Anatomical Variation

As a largely under-recognized problem, snapping scapula stems from the disruption of normal mechanics in scapulothoracic articulation. It is especially common in the young, active patient population, and symptoms are frequently seen with overhead and throwing motions. Understanding the anatomy of the scapula and surrounding neurovascular structures is crucial in making a differential diagnosis and providing both nonoperative and surgical treatments. Common causes of snapping scapula include bursitis, muscle abnormality, and bony or soft-tissue abnormalities. Anatomic variations, such as excessive forward curvature of the superomedial border of the scapula, may also be a cause for snapping. Benign tumor conditions of the scapula can also predispose one to snapping scapula syndrome and should be thoroughly investigated during the course of treatment. Patients with snapping scapula syndrome typically present with a history of pain with overhead activities. Snapping scapula is associated with audible and palpable crepitus near the superomedial border of the scapula. Various imaging studies may be used to rule out soft-tissue and bony masses, which may cause impingement at the scapulothoracic articulation. In most cases nonoperative treatment is curative and includes physical therapy for scapular muscle strengthening and nonsteroidal anti-inflammatory medications. Corticosteroid injections may also be used for therapeutic and diagnostic purposes. In most cases overuse injuries and repetitive strains respond well to nonoperative treatments. When nonoperative measures fail, surgery is a proven modality, especially if a soft-tissue or bony mass is implicated. Both open and arthroscopic techniques have been described with predictable results.

The brachial plexus is the complex network of nerves, extending from the neck to the axilla, which supplies motor, sensory, and sympathetic Wbers to the upper extremity. Typically, it is formed by the union of the ventral primary rami of the spinal nerves, C5-C8 & T1, the so-called "roots" of the brachial plexus. By examining the neural architecture of the brachial plexus, the most constant arrangement of nerve Wbers can be delineated, and the most predominate variations in the neural architecture deWned. A thorough understanding of the neuroanatomy of the brachial plexus, with an appreciation of the possible anatomic variations that may occur is necessary for eVective clinical practice.

Recent advances in radiation oncology are based on improvement in dose distribution thanks to IMRT and improvement in target definition through new diagnostic imaging such as spectroscopic or functional MRI or PET. However, anatomic variations may occur during treatment decreasing the benefit of such optimization. Image-guided radiotherapy reduces geometric uncertainties occurring during treatment and therefore should reduce dose delivered to healthy tissues and enable dose escalation to enhance tumour control. However, IGRT experience is still limited, while a wide panel of IGRT modalities is available. A strong quality control is required for safety and proper evaluation of the clinical benefit of IGRT combined or not with IMRT.

Variations in the anatomy of the inferior alveolar nerve were seen in 2 of the 20 dissections of the infratemporal fossa in 10 cadavers. A connecting nerve branch that originated from the auriculotemporal nerve joined the inferior alveolar nerve on both sides. The second part of the maxillary artery passed between the mandibular nerve, the root of the inferior alveolar nerve, and the connecting nerve branch which formed a loop. The maxillary artery seemed to be entrapped. Neurovascular entrapment can cause pain and numbness. Anatomical variations in this region should be kept in mind, particularly in cases of failed treatment of trigeminal neuralgia.

Patients with lumbosacral and buttock pain provide tacit support for recognizing the piriformis muscle as a contributing factor to the pain (piriformis syndrome). One hundred and twelve cadaveric specimens were observed to elucidate the anatomical variations of the piriformis muscle referred to the diagnostic and treatment of the piriformis syndrome. The distance between the musculotendinous junction and the insertion was measured and the piriformis categorized into three types: Type A (71, 63.39%): long upper and short lower muscle belly; Type B (40, 35.71%): short upper and long lower muscle belly; Type C (1, 0.9%): fusion of both muscle bellies at the same level. The diameter of the piriformis tendon at the level of the musculotendinous junction ranged from 3 to 9 mm (mean: 6.3 mm). The piriformis showed the following possible fusions with adjacent tendons. In type one (60, 53.57%) a rounded tendon of the piriformis reached the upper border of the greater trochanter. In type two (33, 29.46%) it Wrst joined into the gemellus superior tendon and at last both fused with the obturator internus tendon and inserted into the medial surface of the greater trochanter. A fusion of the piriformis, obturator internus and gluteus medius tendon with the same insertion area as above was observed in type three (15, 13.39%) and Wnally in type four (4, 3.57%) the tendon fused with the gluteus medius to reach the upper surface of the greater trochanter. Based on this survey anatomical causes for the piriformis syndrome are rare and a more precise workup is necessary to rule out more common diagnosis.

Purpose The purpose of this narrative review is to describe an anatomical approach for residents-in-training and anesthesiologists who are learning techniques of ultrasound-guided regional anesthesia of the neck and upper limb Sources Relevant articles relating anatomy and anatomical variation to the emerging practice of ultrasoundguided regional anesthesia for the neck and upper limb were sourced via both Medline and PubMed databases. Also, our approach to teaching ultrasound technique has developed from using anatomical resources and cadaveric workshops. This approach emphasizes precise image acquisition, a detailed knowledge of anatomy and anatomical variations, and, importantly, visual interpretation of sonographic landmarks based on pattern recognition when interpreting sonograms. Principal findings Typical sonographic patterns orient the examiner to nerve position, which is necessary for executing successful regional anesthesia of the neck and P. Soeding, MBBS (&)

The neurovascular bundle may be vulnerable during surgical procedures involving the mandible, especially when anatomical variations are present. Increased demand of implant surgeries, wider availability of three-dimensional exams, and lack of clear definitions in the literature indicate that features of anatomical variations should be revisited. The objective of the study was to evaluate features of anatomical variations related to mandibular canal (MC), such as bifid canals, anterior loop of mental nerve, and corticalization of MC. Additionally, bone trabeculation at the submandibular gland fossa region (SGF) was assessed and related to visibility of MC. Cone beam computed tomography exams from 100 patients (200 hemimandibles) were analyzed and the following parameters were registered: diameter and corticalization of MC; trabeculation in SGF region; presence of bifid MC, position of bifurcations, diameter, and direction of bifid canals; and measurement of anterior loops by two methods. Corticalization of the MC was observed in 59% of hemimandibles. In 23%, MC could be identified despite absence of corticalization. Diameter of MC was between 2.1 and 4 mm for nearly three quarters of the sample. In 80% of the sample trabeculation at the SGF was either decreased or not visible, and such cases showed correlation with absence of MC corticalization. Bifid MC affected 19% of the patients, mostly associated with additional mental foramina. Clinically significant anterior loop (>2 mm of anterior extension) was observed in 22–28%, depending on the method. Our findings, together with previously reported limitations of conventional exams, draw attention to the unpredictability related to anatomical variations in neurovascularization, showing the contribution of individual assessment through different views of three-dimensional imaging prior to surgical procedures in the mandible.

Carpal tunnel syndrome is an exceedingly common orthopaedic problem in the United States. When conservative management is unsuccessful, most surgeons proceed to surgical treatment. Though the carpal tunnel release procedure is usually curative, many patients experience postoperative complications, such as scar sensitivity, pillar pain, recurrent symptoms, and grip weakness, regardless of whether the release was done through an open, mini-open, or endoscopic approach. The exact causes of these and other complications of carpal tunnel release remain unclear. Release of the carpal tunnel has an effect on carpal anatomy and biomechanics, including an increase in carpal arch width, carpal tunnel volume, and changes in muscle and tendon mechanics. We set out to review the morphological and biomechanical changes caused by carpal tunnel release with the goal of better understanding the root causes of postoperative complications. This article first reviews normal carpal tunnel anatomy and anatomic variations, then available surgical techniques for carpal tunnel release, and finally the literature on morphologic, physiologic and biomechanical alterations in the wrist after carpal tunnel release.

The purpose of the study was to determine anatomical variations at the suprascapular notch for better understanding of possible predisposing factors for suprascapular nerve entrapment. We dissected 32 shoulders of 16 cadavers between the ages of 39 and 74 years. We observed abnormally oriented superior fibers of the subscapularis muscle in five shoulders of the 16 cadavers, which were covering the entire anterior surface of the suprascapular notch and significantly reducing the available space for the suprascapular nerve. We also detected anterior coracoscapular ligament in six of the 32 shoulders, and calcified superior transverse scapular ligament in four of the shoulders. In this study, we classified the variations for the superior transverse scapular ligament. In conclusion, knowing the anatomical variations in detail along the course of the suprascapular nerve might be important for better understanding of location and source of the entrapment syndrome, especially for individuals who are involved in violent overhead sports activities such as volleyball and baseball. To our knowledge, close relationship of subscapularis muscle with the suprascapular nerve as a possible risk factor for suprascapular nerve entrapment has not been mentioned previously.

Background: Anterior communicating artery complex is the most frequent site of intracranial aneurysms in most reported series. Anterior communicating artery aneurysms are the most complex aneurysms of the anterior circulation due to the angioarchitecture and flow dynamics of the ACoA region, frequent anatomical variations, deep interhemispheric location, and danger of severing the perforators with ensuing neurologic deficits. The authors review the practical microsurgical anatomy, importance of preoperative imaging in surgical planning, and microneurosurgical steps in dissection and clipping of ACoAAs. Methods: This review, and the whole series on intracranial aneurysms, are mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve, without patient selection, the catchment area in Southern and Eastern Finland. Results: These 2 centers have treated more than 10 000 patients with aneurysm since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients with 4253 aneurysms, 1145 patients (38%) had altogether 1179 ACA aneurysms; of them, 898 patients harbored 921 (78%) ACoAAs. In this series, 715 patients (80%) presented with ruptured ACoAAs with the median diameter of 7 mm. Giant ACoAAs were present in 15 (2%), whereas only 3 (0.3%) were classified as fusiform. Conclusions: Anterior communicating artery aneurysms present frequently with SAH at small size. Furthermore, unruptured ACoAAs may have increased risk of rupture regardless of size, also as an associated aneurysm, and require treatment. The aim in microneurosurgical management of an ACoAA is total occlusion of the aneurysm sac with preservation of flow in all branching and perforating arteries. This demanding task necessitates perfect surgical strategy based on review of the 3D angioarchitecture and abnormalities of the patient's ACoA complex with its ACoAA and to orientate accordingly during the microsurgical dissection. The surgical trajectory should provide optimal visualization of the ACoA complex without massive brain retraction. Precise dissection in the 3D anatomy of the ACoA complex and perforators requires not only experience and skill but Abbreviations: 3D, 3-dimensional; A1, Proximal segment of anterior cerebral artery; A2, postcommunicating segment of anterior cerebral artery; A1A, aneurysm of the A1 segment; A2A, aneurysm of the A2 segment; A3A, aneurysm of the A3 segment; patience to work the dome and base under repeated protection of temporary clips and pilot clips. This is particularly important with the complex, large, and giant aneurysms.

Non-rigid image registration (NIR) is an essential tool for morphologic comparisons in the presence of intra- and inter-individual anatomic variations. Many NIR methods have been developed, but are es- pecially difficult to evaluate since point-wise inter-image correspondence is usually unknown, i.e., there is no "Gold Standard" to evaluate perfor- mance. The Non-rigid Image Registration Evaluation Project (NIREP) has been started

Understanding the neural control and mechanics of human eye movement has significant implications for treating vision disorders. A computational model incorporating physiological properties and nonlinear kinematics of the oculomotor plant's geometry and extraocular muscle (EOM) mechanics is desirable for scientific studies and clinical applications. We simulate realistic three-dimensional eye fixation using a new biomechanical simulation framework. We model EOMs as a collection of "strands," which are modeling elements for musculotendon mechanics based on splines with inertia. Anatomical variations in EOM and globe geometry across individuals can be taken into account. Complicated nonlinear EOM mechanics as well as the recently discovered pulleys are included in the computation. The resulting model generates realistic gaze positions and trajectories given EOM innervations.

The RLN was always routinely exposed and identified in 1,543 thyroidectomies. All patients underwent laryngoscopic evaluation before surgery and at the time of discharge. A total of 2,626 RLN were observed. The number of nerves exposed to risk was 673 (25.6%). In the whole series, of ...

Purpose The human insula constitutes the invaginated portion of the cerebral cortex and is less well understood than other cortical areas because of its hidden location. Our purpose was to study the neurosurgical anatomy of the human insula via a combined and comparative study of its gross and imaging anatomy. Methods We totally studied the anatomy of 148 normal insulae in anatomic specimens and radiologic images. We evaluated the number of all insular gyri (short and long), we statistically analyzed our results, and we made comparisons among hemispheres and gender. We also compared the two studies. Finally, we searched in the literature to make comparisons with other authors and to add our experience to the today existing knowledge of the insular anatomy.

The "La Chapelle" archaeological site at Jau-Dignac-et-Loirac  in the  Lower Médoc,region of the Gironde estuary in south-western France lies in a unique and unstable  environment. Despite the difficulties arising from the instability of the site, La Chapelle has produced evidence of four main settlement periods, from  Antiquity to the modern period. To find out whether the settlement was continuous at the site and how the population organised their burial place, we studied 24 dental non metric variations in two populations buried at the site: one dating from the High Middle Ages and another from the Late Middle Ages and  the modern period. Results clearly point to the existence of a subgroup within the high Middle Ages group, but they also, and especially, suggest  a continuous settlement at the site.

The success of endodontic treatment depends on the identification of all root canals so that they can be cleaned, shaped, and obturated. This study investigated internal morphology of maxillary first molars by 3 different methods: ex vivo, clinical, and cone beam computed tomography (CBCT) analysis. In all these different methods, the number of additional root canals and their locations, the number of foramina, and the frequency of canals that could or could not be negotiated were recorded. In the ex vivo study, 140 extracted maxillary first molars were evaluated. After canals were accessed and detected by using an operating microscope, the teeth with significant anatomic variances were cleared. In the clinical analysis, the records of 291 patients who had undergone endodontic treatment in a dental school during a 2-year period were used. In the CBCT analysis, 54 maxillary first molars were evaluated. The ex vivo assessment results showed a fourth canal frequency in 67.14% of the teeth, besides a tooth with 7 root canals (0.72%). Additional root canals were located in the mesiobuccal root in 92.85% of the teeth (17.35% could not be negotiated), and when they were present, 65.30% exhibited 1 foramen. Clinical assessment showed that 53.26%, 0.35%, and 0.35% of the teeth exhibited 4, 5, and 6 root canals, respectively. Additional root canals were located in this assessment in mesiobuccal root in 95.63% (27.50% could not be negotiated), and when they were present, 59.38% exhibited 1 foramen. CBCT results showed 2, 4, and 5 root canals in 1.85%, 37.05%, and 1.85% of the teeth, respectively. When present, additional canals showed 1 foramen in 90.90% of the teeth studied. This study demonstrated that operating microscope and CBCT have been important for locating and identifying root canals, and CBCT can be used as a good method for initial identification of maxillary first molar internal morphology.

Apicoectomy of the superior first molar palatine root until recently involved relatively destructive and laborious surgery because of the palatal access route, which not only necessitates an extensive flap, but also the readying of procedures required to deal with a possible hemorrhage ...

Talo-calcaneal coalitions may be intra-articular or extra-articular in position and may be classified as fibrous, cartilaginous or osseous in morphology. Fibrous coalitions, particularly extra-articular talo-calcaneal coalitions, may have cross-sectional imaging findings that resemble normal anatomic variants, particularly the medial talo-calcaneal ligament and to a lesser extent the presence of an accessory articular facet between the posterior margin of the sustentaculum and postero-medial process of the talus. Typically, in the adult fibrous coalition, there will be some osseous deformity at the entheses, allowing differentiation from a medial talo-calcaneal ligament. The anatomy of the subtalar joint and its ligamentous supports, normal anatomic variations and their corresponding imaging appearance are reviewed in the first part of this article. In the second part, the various forms of talo-calcaneal coalition and their imaging appearance are reviewed.

Duplication of the internal jugular vein (IJV) is a rare malformation. Three intraoperative cases are reported. In our personal experience, the clinical incidence of the anomaly is approximately 4 per 1,000 unilateral neck dissections. The venous duplication is at a variable height, affecting the superior part of the IJV. The lateral branch of the accessory nerve (XI) always passes medially to the anterior vein and laterally to the posterior vein, between the venous duplication. This is most often unilateral but sometimes bilateral. The IJV may be normal, dilated or ectatic. The discovery of this anatomical variation has practical implications during cervical lymph node clearance, either functional or radical, during oncological surgery necessitating viewing the IJV and its affluents and the lateral branch of the accessory nerve. The embryological explanation suggests a topographical ''conflict'' between the development of the IJV and the lateral branch of the accessory nerve. The French version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer LINK server located at http://dx.Duplication haute de la veine jugulaire interne: pre´valence, clinique chez l'adulte et conse´quences chirurgicales, a`propos des 3 cas cliniques Re´sume´La duplication de la veine jugulaire interne (VJI) est une malformation rare. Trois observations per-ope´ratoires sont rapporte´es. Dans notre expe´rience personnelle, l'incidence clinique de cette anomalie est approximativement de 4 pour 1000 dissections cervicales unilate´rales. La duplication veineuse est de hauteur variable, touchant la partie supe´rieure de la VJI. La branche late´rale du nerf accessoire (XI) passe toujours me´dialement a`la veine ante´rieure, late´ralement a`la veine poste´rieure, a`travers la duplication veineuse. Celle-ci est le plus souvent unilate´rale, parfois bilate´rale. La VJI peut eˆtre normale, dilate´e ou phle´bectasique. La de´couverte de cette variation anatomique a des implications pratiques lors des curages cellulo-ganglionnaires cervicaux, fonctionnels ou radicaux a`vise´e carcinologique, imposant le repe´rage de la VJI, de ses affluents et de la branche late´rale du nerf accessoire. L'explication embryologique privile´gie un «conflit» topographique de de´veloppement de la VJI et de la branche late´rale du XI.

This study determined the prevalence and specific anatomic types of disc displacement in asymptomatic versus symptomatic subjects using magnetic resonance imaging (MRI). A detailed MRI assessment was performed on both temporomandibular joints (TMJ) in 76 volunteers and 102 successive patients. Attention was placed on the functional aspects of disc displacement with and without reduction and on the anatomic aspects of disc displacement in the anterior, lateral, medial, anterolateral, and anteromedial directions. These assessments were made by radiologists blinded to the clinical information. Disc displacement was found in at least one joint in 25 of 76 (33%) of asymptomatic subjects and 79 of 102 (77%) of symptomatic subjects. The anatomic types of disc displacement between groups was not statistically significant (P = .55). However, there was a significant difference between asymptomatic and symptomatic subjects, with an odds ratio of 3.91 for disc displacement with reduction and 42.71 for disc displacement without reduction (P < .001). Although there was a 33% prevalence of disc displacement in asymptomatic volunteers, there was a highly significant difference in the prevalence of internal derangement in symptomatic subjects. Bruxing was statistically linked to TMJ disc displacement and could explain the anatomic variation in abnormal disc position.

Endoscopic endonasal surgery has been performed in children. Therefore, we need to know the precise anatomy and anatomic variations of the lateral nasal wall. This is important in order to achieve better surgical results and avoid complications. We also need to know the relationship between the anatomic variations and sinonasal disease. For the purpose of this study we assessed the anatomic variations of the lateral nasal wall and the association of these variations with chronic sinusitis in children. Forty-seven children with chronic sinus disease were included in the study. There were 25 female and 22 male patients with ages ranging from 2 to 16 years (mean 10.5+/-3.8 years). On coronal and axial computed tomographic (CT) scans, the anatomic variations of the lateral nasal wall and sinusitis were assessed. A pneumatized middle concha (MC) was the most common anatomic variation, followed by pneumatization of the superior concha (SC), Haller cell and agger nasi cell. Secondary MC, l...

Our objective was to document variations in the topography of pelvic floor nerves (PFN) and describe a nerve-free zone adjacent to the sacrospinous ligament (SSL). Pelvic floor dissections were performed on 15 female cadavers. The course of the PFN was described in relation to the ischial spine (IS) and the SSL. The pudendal nerve (PN) passed medial to the IS and posterior to the SSL at a mean distance of 0.6 cm (SD=±0.4) in 80% of cadavers. In 40% of cadavers, an inferior rectal nerve (IRN) variant pierced the SSL at a distance of 1.9 cm (SD=±0.7) medial to the IS. The levator ani nerve (LAN), coursed over the superior surface of the SSL-coccygeus muscle complex at a mean distance of 2.5 cm (SD=±0.7) medial to the IS. Anatomic variations were found which challenge the classic description of PFN. A nerve-free zone is situated in the medial third of the SSL.

In this study a morphological and anatomical variation analysis was carried out with leaves and fruits of Sechium edule, collected in the central region of Veracruz, Mexico. The collected fruits were classified in eight groups according to their typical characteristics. The results showed that the phenotypical distinction of the studied infraspecific S. edule complex is related to morphological and anatomical changes in order to improve the adaptive specialization of the different chayote types with respect to the environment, and suggests that cultivated chayotes have followed different routes in the process of coevolution with man, showing stable variation patterns in the so-called ''green'' and ''yellow'' groups. Considering the phenotypic variability existing in the analyzed characters, a certain prediction may be proposed about the direction the variation patterns may follow facing the transference of chayotes to environments of lower altitudes than mountain cloud forest.

Chronic rhinosinusitis endoscopic surgery requires an accurate evaluation of diseases and paranasal sinus anatomic variations. This study aims to show the main anatomical variations in the ostiomeatal complex and paranasal sinuses which are usually depicted by computed tomography (CT). CT scans obtained 2 mm thickness in axial and coronal plane from a series of 200 patients with chronic sinusitis were examined to determine the prevalence of anatomic variants. Anatomical variations determined were supraorbital recess in 6%, concha bullosa in 30%, sphenomaxillary plate in 17%, infra-orbital ethmoid cells (Haller's cells) in 6%, spheno-ethmoid cells (Onodi's cells) in 12%, pneumatization of the anterior clinoid process in 6%, carotid artery bulging into the sphenoid sinus in 8%, pneumatization of the uncinate process in 2%, paradoxical curvature of the middle turbinate in 3% and septal deviation in 36%. Level difference between the ethmoid roof and nasal vault was an average of 8 mm in right side and 9.5 mm in left side. Awareness of these different variations will help the rhinologic surgeon in his orientation during endoscopic surgical procedures.

Impingement by the distal fascicle of the anterior inferior tibiofibular ligament (AITFL) is a relatively new entity among the known causes of anterolateral impingement syndromes of the ankle. This study investigated the anatomy of the anterior inferior tibiofibular ligament and its possible role in talar impingement in 47 ankles of 27 cadavers. The length, width, insertion point to the fibula and the interactions with talus were noted, as was the relationship of the fascicle and talus during different ankle movements before and after incision of the lateral ligaments. A distal fascicle of the AITFL was found in 39 of the 47 ankles (83%) and appeared as a single-complete ligament in the remaining 8 ankles (17%). The fascicle averaged 16.1±2.94 mm in length (range 10–21) and 4.2±1.00 mm in width (range, 3–7). The insertion point of the fascicle on the fibula averaged 10.3±2.27 mm (5–13) distal to the joint level. Contact between the ligament and the lateral dome of the talus was observed in 42 specimens (89.3%). Bending of the fascicle was observed in 8 of these 42 ankles with forced dorsiflexion. These 8 specimens were significantly wider and longer than the specimens without bending of the fascicle. Incision of the anterior talofibular ligament led to bending in dorsiflexion in additional 11 ankles. The total 19 fascicles with bending after incision of the anterior talofibular ligament were significantly longer and inserted more distally than the remaining 20 fascisles without bending. Manual traction simulating distraction during arthroscopic procedures relieved the contact. These findings show that the presence of the distal fascicle of the AITFL and its contact with the talus is a normal finding. However, it may become pathological due to anatomical variations and/or instability of the ankle resulting from torn lateral ligaments. When observed during an ankle arthroscopy, the surgeon should look for the criteria described in the present study to decide whether it is pathological and needs to be resected.

A mandibular first molar with more than four canals is an interesting example of anatomic variations, especially when four of these canals are located in distal roots. This report describes a case of a mandibular first molar with six canals (two mesial and four distal canals in two distal roots). The canals were equipped with a K-file and irrigated with NaOCl (5.25%) and normal saline as the final irrigant. The canals were filled laterally with gutta percha and AH26 sealer (De Trey, Dentsply, Switzerland). This case shows a rare anatomic configuration and points out the importance of looking for additional canals. (J Endod 2007;33:1481-1483

The course of the internal carotid artery (ICA), particularly the C4 -C6 segments, cavernous, clinoid, and ophthalmic, respectively, as described by Bouthillier et al. traverses a relatively compact region of complex anatomical relationships. The bony, dural, connective tissue, and neurovascular elements of this region frequently deter access or ''block'' surgical entry. The key to unlocking this region is a detailed understanding of its surgical anatomy. The treatment of aneurysms in proximity to the distal dural ring (DDR), e.g. clinoid, superior hypophyseal, or carotid ophthalmic aneurysms, presents considerable challenges to the neurosurgeon. The anterior clinoid process (ACP) and its associated anatomical variations, including a prominent middle clinoid process (MCP) and aerated optic strut, must be considered and anticipated when performing an anterior clinoidectomy. Aneurysms of the C4 -C6 segments can transgress either the proximal or distal dural rings or both; this transgression (so-called transitional aneurysms) can occur in either direction making an extradural aneurysm and also intradural or vice versa. The existence of a carotid cave as originally described by Kobayashi et al. must be taken into consideration in the analysis of aneurysms of the ICA in proximity to the DDR. Again, determination of the relationship of the aneurysm to the DDR is critical to the decision making process; extradural aneurysms have a considerably different prognosis and treatment than intradural aneurysms. The correlation of cadaveric anatomy to surgical anatomy will serve as a guide to improve surgical techniques, strategies, and outcome. D

Pulsatile blood flow in the cerebral circulation is simulated using a nonlinear, one-dimensional model of the arterial haemodynamics coupled in the time domain with lumped parameter and flow auto-regulation models of the perfusion of the microcirculation. A linear analysis of the coupling shows that a resistance equal to the characteristic impedance of the blood vessel is required at the inflow of a terminal windkessel model to avoid the generation of non-physiological wave reflections. The cerebral model suggests that the worst anatomical variation of the circle of Willis in terms of restoring normal cerebral flows after a sudden carotid occlusion is a circle without the first segment of the contralateral anterior cerebral artery.

The knowledge of root canal morphology and the existing anatomical variations is essential for successful endodontic therapy. This report presents an extraordinary case of unusual tooth morphology involving the bilateral existence of 7 maxillary and mandibular first and second molars with a single root and a single canal in a patient. Endodontic retreatment of the affected teeth #15, #19, and #18 was performed. Cone-beam computed tomography (CBCT) images confirmed our diagnostic and therapeutic measures after endodontic management of the teeth. This morphologic variation has not been reported in the literature. The availability of 3-dimensional images further provided the opportunity for the precise description of the anatomy of 7 maxillary and mandibular molars with single roots and single canals.

The aim of this study was to identify and to classify anatomical hepatic artery (HA) variations concerning 932 HA dissections in liver transplantation (LT). Normal HA distribution was found in 68.1%. Variations of HA were detected in 31.9% and were divided into three groups describing 48 common hepatic artery (CHA) anomalies, 236 left or right hepatic artery (RHA) anomalies and 13 rare variations including one case of RHA stemmed from the inferior mesenteric artery and one case of normal CHA passed behind the portal vein. The authors propose a modified classification for HA anomalies which are based on the origin of the hepatic arterial supply (either by the CHA as the only source of the arterial vascularization or by additional or replaced right and left arteries) in order to improve management of liver disease thus as in LT.

Background Sacral approach to epidural space produces reliable and eVective block of sacral nerves. It is necessary to have a detailed knowledge of sacral hiatus (SH) for optimal access into sacral epidural space. This study was undertaken to evaluate various landmarks of SH. Methods One hundred and fourteen adult dry human sacral bones were examined for morphometric analysis using vernier caliper. SH was categorized on the basis of shape. Results Most commonly encountered shape of hiatus was inverted U (40.35%). Its apex and base were most commonly observed against fourth and Wfth sacral vertebrae, respectively. Various defects in dorsal wall of sacral canal were recorded. Height and anteroposterior depth at the apex of hiatus were ranged 4.30-38.60 and 1.90-10.40 mm, respectively. Mean intercornual distance at base was 11.95 § 2.78 mm. The triangle formed by right and left posterior superior iliac spines and apex of SH was found equilateral in 45% cases only. Sacral cornua were marked by their bilateral presence in 55.26% and impalpable in 21.05% cases. Minimum distance between S2 and apex was 7.25 mm which suggested that it would not be safe to push the needle beyond 7 mm into sacral canal so as to avoid dural puncture. In 8.77% cases, depth of hiatus was less than 3 mm. Conclusions Single bony landmark may not help in locating SH because of anatomical variations. Depth of hiatus less than 3 mm may be one of the causes for failure of needle insertion. Surrounding bony irregularities, diVerent shapes of hiatus and defects in dorsal wall of sacral canal should be taken into consideration before undertaking caudal epidural block so as to avoid its failure.

Objectives: to investigate the incidence, clinical significance, anatomical variation and physiology of non-saphenofemoral venous reflux (non-SF reflux) in the groin. Design: prospective study. Materials: a total of 1072 vascular diagnostic workups in 680 patients with possible venous diseases to the legs were included. Methods: duplex scanning and air plethysmography. Results: a total of 1022 legs had venous diseases. Of these, 101 (9.9%) had non-SF reflux in the groin. Such reflux occurred in recurrent varicose veins (RVV) in 16.3%, in primary varicose veins (PVV) in 6.1% and in deep venous thrombosis (DVT) in 8.0%. Two patterns of reflux were distinguished: epigastric reflux from lower abdominal wall veins (71 legs) and pudendal reflux from perineal and/or gluteal veins (30 legs). Pudendal reflux was almost exclusive to women and did not occur with DVT. If there was only non-SF reflux at the groin the venous filling indices (VFI) were close to normal (1.7±1.0 ml/s for RVV, 1.9±1.2 for PVV, 1.7±1.0 for DVT) and no active ulcers were observed. However, if non-SF reflux was associated with saphenofemoral or other reflux the VFIs (3.3±2.3 ml/s for RVV, 3.8±1.5 ml/s for PVV) were abnormal (p<0.05) and ulcers occurred in 11/32. Conclusion: non-SF reflux in the groin is common. Such reflux may be missed at initial surgery and lead to recurrence of varicose veins. However, the venous physiological disturbance of such reflux is mild and it is not associated with ulcers unless combined with reflux at other sites in the leg.

The anatomic variations and the degenerative changes in the collateral cartilages and middle and distal phalanges in 6 Ardenner colts were characterized by radiography, scintigraphy, and magnetic resonance imaging (MRI). The radiographic changes were assessed between the ages of 16.5 and 25 months. An anatomic variation of the middle and distal phalanges was demonstrated in some of the colts. MRI examination of the 6 colts revealed an association between the deep digital flexor tendon cross-sectional area and body weight as well as foot circumference. Also, a thin collateral sesamoidean (suspensory navicular) ligament was observed subjectively. The presence of an extensive ossification of the collateral cartilages of the foot was found in these young horses. The ossification was characterized by the existence of 2 separate ossification centers, which had a tendency to unite. The radiographic interphalangeal degenerative lesions seen appear as bone remodeling of the dorsal edges of the middle and distal phalanx, on the insertion sites of collateral ligaments of the distal interphalangeal joint, the digital extensor tendon, and the distal interphalangeal joint capsule.

Objective: This study aims to determine the types and prevalence rates of anatomic variations of the hepatic veins, portal vein, inferior vena cava and renal veins, and to establish statistical correlations between various anomalies and frequency differences between male and female using multi-detector row computed tomography (CT). Materials and methods: One thousand one hundred and twenty patients (588 men, 532 women) were evaluated with routine abdominal CT. Frequencies of different variants were noted and compared, and correlations between three categories of variation were tested. Results: In total, 1261 abdominal vein variants and anomalies were identified in 756 (67.5%) of 1120 patients. Six hundred and forty-two hepatic vein variants were detected in 468 (41.8%) patients. One or more inferior right hepatic veins were identified in 356 (31.8%) individuals, and tributary hepatic veins were detected in 147 (13.1%) patients. Portal vein variations and anomalies were observed in 307 (27.4%) cases. The most frequent of these was trifurcation (139 patients, 12.4%). A total of 311 inferior vena cava and renal vein variants were identified in 258 (23%) cases. Six patients (0.5%) exhibited inferior vena cava anomalies, 62 (5.5%) had circumaortic renal veins, 53 (4.7%) had retroaortic renal veins, and 210 (18.8%) had multiple renal veins. Conclusion: The prevalence of abdominal vein variations is high, and routine abdominal CT demonstrates these abnormalities very well. The data suggest that hepatic vein variants and multiple right renal veins are more frequent in women than in men, and that hepatic vein variation is correlated with portal vein variation.

Background In most references to the nasal anatomy, the shape of the lower lateral cartilage (LLC) is described as a two-dimensional structure. However, the authors have found different forms of LLC in at least 40% of their open rhinoplasty cases during the past 20 years. This cartilage was found to have a three-dimensional hemispheric appearance and to be connected to the upper lateral cartilage (ULC) at the scroll area by an inward limb of this hemisphere. This inward limb may have an important role in producing asymmetry and flare of the nostril. Methods The LLC of 286 patients was evaluated during open rhinoplasty over a 2-year period, with a focus mainly on the shape of this structure, especially at the LLC–ULC junction (scroll area). Results A dome-shaped appearance of the LLC was noted in 40.9% of cases, and 11.5% of cases had bilateral LLC variation. This different anatomic form was seen mostly in patients with a strong bulbous nasal tip, although it was observed less frequently also in patients with narrow nasal tips. Conclusion At least one-third of the LLCs analyzed had a medial wall in addition to the lateral wall, which significantly increased the flare and recoil force of this structure. This makes this cartilage more redundant to reshaping procedures (straightening). Thus, special attention must sometimes be paid to this common anatomic variation to produce symmetric nostrils and to obtain a more aesthetically acceptable alar tip.

Background: Pyloric atresia (PA) is a rare pathology. Calder presented the first pyloric atresia case in 1749 and Touroff, Sussman, Meltz, and their colleagues presented the first successful operation in 1940. PA has 3 types of anatomic variations: (1) type A, pyloric membrane or web; (2) type B, the pyloric channel is a solid cord; and (3) type C, in which there is a gap between the stomach and duodenum. Associated anomalies also have been described. Epidermolysis bullosa (EB) and intestinal anomalies occur most often with this condition. Methods: Charts of 16 cases of congenital PA, aged 1 to 30 days and admitted to our department between 1986 and 2001, were studied retrospectively in regard to sex, prenatal diagnosis, presence of polyhydramnios, time of admission, pathology, type of operation, associated anomalies, and mortality rate.

The zygomatic nerve may be disrupted when elevating periorbita from the lateral wall during orbital surgery, and care should be taken to prevent injury to this nerve during lateral orbitotomy approaches to access intraorbital soft-tissue tumors. Furthermore, the precise introduction of anesthetics to the zygomaticoorbital (ZO), zygomaticofacial (ZF) and zygomaticotemporal (ZT) foramina could be important data for the plastic and reconstructive surgeon operating in the area. The aim of the present study was to investigate the morphologic and topographic anatomy, and variations of the ZO, ZF and ZT. The present study was performed using 200 dry human skulls. The ZF, ZO and ZT foramina varied from being absent to as many as four small openings. We classified each of these foramina as types I-V for single, double, triple, quadruple and absent foramina, respectively. The relative frequency was as follows: type I, ZO 50%, ZF 40%, ZT 30%; type II, ZO 20%, ZF 15%, ZT 15%; type III, ZO 10%, ZF 5%, ZT 5%; type IV, ZO 3%, ZF 1%, ZT-; and type V, ZO 17%, ZF 39%, ZT 50%. A detailed knowledge of the anatomic morphometry of this area is necessary for a surgeon when performing maxillofacial surgery and regional block anesthesia. Anatomic variations in this area may be present and a surgeon must take this into consideration so as to increase surgical success.

Purpose: The aim of this study was to select patients with heart anatomy that is specifically unfavorable for tangential irradiation in whole-breast radiotherapy (WBRT), to be used as an experimental cohort to compare cardiac dosimetric and radiobiological parameters of three-dimensional conformal external beam accelerated partial breast irradiation (3D-CRT APBI) to WBRT with techniques as defined by the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-39/Radiation Therapy Oncology Group (RTOG) 0413 clinical trial. Methods and Materials: A dosimetric modeling study that compared WBRT and 3D-CRT APBI was performed on CT planning data from 8 patients with left-sided breast cancer. Highly unfavorable cardiac anatomy was defined by the measured contact of the myocardium with the anterior chest wall in the axial and para-sagittal planes. Treatment plans of WBRT and 3D-CRT APBI were generated for each patient in accordance with NSABP B-39/RTOG 0413 protocol. Dose-volume relationships of the heart, including the V 5 min (minimum dose delivered to 5% of the cardiac volume), biological effective dose (BED) of the V 5 min, and normal tissue complication probability (NTCP) were analyzed and compared. Results: Despite expected anatomic variation, significantly large differences were found favoring 3D-CRT APBI in cumulative dose-volume histograms (p < 0.01), dose to the entire heart (mean difference 3.85 Gy, p < 0.01), NTCP (median difference, 1.00 Gy; p < 0.01), V 5 min (mean difference, 24.53 Gy; p < 0.01), and proportional reduction in radiobiological effect on the V 5 min (85%, p < 0.01). Conclusions: Use of 3D-CRT APBI can demonstrate improved sparing of the heart in select patients with highly unfavorable cardiac anatomy for WBRT, and may result in reduced risk of cardiac morbidity and mortality.

In modern surgical and transplantation procedures the recognition of anatomic vascular abnormalities of the hepatic arteries is of greater importance than ever. The purpose of this study was to evaluate and classify these variations with respect to their impact on visceral surgery. A total of 604 selective celiac and superior mesenteric angiographies performed on patients with known or suspected liver cirrhosis or hepatic or pancreatic malignancies and on donors of partial liver grafts were analyzed retrospectively. The vascular anatomy of the liver was classified according to different established systems and with particular attention to rare variations. Hepatic arterial anatomy as considered normal in textbook descriptions was found in 79.1%, an aberrant or accessory left hepatic artery (LHA) arising from the left gastric artery in 3.0% and an aberrant or accessory right hepatic artery (RHA) branching off the superior mesenteric artery in 11.9% of the cases. In 1.4% of the cases there was a combination of anomalies of both the LHA and RHA. Variants of the celiac trunk, double hepatic arteries branching at the celiac trunk or hepatic arteries arising directly from the aorta, occurred in 4.1% of the cases. Further atypical branches of the LHA and RHA were found in 0.5% of the cases. Since the incidence and pattern of different types of hepatic arterial anatomy can require specialized preoperative diagnostic as well as intraoperative strategies, knowledge of these abnormalities and their frequency is of major importance for the surgeon as well as the radiologist.

Background: The anterolateral thigh (ALT) flap has become increasingly popular due to its versatility and minimal donor site morbidity. Its major limitation has been uncertainty in predicting perforator anatomy, with the occasional absence of suitable perforators and high variability in their size and course. The variability of this anatomy has not been adequately explored previously. Methods: A cadaveric study was undertaken, in which 19 thighs (from 10 fresh cadavers) underwent contrast injection and angiographic imaging. Anatomical variations of the vasculature were recorded. A clinical study of 44 patients undergoing ALT flap reconstruction was also undertaken. Perforator anatomy was described in the first 32 patients, and the subsequent 12 patients underwent computed tomography angiography with a view to predicting individual anatomy and improving operative outcome. Results: Cadaver angiography was able to highlight and classify the variations in arterial anatomy, with four patterns observed and marked variability between cases. In 32 patients undergoing ALT flaps without preoperative CT angiography (CTA), five patients (16%) did not have any suitable perforators from the descending branch of the lateral circumflex femoral artery. By selecting the limb of choice with preoperative CTA, the incidence of flap unsuitability was reduced to 0%. Comparing CTA with Doppler, CTA was more accurate (sensitivity 100%) and provided more information. Conclusion: The perforators supplying the ALT flap show significant variability in location and course, with the potential for unsuitable perforators limiting flap success. Preoperative CTA can demonstrate the vascular anatomy and can aid perforator selection and operative success.

Cardiac SPECT images are degraded by photons scattered in the thorax. Accurate correction for scatter is complicated by the nonuniform density and varied sizes of thoraxes and by the additional attenuation and scatter caused by female patients' breasts. Monte Carlo simulation is a general and accurate method for detailed modeling of scatter. Hence, for 99m Tc we compared statistical reconstruction based on Monte Carlo modeling of scatter with statistical reconstruction that incorporates the more commonly used triple-energy-window scatter correction. Both of these scatter correction methods were used in conjunction with attenuation correction and resolution recovery. Methods: Simultaneous attenuation, detector response, and Monte Carlo-based scatter correction were implemented via the dual-matrix orderedsubset expectation maximization algorithm with a Monte Carlo simulator as part of the forward projector (ADS-MC). ADS-MC was compared to (i) ordered-subset expectation maximization with attenuation correction and with detector response modeling (AD); (ii) like (i) but with scatter correction added using the tripleenergy-window method (ADS-TEW). A dual-detector SPECT system equipped with 2 153 Gd scanning line sources was used for acquiring 99m Tc emission data and attenuation maps. Four clinically realistic phantom configurations (a large thorax and a small thorax, each with and without breasts) with a cardiac insert containing 2 cold defects were used to evaluate the proposed reconstruction algorithms. In these phantom configurations, we compared the performance of the algorithms in terms of noise properties, contrast-to-noise ratios, contrast separability of cold defects, and robustness to anatomic variation. Results: Noise was found to be approximately 14% lower in the ADS-MC images than in the ADS-TEW and AD images. Typically, the contrast obtained with the ADS-MC algorithm was 10%-20% higher than that obtained with the other 2 methods. Furthermore, compared with the other 2 algorithms, the ADS-MC method was less sensitive to anatomic variations. Conclusion: Our results indicate that the imaging performance of 99m Tc SPECT can be improved more by Monte Carlo-based scatter correction than by window-based scatter correction.

Purpose: Congenital anomaly of the carotid artery is a rare abnormality. It is usually discovered incidentally by color Doppler carotid sonography, angiography, computed tomography (CT), or magnetic resonance imaging (MRI) of the head and neck taken for some other reason. Most patients are not symptomatic because of sufficient cerebral circulation supplied to the defective area by the communicating arteries of the circle of Willis, intercavernous anastomosis, communicating arteries from external carotid artery, and by persistent embryologic arteries to the carotid artery territory. However, sometimes, this anatomic variation may eventually lead to some clinical signs and symptoms in particular circumstances in the head and neck of which surgeons are unaware. A retrospective study was designed to emphasize the characteristic radiologic and clinical picture in patients with the congenital absence (agenesis and aplasia) or hypoplasia of the carotid artery, to delineate the associated abnormalities and existing collateral vessels, and to find out its incidence. Material and Methods: Five thousand one hundred cerebral MRI and/or catheter angiograms performed between February 1988 and March 2002 were reviewed for carotid artery abnormality. Results: Seven patients with congenital absence or hypoplasia (4 of these patients were presented with hypoplasia of internal carotid artery [ICA], 3 with absence of ICA) of ICA were identified (0.13%). The radiologic and clinical study of 5 patients with unilateral (3 of these patients were presented with hypoplasia and 2 with absence of ICA) and 2 patients with bilateral (1 was presented with absence of ICA, whereas the other was hypoplasia) congenital abnormality with absence or hypoplasia of ICA demonstrate that those patients are usually asymptomatic and they are diagnosed incidentally. Conclusion: It has been concluded that the combined use of magnetic resonance angiography and CT scanning of the skull base may disclose small but patent ICA. Collateral vessels seem to be usual in such cases, but they may be prominent in cases of acquired vascular occlusion, or increased hemodynamic pressure in dysplastic changes in collateral arteries are known causes of aneurysms. The main vascular supply for the brain in patients with congenitally small (hypoplasia) or absent (agenesis or aplasia) ICA is the vertebrobasilar system in bilateral cases. However, contralateral carotid vessel is the dominant arterial supply for unilateral cases, which has to be borne in mind in surgical interventions to the involved side. (Am J Otolaryngol 2004;25:339-349.

The Crustacea contain an amazing, and often (to humans) bizarre, array of visual designs. This diversity includes many different examples of both simple and compound eyes, each with standard or uniquely crustacean features. In this review, we focus on the anatomical variation, optical principles, and molecular diversity of crustacean compound eyes to illustrate how the complicated structures involved in vision are adapted for particular environments. Using this knowledge as a starting point, and considering what is known of crustacean evolution overall, we present the most recent ideas of how crustacean compound eyes have evolved and show how eyes that are based on fundamentally different optical principles can in fact be derived from each other and thus be closely related through common descent.

The location of lateral femoral cutaneous nerve (LFCN) in relation to the anterior superior iliac spine (ASIS) and the iliac crest was investigated in 96 embalmed cadaveric specimens. Fifty-six nerves (58.3%) passed medial to the ASIS. Twenty-two nerves (22.9%) passed at the ASIS. Eighteen nerves (18.8%) passed lateral to the ASIS. The LFCN is usually located at 2.1 ± 0.8 to 3.9 ± 1.0 cm below the crest in the range of 2-5 cm lateral to the ASIS, respectively. When the anterior iliac crest bone graft harvesting is planned, the anatomical variation in this area should be concerned to reduce the risk of LFCN injury.

In 1817, the denominated conduct of Serres was described as a formation that was highly prevalent in children's jaws, but considered as an anatomical variation in adults. In this study we analyze the presence of the denominated Serres´-conduct in 324 jaws belonging to the collection of the Universidade Federal de São Paulo (UNIFESP), with sex and age registration, 68 subadults of age between 0 and 2 years and 256 adults of age between 18 and 100 years. We found that the prevalence was in order to 100% in the subadults group and 42.6% in the adults group. In adults, the prevalence of this anatomical structure was greater in women than in men, with a difference statistically significant for the variable sex (Chi2 = 0.0148; I.C 95%=0.29-0.91; O.R. =0.51). According to the age, the biggest prevalence was in the fourth decade of the life, not being of any statistical significance for this variable. Based on the opposing evidence, this article discusses the character of anatomical variation of this formation and based on the anatomical terminology, intending to denominate the paramandibular canal.

Purpose To study the morphology of the gyri and sulci of the insular region. Materials and methods This study examined 20 formalinfixed cerebral hemispheres (10 right and 10 left). Observations described: the peri-insular sulci, anatomical variations in the insular sulci and gyri, and the relationships between the central insular sulcus and the central cerebral sulcus and the anatomy of the insular arteries. Results Each insula had a trapezoid shape, surrounded by four peri-insular sulci (anterior, superior, posterior, and inferior). We differentiated the posterior peri-insular sulcus from the inferior peri-insular sulcus. These two sulci have two different axes separated by a clear angle. The central insular sulcus divides the insula into two parts. The anterior insula includes three short gyri and the anterior insular pole. The posterior insula includes two long gyri and the posterior insular pole. This structure defines two intrainsular opercula. In 60% of cases, the superior extremity of the central insular sulcus is in direct continuity with the inferior extremity of the cerebral central sulcus. The superior branch of the middle cerebral artery supplies the majority of the anterior insular gyri, and the inferior branch supplies the majority of the posterior insular gyri. Conclusions This study details the morphology of each insular structure (gyri, sulci and poles), data which could facilitate surgical access to this deep cortical area and assist in future work correlating anatomy with function.

Background and aims Recognition of variations of the inferior laryngeal nerve is essential. We aimed to investigate the relationship of the inferior laryngeal nerve with the inferior thyroid artery. Materials and methods A study was undertaken between August 2005 and August 2006. A total of 253 adult patients undergoing thyroid surgery were included in this prospective, non-randomized study. Both sides of the thyroid gland were considered separately. Results Sixteen variations of the nerve were clarified. In the most observed variation, the nerve was deep to the artery. Two and three nervous branches were seen in 22.5% and 1.6% of the patients, respectively. Bifurcation of the nerve was mostly observed on the left side. No non-recurrent laryngeal nerve was found. Conclusion To avoid the risk of nerve damage during thyroid surgery, a good knowledge of the variations of the inferior laryngeal nerve is essential. This is important to achieve an undisturbed quality of life for the thyroid patient.