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PubMed2004

[Anatomical variations of vermiform appendix].

Vermiform appendix (VA) is characterized by great variability of its location and morphology. Acute inflammatory changes are the most frequent cause of surgical abdominal interventions. Inflammation of atypically located VA may imitate inflammation of other organs, which leads to diagnostic errors. Based on anatomical and clinical data, especially those concerning location variability, different anatomical variations of VA are presented.

Appendectomy↗
PubMed2005

A biomechanical model for size, speed and anatomical variations of the energetic costs of running mammals.

Here we propose a model of energetic costs and the muscle-tendon unit function on running mammals. The main goal is to set a simple theoretical framework which gives an understanding of the biomechanical principles behind the size, speed and anatomical variations of the energetic costs of running mammals. The model is a point-like mass withstood by a two-segment leg with an extensor muscle serially attached to a tendon. We considered withstanding body weight during the stance phase as the main role of the muscle-tendon unit during fast locomotion. The ground reaction force dependence on speed and the time of stance phase as well as other biomechanical characteristics were taken from previous empirical studies of running. At the same time, the morphological variations with body mass were taken from empirically well-established allometric equations for mammals. The metabolic cost was estimated from an empirical equation relating metabolic power with muscular force and speed in shortening and stretching. Our model predicts the pattern of mass specific metabolic rate variations with both speed and body mass. It also gives an explanation of the experimentally reported linear inverse relationship between the rate of energy used for running and the time of application of force by the foot to the ground during each stride. It also suggests an explanation of the unusual energy saving adaptations of large macropodids. It provides some predictions on the relationship, between energy costs and muscle-tendon unit characteristics, testable on further experiments.

Animals↗
PubMed1981

Supernumerary extensor tendon to the thumb: a report on a rare anatomic variation.

A supernumerary extensor tendon to the left thumb was observed in a black female cadaver. It came from a bipinnate extensor indicis proprius and passed through the fourth synovial compartment, where it fused with the extensor pollicis longus at the midshaft level of the first metacarpal. This appears to be a rare anatomic variation. Since the review of LeDouble in 1897, only two cases have been reported. A reminder of this oddity at this time seems appropriate because of its perceivable clinical significance.

Female↗
PubMedDate not supplied

The internal acoustic meatus. Anatomic variations and relations to other temporal bone structures.

The internal acoustic meatus was evaluated in 97 temporal bone specimens, half of which were radiographed in different projections. Part of the material was also examined by multidirectional and computed tomography. Casts of the specimens were prepared and the meatuses were measured in different planes. The anatomic variations, especially in the transverse plane, and their relations to other structures in the petrous bone, were assessed. The meatus varied in shape, being mainly either long and thin, short and broad, funnel-shaped or pear-shaped. The pear-shaped meatus was practically always broad. The angle formed by the long axis of the meatus and the posterior wall of the pyramid varied inversely with the meatal length, a long meatus forming a small angle and vice versa. Large anteroposterior diameters were correlated to large meatal angles, but there was no direct correlation between meatal length and width. In addition, the meatal length was correlated to the perilabyrinthine and mastoid pneumatization and also to the dimensions of the pyramid.

Humans↗
PubMed1985

Anatomic variations in the motor and sensory supply of the thumb.

Variations in the motor and sensory nerve supply to the thumb exist despite stereotyped descriptions in modern anatomy texts. A careful dissection of ten specimens under high magnification has been made with special reference to the nature and incidence of anatomic variations. Transligamentous passage of the recurrent motor branch of the median nerve was noted in six dissections; two of these included multiple motor branches to the thenar musculature. The Riche-Cannieu anastamosis was observed in three specimens. Variations in the branch pattern of the median nerve fibers supplying sensation to the thenar eminance and palmar thumb were also noted. No dorsal (superficial radial nerve) to palmar communications were detected, although this pattern has been described clinically. The differences give rise to an element of diagnostic uncertainty in treating the nerve-injured patient; functional deficits and therapeutic consequences are discussed in relation to the authors' observations and a review of the literature.

Humans↗
PubMed1980

Anatomic variations in the first ray: Part II. Disorders of the sesamoids.

Cadaveric and fresh amputation dissection studies revealed that condylar anomalies, metatarsal axial rotation, and bowstrung flexor tendos will commonly produce subluxation and degenerative changes at the metatarsophalangeal-sesamoid joint. The average arc of motion of the sesamoids from maximum plantar- and dorsiflexion was measured at 71.9 +/- 11 degrees. The anatomic variations presented are correlated with the incidence of chronic sesamoiditis, painful bipartite sesamoids, and chronic nonunions.

Adolescent↗
PubMed1994

The significance of anatomical variations of hepatic artery and multiple arterial supplies in embolization of liver tumors.

A new therapeutic measure-step by step-embolization of every feeding vessel in dealing with liver cancer has been proposed on the base of the following criteria after reviewing the coeliac and superior mesenteric arteriographies in 100 cases of liver cancer. The emphasis is put on: 1. Anatomic variation of hepatic arteries. 2. Multiple feeding vessels, and 3. The importance of the presence of stenosis after embolization and the formation of collateral circulation.

Adult↗
PubMed1987

The influence of temporal bone anatomical variation upon the caloric stimulus.

This study involved a comparison of temperature changes occurring in isolated cadaveric temporal bones as a result of caloric stimulation, with information gained from radiological examination of the bones by means of high resolution computed tomographic scanning. This was performed in order to investigate the complex nature of heat transfer within the temporal bone and the influence which anatomical variations may have upon the accuracy of evaluation of vestibular function by means of the caloric test. No significant correlation could be found between the maximum temperature change occurring across the lateral semicircular canal and any of the parameters obtained from radiological assessment except for the diameter of the internal auditory meatus. It was deduced that an intra-subject difference in the diameters of the internal auditory meatus of 0.5 mm would introduce an absolute error in the evaluation of percentage canal paresis of 10%. Since normal intra-subject differences in internal meatus diameter can exceed 0.5 mm, this finding was considered to be highly significant.

Caloric Tests↗
PubMed1976

[Anatomic variation of the aortic coronary openings (apropos of 80 dissections)].

A series of 80 heart dissections, compared with a survey of the literature shows that:--both coronary ostia are usually in the right anterior and in the left posterior position, in the commissural plane, at the level of the corresponding sinus of Valsalva (the left one being often superior in size to the right one).--anatomic variations of the coronary ostia (especially variations of the left coronary ostium) may be summed up into 3 patterns: Variations in number : sometimes, there is only one aortic coronary ostium, usually owing to a left coronary artery originating from the pulmonary artery; a common aortic ostium for a single coronary artery is not frequent. Multiple ostia are the most common variations : an accessory artery may arise from a separate ostium (often the "third coronary artery" from the right aortic sinus; sometimes the anterior descending and the circumflex arteries may originate from separated orifices). Variations in origin remain few, affecting most often the left ostium. Variations in size reflect the corresponding coronary plexus preponderance.

Coronary Vessel Anomalies↗
PubMed1985

[Anatomical variations in blood vessels and their effect on the technic in toe transfer].

In the absence of grasp, either traumatic or congenital, free transfer of the second toe to the hand is one of the reconstructive possibilities. An essential prerequisite for the acceptance of the transferred toe is a guaranteed blood supply through the vascular pedicle. The blood supply of the second toe can be either by dorsal or plantar arteries, a fact which is due to anatomic variations. Through preoperative angiographic examination the arterial blood supply of the second toe can be defined. The location and length of the vascular pedicle have to be considered in the design of the anastomosis with the recipient vessels of the hand.

Adolescent↗
PubMed2003

Subtle lung nodules: influence of local anatomic variations on detection.

PURPOSE: To assess the influence of local anatomic noise on the detection of subtle lung nodules depicted on chest radiographs. MATERIALS AND METHODS: Six 8 x 8-cm lung regions were extracted from digital chest radiographs obtained in healthy subjects. Simulated nodules emulating the radiographic characteristics of subtle tissue-equivalent lesions 3.2-6.4 mm in diameter (equivalent to 0.1-0.4 mm in contrast-diameter product [CD]) were added to the images. On multiple renditions of each image, nodules were inserted at slightly different locations within 6 mm of the center; this process allowed different local background patterns to overlie the nodules. An observer detection study involving 15 experienced radiologists was performed. The authors performed analysis of variance and pairwise t test analyses to determine variations in nodule detectability related to nodule location and size on each image. RESULTS: Results indicated a strong correlation between nodule size and observer detection score and significant variation in nodule detectability as a function of location. Changes in nodule position caused observer score variations that were equivalent to the variation caused by an up to 185% change in nodule CD (78% average over all six images), an up to 68% change in diameter (32% average), and an up to 28% change in area under the receiver operating characteristic curve (Az) (14% average). CONCLUSION: Local anatomic variations surrounding and overlying a subtle lung nodule on a chest radiograph that are created by the projection of anatomic features in the thorax, such as ribs and pulmonary vessels, can greatly influence the detection of nodules, altering the Az by as much as 28%.

Analysis of Variance↗
PubMedDate not supplied

Anatomical variations of the ulnar and median nerves in the upper limb.

The aim of our study was the evaluation of the anatomy of ulnar and median nerves in the upper limb in order to ameliorate knowledge on the clinical anatomy of these nerves. In fact, further information on this topic may be useful owing to its possible clinical relevance when planning surgical anatomy and reconstructive surgery in tumor affected and injured patients. The relationships between ulnar and median nerve and neighbouring anatomical structures have been examined, together with the course and ramification of the ulnar and median nerves in six fresh cadavers. Moreover, we have performed a review of the literature. Four specific aspects were evaluated during dissection: 1) division modality of the ulnar nerve at the wrist; 2) anatomical details of the medial humeral epicondyle; 3) anatomical relationships between median nerve and retinaculum flexorum; 4) median-ulnar nerves anastomosis. Our results show that: the medial humeral epicondyle shows specific anatomical details in relation to the ulnar nerve; the relationships between the median nerve and the transverse carpal ligament may be characterized by one or two nerve trunks (two cases of bifid median nerve in our experience); median-ulnar nerve anastomosis may be also found at various levels. Comparing our results with those of the available literature we can conclude that anatomical variations of ulnar and median nerve in the upper limb are not an infrequent finding and their clinical, diagnostic and surgical relevance should be considered.

Aged↗
PubMed2006

Modelling the circle of Willis to assess the effects of anatomical variations and occlusions on cerebral flows.

Blood flow in the circle of Willis (CoW) is modelled using the 1-D equations of pressure and flow wave propagation in compliant vessels. The model starts at the left ventricle and includes the largest arteries that supply the CoW. Based on published physiological data, it is able to capture the main features of pulse wave propagation along the aorta, at the brachiocephalic bifurcation and throughout the cerebral arteries. The collateral ability of the complete CoW and its most frequent anatomical variations is studied in normal conditions and after occlusion of a carotid or vertebral artery (VA). Our results suggest that the system does not require collateral pathways through the communicating arteries to adequately perfuse the brain of normal subjects. The communicating arteries become important in cases of missing or occluded vessels, the anterior communicating artery (ACoA) being a more critical collateral pathway than the posterior communicating arteries (PCoAs) if an internal carotid artery (ICA) is occluded. Occlusions of the VAs proved to be far less critical than occlusions of the ICAs. The worst scenario in terms of reduction in the mean cerebral outflows is a CoW without the first segment of an anterior cerebral artery combined with an occlusion of the contralateral ICA. Furthermore, in patients without any severe occlusion of a carotid or VA, the direction of flow measured at the communicating arteries corresponds to the side of the CoW with an absent or occluded artery. Finally, we study the effect of partial occlusions of the communicating arteries on the cerebral flows, which again confirms that the ACoA is a more important collateral pathway than the PCoAs if an ICA is occluded.

Animals↗
PubMed2002

Anatomic variations of the coracoacromial ligament in neonatal cadavers: a neonatal cadaver study.

One of the most common causes of pain and disability in the upper limb is inflammation of the rotator cuff tendons. When no significant bony abnormality exists in the surrounding structures, the coracoacromial ligament has been implicated as a possible cause of impingement on the cuff tendons and various morphological variants of the ligament have so far been claimed to be either the cause or the result of impingement. In this study, 110 shoulders from 60 neonatal cadavers that were preserved in a preparation of formaldehyde were dissected. Anatomic variations of coracoacromial ligaments were investigated with metric and histologic analysis. Three main ligament types were identified: quadrangular, broad band and U-shaped. The multiple banded ligament was not found. Histologic analysis showed that in U-shaped ligaments a thin tissue existed in the central part of the ligament close to the coracoid. Comparing our data with the adult measurements of a previous study we suggest that the primordial ligament is broad shaped, but assumes a quadrangular shape due to the different growth rates of the coracoid and acromial ends. We also suggest that broad and U-shaped ligaments account for the primordial and quadrangular and Y-shaped ligaments account for the adult types of the single or double banded anatomic variants respectively. Our results show that various types of the coracoacromial ligament are present at the neonatal period and that the final shape of the ligament should be defined by developmental factors, rather than degenerative changes.

Acromioclavicular Joint↗
PubMedDate not supplied

Anatomical variations of the lateral femoral cutaneous nerve and the consequences for surgery.

PURPOSE: This two-part study was undertaken to (a) determine the course and variations of the lateral femoral cutaneous nerve in a cadaver study and (b) develop prospectively the preoperative protocol to diminish the possibility of a postoperative meralgia paresthetica; the latter was achieved by reviewing the patient series retrospectively for complaints of a lateral femoral cutaneous nerve (LFCN) lesion and by studying the relation of the course of the LFCN and meralgia paresthetica. METHODS: Anatomical studies were performed on 200 recently deceased patients. After exploring the LFCN from its origin to the inguinal region to determine its course, we classified 149 patients as "normal" and fifty-one as abnormal. We then identified eighty-two patients who, between 1989 and 1994, experienced LFCN lesion as a complication of pelvic surgery following an ilioinguinal approach. RESULTS: Thirty-seven of these patients reported altered sensation for several years postoperatively (minimum follow-up one year), including eleven patients whose complaints persisted. In five of these cases, symptoms prompted an eventual exploration of the nerve, and nerve entrapment was confirmed. Between 1994 and 1996, perioperative care intended to lessen the chance of future LFCN problems was administered to forty patients. Thirty-three patients underwent neurolysis, and seven underwent nerve transection because an LFCN lesion occurred during the operation. Within a twelve-month follow-up period, no meralgia paresthetica was noted. CONCLUSION: The practical importance of the present study lies in alerting the surgeon to a possible anatomical variation of the LFCN in about 25 percent of the patient population. It also confirms that the new perioperative protocol lowers the incidence of meralgia paresthetica.

Acetabulum↗
PubMed1982

Iatrogenic myocardial infarction. A possible complication of mitral valve surgery related to anatomical variation of the circumflex coronary artery.

Following mitral valve replacement, a 43-year-old male presented electrocardiographic signs of myocardial ischemia-injury in the postero-inferior wall, and subsequently died. The post mortem examination revealed a subendocardial myocardial infarction in the postero-inferior wall. The myocardial infarction was related to the accidental ligation of the circumflex coronary artery by one of the sutures fixing the prosthetic valve. Technically, this surgical accident can be explained by the anomalous origin and course of the circumflex coronary artery found in this patient at the time of the post mortem examination. Anatomical variations of the coronary arteries and their surgical implications are discussed. This iatrogenic complication could have been avoided by performing a preoperative coronary angiography, which was not done in the reported case for medical reasons.

Adult↗