. From this, we derived implications for the implantation of a short stem prosthesis. In 50% of all cases, we found an increased gap between the stem and the medial cortex. An increased gap did not significantly affect stem size, position, or subsidence rate, but in cases with an increased gap we found fewer stems with a radiologically optimum fit. The calcar could be identified in all 60 cadavers. The calcar femorale angle showed a high correlation with the mechanical antetorsion (0.87, p = 0.02) and the functional antetorsion (0.86, p = 0.05) of the femur. The calcar femorale is a consistent anatomical structure which may be the cause for an increased gap medial to the short stem in 50% of our cases. It limits the intramedullary space and influences both stem size and orientation. The CF angle which correlates with femoral antetorsion may influence the anteversion of the stem.

Frequency, localization, and diameter of the accessory maxillary ostium and its relationship with sinus pathologies and nasal cavity variations: an anatomical study based on cone beam computed tomography.

The aim of the present study was to determine the presence, frequency, and characteristics of the accessory maxillary ostium (AMO) in a specific Turkish population using cone beam computed tomography (CBCT) and to evaluate the frequency of pathologies and anatomical variations in the nasal cavity and maxillary sinus and to assess their relationship with the AMO. This study retrospectively evaluated the presence of AMO in CBCT images of 543 patients, the patients' age, gender, and dentition status, the presence of nasal cavity variations and maxillary sinus pathologies, and their relationship to the presence of AMO. Descriptive values of the data and comparative results were included. 249 males and 294 females participated in the study. The majority of right and left sinus pathologies were irregular type mucosal thickenings (right/left; 14%, 14.9%). The majority of nasal variations were concha bullosa (right/left; 37.9%, 39.2%). There were 148 (27.3%) and 138 (25.4%) AMOs on the right and left sides, respectively, with the majority in the middle position (right/left; 21.2%/17.5%). The frequency of right and left AMOs was significantly higher in men (P = 0.019 and P = 0.020, respectively). The left AMO frequency was significantly higher in patients with left-sided sinus pathology (P = 0.003). AMO diameters were larger in men (right/left P = 0.010 and P = 0.021, respectively), and left AMO diameter was significantly larger in patients with left sinus pathology (P = 0.006). Before any surgical intervention in the maxillary sinus and osteomeatal region, the presence and location of the AMO, existing pathologies, and variations in the region should be carefully checked to avoid complications.

Theoretical model of impact mitigation mechanisms inherent to the North American bison skull

ABSTRACT North American bison (Bovidae: Bison bison) incur blunt impacts to the interparietal and frontal bones when they engage in head-to-head fights. To investigate the impact mitigation of these bones, a finite element analysis (FEA) of the skull under loading conditions was performed. Based on anatomical and histological studies, the interparietal and frontal bones are both comprised of a combination of haversian and plexiform bone and are both underlain by bony septa. Additionally, the interparietal bone is thicker than the frontal bone. Data regarding the mechanical properties of bison bone are scarce, but the results of a phylogenetic analysis infer that the material properties of the closely related domestic cow bone are a suitable proxy for use in the FEA. Results of the FEA suggest that the thickness of the interparietal bone in conjunction with the bony septa may prevent fracture stresses by helping to absorb and disperse the blunt impact energy throughout the skull. Monotonic stress levels of 294 MPa, which are below the compressive strength of bone were exhibited in the simulated bison head impacts indicating no fracture of the bones.

Persistent median artery: paedogenesis of the antebrachial arterial system in the human body.

The persistence of the median artery in adult life, a remnant of the early brachial artery in the embryonic stage, has been reported in many anatomical and clinical studies. Herein, we aimed to investigate the prevalence and origin of the median artery in cadavers. We examined 53 adult Japanese cadavers and carefully dissected 106 upper limbs, and the arterial systems in the forearms and hands were observed macroscopically. We found the palmar type of the median artery on 106 sides in 53 cadavers, and found that it passes through the carpal tunnel and forms the superficial palmar arch in the hand in only two cadavers. The antebrachial type, ending in the forearm before reaching the wrist joint, was detected on 63 sides in 44 cadavers. The proportions of the origins of the median artery examined in this study were as follows: originating from the common interosseous artery (CIA) on 15 sides (23%), anterior interosseous artery (AIA) on 9 sides (14%), ulnar artery (UA) on 16 sides (24%), and CIA-UA trunk on 26 sides (39%). None arose from other arteries in the upper limbs. Based on our results and the current theory on vascular development, we conclude that the term 'persistent median artery' must be strictly used for the one that arises from the arteries in the forearm except for the radial artery, and the presence of this ontogenetic remnant can be interpreted as paedogenesis in the human body. We also describe that the increasing trend in the incidence of the median artery since the nineteenth century, as pointed out by a few researchers, may represent 'nearly neutral evolution' at the phenotypic level in human populations.

Dynamic anatomical study of the posterior brachial artery perforator flap: Aesthetic refinement and clinical results

BackgroundReconstruction of the axillary fossa represents a surgical challenge given the functional implications for mobility of the upper limb. The posterior brachial flap is a solution of choice for this indication, providing fine and functional local reconstruction, but little is known about its perforasome. This study aimed to identify the location of the perforator, analyze perfusion flow, and link vessel distribution, and propose an aesthetic refinement to the surgical technique by medializing the skin paddle to conceal aesthetic scarring at the donor site. MethodsFifteen fresh cadavers were harvested and dissected. Twenty-six arms were injected with methylene blue. Two arms were injected with radiopaque dye. A dynamic (4-dimensional) computed tomographic angiography was performed to complete the analysis. ResultsThe perforasome was centered on the posterior axis of the arm with a perfusion area ranging from 82.2 to 142.9 cm², with a median of 112.7 (96.7–125.6) cm². The median length of the pedicle was 83 mm on an average (65–91 mm). Its caliber at the emergence of the source vessel had a mean diameter of 1.43 mm (1.27–1.61 mm). The distal limit of the paddle was located on an average 10.7 cm from the olecranon (7.8–12.2 cm). The scans showed direct linking vessels toward the perforasomes on the medial side of the arm, suggesting that it is possible to medialize the cutaneous paddle. ConclusionThe posterior brachial flap presents with a constant perforasome. It can be harvested more medially than previously described to improve the aesthetic results, while maintaining reproducibility and satisfactory vascular reliability.

Arbor vitae cerebelli: Fractal properties and their quantitative assessment by novel “contour scaling” fractal analysis method (an anatomical study)

BackgroundArbor vitae cerebelli (tree-like branching white matter of the cerebellum) has a complex spatial configuration that is challenging to assess using conventional morphometric methods. This study proposes a fractal approach to describe and quantify the anatomy of Arbor vitae cerebelli. For this purpose, a new “contour scaling” method for fractal analysis of cerebellar white matter was developed. Material and methodsThe cerebella of 100 cadavers (50 male and 50 female) who died from causes unrelated to brain pathology, aged 20–95 years, were examined. Mid-sagittal sections of the cerebellar vermis were studied. The fractal dimension values of the cerebellar white matter were determined using both the developed fractal analysis method and the conventional “box counting” method, along with measurements of non-fractal parameters including cerebellar weight, area and perimeter of the vermis cross-section, perimeter-to-area ratio, and circularity. ResultsConsidering the cerebellar white matter as a tree-like fractal, it was found to have 7 or 8 primary branches, which subdivide into 10-18 second-iteration branches, 19–38 third-iteration branches, and 34–53 fourth-iteration branches. Females more often had 8 primary branches compared to males, while males had a greater number of branches in the second to fourth iterations. The mean fractal (Hausdorff) dimension was 1.697 (1.721 in males, 1.674 in females, P = 0.01). The fractal dimension correlated most strongly with the perimeter and area of the vermis cross-section and had no significant relationship with age. ConclusionThe fractal (Hausdorff) dimension, determined using the novel “contour scaling” method, quantitatively assesses the degree of branching of the cerebellar white matter. An increase in the absolute size of the cerebellum leads to a higher degree of branching of its white matter and an increase in the number of its constitutive components – white matter branches and folia.

Is the golden ratio present in the coxal bone? An anatomical pilot study.

The coxal bone is crucial for movement, stability, and childbirth. Although most morphometric studies estimate gender and age, ratio, correlation and index calculations, there are no studies on the golden ratios in the coxal bone. Inspired by this idea, we investigated the presence of the golden ratio in the coxal bones. In this study, 95 adult dry coxal bones were measured using a digital caliper. Morphometric measurements were conducted based on 18 identified parameters. 12 of these parameters were related to the distances between two points in various parts of the bone. New ratios were determined with those measurements. In our study, we detected a constant coefficient between the following lengths: anterior superior iliac spine (ASIS)- posterior superior iliac spine (PSIS) and anterior inferior iliac spine (AIIS)- posterior inferior iliac spine (PIIS), vertical and transverse diameters of the acetabulum (AC), ASIS-AC and AIIS-AC, PSIS-AC and PIIS-AC, ASIS-auricular surface and AIIS-auricular surface, ASIS-symphyseal surface and AIIS-symphyseal surface (respectively, 1.29, 1.05, 1.18, 2.32, 1.26, 1.32). In order to check the accuracy of this hypothesis, length of between AIIS-PIIS, transverse diameter of the acetabulum, length of between PIIS-AC, length of between AIIS-AC, shortest distance between AIIS-auricular surface, length of between AIIS-symphyseal surface were estimated with the help of new equations. We detected constant ratios between some lengths in the coxal bone. Estimated distances should be taken into account during surgical procedures to prevent complications. In this context, the constant ratios identified in our study will serve as a guide for surgeons.

Three-dimensional virtual histology of the rat uterus musculature using micro-computed tomography.

Contractions of the uterus play an important role in menstruation and fertility, and contractile dysfunction can lead to chronic diseases such as endometriosis. However, the structure and function of the uterus are difficult to interrogate in humans, and thus animal studies are often employed to understand its function. In rats, anatomical studies of the uterus have typically been based on histological assessment, have been limited to small segments of the uterine structure, and have been time-consuming to reconstruct at the organ scale. This study used micro-computed tomography imaging to visualise the muscle structures in the entire non-pregnant rat uterus and assess its use for 3D virtual histology. An assessment of the rodent uterus is presented to (i) quantify muscle thickness variations along the horns, (ii) identify predominant fibre orientations of the muscles and (iii) demonstrate how the anatomy of the uterus can be mapped to 3D volumetric meshes via virtual histology. Micro-computed tomography measurements were validated against measurements from histological sections. The average thickness of the myometrium was found to be 0.33 ± 0.11 mm and 0.31 ± 0.09 mm in the left and right horns, respectively. The micro-computed tomography and histology thickness calculations were found to correlate strongly at different locations in the uterus: at the cervix, r = 0.87, and along the horn from the cervical end to the ovarian end, respectively, r = 0.77, r = 0.89 and r = 0.54, with p < 0.001 in every location. This study shows that micro-computed tomography can be used to quantify the musculature in the whole non-pregnant uterus and can be used for 3D virtual histology.

Immersive Photorealistic Three-Dimensional Neurosurgical Anatomy of the Cerebral Arteries: A Photogrammetry-Based Anatomic Study.

Neurosurgeons need a profound knowledge of the surgical anatomy of the cerebral arteries to safely treat patients. This is a challenge because of numerous branches, segments, and tortuosity of the main blood vessels that supply the brain. The objective of this study was to create high-quality three-dimensional (3D) anatomic photorealistic models based on dissections of the brain arterial anatomy and to incorporate this data into a virtual reality (VR) environment. Two formaldehyde-fixed heads were used. The vessels were injected with radiopaque material and colored silicone and latex. Before the dissections, the specimens were computed tomography scanned. Stratigraphical anatomic dissection of the neck and brain was performed to present the relevant vascular anatomy. A simplified surface scanning method using a mobile phone-based photogrammetry application was used, and the data were incorporated into a VR 3D modeling software for post-processing and presentation. Fifteen detailed layered photorealistic and two computed tomography angiography-based 3D models were generated. The models allow manipulation in VR environment with sufficient photographic detail to present the structures of interest. Topographical relevant anatomic structures and landmarks were annotated and uploaded for web-viewing and in VR. Despite that the VR application is a dedicated 3D modeling platform, it provided all necessary tools to be suitable for self-VR study and multiplayer scenarios with several participants in one immersive environment. Cerebral vascular anatomy presented with photogrammetry surface scanning method allows sufficient detail to present individual vessel's course and even small perforating arteries in photorealistic 3D models. These features, including VR visualization, provide new teaching prospects. The whole study was done with simplified algorithms and free or open-source software platforms allowing creation of 3D databases especially useful in cases with limited body donor-based dissection training availability.

Morphology and arterial supply of the pyramidalis muscle in an Australian female population using computed tomography angiography

IntroductionThe structure and function of the human anterolateral abdominal wall have been thoroughly described. However, there has been limited anatomical study of the pyramidalis muscle and its arterial supply. The aim of this study was to analyse the patterns of arterial supply to the pyramidalis in a female population.MethodsA retrospective study of 32 computed tomography angiography scans of the abdominal wall of adult women was performed to assess the prevalence (bilateral or unilateral presence, or absence), morphology (medial border height, base width and thickness) of pyramidalis and patterns of arterial supply.ResultsPyramidalis prevalence was bilateral in 75% of computed tomography angiography studies (24/32), unilateral in 6.3% (2/32) and absent in 18.8% (6/32). Of the five patterns of pyramidalis arterial supply observed and described in detail, the most frequent (68%, 34/50 of cases) originated from an exclusive muscular branch of the inferior epigastric artery. Origin from the pubic branch of the inferior epigastric artery was seen in 4% (2/50). There was a single case (2%, 1/50) of artery origin from a variant obturator artery, a common trunk with the pubic branch from the inferior epigastric artery, and from the muscular branch to rectus abdominis. The artery could not be defined in 22% (11/50).ConclusionIn this computed tomography angiography study of women, five patterns of Pyramidalis arterial supply were identified. In the majority of cases, the pyramidalis derived its arterial supply from an exclusive, isolated muscular branch of the inferior epigastric artery.

The Bony Nasal Cavity and Paranasal Sinuses of Big Felids and Domestic Cat: A Study Using Anatomical Techniques, Computed Tomographic Images Reconstructed in Maximum-Intensity Projection, Volume Rendering and 3D Printing Models.

This study aims to develop three-dimensional printing models of the bony nasal cavity and paranasal sinuses of big and domestic cats using reconstructed computed tomographic images. This work included an exhaustive study of the osseous nasal anatomy of the domestic cat carried out through dissections, bone trepanations and sectional anatomy. With the use of OsiriX viewer, the DICOM images were postprocessed to obtaining maximum-intensity projection and volume-rendering reconstructions, which allowed for the visualization of the nasal cavity structures and the paranasal sinuses, providing an improvement in the future anatomical studies and diagnosis of pathologies. DICOM images were also processed with AMIRA software to obtain three-dimensional images using semiautomatic segmentation application. These images were then exported using 3D Slicer software for three-dimensional printing. Molds were printed with the Stratasys 3D printer. In human medicine, three-dimensional printing is already of great importance in the clinical field; however, it has not yet been implemented in veterinary medicine and is a technique that will, in the future, in addition to facilitating the anatomical study and diagnosis of diseases, allow for the development of implants that will improve the treatment of pathologies and the survival of big felids.

Direct Suturing of Ulnar or Median Nerve Defects in High-Degree Elbow Flexion: An Experimental Cadaver Study

The aim of this study is to determine the maximum loss of median and ulnar nerve substances that can be treated by direct suture in elbow flexion and to quantify this elbow flexion. The other objective is to determine the participation of the wrist position in this direct suture in elbow flexion. We performed an experimental study on 6 ulnar nerve lesions and 6 median nerve lesions. For each defect, a direct tensionless suture was performed with elbow flexion and in three different positions of the wrist (wrist extension, neutral position, and wrist flexion). A 90° elbow flexion allowed direct suturing of defects up to 40 mm in the 3 positions of the wrist. A bowstringing effect (i.e., increase of the perpendicular distance of the nerve from the axis of rotation of the elbow) was noted starting from 25 mm of nerve defect. Wrist extension placed tension on the nerve suture for both nerves. The results of this first anatomical study clarified the conditions for direct suturing of ulnar and median nerve defects in the flexed elbow position and flexed wrist position. This is an approach to consider for limited nerve defects to the elbow or when allograft harvesting is to be avoided.

Typology of Terminal Colon at the Chu of Point G in Bamako

Purpose: To describe the morphometric types of the terminal colon. Patients and Methods: This was an anatomical study by laparotomy for the terminal colon on 7 living subjects and by anatomical dissection on 8 fresh cadaveric subjects in the department of surgery B of the CHU of Point G and in the anatomy laboratory of the faculties of medicine of odonto-stomatology (FMOS) and pharmacy (FAPH) of Bamako from January 1, 2018 to December 31, 2019 or 2 years. Patients without a mass on the terminal recto-colonic junction or volvulus of the terminal colon or abdominopelvic mass on the terminal colon and fresh cadavers declared unknown without a laparotomy scar coming from Bamako University Hospitals or Reference Centers (CS Réf) were included in this study. Results: We investigated 15 cases, including 7 live cases and 8 cadavers. Males accounted for 60% (n=9) and females 40% (n=6), i.e. a sex ratio of 1.5. Mean age was 47.14 ±15.57 years. The mean length of the terminal colon was 41.79 cm±13.37. The mean length of the terminal mesocolon was 11.18 cm. The maximum height of the terminal mesocolon averaged 10.70 cm ± 3.61 cm. There were 46.72% (n=7) medium-form cases, 33.30% (n=5) short-form cases and 19.98% (n=3) long-form cases. Conclusion: The terminal colon can be short, medium or long, depending on its length and the height of its meso.

Comparative Anatomical Studies of Adrenal Glands in Large White Yorkshire Pigs Reared at Low and High Altitudes in Kerala

The adrenal gland plays a crucial role in the body's homeostasis and during the stress response. However, less attention was given to the structural variation of the adrenal glands in pigs reared at different altitudes. Hence, the present study was conducted to correlate structural variation in the adrenal glands in 24 ten-month-old Large White Yorkshire pigs of either sex reared at low-altitude and high-altitude regions of Kerala, India. Microscopically, the adrenal gland presented the three typical concentric cortical zones: zona glomerulosa, zona fasciculata, zona reticularis, and a central medulla. The arrangement pattern of cells of the zona glomerulosa resembled the arcs; zona fasciculata, similar to cords separated by intervening trabeculae; and zone reticularis, like irregularly anastomosing cords. Two types of cells were present in the medulla: large, granular, intensely-stained cells towards the periphery and small polyhedral cells towards the centre of the medulla. Chromaffin was identified in the medulla, while undifferentiated cells were identified within the capsule, subcapsular zone, the transitional zone between zona glomerulosa and zona fasciculata, and even medulla. Zona fasciculata formed the largest zone of the adrenal cortex, and its thickness was significantly higher in the low-altitude male and female groups than in the corresponding high-altitude groups, which was correlated to serum cortisol levels. The comparative micrometrical data revealed a larger zona fasciculata in the low-altitude male and female groups than in the corresponding high-altitude groups, indicating variation between the groups.

Abstract P388: Electrical Stimulation of the Porcine Carotid Sinus Nerve Reliably Decreases Blood Pressure and Heart Rate

Introduction: Neuromodulation of the baroafferent pathway via direct carotid sinus nerve (CSN) stimulation is recognized as a potential therapeutic modality for treating uncontrolled hypertension. Although proof of concept has been demonstrated acutely in humans, there are many questions that remain in both acute and chronic applications. A translational non-companion large animal model is vital for safe development of this modality. Here we present data on the effects of CSN and baroafferent stimulation in farm pigs. Hypothesis: We hypothesized that an effective CSN-bioelectode interface in the pig would demonstrate significant and reproducible reductions in blood pressure in tandem with pulse rate (PR). Methods: Acute CSN stimulation was investigated in 9 anesthetized Yorkshire pigs. Following general anesthesia, CSNs were exposed and an application-specific electrode was placed. A fixed current paradigm was employed at constant 100Hz and 100µs pulse width. Following contact mapping to identify the baroafferent neurointerface, electrical current was escalated to establish dose-response curves. The primary outcome was systolic blood pressure (SBP) and secondary outcomes were diastolic pressure (DBP) and PR. Data were analyzed in Matlab to extract the baseline BP and PR, during and following stimulation. Statistical calculations used a one-sample Wilcoxon signed rank test. Explanted electrodes with surrounding tissue were evaluated using micro-computed tomography (μCT) and histologically. Results: Six of 9 animals were responders (n=7, 2 sides were stimulated in one animal), CSN stimulation caused average (mean±SD, p&lt;0.001) decreases in SBP (6.8±7.2mmHg) and DBP (3.9±3.7mmHg), which tracked closely with decreases in PR (6.2±5.7bpm). Average maximum decreases were: SBP, 9.3±9.9mmHg; DBP, 7.7±6.4mmHg; and PR, 9.7±8.3bpm. Upon stimulation withdrawal, there was near-immediate recovery of both BP and HR. μCT and histological analysis of tissue samples demonstrated inter-animal anatomic heterogeneity. Conclusions: CSN stimulation causes reproducible reduction in BP synchronous with PR drops followed by near immediate recovery of both with stimulation withdrawal. Variations in animal response may be due to anatomical variation in CSN anatomy that can be overcome with further anatomical study. Pigs provide a robust large-animal model for investigating CSN stimulation, offering a platform to better understand baroafferent stimulation as treatment for uncontrolled hypertension.

Gross anatomical study on bones of pectoral girdle in black swan (Cygnus atratus)

Gross anatomical study on bones of pectoral girdle in black swan (Cygnus atratus)