Oblique Course Research Articles

MRI of the female urethra and pelvic floor

— MRI is the most powerful imaging procedure to visualize the structures of the pelvic floor. We have been interested in the use of MRI towards a better understanding of the pathophysiology of genuine stress incontinence due either to anatomical malposition of the pelvic viscera or to an intrinsically damaged urethra. Axial continuous images were obtained with T2 weighted spin-echo sequence in a total of 47 patients. In stress incontinent patients the urethra was usually more distant from the pubic bone than in normal controls. The urethro-pelvic ligaments were seen to extend downward in an oblique course. The levator sling was frequently deficient, usually thin or partially replaced by fat and connective tissue. In our experience, MRI provides information about the quality of the urethral wall and the pelvic floor. It is clearly superior to other radiological methods and will likely assume an even greater role in evaluating the urethra with paraurethral area and the female pelvis.

Anatomy of the bilioduodenal junction of the opossum.

Prevention of reflux is a major function of the terminal biliary duct system at its junction with the duodenum. We examined this area via scanning electron microscopy and light microscopy to explore anatomic features that might play such a role in the Virginia opossum, a species with a highly developed sphincter of Oddi (SO). The terminal apparatus, most of which consists of a dilated extramural ampulla, has a lumen with abundant folds. Mucus is produced by the lining epithelium and by a plethora of glands. Three muscle layers constitute the SO: an inner longitudinal, an outer circular, and a less consistent outermost longitudinal. The terminal apparatus forms an acute angle and narrows as it enters the duodenum; at this point, the SO becomes continuous with the muscularis externa of the intestine. Four anatomical features with potential antireflux properties may be identified: mucus production, luminal folds, and the narrow opening and oblique course of the intramural duct.

Anatomy and relationships of the suprascapular nerve

Thirty-one shoulders in eighteen cadavera were dissected to allow study of the neurovascular anatomy of the rotator cuff and to help determine the limits of mobilization of the cuff for the repair of chronic massive retracted tears. The dissection demonstrated the diameter, length, and relationships of the suprascapular nerve and its branches and made clear the dangers of extensive mobilization and advancement of the supraspinatus and infraspinatus muscles. The suprascapular nerve ran an oblique course across the supraspinatus fossa, was relatively fixed on the floor of the fossa, and was tethered underneath the transverse scapular ligament. In twenty-six (84 per cent) of the thirty-one shoulders, there were no more than two motor branches to the supraspinatus muscle, and the first was always the larger of the two. In twenty-six (84 per cent) of the thirty-one shoulders, the first motor branch originated underneath the transverse scapular ligament or just distal to it. In one shoulder (3 per cent), the first motor branch passed over the ligament. The average distance from the origin of the long tendon of the biceps to the motor branches of the supraspinatus was three centimeters. In fifteen (48 per cent) of the thirty-one shoulders, the infraspinatus muscle had three or four motor branches of the same size. The average distance from the posterior rim of the glenoid to the motor branches of the infraspinatus muscle was two centimeters. The motor branches to the supraspinatus muscle were fewer, usually smaller, and significantly shorter than those to the infraspinatus muscle. The standard anterosuperior approach allowed only one centimeter of lateral advancement of either tendon and limited the ability of the surgeon to dissect safely beyond the neurovascular pedicle. The advancement technique of Debeyre et al., or a modification of that technique, permitted lateral advancement of each muscle of as much as three centimeters and was limited by tension in the motor branches of the suprascapular nerve. In some situations, the safe limit of advancement may be even less. We concluded that lateral advancement of the rotator cuff is limited anatomically and may place the neurovascular structures at risk.

Anatomic and experimental basis for the insertion of a screw at the first sacral vertebra

The authors present the anatomic and experimental basis of an original technique for screwing at the first sacral level employed in lumbosacral fusion. The anatomic studies were based on specimens from the anatomy museum, frozen sections of the sacrum and CT examinations with three-dimensional reconstruction and assessment of the density of the different structures of S1 in Hounsfield units (HU). The findings were that the ala and lateral portions of S1 contain yellow marrow forming what amounts to a fatty sphere bounded by the cortical bone of the sacroiliac joint, the linea terminalis and the spongy bone of the pedicles and of the body of S1. The experimental study was made by avulsion of sacral screws (system of Cotrel Dubousset), each of 7mm diameter. No screw perforated the sacral cortex. Three directions were tested. The insertion of a screw through the pedicle and body of S1 is advised, with the point of insertion below and lateral to the articular process of S1 and an oblique course forward and inward at an angle of 10 degrees to the sagittal plane. This internal obliquity is limited by the posterior prominence of the iliac ala.

Architecture of the Myosalpinx of the Isthmus in the Guinea Pig by Means of Scanning Electron Microscopy

The three-dimensional architecture of the isthmic myosalpinx in the guinea pig was investigated by means of a technique that involves stretching the myosalpinx under a dissecting microscope, followed by selective digestion of the interstitial connective tissue with KOH and, finally, observation under a scanning electron microscope. The images obtained in this way prove that the myosalpinx is arranged in single bundles of smooth muscle cells which essentially do not show any specific geometrical course. Furthermore, smooth muscle cell bundles following an oblique course, not referred in the literature prior to this report, were demonstrated. These new three-dimensional microanatomical results call for a reevaluation of the functional role of oviduct motility.

Magnetic Resonance Imaging as a Noninvasive Standard for the Quantitative Evaluation of Left Ventricular Mass, Ischemia, and Infarctiona

Because magnetic resonance imaging (MRI) acquires data in a spatially unambiguous fashion and the three-dimensional interrelationships of one image plane to another are easily ascertained, there are far fewer technical restrictions imposed on this method than on other imaging techniques. Furthermore, the multiplanar nature of MRI image acquisition, in any plane desired, is a feature unique to this imaging technology. MRI is thus well suited to the highly accurate quantification of global and regional left ventricular (LV) size and function, and can be used as a standard for comparison to other techniques, once validated. Because the determination of LV mass by MRI requires no assumptions about ventricular shape, it should be well suited to the evaluation of both normal hearts and those distorted by infarction. We performed gated MRI on 15 dogs before and after myocardial infarction. LV mass was calculated with 5 short axis planes. The correlation was excellent between actual mass before infarction and after MI. Accuracy was similar for both end-diastole and end-systole. Thus, MRI accurately determines LV mass in both distorted and normal hearts. We have also developed a method for quantification and mapping of regional wall thickening throughout the LV as an index of regional ischemia by utilizing the 3D geometry to calculate the perpendicular wall thickness of a 3D volume element of tissue. This 3D volume element results in less variability of normal wall thickening and provides a better discriminator of ischemic from nonischemic zones in a canine model of acute ischemia, whereas there is considerably greater overlap between ischemic and normal zones with standard planar MRI techniques. The 3D method is more accurate than planar methods in avoiding biases resulting from the oblique course of an image plane through the LV wall, resulting in better distinction of ischemic from nonischemic tissue. Finally, the accurate assessment of regional LV function for the identification of ischemic or infarcted myocardium has been enhanced greatly by a new technique, myocardial tissue tagging, in which an electronic marker is applied to the myocardium which persists through ejection, enabling the accurate tracking of specific areas of the heart as they move and rotate through the cardiac cycle.

The Role of Perineural Space Invasion in the Local Spread of Prostatic Adenocarcinoma

In 176 radical prostatectomy specimens areas of capsule penetration by cancer and positive surgical margins were quantified and located over the prostate surface. The presence of cancer within the perineural space was sought in these areas and compared to the normal distribution of prostatic nerve branches. Capsule penetration was found in 78 of 156 stage B carcinomas, and in 39 of these 78 (50 per cent) it occurred entirely by cancer extension through the capsule within perineural spaces. In the remaining 39 prostates capsule penetration by perineural space invasion predominated but direct spread also was found. Most often, perineural space invasion followed the oblique vertical course of nerve branches that extended superiorly to the superior pedicle near the prostate base. In such cases capsule penetration areas were localized near the superior margin of the cancer, and in 11 per cent positive superior pedicle margins resulted from continued perineural space invasion outside the capsule. In cancers near the prostate apex capsule penetration by perineural space invasion produced positive margins in 89 per cent of 18 cases because of the short inferior pedicle. The role of perineural space invasion by cancer was less prominent in 4 of 20 stage A cancers that showed capsule penetration.

Course of the recurrent laryngeal nerve relative to the tracheoesophageal plane and the axis of the trachea

AbstractAn awareness of the surgical anatomy and the possible dispositions of the recurrent laryngeal nerve (RLN) is helpful in avoiding its injury during thyroidectomy.The relationship of the RLN to the trachea and its course relative to the tracheoesophageal plane were studied in 151 patients undergoing thyroidectomy. One hundred sixty‐six (166) nerves were identified, 95 on the right and 71 on the left.Most nerves, both on the right (59%) as well as the left (53.5%), ran posterior to the tracheoesophageal plane. Most right nerves (84.2%) had an oblique course in the frontal plane as related to the tracheal axis or midline (deviation); on the left, most nerves (57.8%) showed no significant deviation. The nerves were found to course from posterior to anterior in the sagittal plane as they ascended the neck in 52.5% of cases on the right (type II obliquity), whereas on the left, 50.7% of the nerves ran in this direction. Approximately 37.2% of the nerves on the right, and 40.8%, on the left, had no obliquity in the sagittal plane paralleling the tracheal axis.

Localization of Left Free‐Wall and Posteroseptal Accessory Atrioventricular Pathways by Direct Recording of Accessory Pathway Activation

With the advent of catheter ablation techniques, precise localization of accessory AV pathways (AP) assumes greater importance. In an effort to define the course of AP fibers, we attempted to record activation of 56 left free-wall and 23 posteroseptal APs in 62 patients undergoing electrophysiological study. The coronary sinus (CS) and great cardiac vein (GCV) were mapped using orthogonal catheter electrodes, which provide a recording dipole perpendicular to the AV groove. The tricuspid annulus (TA) was mapped using a 2 mm spaced octapolar electrode catheter. Potentials were considered to represent AP activation only if they could be dissociated from both atrial and ventricular activation by programmed stimulation. Orthogonal catheter electrodes in the CS and GCV were advanced beyond the site of earliest retrograde atrial activation and/or earliest antegrade ventricular activation in 45 of the 56 left free-wall APs, and AP potentials were recorded from 42 (93%). An oblique course was identified in 36 APs, with the ventricular insertion being recorded 4-30 mm (median 15 mm) distal or anterior to the atrial insertion. In three patients, antegrade and retrograde conduction proceeded over different (but close) parallel fibers. AP potentials were recorded from 19 of 23 posteroseptal pathways. Ten pathways (left posteroseptal) were recorded from the CS, beginning 5-11 mm (median 9 mm) distal to the os, with potentials extending 8-18 mm (median 11 mm) distally. Four pathways (mid-septal) were recorded along the TA, anterior to the CS ostium and posterior to the His bundle catheter. Five pathways (right posteroseptal) were recorded along the TA, directly opposite or immediately posterior to the CS ostium. One of the patients had both midseptal and left posteroseptal pathways and three patients had both right posteroseptal and left posteroseptal pathways. We conclude: 1) left free-wall APs transit the AV groove obliquely and may be comprised of multiple, closely spaced, parallel fibers; 2) the anatomical location of "posteroseptal" pathways is variable and the presence of fibers at multiple sites is common; and 3) direct recordings of AP activation facilitate tracking of the accessory pathway along its course from atrium to ventricle and help identify the presence of multiple fibers.

Age-related changes in capillaries of rat oral mucosa. A quantitative electron microscopic study

Ultrastructural age changes in capillaries of the buccal mucosa were examined in montages of cross sections made from electron micrographs at 37 500 x. Six rats aged 6 months and 6 aged 30 months were perfused with glutaraldehyde and conventional thin sections obtained. Two capillaries located within a connective tissue papilla were studied from each rat. Capillaries of the old group differed from those of the young group by statistically significant increases in several parameters. The endothelial cell was increased in thickness, especially in the vicinity of junctions. The frequency of pinocytotic vesicles/unit length of the cell circumference was nearly doubled. Junctions were of nearly double length and took a more oblique course. All parts of the basement membranes were thickened, though perhaps less than seems true in skin. In striking contrast to epidermis, the epithelium of oral mucosa undergoes no appreciable thinning with age. We suggest that the observed age increases in frequency of pinocytotic vesicles and in the length of junctions may facilitate blood/tissue exchange, thus compensating for impaired exchange due to the thickened basement membranes. These compensatory changes in conjunction with the unchanged size of the mucosal capillary bed in the aged rat (demonstrated previously) could explain the unchanged thickness of the oral epithelium.

New catheter technique for recording left free-wall accessory atrioventricular pathway activation. Identification of pathway fiber orientation.

The ability to record accessory atrioventricular (AV) pathway activation consistently may be uniquely beneficial in improving pathway localization, identifying anatomic relations, and providing insight into unusual conduction properties. For the purpose of recording left AV accessory pathway activation, an electrode catheter was specially designed for use in the coronary sinus. The orthogonal catheter has three sets of four electrodes spaced evenly around the circumference. Electrograms were recorded at low gain (less than 1 cm/mV) between adjacent electrodes on the same set (interelectrode distance, 1.5 mm, center to center). This provides a recording dipole perpendicular to the atrioventricular groove to enhance recording of accessory pathway activation while minimizing overlapping atrial or ventricular potentials. The orthogonal electrode catheter was used in the electrophysiological study of 48 consecutive patients with 59 left AV accessory pathways. The catheter could be advanced along the coronary sinus beyond the site of earliest retrograde atrial activation in 49 of the 59 accessory pathways. Activation potentials were recorded from 45 of the 49 (92%) accessory pathways accessible to the catheter (5 of 5 anterior, 8 of 8 anterolateral, 15 of 16 lateral, 5 of 5 posterolateral, 5 of 5 posterior, and 7 of 10 posteroseptal). Accessory pathway potentials were validated by dissociating them from both atrial and ventricular activation by programmed-stimulation techniques. During surgery, accessory pathway potentials were identified from orthogonal catheter electrodes in the coronary sinus in 14 of 16 accessory pathways (12 patients). Epicardial mapping confirmed the location of the accessory pathway, and direct pressure over the orthogonal catheter electrode that recorded the accessory pathway potential resulted in transient conduction block in nine of the 14 accessory pathways. Orthogonal electrode maps of the coronary sinus identified an oblique course in 39 of 45 recorded accessory pathways. Thirty-two of 38 left free-wall accessory pathways were oriented with atrial insertion 4-30 mm (median, 14 mm) proximal (posterior) to the ventricular insertion. In the remaining six free-wall accessory pathways, the lateral excursion could not be determined because either only the atrial end of the accessory pathway was recorded or activation of multiple pathway fibers prevented tracking of individual strands. The seven recorded posteroseptal pathways exhibited accessory pathway potentials throughout an 8-18-mm (median, 10 mm) length of the proximal coronary sinus, but fiber orientation was difficult to determine.(ABSTRACT TRUNCATED AT 400 WORDS)

A potential pitfall of pelvic computed tomography.

The cross-sectional areas of the common iliac veins were measured by pelvic computed tomography (CT) in 51 patients. The left common iliac vein was significantly larger than the right (p less than 0.01) and in 35% of patients there was at least a two-fold difference between the cross-sectional areas of the veins. Recognition of this normal asymmetry is important when interpreting pelvic CT scans. It is thought to be due to the oblique course of the left common iliac vein and to partial obstruction of the left common iliac vein by the right common iliac artery.

Morphometric analysis of serotoninergic bipolar cells in the retina and its implications for retinal image processing.

The entire population of retinal serotoninergic bipolar cells in the turtle Pseudemys scripta elegans was labeled by immunocytochemical methods. This allowed a systematic analysis to be made of the morphological variabilities among a functionally homogeneous neuronal population. The analyzed morphological characteristics included: size of the Landolt club, size of the soma, lateral extension of the ramification within the outer plexiform layer, course of the axon across the inner nuclear layer, pattern of the axonal ramification within the inner plexiform layer, lateral extension of these ramifications, and density of the cells. Whereas characteristics 1-4 and 7 show a morphological variability strictly related to the location of the bipolar cell with respect to the visual streak, a fovealike structure, characteristics 5 and 6 show no such correlation. The size of the soma increases by a factor of 4 from the visual streak toward the periphery. The area covered by the ramification in the OPL increases from 330 micron 2 at the visual streak to 50,000 microns 2 at the dorsal and ventral edges of the retina. The coverage factor remains the same throughout the retina, as well as the area covered by the ramifications in the IPL, which is about 2,000 microns 2. At the visual streak and at 110 degrees ventral and 68 degrees dorsal of the visual streak, the bipolar axons cross the INL perpendicularly. In between the axons take an oblique course leading to an axon-induced shift between input and output of up to 250 microns.(ABSTRACT TRUNCATED AT 250 WORDS)

Intrinsic connections of the retrohippocampal region in the rat brain. II. The medial entorhinal area

The present study describes the efferent projections and terminal distributions within the retrohippocampal region of individual layers of the rat medial entorhinal area (MEA) as studied by the methods of anterograde transport of the lectin Phaseolus vulgaris leucoagglutinin (PHA-L) and retrograde transport of the fluorescent dye Fast Blue (FB). Analysis of the PHA-L injections that were relatively well restricted to single layers of the MEA reveals very sparse projections to the parasubiculum, presubiculum, and subiculum, while numerous projections within the MEA are found. The course and the termination of the intra-entorhinal projections differ depending upon the particular layer under study, and marked differences are found between the deep and the superficial layers in terms of the divergence of their respective projections. However, the general intra-entorhinal orientation of these projections is essentially the same for all layers: longitudinal with a slightly oblique course, such that at ventral levels the center of a particular terminal field is always located lateral to the center of the respective PHA-L injection. PHA-L injections into layer II label axons running horizontally within this layer as well as within the deep part of layer I, and PHA-L injections into the medial sector of layer II reveal horizontal projections that innervate most of the second layer. The horizontal projections of layer III are more restricted than those of layer II but both layer II and III have prominent longitudinal projections directed ventrally. From layers II and III, numerous axons project to the deep layers (IV-VI) probably en route to extra-entorhinal structures, since no major terminal fields were detected in the deep layers. The PHA-L and the FB experiments show that the deep layers (in particular IV and VI) have far more divergent intra-entorhinal projections than have layers II and III. PHA-L injections into layers IV, V, and VI reveal widespread efferent projections to all of the more superficially located layers of the MEA in addition to projections to the lateral EA. The retrograde transport studies show that layers IV and VI are the major sources of these divergent projections and that cells situated throughout the entire medial to lateral width of these layers project to every sector of the retrohippocampal region. Taken together, the findings of the present experiments suggest that (1) all layers of the MEA have longitudinal projections directed primarily toward the ventral (or temporal) part of this cortex, (2) the projections of layers II and III are relatively restricted compared of the deeper layers.(ABSTRACT TRUNCATED AT 400 WORDS)

On areas of transition between entorhinal allocortex and temporal isocortex in the human brain. Normal morphology and lamina-specific pathology in Alzheimer's disease.

The allocortical entorhinal region does not gradually transform into the temporal isocortex. Instead, there is an extended stretch of "transentorhinal" cortex with interdigitation of allocortical and isocortical laminae. The main feature of this transition zone is that the superficial layer of large multipolar nerve cells (Pre-alpha) of the entorhinal region gradually sweeps downward and follows an oblique course through the outer layers. During this course the star-shaped nerve cells of Pre-alpha are transformed into pyramidal cells. The layer Pre-alpha projection cells are particularly prone to the development of neurofibrillary changes of the Alzheimer type. In cases of presenile and senile dementia almost all of the layer Pre-alpha projection neurons are changed pathologically. The isocortical pyramidal cells of layers II to IV are far less inclined to develop neurofibrillary changes. In the transentorhinal cortex, the tangle-bearing neurons follow an oblique course through the superficial laminae and are finally located between the isocortical layers III and IV, findings that confirm the assumption that these neurons are constituents of the allocortical layer Pre-alpha. Layer-specific pathology of the profound stratum as well confirms the transentorhinal region as being formed by interdigitating allocortical and isocortical layers.

Marginal habitats of chimpanzees

(1) This paper aims to define the marginal habitat of the chimpanzee before the advent of man-made bushfires and agriculture. (The numbers in this abstract refer to the sections of the paper). (2) Written inquiries and personal interviews resulted in a map of the geographical range of the chimpanzee. (3) The rainfall data produced by McGrew et al. (1981) are inadequate because they are based upon short-term measurements during the years of the Sahel drought. On a long-term basis, Mt Assirik probably receives more annual rainfall (1200–1300 or even 1400 mm) than Gombe (∼1100–1300 mm?). The driest chimpanzee sites are Falémé-Bafing in Mali (∼1000 mm) and Ugalla in Tanzania (∼800–900 mm). The annual amount of rainfall is, however, not the decisive factor determining the geographical range. (4) The climatically determined belts of natural vegetation in tropical Africa are described and defined. The ecological limit of the chimpanzee runs obliquely through the Isoberlinia soudanien belt, i.e. from the southern part of the dry soudanien belt in Senegal and Mali to the relatively humid soudano-guinéen belt in the Sudan. This lack of fit between vegetation belts and chimpanzee range cannot be explained by the presence or absence of drinking water in the dry season. (5) Before the advent of agriculture, the chimpanzee's geographical range was covered predominantly by rain forests in the equatorial zone, and by dry forests in the soudanien belt. Man has converted these into mosaic landscapes of savannas, woodlands, secondary forests and relict forests. (6) However, before that time, the social herbivores (from elephants to locusts) had a more or less similar mosaic-forming impact, though to a lesser degree. Statements on ecosystems and their fauna should, therefore, be preceded by and based upon an analysis of the status and dynamics of the vegetation. (7) In mosaic landscapes in Guinea and Senegal, chimpanzee population densities at different sites appear not to be correlated with the local floristic composition in terms of percentages of drought-adapted vs humid flora, but they are correlated with the degree of floristic richness and diversity at these sites. In the dry parts of the chimpanzee range in Tanzania the apes depend on a combination of drought-adapted and humid flora. Apparently their need for a diversified diet determines their ecological limit. The oblique course of the range boundary across the soudanien belt can perhaps be explained by increasing floral impoverishment towards the East, owing to man's activities. The surprising absence of chimpanzees East of the Western Rift system must be attributed to ecological barriers and palaeo-conditions. (8) A confusing phenomenon is that drought-adapted types of arboreal vegetation have, in general, higher powers of regeneration than humid (rain forest) types. (9) The comparison between chimpanzees and Bushmen as made by McGrew et al. is inappropriate because the vegetation of Mt Assirik is degraded whereas that of the Kalahari is natural.

A reassessment of the forms of nonpyramidal neurons in area 17 of cat visual cortex.

AbstractThe nonpyramidal neurons in area 17 of cat visual cortex have been examined in Golgi preparations. From their dendritic patterns, neurons are classified as being multipolar, bitufted, or bipolar, and on the basis of the abundance of dendritic spines as spinous, sparsely spinous, or smooth. When neurons are so classified seven different types of nonpyramidal neurons are encountered in layers II through V.Three of the types of multipolar neurons in layers II through V have spherical dendritic trees. The small multipolar cells have smooth dendrites and are the smallest neurons in the cortex. They have short dendrites and dense local axonal plexuses and occur throughout layers II to V The sparsely spinous stellate cells have longer dendrites, are confined to layer II/III, and have local axonal arborizations, whereas the spinous stellate cells are limited to layer IV. A fourth type of multipolar neuron in layers II through V is the basket cell. Such neurons have elongate dendritic trees and either smooth or sparsely spinous dendrites. Depending upon the orientation of the neurons in the sections, their axons appear to form arcades or long, horizontally extended branches, or a mixture of these two axonal patterns. The terminal portions of the axons of these basket cells pass around the cell bodies of adjacent neurons.The two types of bitufted neurons in layers II through V have vertically oriented dendritic trees. One type, the chandelier cell, has smooth dendrites and a characteristic axon forming vertical strings of terminals. The other sparsely spinous bitufted neurons have axons producing vertically oriented plexuses. The remaining type of neuron encountered in layers II through V is a bipolar cell. The bipolar cell has a single major dendritic trunk arising from each pole of the cell body, and each of these gives rise to a very narrow, long, and vertically oriented dendritic tree. The axon usually takes origin from one of the primary dendrites.In layer I are horizontally oriented, bitufted cells with smooth dendrites. The axons of these horizontal cells of layer I arise from one of the primary dendritic trunks and appear to form a plexus confined to layer I. Horizontally oriented neurons are also present in deep layer VI, but the horizontal cells of layer VI are bipolar. The other two neuronal types in layer VI are multipolar cells with sparsely spinous dendrites. The larger of these two types resembles the basket cells in layers II through V, the only important difference between them being that in addition to the long horizontal branches, the axons of the basket cells of layer VI have a long ascending branch which reaches at least as far as layer IV. The other sparsely spinous cells of layer VI are medium sized. Their axons take a descending and oblique course before elaborating a locally distributed plexus.The various types of neurons defined in this study are compared with neurons described by previous authors who have examined the populations of nonpyramidal cells in area 17 of cat visual cortex and in other visual and nonvisual cortical areas of cats, monkeys, and rodents. In some cases it has been possible to postulate the functional roles that particular types of neurons might play within cat visual cortex.

Lateral Forces on a Ship Approaching a Vertical Wall: A Theoretical Model

This paper deals with the unsteady hydrodynamic problem of a ship approaching a vertical wall on an oblique course. The ship is considered as a slender body with a trailing edge. The sway force and yaw moment acting on the ship are computed for various water depths and heading angles. The main result of this theoretical study is that generally the force is directed toward the wall and the moment tends to turn the bow away from the wall.

The spiral constrictor of the gastroesophageal junction.

The gastroesophageal region was reconstructed from the histological analyses of five human newborn infants. In addition, the nusculature of eight (3 newborn and 5 adult) human stomachs obtained from autopsies, with the lower one-third of the esophagus attached, was dissected with the aid of a binocular dissecting microscope. The muscularis mucosae, in the region of the gastroesophageal junction, exhibited no increase in thickness, nor was there any indication of special mucosal folds. In addition, the gastroesophageal junction contained no morphologic evidence that would support the existence of an anatomic sphincter (a localized thickening of circular muscle fibers). However, the obliquely arranged inner circular muscle fibers of the esophagus separated into fascicular bundles below the esophageal opening. Some of the fasciculi, as they descended, again became circular in shape and continued into the stomach, forming the middle circular muscle layer, while other fasciculi maintained their oblique course toward the left surface of the esophagus. These fasciculi, coursing on the anterior and posterior surfaces of the esophagus, crossed and interdigitated along the left surface of the esophagus in the region of the incisura cardiaca. After crossing, the oblique fasciculi descended into the stomach forming the inner oblique muscle layer. Based upon this description of crossing and interdigitating fasciculi, it is suggested that closure of the gastroesophageal junction may be due to contraction of spirally arranged muscle. Since the term "sphincter" generally implies a circular structure, it is proposed that the term "spiral constrictor" be considered in naming this anatomical arrangement.

Hemodynamic assessment of obstructive aortoiliac disease.

Angiographic demonstration of obstructive aortoiliac disease is of paramount importance prior to surgery. Obstructive disease in the femoral popliteal system can only be surgically relieved if inflow is adequate. Severely stenotic lesions may be missed by angiography due to the oblique course of the iliac arteries and inability to obtain right angle views. Translumbar downstream catheterization of the abdominal aorta and puncture of both femoral arteries allows simultaneous pressure recordings. The injection of 30 mg of papaverine into the femoral artery assures maximal vasodilatation mimicking conditions under exercise. A minimal gradient at rest may become obvious following the injection of papaverine, indicating hemodynamically significant disease and warranting surgical correction. The technique has proved to be simple and valuable, and there have been no complications.