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An anatomical study of the vestibulocochlear anastomosis (anastomosis of Oort) in humans: preliminary results.

Von Oort first described the vestibulocochlear anastomosis in 1918, and there have been very few anatomical studies of it. It is located at the bottom of the internal auditory meatus and links the saccular nerve to the cochlear nerve. The aim of this study was to investigate the micro-anatomical characteristics of this anastomosis. We dissected 10 human temporal bones from five heads. We found the vestibulocochlear anastomosis in seven of the specimens, of which six were clearly visible. We were unable to uncover it in three specimens due to dissection problems. Its length was evaluated to be between 0.5 and 1 mm, with a diameter of 0.5 mm. The vestibulocochlear anastomosis could be the pathway for the nerve fibers of the cochlear efferent system, whose description remains incomplete. However, no anatomist, histologist or physiologist has demonstrated this function. From the results of this study, it seems likely that the vestibulocochlear anastomosis exists. Other studies are necessary to link it to the efferent system.

Aged↗

A detailed observation of variations of the facial artery, with emphasis on the superior labial artery.

The reconstruction of lip defects through the use of the Abbe flap and other lip flap procedures involves surgical manipulation of one of the major branches of the facial artery, specifically the superior labial artery (SLA). We examined 284 hemifaces derived from 142 formalin fixed cadavers. Observations regarding the distribution patterns of the facial artery were recognized and categorized into five Types, labeled "A" through "E". Type A (135, 47.5%): facial artery bifurcates into SLA and lateral nasal (the latter gives off inferior and superior alar and ends as angular); Type B (110, 38.7%): similar to Type A, except lateral nasal terminates as superior alar (angular artery is absent); Type C (24, 8.4%): facial artery terminates as SLA; Type D (11, 3.8%): angular artery arises directly from facial arterial trunk rather than as the termination of lateral nasal, with the facial artery ending as superior alar; Type E (4, 1.4%): facial artery terminates as a rudimentary twig without providing any significant branches. Furthermore, we were able to categorize variations within each Type. Sub-Type variations were examined in Types A through C (A: 1-7; B: 1-4; C: 1-3). Our aim was to equip both the anatomist and surgeon with a more thorough understanding of the vasculature of the face, as well as to enable plastic surgeons to have a more confident approach to reconstructive procedures in this region.

Adult↗

Rare variation in course and affluence of internal iliac vein due to its anatomical and surgical significance.

During regular dissection of the retroperitoneal region, three uncommon anatomical variations of the internal iliac veins were found on dissected specimens: in the first case, the internal iliac veins converge forming a common trunk draining into the left external iliac vein. In the other two cases, the internal iliac vein crosses the median plane and flows into the contralateral common iliac vein. These anomalies result from a persistence of the embryonic inferior branch of the cardinal vein and are important to be known for they may be undetected or may not appear in imaging. These data have implications for both pelvic surgeons and anatomists who manipulated this anatomical area.

Dissection↗

High-resolution ultrasound evaluation of internal jugular venous valves.

Although the presence of valves in the distal portion of the internal jugular veins has been widely described by anatomists and pathologists, their existence remains underscored in the medical literature. We set out to demonstrate their sonographic aspect and to evaluate their morphology, location and prevalence. Seventy-five cadavers were evaluated for the presence and aspect of such valves through neck dissections. Concurrent evaluation of the sonographic character of these structures was performed in another cohort of 75 adults. Valves of the distal portion of the internal jugular veins were found in 93 % of the cadaveric studies. Ultrasonography easily demonstrated the valve leaflets in 87 % of patients; all were observed in the distal portion of the internal jugular (IJ) veins. Sixty percent were bilateral with the majority of unilateral veins found on the right side. High-resolution ultrasonography easily demonstrates valves in the distal portion of the IJ veins which are present in the great majority of persons. Their evaluation may be of use in percutaneous procedures using this venous access.

Aged↗

Measurement of the humeral head retroversion angle. A new radiographic method.

BACKGROUND: In this study, a simple and reliable radiographic method is described to determine the torsional profile of the humeral head. METHODS: First, by using a specially developed frame, the humeral head retroversion angles (HRAs) of 20 dry humeri were measured by an anatomist and an orthopedist. Then the HRA of these humeri were measured by two orthopedists on radiographs taken in semi-axial view when the humeri were in 20 degrees abduction. RESULTS: The results were assessed with the SPSS 9.05 program, and the repeatability coefficient of both methods was 98%. The average difference in angle determination between the two methods was 0.9 degrees; the maximum difference was 3 degrees. After that, posteroanterior semi-axial radiographs of both humerus bones of 40 healthy volunteers were taken by positioning their arms in 20 degrees abduction to the X-ray axis. The mean HRA difference between the right and left sides was 0.4 degrees (maximum difference 3 degrees ) and is of no clinical significance. It was determined that left and right HRAs can be taken as a reference to each other. For measurement of the HRA in the planning of proximal humeral rotation osteotomy and prosthesis replacement arthroplasty, the presented radiographic method can be used with a high rate of accuracy.

Adult↗

Computed tomographic imaging to determine the frequency of anatomical variations in pneumatization of the ethmoid bone.

The present study was performed on axial and coronal CT scans of 212 patients. Scans were analyzed by an anatomist and a radiologist for the presence of Haller's cells, agger nasi cells, Onodi's cells and pneumatized crista galli. Results demonstrated the presence of Haller's cells in 21.2%, Onodi's cells in 10.4% and pneumatized crista galli in 2.4% of patients. A pneumatized anterior clinoid process was found in 0.5% of the patients. The data obtained in our study were compared with those reported in other anatomic and radiologic studies.

Adult↗

A re-evaluation of the premaxillary bone in humans.

The discovery of the premaxillary bone (os incisivum, os intermaxillare or premaxilla) in humans has been attributed to Goethe, and it has also been named os Goethei. However, Broussonet (1779) and Vicq d'Azyr (1780) came to the same result with different methods. The first anatomists described this medial part of the upper jaw as a separate bone in the vertebrate skull, and, as we know, Coiter (1573) was the first to present an illustration of the sutura incisiva in the human. This fact, and furthermore its development from three parts:-(1) the alveolar part with the facial process, (2) the palatine process, and (3) the processus Stenonianus-can no longer be found in modern textbooks of developmental biology. At the end of the nineteenth and in the early twentieth century a vehement discussion focused on the number and position of its ossification centers and its sutures. Therefore, it is hard to believe that the elaborate work of the old embryologists is ignored and that the existence of a premaxillary bone in humans is even denied by many authors. Therefore this re-evaluation was done to demonstrate the early development of the premaxillary bone using the reconstructions of Felber (1919), Jarmer (1922) and data from our own observations on SEM micrographs and serial sections from 16 mm embryo to 68 mm fetus. Ossification of a separate premaxilla was first observed in a 16 mm embryo. We agree with Jarmer (1922), Peter (1924), and Shepherd and McCarthy (1955) that it develops from three anlagen, which are, however, not fully separated. The predominant sutura incisiva (rudimentarily seen on the facial side in a prematurely born child) and a shorter sutura intraincisiva argue in this sense. The later growth of this bone and its processes establish an important structure in the middle of the facial skull. Its architecture fits well with the functional test of others. We also focused on the relation of the developing premaxilla to the forming nasal septum moving from ventral to dorsal and the intercalation of the vomer. Thus the premaxilla acts as a stabilizing element within the facial skeleton comparable with the keystone of a Roman arch. Furthermore, the significance of the premaxillary anlage for the closure of the palatine was documented by a synopsis made from a stage 16, 10.2 mm GL embryo to a 49 mm GL fetus. Finally the growth of the premaxilla is closely related to the development of the human face. Abnormal growth may be correlated to characteristic malformations such as protrusion, closed bite and prognathism. Concerning the relation of the premaxillary bone to cleft lip and palate we agree with others that the position of the clefts is not always identical with the incisive suture. This is proved by the double anlagen of an upper-outer incisor in a 55 mm fetus and an adult.

Anatomy↗

The discovery of perforating veins.

Many authors of the 19th century are erroneously credited for their discovery of perforating veins. In this report, we show the first representations of perforating veins, dated 1793. These are from the German anatomist Justus Christian Von Loder, who correctly described most of the groups of perforating veins we currently know. These drawings have never appeared in the modern literature.

Anatomy↗

Evolution of hernia repair: a salute to Professor Piero Pietri.

This subject has been well covered in recent years. Yet it seems appropriate to search for major advances in hernia methodology during the last 100 years. Eduardo Bassini is credited with pioneering the modern era. His "triple layer" repair was corrupted through the years and, as a result, he did not receive sufficient credit for his attention to the posterior inguinal wall. Chester McVay, renowned surgeon-anatomist, renewed interest in the Cooper's ligament and the posterior inguinal wall. Surgeons from the Universities of Washington and Illinois perfected approaches to the posterior inguinal wall. Thus, these investigators paved the way for several effective posterior hernia operations. The name of Usher will forever be remembered in terms of practical prosthetic mesh (polypropylene). This material, as well as others, has become an important addition to the surgeon's armamentarium. Rene Stoppa reminded us of the Pascal principle and clearly demonstrated how giant prostheses can remain in the preperitoneal space without the need for sutures. Tension-free operations, plug techniques, and laparoscopic hernia methodology must await further analysis.

Eponyms↗

The unified theory of hernia formation.

The perusal of surgical journals suggests that the etiology and the treatment of hernias are still based on the understanding of a simple mechanical defect, an idiopathic happenstance requiring a reliable hernia repair, preferably with a prosthetic mesh or device. The need for additional elucidation does not constitute an aim that is pervasive in the surgical community or with the corporate manufacturers of surgical implements. This may well be because surgeons are not trained scientists and laboratory workers. Fortunately, several disciplines are injecting a healthy dose of curiosity matched by ingenuity. Among these contributors, we can count anatomists, electron microscopists, biochemists, organic chemists, pathologists, geneticists, and molecular biologists, who have looked at collagen, enzymes, tobacco smoke, congenital diseases, and chromosomal defects. Every aspect of the researchers' work has identified and converged onto a final common organ: collagen. It is the pathological changes in collagen that set the stage for the development of a hernia. The multiple theories on mechanisms of hernia formation have, at last, melded into one single Unified Theory of hernia formation.

Female↗

The meandering mesenteric artery: a historic review and surgical implications.

PURPOSE: The aim of this study was to review the literature regarding collateral mesenteric circulation with emphasis on the mesenteric meandering artery (of Moskowitz). Standard vascular embryology and anatomy are described as are the collateral mesenteric vessels that can develop with arterial stenosis or occlusion. A discussion on the correct usage of terms for describing mesenteric collateral vessels follows. METHODS: We undertook review of the historical literature to discuss the surgical implications of the meandering mesenteric artery. RESULTS: Despite a long history of study by anatomists and surgeons, confusion still persists regarding both the number and correct descriptive terminology of the collateral mesenteric vessels. CONCLUSIONS: The use of the vague historic term "arc of Riolan" should be discarded for the more precise term "meandering mesenteric artery." The meandering mesenteric artery should routinely be preserved in all surgical procedures, to include resection for cancer, given its critical function in providing collateral mesenteric circulation. Further evaluation in the asymptomatic patient, however, is unnecessary.

Collateral Circulation↗

Apoptosis and oncosis in acute coronary syndromes: assessment and implications.

The rational design of therapeutic interventions for protection of ischemic myocardium from ultimate death requires an understanding of the mechanistic basis of cardiomyocyte (CM) cell death, its timing and the tools for its quantification. Until recently, CM cell death following ischemia and/or reperfusion was considered to involve necrosis or 'accidental cell death' from very early on. Collective evidence over the past decade indicates that early CM cell death after myocardial ischemia and post-ischemic reperfusion involves apoptosis with cell shrinkage and drop-out, and/or oncosis with cell swelling followed by necrosis. This paradigm shift suggests that different approaches for cardioprotection are required. Oncologists, pathologists, anatomists and basic scientists who have studied apoptosis over the last three decades separated physiological apoptosis from inappropriate apoptosis in pathological states. Until recently, cardiologists resisted the concepts of CM apoptosis and regeneration. Cumulative evidence indicating that apoptosis in the heart may occur in different cell types, spread from one cell type to another, and occur in bursts, may have profound implications for therapies aimed at protection of ischemic myocardium by targeting CM apoptosis in acute coronary syndromes. This review focuses on a critique of the methods used for the assessment of CM apoptosis and the implications of CM apoptosis in acute coronary syndromes.

Animals↗

John Hunter, angina pectoris and medical education.

The cardiac death of John Hunter, the 18th century surgeon and anatomist, occurred during a period of emerging understanding of the relation between angina pectoris and coronary artery disease. Although this association was first recognized by Edward Jenner, Hunter's pupil, consideration for his friend and teacher kept Jenner's insight unpublished during Hunter's lifetime. A fascinating controversy on medical education surrounded Hunter during his final year and probably contributed to his death.

Anatomy↗

Johann Friedrich Meckel, the Younger (1781-1833).

Meckel's name is well known in the medical world because of the intestinal abnormality that carries his eponym. We are less familiar with his personal life and his far-reaching achievement as a prominent anatomist. Also described is his complex personality as well as the indelible impression he made on his contemporaries.

General Surgery↗

Retinohypothalamic pathway: a breach in the law of Newton-Müller-Gudden?

Theories of binocular vision originally imagined by Newton provided the foundation for subsequent investigations of the visual system by early anatomists and physiologists. These studies led to the widely accepted concept that degree of optic fiber decussation in the chiasm is inversely related to frontal orientation of the optical axes of the eyes (law of Newton-Müller-Gudden). A survey of 23 species from 11 mammalian orders demonstrates that, in contrast to other visual pathways, the retinohypothalamic projection does not obey this general principle. In further contradiction, an unexpected finding in primates is the predominance of ipsilateral, rather than contralateral, retinal input to the suprachiasmatic nucleus. This unusual organization underlines the functional and evolutionary specificities of this 'non-image forming' visual pathway.

Animals↗

Different effects of hypoxia on the membrane potential and input resistance of isolated and clustered carotid body glomus cells.

Intracellular recordings were made from cultured glomus cells of rat carotid bodies. Hypoxia (PO2 1-61 Torr), induced by Na-dithionite (Na2S2O4), differentially affected cells that were clustered and those that were isolated. More than 80% of clustered cells depolarized and their input resistance decreased, whereas about 60% of isolated cells hyperpolarized and their input resistance increased. In both groups, the mechanisms for cell depolarization or hyperpolarization appeared similar. Differences between clustered and isolated cells seemed to be conditioned by the sustentacular cells. Their processes surrounded clustered cells but were absent around isolated ones. However, we may have also functionally different glomus cells which may or may not correspond to the different types described by anatomists.

Carotid Body↗

A microcomputer-aided system for the graphic reproduction of neurohistochemical maps.

In this report we describe the computer hardware and software used in the production of microscopic maps from histochemical data. The maps may consist of lines, shaded and symbols, each drawn in any of four styles and in any of four colors. The system employs a microscope stage digitizer and plotter to produce an initial map containing precise positional information. A desktop computer equipped with a four-color digital plotter and a digitizing tablet is used to produce the final map. The positional information of the initial map is traced on the computer's digitizer to produce the final map. The software enabling this transformation is specialized for three basic types of structures. Cytoarchitectural landmarks and macroscopic morphology are represented by lines. Areas of a microscopic field which have some degree of visibly definable characteristics such as axonal staining are represented by areas shaded with dots. Microscopic structures of individual interest are represented by various symbols. Other program options allow the computation and printing of figure areas and perimeters while digitizing shaded areas, storage of all map information on a mass-storage medium, the drawing of alignment registration marks, and flexible access to and prompting for all program options. While the role of the anatomist in recognition and discrimination of meaningful histochemical information is unchanged, production of microscopic maps using this system consumes far less time than hand methods and results in uniform, accurate illustration.

Animals↗

A nineteenth century view of the optic commissure.

Historically, ophthalmologists and anatomists have been intrigued by the optic nerve and its decussation. Isaac Newton was the first to describe and suggest the significance of the chiasmal crossing, while W.H. Wollaston defined the importance of hemiretinal differentiation in 1824. However, at that time, the vertical meridian separating nasal from temporal retina was believed to be located at the optic papillae. This theory was disproved in 1870 by two Philadelphia ophthalmologists, who demonstrated and documented the vertical meridian at the macula during their examination of an injured Civil War soldier.

History, 19th Century↗