The Posterior Auricularis Muscle as Superficial Landmark for the Sigmoid Sinus and Transverse-Sigmoid Sinus Junction: An Anatomical Study.

OBJECTIVE: Neuronavigation systems coupled with previously reported external anatomical landmarks assist neurosurgeons during intracranial procedures. We aimed to verify whether the posterior auricularis muscle (PAM) could be used as an external landmark for identifying the sigmoid sinus (SS) and the transverse-sigmoid sinus junction (TSSJ) during posterior cranial fossa surgery. METHODS: The PAM was dissected in 10 adult cadaveric heads and after drilling the underlying bone, the relationships with the underlying SS and TSSJ were noted. The width and length of the PAM, and the distance between the muscle and reference points (asterion, mastoid tip, and midline), were measured. RESULTS: The PAM was identified in 18 sides (9 left, 9 right). The first 20 mm of the muscle length (mean 28.28 mm) consistently overlay the mastoid process anteriorly and the proximal half of the SS slightly posteriorly on all sides. The superior border was a mean of 2.22 mm inferior to the TSSJ and, especially when the muscle length exceeded 20 mm, this border extended closer to the transverse sinus; it was usually found at a mean of 3.11 mm (range 0.0-13.80 mm) inferior to the distal third of the transverse sinus. CONCLUSIONS: Superficial landmarks give surgeons improved surgical access, avoiding overexposure of deep neurovascular structures and reducing brain retraction. On the basis of our cadaveric study, the PAM is a reliable and accurate direct landmark for identifying the SS and TSSJ. The PAM could potentially be used for guiding the retrosigmoid approach.

Renal vein valves: a prevalence, microanatomical and histological study.

PURPOSE: In the modern era of robotic renal procedures and diagnostics, an even more detailed anatomical understanding than hitherto is necessary. Valves of the renal veins (RVV) have been underemphasized and have been disputed by some authors, and few textbooks describe them. The current anatomical study was performed to address such shortcomings in the literature. METHODS: One hundred renal veins were studied in fifty adult formalin-fixed cadavers. Renal veins were removed from the abdomen after sectioning them flush with their entrance to the renal hilum. The inferior vena cava was then incised longitudinally and opened, and RVV were examined grossly and histologically. A classification scheme was developed and applied to our findings. RESULTS: Nineteen RVVs were observed in the fifty cadavers (38%). Four (8%) valves were found on right sides and fifteen (30%) on left sides. The valves were seen as cord/band-like, folds, and single and double leaflets. Histologically, they were all extensions of the tunica intima. CONCLUSION: On the basis of our study, RVV are not uncommon. They were more common on left sides, and on both sides, they were found within approximately one centimeter of the junction of the inferior vena cava and renal vein. Although the function of such valves cannot be inferred from this anatomical study, the structures of the Single leaflet valve (TS2) and Double leaflet valve (TS3) valves suggest they could prevent venous reflux from the IVC into the kidney.

L5 spondylolysis: Anatomical study comparing healed and unhealed lesions.

The anatomy and pathogenesis of spondylolysis has been widely studied; however, the microanatomy of spondylolysis of the lumbar vertebra has not been well described. Therefore, we aim to better elucidate this anatomy. Twenty dry bone specimens of healed and unhealed spondylolysis of the L5 vertebra were collected from human skeletal remains. Twelve L5 vertebrae were examples of unhealed spondylolysis and eight specimens exhibited a healed (i.e., bony fusion of the lesion) spondylolysis lesion. The specimens underwent macro and microanatomical analysis followed by CT and microCT imaging. Finally, selected healed and unhealed lesions were submitted for histological analysis using Mason Trichrome staining. The pars interarticularis of two L5 vertebrae without signs of healed/unhealed spondylolysis were evaluated histologically as controls. Of the 12 unhealed L5 pars defects, three were unilateral on left side. Of the eight healed pars defects, all were unilateral and seven of these were on left sides. One unilateral pars defect also had spina bifida occulta. Both on imaging and histological analysis, healed pars defects were only so superficially and not at deeper levels. Histologically, unhealed edges were made up of dense cortical bone while healed edges were made up primarily of trabecular bone. Based on our anatomical findings, the so-called healed spondylolysis lesions, although externally fused, are not thoroughly fused internally. Moreover, the anterior and posterior edges of the unhealed spondylosysis lesions are irregular and show signs of long-term disarticulation. Taken together, these data suggest that such 'healed' lesions might not be as stable as the normal L5 pars interarticularis.

Surgical anatomy of the cerebellar tonsils: A cadaveric study.

BACKGROUND: Knowledge of the normal anatomy of the cerebellar tonsils is a prerequisite in various surgeries of the posterior cranial fossa Clinical conditions, as the Chiari I malformations (CIM) alter the normal position of the cerebellar tonsils. OBJECTIVE: Therefore, we aim to better elucidate the surgical anatomy of and around the cerebellar tonsils in regard to the CIM. METHODS: Fifty formalin-fixed adult cadavers injected with colored latex through vertebral arteries underwent craniotomy and durotomy to expose the cerebellar tonsils and related structures. The tonsils and their surrounding anatomy were then studied. RESULTS: Forty cerebellar tonsils were at or above the foramen magnum. Five specimens presented with CIM with the tonsils below (3-5 mm) the FM with a mean tonsillar decent of 7.9 ± 2.3 mm. Of the cadavers without CIM, in forty-two cases, the thickness of the dura mater was within ±3SD ranges. In three cases, the dura mater was thinner at the CVJ and one case; the dura adhered tightly to the inner aspect of the occipital squama. In five CIM cadavers, the dura mater was markedly thicker at the CVJ. The PICA caudal loop was 5.9 ± 1.6 mm long. In CIM cases, the PICA loop was longer, nearer the dura, 1 mm below the superior border of the C1 posterior arch. The distances from the PICA loop were markedly reduced by 3 mm from the spinal accessory nerve and 2 mm from the first spinal nerve. The DN was significantly closer to the tonsillar peduncle in CIM cases. CONCLUSION: These data are important for better understanding the intrinsic and extrinsic anatomy of the cerebellar tonsils in patients with and without CIM. Importantly, tonsillectomy/tonsillar coagulation must consider the close relationship of the dentate nucleus to the base of the cerebellar tonsil to avoid iatrogenic injury.

A rare case of the auriculotemporal and inferior alveolar nerves communication.

This case study describes anatomical variations in the branching pattern of the posterior division of the trigeminal nerve and its clinical implications for dental and craniofacial surgery. The study presents two uncommon variations observed in an elderly male cadaver. A communicating branch connecting one of three roots of the auriculotemporal nerve and inferior alveolar nerve just before entering the mandibular foramen on the right side, and three communicating branches between the IAN and lingual nerve on the left side. The presence of such variations may complicate anesthesia associated with oral surgery procedures.

Investigating the Glucagon-like Peptide-1 and Its Receptor in Human Brain: Distribution of Expression, Functional Implications, Age-related Changes and Species Specific Characteristics.

Introduction: Emerging evidence has shown that the glucagon-like peptide-1 (GLP-1) agonist can be used to treat Alzheimer disease; however, knowledge of its neural targets is limited. To understand the neural substrates of GLP-1, we have done whole brain mapping for GLP-1 and its receptor (GLP-1R), in 30 human brains. Methods: GLP-1 expression was studied by immuno-histochemistry and confirmed by the western blot method. The GLP-1R gene expression was studied by reverse transcription polymerase chain reaction. Results: GLP-1 expression was observed in most of the cortical areas (maximum in frontal, prefrontal and parietal cortex), diencephalon, and brainstem, but not in the cerebellum. Protein expression studies validated these results. The highest expression of GLP-1R was found in the frontal cortex. The orbitofrontal cortex and cerebellum had negligible expression. Hippocampus demonstrated a significant presence of GLP-1R but patchy immunoreactivity to GLP-1. GLP-1R presence in most of the human cortical regions and absence in the cerebellum is the major deviation from the animal brain. Sites that might be of interest in Alzheimer have been identified. GLP-1 demonstrated an age-related decline in most of the areas after the fifth decade. At 60 years, GLP-1 was not found in any of the cortical areas except in the prefrontal cortex; however, it was present in the sub-cortical areas. Conclusion: Age-related profiling of GLP-1 in various brain areas has been analyzed, which can have an important bearing on understanding Alzheimer disease. This study provides a detailed description of GLP-1 and an brain mapping for the first time and may lead to novel treatment options targeting the GLP-1 receptors. Highlights: Glucagon like peptide-1 (GLP-1) agonist can be used for treating Alzheime'rs disease.GLP-1 gene expression was seen in cortical areas, diencephalon and brainstem, but not in cerebellum.Hippocampus demonstrated significant presence of GLP-1R but patchy immunoreactivity to GLP-1.GLP-1 demonstrated age related decline in most of the areas after fifth decade.A detailed description of GLP-1 and amp; GLP-1R locations was given which may lead to novel treatment options. Plain Language Summary: Emerging evidence has shown that the glucagon like peptide-1 (GLP1-1) agonist can be used for treating Alzheimer's disease but knowledge of its neural targets is limited. To understand the neural substrates of GLP-1, we have done whole brain mapping for GLP-1 and its receptor (GLP-1R), in 30 human brains. GLP-1 expression was studied by immuno-histochemistry and confirmed by western blot method. GLP-1R gene expression was studied by RT-PCR. GLP-1 expression was seen in most of the cortical areas (maximum in frontal, prefrontal & amp; parietal cortex), diencephalon and brainstem, but not in cerebellum. Protein expression studies validated these results. Highest expression of GLP-1R was found in the frontal cortex. The orbito-frontal cortex and cerebellum had negligible expression. Hippocampus demonstrated significant presence of GLP-1R but patchy immunoreactivity to GLP-1. GLP-1R presence in most of the human cortical regions and absence in cerebellum is the major deviation from the animal brain. Sites which might be of interest in Alzheimer's have been identified. GLP-1 demonstrated age related decline in most of the areas after 5 th decade. At 60 years GLP-1 was not found in any of the cortical areas except in the prefrontal cortex but it was present in the sub-cortical areas. Age related profiling of GLP-1 in various brain areas has been analysed, which can have important bearing on understanding the Alzheimer's. This study provides detailed description of GLP-1 and ations by complete human brain mapping for the first time and may lead to novel treatment options targeting the GLP-1 receptors.

Quadricuspid Pulmonary Valve With Fenestration: Cadaveric Findings.

Quadricuspid pulmonary valves (QPV) are rare entities. Such valves can be associated with other cardiac anatomical anomalies. In this report, we present a case of a quadricuspid valve with an additional variant and discuss the morphometrics of this anatomical variation. During the routine dissection of an adult male body, two anatomical variations were found within the pulmonary trunk. This individual had a QPV. In addition, one of the leaflets of this valve contained fenestrations. No additional cardiac anomalies were identified. Clinicians who review imaging of the heart or treat patients with cardiac conditions should be well-informed about QPV.

Revisiting the transorbital approach for emergency external ventricular drainage: an anatomical study of relevant parameters and their effect on the effectiveness of using Tubbs' point.

The transorbital approach (TOA) can provide immediate access to the lateral ventricles by piercing the roof of the orbit (ROO) with a spinal needle and without the need of a drill. Reliable external landmarks for the TOA ventriculostomy have been described, however, the necessary spinal needle gauge and other relevant parameters such as the thickness of the ROO have not been evaluated. Nineteen formalin-fixed adult cadaveric heads underwent the TOA. Spinal needles of different gauges were consecutively used in each specimen beginning with the smallest gauge until the ROO was successfully pierced. The thickness of the ROO at the puncture site and around its margins was measured. Other parameters were also measured. The TOA was successfully performed in 14 cases (73.68%), where the most suitable needle gauge was 13 (47.37%), followed by a 10-gauge needle (36.84%). The mean thickness of the ROO at the puncture site, and the mean length of the needle to the puncture site were 1.7 mm (range 0.2-3.4 mm) and 15.5 mm (range 9.2-23.4 mm), respectively. A ROO thickness of greater than 2.0 mm required a 10-gauge needle in seven cases, and in five cases, a 10-gauge needle was not sufficient for piercing the ROO. The presence of hyperostosis frontalis interna (HFI) (21.05%) was related to the failure of this procedure (80%; p < 0.00). Using a 13/10-gauge spinal needle at Tubbs' point for TOA ventriculostomy allowed for external ventricular access in most adult specimens. The presence of HFI can hinder this procedure. These findings are important when TOA ventriculostomy is considered.

Histology and immunohistochemistry of the human carotid sinus nerve.

The carotid sinus nerve (CSN) is well known as mediating baroreflexes. However, studies of its detailed histological analysis are scant in the literature. Therefore, the current anatomical study sought to better elucidate the microanatomy of the CSN. Ten fresh frozen adult cadavers underwent dissection of the CSN. Then, it was harvested and submitted for histological and immunohistochemical staining. Specimens were all shown to be nerve fibers on histology and immunohistochemistry. We identified tyrosine hydroxylase positive fibers in all CSN specimens. These fibers were always found to be within the CSN and not on its surface i.e., epineurium. Based on our findings, the majority of fibers contained in the CSN are tyrosine positive in nature. Further studies are necessary to understand the true function of this autonomic nerve fibers.

Bilateral Sternalis Muscle With the Absence of Unilateral Sternocostal Part of the Pectoralis Major and Variation of Pectoralis Minor Muscles.

This study aims to report a 57-year-old male cadaver with a rare muscular variation of the sterno-pectoral region. An unusual sternalis muscle was observed on both sides, arising from the external oblique muscle aponeurosis. The fibers converged upwards and medially in a curved course, producing a bundle 99.50 mm long on the right side and 74.60 mm on the left. The muscles on both sides were supplied by the second, third, and fourth intercostal nerves. In the right pectoralis major (PM) muscle, the sternocostal head was completely absent, and the clavicular head arose from the medial two-thirds of the clavicle, whereas abdominal fibers arose from the aponeurosis of the external abdominal oblique muscle and ran upward and laterally and joined the clavicular fibers with a wide triangular gap. On the left side, there was an anatomically normal PM muscle. The origin of the pectoralis minor was unusually high on both sides. The morphological variations of sterno-pectoral musculature have significant implications for clinical practice, which allows more precise surgical or radiological outcomes. Clinicoradiological evaluation of these variations is important to achieve appropriate dissection planes during chest wall surgery.

The superior vesical artery: A review of conflicting definitions and how these could affect invasive procedures.

Since the superior umbilical artery is the only functioning branch of the patent umbilical artery, some anatomical and surgical books/atlases fail to clarify that it is a branch of the umbilical artery and not a direct branch of the anterior division of the internal iliac artery and so specifically state that it is a direct branch of the internal iliac artery. This discrepancy in nomenclature can obviously affect invasive procedures and communication between physicians. Therefore, the present review is intended to highlight this issue. The term "superior vesical artery" was searched using standard search engines, for example, PubMed and Google Scholar. Several standard and specialized anatomy textbooks were also examined to ascertain how the superior vesical artery was described. Thirty-two articles were identified that used the terms "superior vesical artery" or "superior vesical arteries." After applying exclusion criteria, in 28 papers, the definition of the superior vesical artery was undetermined in eight, described as a direct branch of the internal iliac artery in 13, described as a branch of the umbilical artery in six, and defined as being equivalent to the umbilical artery in one. Of the sampled textbooks, some defined the superior vesicle artery as a branch of the umbilical artery, some as a direct branch of the internal iliac artery and some as both. Taken all together, most define the superior vesical artery as a branch of the umbilical artery. As the superior vesical artery is described as a branch of the umbilical artery in the internationally accepted terminology (Terminologia Anatomica), we recommend that this definition be used by anatomists and physicians alike so that communication is clear.

Anatomy and Histology of the Petrous Carotid Membrane: Application to Skull Base Surgery.

BACKGROUND: Published reports regarding the tissue types that surround the internal carotid artery (ICA) as it travels through the carotid canal vary. Reports have variably defined this membrane as periosteum, loose areolar tissue, or dura mater. With such discrepancies and realizing that knowledge of this tissue might be important for skull base surgeons who expose or mobilize the ICA at this location, the present anatomical/histological study was performed. METHODS: In 8 adult cadavers (16 sides), the contents of the carotid canal were evaluated; specifically, the membrane surrounding the petrous part of the ICA was studied, and its relationship to the deeper lying artery was observed. These specimens were stored in formalin and submitted for histological evaluation. RESULTS: Grossly, the membrane within the carotid canal traversed the entire carotid canal and was loosely adherent to the underlying petrous part of the ICA. Histologically, all membranes surrounding the petrous part of the ICA were consistent with dura mater. The dura mater of the carotid canal had an outer endosteal layer and an inner meningeal layer as well as a clear dural border cell layer in most specimens that approximated and was loosely applied to the adventitial layer of the petrous part of the ICA. CONCLUSIONS: The membrane that surrounds the petrous part of the ICA is dura mater. To our knowledge, this is the first histological investigation of this structure and thus serves to establish the true identity of this membrane and correct previous reports in the literature that have erroneously concluded that it is periosteum or loose areolar tissue.

Granular Foveolae in the Groove of the Sigmoid Sinus: An Anatomical Study.

Background Granular foveolae in the groove of the sigmoid sinus have rarely been reported in the literature compared to numerous published reports on the granular foveolae near the superior sagittal sinus and its sulcus on the internal aspect of the calvaria. The present study was performed to better elucidate their prevalence and locations. Materials and methods One hundred and ten adult dry skulls (220 sides) were analyzed for the presence of granular foveolae within the groove of the sigmoid sinus. The exact position of the foveolae was documented, and the diameter of the granular foveola was measured. Results Granular foveolae were found in the groove of the sigmoid sinus on 3.6% of the sides. These were at or within a mean of 1.3 cm inferior to the transverse-sigmoid junction. When a mastoid foramen was noted in the groove, it was always located inferior to the granular foveolae when present. The mean diameters of the granular foveolae of the left groove of the sigmoid sinus were 2.8 mm and 4 mm for the right grooves. The mean depth of the granular foveolae in the left groove of the sigmoid sinus was 2.7 mm and 3.5 mm for the right grooves. Granular foveolae were statistically larger and deeper on the right versus left sides (p<0.05). Conclusions Granular foveolae of the groove of the sigmoid sinus were identified most commonly on the right sides and 3.6% on all sides. If identified on medical imaging, these uncommon structures at the skull base should be considered normal anatomical variations.

Evaluation of Progesterone Receptor Antagonist and Maxi-K Channel Agonist as Neuroprotective in Feeney's Weight Drop Model of TBI.

Background: Neuroprotection in traumatic brain injury (TBI) is an unmet medical need. Objective: We evaluated two agents, aglepristone (progesterone receptor antagonist) and N-salicyloyltryptamine (STP) (activator of Maxi-K channel in GH3 cells), for neuroprotection in Feeney's weight drop model of TBI. Material and Methods: Forty-eight male Wistar rats were divided into six groups (n = 8 per group). A battery of six neurobehavioral tests was evaluated at the end of the first week (EO1W), second week (EO2W), and third week (EO3W). In addition, histopathological and immunohistochemistry (BAX, Bcl-2, and M30 Cytodeath) tests were performed at EO3W. Results: Aglepristone at 10 mg/kg showed significant neuroprotection compared to control as assessed by Rota-rod test at EO1W, VEFP right paw and 28-point neurobehavioral test at EO2W, MWM test at EO3W, and positive histopathological and IHC findings. Aglepristone at 20 mg/kg showed negative results as assessed by BAX expression, downregulation of Bcl-2, and positive M30 Cytodeath, thereby suggesting toxicity at higher doses. STP 100 mg/kg showed modest neuroprotective activity but failed to show a dose-response relationship at a dose of 50 mg/kg. Conclusion: The study shows that progesterone receptor antagonists have neuroprotection at lower doses and toxicity at higher doses.