From anatomy to angioscopy: 164 years of crocodilian cardiovascular research, recent advances, and speculations

This paper present: a synthesis of current research on the crocodilian cardiovascular system with a view to encourage discussion and debate about the intricacies of this unique system and to provide ideas and suggestions for future studies. Innovative experimental approaches combined with new technologies have helped to resolve the complex flow and pressure patterns observed during non-shunting conditions that predominate in resting instrumented animals and during pulmonary to systemic shunting, which has been observed to occur spontaneously and during diving. The mechanisms and structures that may induce and regulate shunting are presented and the functional significance of a pulmonary to systemic shunt is discussed. (C) 1997 Elsevier Science Inc.

Anterior Selective Amygdalohippocampectomy: Technical Description and Microsurgical Anatomy

OBJECTIVE: We introduce a technique for performing a selective amygdalohippocampectomy (AH) through a minisupraorbital approach. METHODS: A minisupraorbital craniotomy and an anterior selective AH were performed in 8 cadaver heads (16 sides). The anatomic specimens were analyzed, and the extent of resection of the hippocampus and amygdala was evaluated. Surgically relevant measurements were performed using anatomic specimens. An image-guided system was used to document the extent of the anterior AH. Laboratory data were used to support the clinical application of the technique. RESULTS: The anterior route allowed removal of the amygdala and hippocampus, as confirmed by anatomic assessment. The image-guided system and anatomic evaluation confirmed that the amygdala and hippocampus can be accessed and removed through this route. The mean distance between the anterior aspect of the uncus and the tip of the temporal horn was 17.0 +/- 4.6 mm; the mean distance from the head of the hippocampus to the posterior border of the cerebral peduncles was 26.0 +/- 3.2 mm. Clinical application resulted in satisfactory removal of the amygdala and hippocampus. CONCLUSION: The anterior route for selective AH is a logical and straightforward approach to the mesial temporal lobe. Compared with other variations, it is less invasive and destructive, especially in terms of the fibers of the optic pathway, temporal stem, and lateral temporal neocortex.

MICROSURGICAL ANATOMY OF THE TEMPORAL LOBE: PART 2-SYLVIAN FISSURE REGION AND ITS CLINICAL APPLICATION

OBJECTIVE: We present observations of the anatomy of the sylvian fissure region and their clinical application in neuroimaging, microsurgery for middle cerebral artery aneurysms and insular lesions, frontobasal resections, and epilepsy Surgery. METHODS: Sixty adult cadaveric hemispheres and 12 adult cadaveric heads were studied after perfusion of the arteries and veins with colored latex. The anatomic information was applied in more than 200 microsurgeries in and around the sylvian fissure region in the past 15 years. RESULTS: The sylvian fissure extends from the basal to the lateral surface of the brain and presents 2 compartments on each surface, I superficial (temporal stem and its ramii) and 1 deep (anterior and lateral operculoinsular compartments). The temporal operculum is in opposition to the frontal and parietal opercula (planum polare versus inferior frontal and precentral gyri, Heschl`s versus postcentral gyri, planum temporale versus supramarginal gyrus). The inferior frontal, precentral, and postcentral gyri cover the anterior, middle, and posterior thirds of the lateral surface of the insula, respectively. The pars triangularis covers the apex of the insula, located immediately distal to the genu of the middle cerebral artery. The clinical application of the anatomic information presented in this article is in angiography, middle cerebral artery aneurysm surgery, insular resection, frontobasal resection, and amygdalohippocampectomy, and hemispherotomy. CONCLUSION: The anatomic relationships of the sylvian fissure region can be helpful in preoperative planning and can serve as reliable intraoperative navigation landmarks in microsurgery involving that region.

Severe Posterior Epistaxis-Endoscopic Surgical Anatomy

Objective: To describe the anatomy of the sphenopalatine foramen (SPF) region and possible anatomical variations. Study Design: Prospective study accomplished from September, 2006, to January, 2007. Methods: The sphenopalatine foramen (SPF) of 61 cadavers were carefully dissected. Presence of the ethmoidal crest, location of sphenopalatine and accessory foramens, and the number of arterial branches emerging through foramens were observed. Data were analyzed in relation to gender, racial group, and symmetry of the cadaver. Prediction of the presence of accessory foramen was evaluated. Results: Mixed race cadavers prevailed in 122 nasal fossae dissected (75% males). Ethmoidal crest was present in 100% of the cadavers, being anterior to the SPF in 98.4% of the cases. The most frequent SPF location was the transition of the middle and superior meatus (86.9%). Mean distance from the SPF and accessory foramen to anterior nasal spine was 6.6 cm and 6.7 cm, respectively. Accessory foramen was present in 9.83% of the cases. A single arterial stem emerged through the SPF in 67.2% of the cases, and 100% through accessory foramens. The prevalence analyses showed no differences that were statistically significant (P > 0.05) between gender and racial group. The symmetry analyses showed a strong conformity (P < 0.01) between nasal fossae in relation to the SPF location. There was no statistically significant conformity between nasal fossae and accessory foramen (P = 0.53). None of the variables of interest presents any statistically significant (P > 0.05) association with the presence of the accessory foramen. Conclusions: There are anatomical variations in the lateral nose wall that should be considered for successful endoscopic surgical treatment of severe epistaxis.

Transillumination-guided Study of the Endoscopic Anatomy of the Lacrimal Fossa

Dacryocystorhinostomy is the treatment of choice for the obstruction of the lachrymal apparatus. At the end of last century, the development of the endoscopic instruments for nasosinusal surgery has made it possible to do it through the endoscopic pathway. Nonetheless, anatomical variations make it difficult to have reproducibility endonasaly. Aim: study the endoscopic anatomy of the lachrymal fossa through transillumination of the common canaliculus. Study design: experimental. Materials and Methods: we dissected 40 lachrymal pathways from 20 human cadavers, in three stages: 1. identification and dilation of the lachrymal canaliculus. 2 Optic fiber beam introduction; 3 - endoscopic dissection of the lachrymal sac, describing its position. Results: the most frequent position of the lachrymal sac was between the free border of the middle turbinate and its insertion immediately underneath it. The maxillary line was seen in 95% of the cases. Septoplasty was needed in 12.5%, unicifectomy in 35% and middle turbinectomy in 7.5%. Conclusion: Although the lachrymal sac has a more frequent location, its position varied considerably. The transillumination of the common canaliculus proved useful, solving the problem of the anatomical variability.

The implications of microsurgical anatomy for surgical approaches to the sellar region

The knowledge of the normal anatomy and variations regarding the management of tumors of the sellar region is paramount to perform safe surgical procedures. The sellar region is located in the center of the middle cranial fossa; it contains complex anatomical structures, and is the site of various pathological processes: tumor, vascular, developmental, and neuroendocrine. We review the microsurgical anatomy (microscopic and endoscopic) of this region and discuss the surgical nuances regarding this topic, based on anatomical concepts.

Three-dimensional mapping of hippocampal anatomy in unmedicated and lithium-treated patients with bipolar disorder

Declarative memory impairments are common in patients with bipolar illness, suggesting underlying hippocampal pathology. However, hippocampal volume deficits are rarely observed in bipolar disorder. Here we used surface-based anatomic mapping to examine hippocampal anatomy in bipolar patients treated with lithium relative to matched control subjects and unmedicated patients with bipolar disorder. High-resolution brain magnetic resonance images were acquired from 33 patients with bipolar disorder ( 21 treated with lithium and 12 unmedicated), and 62 demographically matched healthy control subjects. Three-dimensional parametric mesh models were created from manual tracings of the hippocampal formation. Total hippocampal volume was significantly larger in lithium-treated bipolar patients compared with healthy controls (by 10.3%; p=0.001) and unmedicated bipolar patients ( by 13.9%; p=0.003). Statistical mapping results, confirmed by permutation testing, revealed localized deficits in the right hippocampus, in regions corresponding primarily to cornu ammonis vertical bar subfields, in unmedicated bipolar patients, as compared to both normal controls (p=0.01), and in lithium-treated bipolar patients (p=0.03). These findings demonstrate the sensitivity of these anatomic mapping methods for detecting subtle alterations in hippocampal structure in bipolar disorder. The observed reduction in subregions of the hippocampus in unmedicated bipolar patients suggests a possible neural correlate for memory deficits frequently reported in this illness. Moreover, increased hippocampal volume in lithium-treated bipolar patients may reflect postulated neurotrophic effects of this agent, a possibility warranting further study in longitudinal investigations.

Microsurgical anatomy of the safe entry zones on the anterolateral brainstem related to surgical approaches to cavernous malformations

OBJECTIVE: To study the microanatomy of the brainstem related to the different safe entry zones used to approach intrinsic brainstem lesions. METHODS: Ten formalin-fixed and frozen brainstem specimens (20 sides) were analyzed. The white fiber dissection technique was used to study the intrinsic microsurgical anatomy as related to safe entry zones on the brainstem surface. Three anatomic landmarks on the anterolateral brainstem surface were selected: lateral mesencephalic sulcus, peritrigeminal area, and olivary body. Ten other specimens were used to study the axial sections of the inferior olivary nucleus. The clinical application of these anatomic nuances is presented. RESULTS: The lateral mesencephalic sulcus has a length of 7.4 to 13.3 mm (mean, 9.6 mm) and can be dissected safely in depths up to 4.9 to 11.7 mm (mean, 8.02 mm). In the peritrigeminal area, the distance of the fifth cranial nerve to the pyramidal tract is 3.1 to 5.7 mm (mean, 4.64 mm). The dissection may be performed 9.5 to 13.1 mm (mean, 11.2 mm) deeper, to the nucleus of the fifth cranial nerve. The inferior olivary nucleus provides safe access to lesions located up to 4.7 to 6.9 mm (mean, 5.52 mm) in the anterolateral aspect of the medulla. Clinical results confirm that these entry zones constitute surgical routes through which the brainstem may be safely approached. CONCLUSION: The white fiber dissection technique is a valuable tool for understanding the three-dimensional disposition of the anatomic structures. The lateral mesencephalic sulcus, the peritrigeminal area, and the inferior olivary nucleus provide surgical spaces and delineate the relatively safe alleys where the brainstem can be approached without injuring important neural structures.

ERCP Using Double-Balloon Enteroscopy in Patients with Roux-en-Y Anatomy

Double-balloon enteroscopy (DBE) is a useful method for endoscopic retrograde cholangiopancreatography (ERCP) in patients with Roux-en-Y anatomy. Depending on the distorted anatomy, endoscopic therapies with conventional scopes were very difficult or impossible before the advent of DBE and patients had to be submitted to a percutaneous or surgical approach. The case of 6 patients with different types of Roux-en-Y-altered anatomy in which DBE-ERCP was performed with 83.3% successful rate (5/6) is reported confirming recent data in the literature on the feasibility of this method. Copyright (C) 2009 S. Karger AG, Basel

Endoscopic Anatomy of the Pterygopalatine Fossa and the Transpterygoid Approach: Development of a Surgical Instruction Model

Introduction: The pterygopalatine fossa (PPF) is a narrow space located between the posterior wall of the antrum and the pterygoid plates. Surgical access to the PPF is difficult because of its protected position and its complex neurovascular anatomy. Endonasal approaches using rod lens endoscopes, however, provide better visualization of this area and are associated with less morbidity than external approaches. Our aim was to develop a simple anatomical model using cadaveric specimens injected with intravascular colored silicone to demonstrate the endoscopic anatomy of the PPF. This model could be used for surgical instruction of the transpterygoid approach. Methods: We dissected six PPF in three cadaveric specimens prepared with intravascular injection of colored material using two different injection techniques. An endoscopic endonasal approach, including a wide nasoantral window and removal of the posterior antrum wall, provided access to the PPF. Results: We produced our best anatomical model injecting colored silicone via the common carotid artery. We found that, using an endoscopic approach, a retrograde dissection of the sphenopalatine artery helped to identify the internal maxillary artery (IMA) and its branches. Neural structures were identified deeper to the vascular elements. Notable anatomical landmarks for the endoscopic surgeon are the vidian nerve and its canal that leads to the petrous portion of the internal carotid artery (ICA), and the foramen rotundum, and V2 that leads to Meckel`s cave in the middle cranial fossa. These two nerves, vidian and V2, are separated by a pyramidal shaped bone and its apex marks the ICA. Conclusion: Our anatomical model provides the means to learn the endoscopic anatomy of the PPF and may be used for the simulation of surgical techniques. An endoscopic endonasal approach provides adequate exposure to all anatomical structures within the PPF. These structures may be used as landmarks to identify and control deeper neurovascular structures. The significance is that an anatomical model facilitates learning the surgical anatomy and the acquisition of surgical skills. A dissection superficial to the vascular structures preserves the neural elements. These nerves and their bony foramina, such as the vidian nerve and V2, are critical anatomical landmarks to identify and control the ICA at the skull base.

A Simple and Efficient Device for Demonstrating Cross-sectional Anatomy of the Head

Described in this article is a novel device that facilitates study of the cross-sectional anatomy of the human head. In designing our device, we aimed to protect sections of the head from the destructive action of handling during anatomy laboratory while also ensuring excellent visualization of the anatomic structures. We used an electric saw to create 15-mm sections of three cadaver heads in the three traditional anatomic planes and inserted each section into a thin, perforated display box made of transparent acrylic material. The thin display boxes with head sections are kept in anatomical order in a larger transparent acrylic storage box containing formaldehyde solution, which preserves the specimens but also permits direct observation of the structures and their anatomic relationships to each other. This box-within-box design allows students to easily view sections of a head in its anatomical position as well as to examine internal structures by manipulating individual display boxes without altering the integrity of the preparations. This methodology for demonstrating cross-section anatomy allows efficient use of cadaveric material and technician time while also giving learners the best possible handling and visualization of complex anatomic structures. Our approach to teaching cross-sectional anatomy of the head can be applied to any part of human body, and the value of our device design will only increase as more complicated understandings of cross-sectional anatomy are required by advances and proliferation of imaging technology. Anat Sci Educ 3: 141-143, 2010. (C) 2010 American Association of Anatomists.

Macroscopic and microscopic anatomy of the oviduct in the sexually mature rhea (Rhea americana)

The morphological characteristics of the oviduct of 12 sexually mature rheas (Rhea americana) were studied. Only the left oviduct is developed as a long tube with a length of 122 +/- 23.1 cm, and is subdivided into infundibulum (15.2 +/- 4.0 cm), magnum (63.3 +/- 9.4 cm), isthmus (5.6 +/- 3.1 cm), uterus (16.0 +/- 4.2 cm) and vagina (11.5 +/- 1.4 cm). The mucous membrane of the oviduct, as a whole, possesses luminal folds covered by ciliated columnar epithelium with secretory cells. The infundibulum part presents a cranial opening with thin and long fimbriae with few tubular glands in caudal tubular portion. In the magnum, the largest portion of the oviduct, the folds are thicker and are filled with tubular glands. The isthmus is short and presents less bulky folds and a few tubular glands. A bag-shaped uterus in the cranial area shows thin folds, and in the caudal region (shell gland) more ramified folds with few tubular glands. The vagina has long luminal folds and a thick muscular tunic; no glands with sperm-storage characteristics have been observed. In conclusion, the oviduct in sexually mature rhea has morphological similarities with the other species of birds already described; however it presents its own characteristics to produce a big egg.

The anatomy of two-rooted mandibular canines determined using micro-computed tomography

P>Aim To investigate the internal and external anatomy of extracted human mandibular canines with two roots and two distinct canals using micro-computed tomography (mu CT). Methodology Fourteen two-rooted human mandibular canines were scanned using a high-resolution mu CT system (SkyScan 1174v2; SkyScan N.V., Kontich, Belgium). The images were processed to evaluate the size of the roots, the furcation regions, the presence of accessory canals, the mean distances between several anatomical landmarks, the position of the apical foramina, the direction of root curvatures, the cross-sectional appearances (SMI index), the volume and surface areas of the root canals. Results Root bifurcation was located in both apical (44%, n = 6) and middle (58%, n = 8) thirds of the root. The size of the buccal and lingual roots was similar in 29% of the sample. From a buccal view, no curvature towards the lingual or buccal direction occurred in either roots. From a proximal view, no straight lingual root occurred. In both views, S-shaped roots were found in 21% of the specimens. Location of the apical foramen varied considerably, tending to the mesio-buccal aspect of both roots. Lateral and furcation canals were observed mostly in the cervical third in 29% and 65% of the sample, respectively. The structure model index (SMI) index ranged from 1.87 to 3.86, with a mean value of 2.93 +/- 0.46. Mean volume and area of the root canals were 11.52 +/- 3.44 mm3 and 71.16 +/- 11.83 mm2, respectively. Conclusions The evaluation of two-rooted mandibular canines revealed that bifurcations occurred in the apical and middle third. S-shaped roots were found in 21% of the specimens. Mean volume, surface area and SMI index of the root canals were 11.52 mm3, 71.16 mm2 and 2.93, respectively.

Ecology, shell morphology, anatomy and sperm ultrastructure of the caenogastropod Pyrgula annulata, with a discussion of the relationship between the 'Pyrgulidae' and Caspian and Baikalian rissooideans

The composition of the Pyrgulidae and its relationships to other member families of the caenogastropod superfamily Rissooidea are examined after a consideration of new anatomical (including gross anatomy, sperm ultrastructure), conchological (including protoconch features), ecological, biogeographical and palaeontological data and a re-evaluation of existing literature. Pyrgulidae can be distinguished from hydrobiids unequivocally only with the aid of the radula. Sperm ultrastructural features suggest a very close relationship between the Pyrgulidae, the Hydrobiidae and the Bithyniidae (in fact no family-diagnostic sperm characters can be found to separate these three taxa). Based upon neontological and fossil evidence it is likely that pyrgulids represent a Miocene offshoot from a paratethyal hydrobiid lineage. Pyrgulids may also represent the stock from which the baicaliids arose, in which case the Pyrgulidae must be considered a paraphyletic group. The huge biogeographic gap between the Caspian Sea and Lake Baikal is to some extent bridged by the finding of a Neogene pyrgulid from the Altai Mountains. An alternative scenario for the origin of baicaliids is presented.