By J. Ugo. Hope College.
The listings preceded by an en-dash (–) under principal sinuses 22 External Morphology of the Central Nervous System Frontal pole Olfactory bulb Longitundinal fissure Orbital sulci Olfactory sulcus (OlfSul) Orbital gyri (OrbGy) Gyrus rectus (GyRec) Olfactory tract Temporal pole (TPole) Basilar pons (BP) Uncus Occipitotemporal sulcus Parahippocampal gyrus Occipitotemporal gyri Collateral sulcus Glossopharyngeal Middle cerebellar nerve peduncle (MCP) Flocculus Facial nerve Vagus nerve Vestibulocochlear nerve Abducens nerve Medulla Olive (inferior); Decussation olivary eminence of pyramids Cerebellum (Cbl) GyRec OlfSul OrbGy Tpole Trigeminal nerve BP BP MCP Fourth ventricle Cbl 2-17 Ventral view of the cerebral hemispheres ayurslim 60 caps with amex, diencephalon order ayurslim 60 caps otc, brainstem ayurslim 60caps with amex, and cerebellum and two MRIs (both T1-weighted images) that shows structures from the same perspective discount ayurslim 60 caps on line. A detailed view of the ventral aspect of the brainstem is seen in Figure 2-20 on page 24. The Brain: Gross Views, Vasculature, and MRI 23 Anterior cerebral artery Internal carotid artery Middle cerebral artery (MCA) Optic nerve, chiasm, and tract Posterior communicating artery Lenticulostriate Oculomotor nerve branches of MCA Posterior cerebral artery Superior cerebellar artery Trochlear nerve Basilar artery Trigeminal nerve Abducens nerve Facial and AICA vestibulocochlear nerves Anterior inferior Branches of AICA cerebellar artery (AICA) Posterior inferior PICA cerebellar artery (PICA) PSA Vertebral artery Branches of PICA Posterior spinal artery (PSA) Anterior spinal artery 2-18 Ventral view of the cerebral hemispheres, diencephalon, son with Figure 2-17 (facing page). Details of the cerebral arterial cir- brainstem, and cerebellum, which shows the arterial patterns created cle and the vertebrobasilar arterial pattern are shown in Figure 2-21 on by the internal carotid and vertebrobasilar systems. Gyri and sulci can be identified by compari- of the cerebral arterial circle and its major branches. Superior ophthalmic vein –from area of ophthalmic artery Sphenoparietal sinus –middle cerebral vein Cavernous sinus –cerebral vein Superior petrosal sinus Intercaverous sinuses –cerebellar veins –inferior cerebral veins –tympanic veins Inferior petrosal sinus Basilar plexus –veins of pons and medulla –auditory veins Sigmoid sinus Internal jugular vein Transverse sinus Anterior vertebral –emissary veins venous plexus –inferior cerebral veins –inferior cerebellar veins Occipital sinus –posterior internal vertebral Sinus confluens venous plexus –straight sinus –superior sagittal sinus 2-19 Ventral view of the cerebral hemispheres, diencephalon, principal sinuses and veins. The listings preceded by a dash (–) under brainstem, and cerebellum showing the locations and relationships of principal sinuses are the main tributaries of that sinus. Lateral to the internal carotid bifurcation is the brain structures and cranial nerves to the arteries forming the verte- M1 segment of the middle cerebral artery (MCA), which divides and brobasilar system and the cerebral arterial circle (of Willis). The terior spinal artery usually originates from the posterior inferior M3 branches of the MCA are those located on the inner surface of the cerebellar artery (left), but it may arise from the vertebral (right). Between the basilar bifurcation and the posterior com- basilar (right), it most frequently originates from the anterior infe- municating artery is the P1 segment of the posterior cerebral artery; rior cerebellar artery (left). Many vessels that arise ventrally course P2 is between the posterior communicator and the first temporal around the brainstem to serve dorsal structures. The cere- structures and cranial nerves on the ventral aspect of the thalamus and bellum and portions of the temporal lobe have been removed. Anterior cerebral artery Olfactory tract Medial olfactory stria Optic nerve Lateral olfactory stria Optic chiasm Anterior perforated substance Optic tract Infundibulum Mammillary body Posterior perforated substance Crus cerebri Trochlear nerve Basilar pons Lateral geniculate body Trigeminal nerve Medial geniculate body Abducens nerve Middle cerebellar peduncle Facial nerve Vestibulocochlear nerve Pyramid 2-23 View of the ventral aspect of the diencephalon and part of the Note structures of the hypothalamus, cranial nerves, and optic struc- brainstem with the medial portions of the temporal lobe removed. The Brain: Gross Views, Vasculature, and MRI 27 Fornix Choroid plexus, third ventricle Optic tract Posterior choroidal arteries Thalamogeniculate artery Lateral geniculate body Dorsal thalamus Posterior cerebral artery Mammillary body Medial geniculate body Quadrigeminal artery Superior colliculus Posterior communicating artery Crus cerebri Internal carotid artery Brachium of inferior colliculus Oculomotor nerve Inferior colliculus Superior cerebellar artery Trochlear nerve Trigeminal nerve Motor root Sensory root Superior cerebellar peduncle Anterior medullary velum Basilar artery Middle cerebellar peduncle Anterior inferior cerebellar artery Vestibulocochlear nerve Labyrinthine artery Facial nerve Abducens nerve Posterior inferior cerebellar artery Glossopharyngeal nerve Choroid plexus, Vagus nerve fourth ventricle Hypoglossal nerve Restiform body Accessory nerve Cuneate tubercle Gracile tubercle Posterior inferior cerebellar artery Posterior spinal artery Anterior spinal artery Vertebral artery 2-24 Lateral view of the brainstem and thalamus showing the rela- tively, are shown as dashed lines. Compare with Figure 2-22 on the fac- tionship of structures and cranial nerves to arteries. Compare to Figure 28 External Morphology of the Central Nervous System Anterior paracentral gyrus (APGy) Central sulcus (CSul) Paracentral sulcus (ParCSul) Posterior paracentral gyrus (PPGy) Precentral sulcus (PrCSul) Marginal sulcus (MarSul) Precuneus (PrCun) Cingulate gyrus (CinGy) Superior frontal gyrus (SFGy) Parieto-occipital sulcus (POSul) Cingulate sulcus (CinSul) Cuneus (Cun) Calcarine sulcus (CalSul) Lingual gyrus (LinGy) Sulcus of corpus callosum (SulCC) Isthmus of cingulate gyrus Paraterminal gyri Occipitotemporal gyri Parolfactory gyri (ParolfGy) Parahippocampal gyrus Temporal pole Uncus Rhinal sulcus APGy PrCSul CSul PPGy ParCSul MarSul SulCC CinGy PrCun CinSul POSul ParolfGy Cun CalSul LinGy SFGy MarSul Corpus callosum POSul CalSul Colloid cyst Internal cerebral vein 2-26 Midsagittal view of the right cerebral hemisphere and dien- A colloid cyst (colloid tumor) is a congenital growth usually dis- cephalon, with brainstem removed, showing the main gyri and sulci covered in adult life once the flow of CSF through the interventricular and two MRI (both T1-weighted images) showing these structures foramina is compromised (obstructive hydrocephalus). The lower MRI is from a patient with a may have headache, unsteady gait, weakness of the lower extremities, small colloid cyst in the interventricular foramen. When compared to visual or somatosensory disorders, and/or personality changes or con- the upper MRI, note the enlarged lateral ventricle with resultant thin- fusion. The Brain: Gross Views, Vasculature, and MRI 29 Internal frontal branches Paracentral branches Callosomarginal branch of ACA Internal parietal branches Parietooccipital Pericallosal branch branches of PCA of ACA Frontopolar branches of ACA Orbital branches of ACA Anterior cerebral artery (ACA) Calcarine branch of PCA Posterior temporal branches of PCA Posterior cerebral artery (PCA) Anterior temporal branches of PCA 2-27 Midsagittal view of the cerebral hemisphere and dien- to serve medial regions of the frontal and parietal lobes, and the same cephalon showing the locations and branching patterns of anterior and relationship is maintained for the occipital and temporal lobes by posterior cerebral arteries. The positions of gyri and sulci can be ex- branches of the posterior cerebral artery. Inferior sagittal sinus Posterior vein of corpus callosum Superior sagittal sinus Internal occipital veins TV Veins of the caudate nucleus Straight sinus Septal veins Sinus confluens Transverse sinus Superior Anterior cerebral vein cerebellar vein Occipital Basal vein sinus Great Internal cerebral vein cerebral vein 2-28 Midsagittal view of the cerebral hemisphere and dien- (facing page). See cephalon that shows the locations and relationships of sinuses Figures 8-2 (p. The MRI (T1- weighted image) shows many brain structures from the same perspec- tive. The Brain: Gross Views, Vasculature, and MRI 31 Body of fornix (For) Dorsal thalamus (DorTh) Septum pellucidum (Sep) Massa intermedia Choroid plexus of third ventricle Interventricular foramen Stria medullaris thalami Column of fornix Habenula Anterior commissure (AC) Suprapineal recess Lamina terminalis Posterior commissure Pineal (P) Supraoptic recess Superior colliculus (SC) Optic chiasm (OpCh) Quadrigeminal HythHyth cistern (QCis) Inferior colliculus (IC) Optic nerve Cerebral aqueduct (CA) Anterior medullary velum (AMV) Fourth ventricle (ForVen) Infundibulum (In) Infundibular recess Mammillary body (MB) Hypothalamic sulcus Posterior inferior Oculomotor nerve cerebellar artery Interpeduncular fossa (IpedFos) Medulla Basilar pons (BP) For DorTh Sep Internal cerebral vein P AC Tentorium cerebelli Hypothalamus QCis OpCh SC In IC Pituitary gland AMV MB ForVen IpedFos BP CA 2-30 A midsagittal view of the right cerebral hemisphere and di- image) shows these brain structures from the same perspective. Hyth encephalon with the brainstem in situ focusing on the details primarily hypothalamus. The MRI (T1-weighted 32 External Morphology of the Central Nervous System A D Midbrain Anterior quadrangular Anterior lobule lobe (AntLb) Posterior quadrangular lobule Posterior Primary superior fissure fissure E Superior semilunar Hemisphere lobule Bpon Vermis (Ver) AntLb SCP B Fourth ventricle Basilar pons (Bpon) Medulla (Med) Flocculus (Fl) Tonsil (Ton) F Biventer lobule Gracile Med lobule Ton Inferior semilunar PostLb lobule Hemisphere Vermis (Ver) Ver C Colliculi: Anterior Superior Cerebellar peduncles: lobe (AntLb) Inferior Superior (SCP) G Middle (MCP) Inferior Primary fissure AntLb Horizontal MCP fissure Fl Flocculus (Fl) Posterior Tonsil (Ton) lobe (PostLb) Nodulus Med PostLb 2-31 Rostral (A, superior surface), caudal (B, inferior surface), with cerebellar structures seen in axial MRIs at comparable levels (D, and an inferior view (C, inferior aspect) of the cerebellum. Structures seen on the inferior surface of the cerebellum, such as in C shows the aspect of the cerebellum that is continuous into the the tonsil (F), correlate closely with an axial MRI at a comparable level. The view in C correlates with su- In G, note the appearance of the margin of the cerebellum, the general perior surface of the brainstem (and middle superior cerebellar pe- appearance and position of the lobes, and the obvious nature of the duncles) as shown in Figure 2-34 on page 34. Note that the superior view of the cerebellum (A) correlates closely The Brain: Gross Views, Vasculature, and MRI 33 A B II,III V II,III IV I V Midbrain (Mid) Primary fissure (PriFis) PriFis Basilar pons (Bpon) VI Mid VII VII Fourth Bpon ventricle (ForVen) ForVen Medulla Med VIII (Med) VIII X X IX IX Posterolateral fissure (PostLatFis) II,III IV V C PriFis Mid VI Bpon VII ForVen Med X IX VIII 2-32 A median sagittal view of the cerebellum (A) showing its re- Lobules I-V are the vermis parts of the anterior lobe; lobules VI-IX lationships to the midbrain, pons, and medulla. This view of the cere- are the vermis parts of the posterior lobe; and lobule X (the nodulus) bellum also illustrates the two main fissures and the vermis portions of is the vermis part of the flocculonodular lobe.
Subgroup analysis showed significant differences of the lnDOR between six different populations of participants generic ayurslim 60caps with mastercard. In three populations there was a strong negative association between sensitivity and specificity ( 0 cheap 60caps ayurslim with visa. Different SROC curves for each subgroup could be fitted (see section on statistical pooling) (Figure 8 buy ayurslim 60 caps cheap. If many studies are available 60caps ayurslim mastercard, a more complex multivariate model can be built in which a number of study characteristics are entered as possible covariates. Multivariate models search for the independent effect of study characteristics, adjusted for the influence of other, more powerful ones. Deciding on the model to be used for statistical pooling Models There are two underlying models that can be used when pooling the results of individual studies. A fixed effect model assumes that all studies are a certain random sample of one large common study, and that differences between study outcomes only result from random error. It consists essentially of calculating a weighted average of the individual study results. Studies are weighted by the inverse of the variance of the parameter of test accuracy, or by the number of participants. A random effect model assumes that in addition to the presence of random error, differences between studies can also result from real differences between study populations and procedures. The weighting factor is mathematically more complex, and is based on the work of Der Simonian and Laird, initially performed and published for the meta-analysis of trials. Homogeneous studies If the parameters are homogeneous, and if they show no (implicit) cut- off effect, their results can be pooled and a fixed effect model can be used. If there is evidence of a cut-off effect, SROC curves can be constructed or ROC curves can be pooled. Heterogeneous studies If heterogeneity is present, the reviewer has the following options: 1. Refrain from pooling and restrict the analysis to a qualitative overview. Subgroup analysis if possible, on prior factors and pooling within homogeneous subgroups. As a last resort pooling can be performed, using methods that are based on a random effect model. In view of the poor methodological quality of most of the diagnostic studies that have been carried out, there is a tendency to advise using random effect models for the pooling of all diagnostic studies, even if there is no apparent heterogeneity. Statistical pooling Pooling of proportions q Homogeneous sensitivity and/or specificity If fixed effect pooling can be used, pooled proportions are the average of all individual study results, weighted for the sample sizes. This is easily done by adding together all numerators and dividing the total by the sum of all denominators14 (see Appendix to this chapter). If a SROC curve can be fitted, a regression model (metaregression) is used, with the natural logarithm of the DOR (lnDOR) of the studies as dependent variable and two parameters as independent variables: one for the intercept (to be interpreted as the mean lnDOR) and one for the slope of the curve (as an estimate of the variation of the lnDOR across the studies due to threshold differences). Details and formulae for fitting the curve can be found in the paper presented by Littenberg and Moses13 (see Appendix). Covariates representing different study characteristics or pretest probabilities can be added to the model to examine any possible association of the diagnostic odds ratio with these variables. Metaregression can be unweighted or weighted, using the inverse of the variance as the weighting factor. A problem that is encountered in diagnostic research is the often negative association of the weighting factor with the lnDOR, giving studies with lower discriminative diagnostic odds ratios – because of lower sensitivity and/or specificity – a larger weight. Individual data points from the selected studies can be used to calculate result specific likelihood ratios,40 159 THE EVIDENCE BASE OF CLINICAL DIAGNOSIS which can be obtained by logistic modelling. The natural log posterior odds are converted into a log likelihood ratio by adding a constant to the regression equation. The constant adjusts for the ratio of the number of “non-diseased” to “diseased” participants in the respective studies17 (see Appendix). Pooling of the ROC curves The results of diagnostic studies with a dichotomous gold standard outcome, and a test result that is reported on a continuous scale, are generally presented as an ROC curve with or without the related area under the curve (AUC) and its 95% CI. To pool such results, the reviewer has three options: to pool sensitivities and specificities for all relevant cut-off points; to pool the AUCs; or to model and pool the ROC curves themselves.
If an experimental meal consisting of solid par- 15 ticles of various sizes suspended in water is instilled in the Discomfort stomach purchase ayurslim 60 caps free shipping, emptying of the particles lags behind emptying of 10 X X the liquid (Fig purchase ayurslim 60 caps without a prescription. If the particles are plastic 0 spheres of various sizes buy 60 caps ayurslim amex, the smallest spheres are emptied 0 100 200 300 400 500 600 first; however purchase ayurslim 60caps without a prescription, spheres up to 7 mm in diameter empty at a slow but steady rate when digestible food is in the stomach. Gastric volume (mL) The selective emptying of smaller particles first is referred Loss of adaptive relaxation following a to as the sieving action of the distal stomach. A loss of adaptive relaxation in the larger than 7 mm in diameter are not emptied while food is gastric reservoir is associated with a lowered threshold for sensa- in the stomach; they empty at the start of the first migrat- tions of fullness and epigastric pain. Osmolality, acidity, and caloric content of the gastric chyme are major determinants of the rate of gastric empty- fibers to inhibitory motor neurons in the gastric ENS (Fig. Feedback relaxation is triggered by the presence of than isotonic liquids. It can involve both local re- creases as the acidity of the gastric contents increases. The docrine cells in the small intestine and transported by the mechanisms of control of gastric emptying keep the rate of blood to signal the gastric ENS. Following a vagotomy, increased tone is emptied the most slowly, or stated conversely, fat is the in the musculature of the reservoir decreases the wall com- most potent inhibitor of gastric emptying. Part of the inhi- pliance, which, in turn, affects the responses of gastric bition of gastric emptying by fats may involve the release of stretch receptors to distension of the reservoir. Pressure- the hormone cholecystokinin, which itself is a potent in- volume curves before and after a vagotomy reflect the de- hibitor of gastric emptying. The The intraluminal milieu of the small intestine is ex- loss of adaptive relaxation after a vagotomy is associated tremely different from that of the stomach (see Chapter with a lowered threshold for sensations of fullness and pain. This response is explained by increased stimulation of the gastric mechanoreceptors that sense distension of the gas- tric wall. These effects of vagotomy may explain disordered Lag phase Emptying phase gastric sensations in diseases with a component of vagus 100 nerve pathology (e. The Rate of Gastric Emptying Is Determined by the Kind of Meal and Conditions in 50 the Duodenum In addition to storage in the reservoir and mixing and grinding by the antral pump, an important function of gas- tric motility is the orderly delivery of the gastric chyme to 0 the duodenum at a rate that does not overload the digestive 0 40 60 20 80 100 and absorptive functions of the small intestine (see Clinical Time after meal (min) Focus Box 26. The rate of gastric emptying is adjusted by neural control mechanisms to compensate for variations in Gastric emptying. The emp- The volume of liquid in the stomach is one of the im- tying of a solid meal is preceded by a lag phase, the time required portant determinants of gastric emptying. The rate of emp- for particles to be reduced to sufficient size for emptying. Undiluted stomach contents have a composition that • Phase I: a silent period having no contractile activity; is poorly tolerated by the duodenum. Mechanisms of con- corresponds to physiological ileus trol of gastric emptying automatically adjust the delivery of • Phase II: irregularly occurring contractions gastric chyme to an optimal rate for the small intestine. With multiple sensors positioned along the in- lality, and enzymatic digestion of the foodstuff (see Clini- testine, slow propagation of the phase II and phase III ac- cal Focus Box 26. At a given time, the MMC occupies a limited length of intestine called the activity front, which has an upper and MOTILITY IN THE SMALL INTESTINE a lower boundary. The activity front slowly advances (mi- grates) along the intestine at a rate that progressively slows The time required for transit of experimentally labeled as it approaches the ileum. Peristaltic propulsion of luminal meals from the stomach to the small intestine to the large contents in the aboral direction occurs between the oral intestine is measured in hours (Fig. The frequency the stomach is most rapid of the three compartments; tran- of the peristaltic waves within the activity front is the same sit in the large intestine is the slowest. Three fundamental as the frequency of electrical slow waves in that intestinal patterns of motility that influence the transit of material segment. Each peristaltic wave consists of propulsive and through the small intestine are the interdigestive pattern, receiving segments, as described earlier (see Fig. Each pattern Successive peristaltic waves start, on average, slightly far- is programmed by the small intestinal ENS. Thus, the entire activity front slowly migrates Small Intestinal Motility Pattern of the down the intestine, sweeping the lumen clean as it goes. Phases II and III are commonly used descriptive terms of Interdigestive State minimal value for understanding the MMC. Contractile ac- The small intestine is in the digestive state when nutrients tivity described as phase II or phase III occurs because of are present and the digestive processes are ongoing.
Jaramillo D ayurslim 60 caps fast delivery, Hoffer F generic 60caps ayurslim visa, Shapiro F ayurslim 60 caps generic, Rand F (1990) MR imaging CT of developmental dysplasia of the hip after reduction: di- of fractures of the growth plate buy ayurslim 60 caps line. Wechsler RJ, Schwertzer ME, Deely DM, Horn BD, Pizzutillo growth plate: normal and abnormal MR imaging findings. PD (1994) Tarsal coalition: depiction and characterization with AJR Am J Roentgenol 158:1105-1111 CT and MR imaging. Leonard MA (1974) The inheritance of tarsal coalition and its AG, Strongwater A (1994) Pediatric elbow fractures: MR eval- relationship to spastic flat foot. Emery KH, Bisset GS 3rd, Johnson ND, Nunan PJ (1998) magnetic resonance imaging of the paediatric elbow. Suzuki S, Kashiwagi N, Seto Y, Mukai S (1999) Location of Chronically stressed wrists in adolescent gymnasts: MR imag- the femoral head in developmental dysplasia of the hip: three- ing appearance. Radiology 195:855-859 dimensional evaluation by means of magnetic resonance im- 49. J Pediatr Orthop 19(1):88-91 (1997) Chronic physeal fractures in myelodysplasia: magnetic 28. McNally EG, Tasker A, Benson MK (1997) MRI after opera- resonance analysis, histologic description, treatment, and out- tive reduction for developmental dysplasia of the hip. Kashiwagi N, Suzuki S, Kasahara Y, Seto Y (1996) Prediction Radiology 191:297-308 of reduction in developmental dysplasia of the hip by magnet- 51. Havranek P, Lizler J (1991) Magnetic resonance imaging in the ic resonance imaging. J Pediatr Orthop 16(2):254-258 evaluation of partial growth arrest after physeal injuries in 30. J Bone Joint Surg Am 73:1234-1241 dysplasia of the hip: three-dimensional evaluation by means 52. Disler DG (1997) Fat-suppressed three-dimensional spoiled gra- of magnetic resonance image. J Pediatr Orthop 15(6):812- dient-recalled MR imaging: assessment of articular and physeal 816 hyaline cartilage. Borsa JJ, Peterson HA, Ehman RL (1996) MR imaging of phy- BJ, Mulkern RV et al (1996) Gadolinium-enhanced MR imag- seal bars. Radiology 199:683-687 ing demonstrates abduction-caused hip ischemia and its rever- 54. AJR Am J Roentgenol 166:879-887 Pediatric knee MR imaging: pattern of injuries in the imma- 32. Jaramillo D, Villegas-Medina O, Laor T, Shapiro F, Millis MB ture skeleton. Radiology 190:397-401 (1998) Gadolinium-enhanced MR imaging of pediatric pa- 55. Fletcher BD (1991) Response of osteosarcoma and Ewing sar- tients after reduction of dysplastic hips: assessment of femoral coma to chemotherapy: imaging evaluation. AJR Am J head position, factors impeding reduction, and femoral head Roentgenol 157(4):825-833 ischemia. Bos CF, Bloem JL, Bloem RM (1991) Sequential magnetic loskeletal magnetic resonance imaging: how we do it. Sebag G, Ducou Le Pointe H, Klein I, Maiza D, Mazda K, formity secondary to brachial plexus birth palsy. J Bone Joint Bensahel H et al (1997) Dynamic gadolinium-enhanced sub- Surg Am 80(5):668-677 traction MR imaging–a simple technique for the early diagno- 58. Ruby L, Mital MA, O’Connor J, Patel U (1979) Anteversion sis of Legg-Calve-Perthes disease: preliminary results. Zurakowski D (1995) Cartilaginous abnormalities and growth Clin Orthop 120:159-163 disturbances in Legg-Calvé-Perthes disease: evaluation with 60. In: Rumack C, M, Montagne JP (1994) Legg-Perthes-Calve disease: staging Wilson S, Charboneau J (eds) Diagnostic ultrasound.