Y. Gelford. Kaplan University.
Doppler echocardiographic index for assessment of global right ventricular function cheap clomipramine 50 mg on line. Prognostic value of a Doppler index combining systolic and diastolic performance in idiopathic-dilated cardiomyopathy buy clomipramine 10 mg visa. Doppler index combining systolic and diastolic myocardial performance: clinical value in cardiac amyloidosis discount clomipramine express. Myocardial tissue Doppler velocity imaging in children: comparative study between two ultrasound systems. Noninvasive assessment of left ventricular force-frequency relationships using tissue Doppler-derived isovolumic acceleration: validation in an animal model. Isovolumic acceleration at rest and during exercise in children normal values for the left ventricle and first noninvasive demonstration of exercise-induced force-frequency relationships. Comparison between different speckle tracking and color tissue Doppler techniques to measure global and regional myocardial deformation in children. Reference values for myocardial two- dimensional strain echocardiography in a healthy pediatric and young adult cohort. Global longitudinal strain as a major predictor of cardiac events in patients with depressed left ventricular function: a multicenter study. Prediction of all-cause mortality from global longitudinal speckle strain: comparison with ejection fraction and wall motion scoring. Contraction pattern of the systemic right ventricle shift from longitudinal to circumferential shortening and absent global ventricular torsion. Physiological consequences of percutaneous pulmonary valve implantation: the different behaviour of volume- and pressure-overloaded ventricles. Acute pulmonary hypertension causes depression of left ventricular contractility and relaxation. Effects of inhaled iloprost on right ventricular contractility, right ventriculo-vascular coupling and ventricular interdependence: a randomized placebo- controlled trial in an experimental model of acute pulmonary hypertension. Ventricular interdependence: significant left ventricular contributions to right ventricular systolic function. Significant left ventricular contributions to right ventricular systolic function. Two-dimensional echocardiographic aortic root dimensions in normal children and adults. Nomograms for aortic root diameters in children using two- dimensional echocardiography. Cardiac ventricular diastolic and systolic duration in children with heart failure secondary to idiopathic dilated cardiomyopathy. Relations between systolic and diastolic function in children with dilated and hypertrophic cardiomyopathy as assessed by tissue Doppler imaging. Left ventricular long-axis changes in early diastole and systole: impact of systolic function on diastole. Tissue Doppler combined with pulsed-wave Doppler echocardiography for evaluating ventricular diastolic function in normal children. The influence of heart rate and age on the systolic and diastolic time intervals in children. Doppler assessment of the ratio of the systolic to diastolic duration in normal children: relation to heart rate, age and body surface area. The natural history of left ventricular filling abnormalities: assessment by two- dimensional and Doppler echocardiography. An index of early left ventricular filling that combined with pulsed Doppler peak E velocity may estimate capillary wedge pressure. Usefulness of tissue Doppler echocardiography for evaluating ventricular function in children without heart disease. Recommendations for the evaluation of left ventricular diastolic function by echocardiography. Diastolic ventricular function in children: a Doppler echocardiographic study establishing normal values and predictors of increased ventricular end-diastolic pressure. Normal patterns of flow in the superior caval, hepatic and pulmonary veins as measured using Doppler echocardiography during childhood. Annular and septal Doppler tissue imaging in children: normal z-score tables and effects of age, heart rate, and body surface area. Impact of cardiac growth on Doppler tissue imaging velocities: a study in healthy children. Left ventricular myocardial velocities in healthy children: quantitative assessment by tissue Doppler echocardiography and relation to the characteristics of filling of the left ventricle. Assessment of myocardial velocities in healthy children using tissue Doppler imaging. Left ventricular wall motion velocities in healthy children measured by pulsed wave Doppler tissue echocardiography: normal values and relation to age and heart rate. Assessment of mitral annulus velocity by Doppler tissue imaging in the evaluation of left ventricular diastolic function. Left ventricular non-compaction cardiomyopathy in children: characterisation of clinical status using tissue Doppler-derived indices of left ventricular diastolic relaxation. Echocardiographic predictors of adverse clinical events in children with dilated cardiomyopathy: a prospective clinical study. Characterization of left ventricular diastolic function by tissue Doppler imaging and clinical status in children with hypertrophic cardiomyopathy. Peak early diastolic mitral annulus velocity by tissue Doppler imaging adds independent and incremental prognostic value. Tissue Doppler imaging detects severely abnormal myocardial velocities that identify children with pre-terminal cardiac graft failure after heart transplantation. Systolic and diastolic time intervals measured from Doppler tissue imaging: normal values and Z-score tables, and effects of age, heart rate, and body surface area. The relationship of left atrial volume and left atrial pressure in patients with hypertrophic cardiomyopathy: an echocardiographic and cardiac catheterization study. Left atrial volume in children without heart disease and in those with ventricular septal defect or patent ductus arteriosus or hypertrophic cardiomyopathy. Regression of left ventricular hypertrophy and improvement of diastolic function in hypertensive patients treated with Telmisartan. Significance of left atrial volume in patients < 20 years of age with hypertrophic cardiomyopathy. Left atrial size in children with hypertension: the influence of obesity, blood pressure, and left ventricular mass. Enlarged left atrial volume in hypertrophic cardiomyopathy: a marker for disease severity.
Hemifacial Microsomia purchase clomipramine 10 mg overnight delivery, Facioauriculovertebral Spectrum generic clomipramine 50 mg visa, and Oculoauriculovertebral Spectrum discount clomipramine 25 mg fast delivery, Goldenhar Syndrome Although Goldenhar syndrome is the most familiar eponym, it is perhaps the least accurate description of what is considered a spectrum of craniofacial anomalies (80). Referring to the complex as possible errors in morphogenesis of the first and second branchial arches is cumbersome though accurate. Other risk factors that have been studied include vasoactive medications and vascular events (326). Involvement is usually unilateral with variable hypoplasia of facial structures (including bone, soft tissue, ears, eyes, or mouth). Ear tags or ear pits, epibulbar dermoids (characteristic of Goldenhar syndrome), and deafness are also typical. Oral clefts may involve the lip, palate, and corner of the mouth, creating macrostomia. There can be associated vertebral, radial, or rib defects, as well as renal anomalies and midline brain defects (especially agenesis of the corpus callosum, encephalocele, and lipoma). The breadth of associated anomalies has prompted many descriptions of overlapping complexes (327,328). The authors acknowledged the wide range of previously reported frequencies (5% to 58%) and attributed this to the selection bias (clinical series, population- based ascertainment) and the variability in case definition. The advent of whole exome sequencing has helped identify additional potential disease genes and developmental pathways on a research basis but require further studies for translation in to the clinical arena (18). An informative parametric linkage analysis identified a disease locus on chromosome 5q. If first-degree atrioventricular block is diagnosed, then periodic evaluation for progression to higher grades of atrioventricular block is warranted, even after surgical repair. Of particular interest was that some patients did not have congenital bicuspid aortic valves but developed aortic valve calcification in later decades of life. The clinician needs to consider whether the patient has (1) truly isolated, sporadic disease, (2) nonsyndromic familial disease, or (3) syndromic features in order to direct genetic testing. Clinical testing for mutations in these genes is now available, allowing improved diagnostics, family screening and genetic counseling, and risk assessment for associated features. Similarly, patients with tetralogy of Fallot may be either syndromic or nonsyndromic and are at risk for different genetic alterations accordingly (19) (Tables 3. Therefore, the patient with tetralogy of Fallot should be carefully evaluated for features of one of the known associated syndromes including trisomy 21, 22q11. As new diagnostic tests and clinical discoveries are made, this list is likely to become more extensive and clinically relevant. Approximately 20% to 25% of infants ≤1 year of age have a noncardiac malformation, and approximately 5% to 17% have a genetic syndrome (16,27,348,349,350,351,352,353). The diagnosis of a genetic syndrome is more likely when growth and developmental delay are also present. It is increasingly evident that one should not ascribe neurocognitive deficits to surgery alone and must consider whether they are a symptom of an P. For example, the infant with interrupted aortic arch type B is so commonly found to have a 22q11. Finally, given the highly variable and often subtle presentation of many genetic syndromes, a concurrent genetic diagnosis can be easily overlooked or delayed if a high level of suspicion and willingness to seek genetic consultation is not maintained. First, diagnosing the patient with a genetic syndrome allows the early identification and treatment of associated noncardiac features. Second, establishing a specific genetic cause allows appropriate family counseling regarding risks of recurrence (350). Depending on the age of the individual and circumstances, the geneticist may provide information about prenatal diagnosis including options for imaging the fetal heart and obtaining appropriate genetic tests. Third, establishing a genetic diagnosis in the future will most likely allow more accurate counseling regarding cardiac and noncardiac clinical outcomes. Several studies already suggest that specific genetic syndromes are associated with a worse clinical cardiac prognosis (1,2,3,4,6,7). Ultimately, determining the patient genetic phenotype is essential to provide more accurate clinical care, estimation of prognosis, and assessment of risk (Table I in 352). When to Refer the Cardiac Patient for a Genetic Evaluation The increasing number of possible genetic diagnoses and the rapid development of new genetic tests necessitates a close collaboration between the referring primary physician, cardiologist, and clinical geneticist (164). Although historically learning disabilities or developmental delay have been attributed to the cardiac defect and surgical intervention, these observations may instead prove to be independent problems that may indicate the presence of a genetic syndrome or genetic alteration. Families may also benefit from a genetic consultation for counseling purposes, particularly with respect to risks of recurrence. Early referral to a clinical geneticist allows the early diagnosis of associated noncardiac features, as well as early intervention and timely counseling. Finally, sometimes the primary care taker or cardiologist orders the basic genetic tests to screen for abnormalities with the intention of consulting genetics if an abnormality is discovered. However, this practice may greatly underserve the patient with no detectable chromosomal alteration who nonetheless may have a genetic syndrome or the patient who could benefit from more specialized genetic testing or interpretation of complex results. In particular, the number of clinically available genetic tests has increased remarkably in the last 5 years, ranging from single gene mutation studies to genome-wide scans. Such tests now report a range of findings, including definitive disease-related mutations, variants of unknown significance and seemingly “negative” results. Genetic testing has therefore become increasingly complex and requires a significant amount of interpretation such that the ordering physician needs to be ever more knowledgeable about both the disease genes involved and genetics. Thus, genetic consultation should be considered in the suspicious patient to allow for specialized assessment and direction of genetic testing. The Genetic Evaluation The goal of the genetic evaluation is to establish a diagnosis and provide information to the patient and family about recurrence risk and expected outcomes that are known (350). The evaluation therefore considers both the patient under evaluation and the family medical history in detail. The geneticist (or genetic counselor) then obtains a complete family history of malformations and genetic conditions, including malformation syndromes (350). Information is also sought about recurrent miscarriages, sudden death in childhood, developmental delay, and mental retardation. Occasionally when an immediate general impression based on characteristic dysmorphic features provides rapid diagnosis, restraint and confirmation is needed. In addition to height, weight, and head circumference, measurements may be made of facial landmarks and distances, or other body parts to quantify the qualitative sense of hypertelorism, small pinnae, or long fingers. Depending on whether the consultation is performed during an admission to the hospital or as an outpatient visit, emergently or as a scheduled visit, and whether the location is the tertiary care center or a small satellite clinic, diagnostic testing can be performed at the same time as the initial evaluation or requested to be obtained under the direction of the primary care giver and/or cardiologist. Radiographic and ultrasonographic tests may be ordered to define internal organ structure and function. Medical, educational, and therapeutic specialists may be requested to characterize multisystem involvement, and to begin treatment. Genetic Testing Historically, the most commonly requested genetic test was a cytogenetic examination ordered as a karyotype of lymphocytes in fresh whole blood. More rapid techniques to detect single nucleotide mutation in a panel of genes are also now available. For those conditions for which there is no identified gene, whole exome and whole genome sequencing are now available as tools for genetic diagnosis. When a Mendelian gene disorder is suspected, the geneticist first determines whether single gene, gene panel, or expanded whole exome testing is most appropriate and counsels the family regarding these options.
In this case the T3 cell is the frst one identifed generic 75 mg clomipramine overnight delivery, followed by a small agger nasi cell safe 50mg clomipramine, and a small medial cell order clomipramine discount. The next step is to identify the drainage pathway of the pathway more anteromedially by occupying some of the me- frontal sinus. Note how the frontal drainage pathway is nar- Once the frontal sinus drainage pathway around the rowed progressively as the T3 cell occupies more and more cells has been established, this can be drawn on the 3D space and squeezes the frontal drainage pathway medi- image, giving the surgeon a clear understanding of the ally. The small medial cell (numbered 3) again pushes this anatomy of the frontal recess and allowing a surgical A, B C D, E F Fig. However, in the wall that occupies the frontal ostium may need to be re- coronal plane, it can be seen that the cell extends more than moved and the roof of the cell may be left if this no longer 50% of the vertical height of the frontal sinus on the scan. This is usually decision as to whether it would be possible to remove this only done if there is technical difculty in reaching the roof is based on the anteroposterior dimension of the frontal os- or dome of the cell or if the roof is too thick to fracture easily tium best evaluated on the parasagittal scan. In this case the 6 Anatomy of the Frontal Recess and Frontal Sinus 73 T3/4 with a Posterior Drainage Pathway This situation occurs when a frontal ethmoidal cell pneu- matizes through the frontal ostium and occupies the en- tire anterior region of the frontal ostium, pushing the frontal sinus drainage pathway posteriorly. In some in- stances this pathway can be very narrow and there may be significant risk when trying to manipulate a probe or curette through this narrow space due to the proximity of the skull base. In most patients this portion of the skull base (fovea ethmoidalis) is quite thick and there should be resistance to penetration. In the follow- ing example the T3 cell almost reaches 50% of the vertical height of the frontal sinus on the coronal scan and there- fore it is marginal if this cell should be termed a T3 or a T4 cell (Fig. In addition this patient has undergone prior surgery and the agger nasi cell and bulla ethmoidalis have been removed. Note how compressed base penetration while placing the probe or curette should be low. If the this pathway becomes and how closely associated it is with the poste- surgeon remains concerned, a frontal minitrephine can be placed. If a building block is placed for each of these cells seen and for the bulla ethmoida- lis (cell number 5) and suprabullar cell (cell number 4), a 3D picture of this complex cellular confguration is estab- lished (Fig. Drainage Pathway (Video 17) If the 3D image is reviewed, the frontal sinus drainage pathway can be placed among these cells. This allows the If the T3/4 cell is large and flls the frontal ostium it will surgeon to decide exactly where the probe or curette should push the drainage pathway either medially, posteriorly, or be placed so that it can be slid up the drainage pathway and anteriorly. The direction it pushes the drainage pathway is the cells that are obstructing the frontal ostium can be re- primarily dependent on where the cell is based (anteriorly, moved (Fig. An example of this anatomical variation struction performed, and drainage pathway determined. Note how the sinus drains anterior to the frontal bulla cell and then medial to the agger nasi cell. If the 3D picture is reviewed and the frontal sinus drain- age pathway is placed, a true 3D image of both the anat- omy and the pathway is formed. This allows planning of each step of the surgical resection of the frontal bulla cell (Fig. The agger nasi cell is proposed as the key to the understanding of this complex area. The surgeon should then go through the surgical Frontal Bulla Cell with Anterior Drainage Pathway steps to be performed. For example: create an axillary fap, (Video 21) raise the fap, remove the anterior wall of the agger nasi cell, place the curette medial or behind the agger nasi cell, This cell has been commonly confused with the T4 cell of the and remove this cell (medial wall and roof). Identify the re- original Kuhn classifcation in which a T4 cell was defned as sidual cells and the frontal sinus drainage pathway around an isolated cell within the frontal sinus. Place the suction curette along the frontal sinus numbered 1 appears to be an isolated cell in the frontal sinus. Such a sur- on the parasagittal scan, it is quite clear that this is a frontal gical plan, formulated from a thorough understanding of bulla cell that originated in the suprabullar space and pneu- the anatomy, allows a confdent dissection of a complex matizes forward along the skull base into the frontal sinus. Chronic frontal sinusitis: the endoscopic frontal recess The videos that accompany this book present a series of approach. Oper Tech Otolaryngol—Head Neck Surg 1996;7:222–229 case studies in which the variations described above are il- 15. Attempt to draw the anatomy of the Laryngoscope 2001;111(4 Pt 1):603–608 frontal recess using building blocks and establish a 3D pic- 16. Then scope 2002;112(3):494–499 review the video of the surgical procedure so that you can 17. Surgical techniques for the removal of frontal re- see how the anatomy seen in the dissection relates to your cess cells obstructing the frontal ostium. Laryngoscope 1997; 107(11 Pt 2):1–36 Surgical Approach to the Frontal Sinus 7 and Frontal Recess The frontal recess has always been considered to be the most the additional technique of frontal sinus mini-trephination difcult area to dissect. This technique has similarities to the fron- and associated transitional spaces (hiatus semilunaris and tal sinus rescue procedure described by Kuhn et al. However, the major diference is that the frontal maxillary sinus and associated transitional spaces will result sinus rescue procedure is designed for the management of in clearance of the frontal recess and sinus disease. The axillary fap technique is de- cations come from the same group of investigators. The broad spectrum of frontal sinus and frontal recess disease, central concept of the axillary fap procedure is removal of we do not advocate this approach. Close11 have advocated a similar approach with removal of Although we agree that surgery on a diseased frontal sinus or the bone above the insertion of the middle turbinate. The recess that is symptomatic is appropriate, we disagree that major diference between these approaches and the axil- this is the only indication for surgery in this region. Patients lary fap approach is the elevation of a mucosal fap which who present with nasal obstruction, postnasal drip, purulent can be replaced at the end of the procedure to cover the rhinorrhea and anosmia, and who have radiological disease raw exposed bone that is seen after removal of the anterior in the frontal sinus or recess need to have this region sur- wall of the agger nasi cell. These patients have their diseased maxil- from forming over the exposed bone with subsequent scar- lary sinuses, ethmoid, and sphenoid sinuses addressed and ring and cicatrization of this area. Such scarring can pull the it makes no sense that just because they do not have local- upper extension of the middle turbinate laterally and close ized frontal pain or tenderness, that the frontal sinus should of the anterior aspect of the frontal recess. It has been well recognized that lead to blockage of the frontal outfow tract and result in retained or residual cells in the frontal recess/sinus is one of recurrent frontal sinusitis. In the easy frontal of residual cells within the frontal recess with the exposure recess and sinus, simple maneuvers in terms of endoscopy of the frontal ostium is usually sufcient to achieve resolu- and surgical access (axillary fap) are advocated and are, in tion of frontal sinusitis. It is our philosophy that where pa- most cases, sufcient to allow clearance of the frontal recess tients have cells in the frontal recess or frontal ostium that and frontal ostium. In the difcult frontal recess or sinus, obstruct the outfow of the frontal sinus, that these should 81 82 Endoscopic Sinus Surgery be removed without enlarging the frontal ostium. Partial surgery of the frontal recess tunity to see if the natural size of their frontal ostium is suf- is never indicated. In some patients, especially those with severe mucosal removed or one of the frontal ethmoidal cells is removed, disease, this ostium may become edematous and obstruct scarring is likely to result. The cells in the frontal recess are and, if this causes symptoms, then enlargement of the ostium usually in close approximation and partial clearance of cells is indicated. However, this occurs in the minority of cases will very likely result in adhesions forming between these and it’s not possible to predict which patients with a par- closely approximated surfaces with obstruction of the drain- ticular frontal ostium size will obstruct and become symp- age pathway of the frontal sinus. Drilling in the frontal ostium without alone or all the cells are removed from the recess with visu- creation of the largest possible ostium is likely to result in an alization of the frontal ostium.
Hence cheap clomipramine 75mg online, the posterior horns are The neurons of the spinal gray matter are primarily the “sensory” parts of the spinal gray arranged in longitudinal groups of functionally matter generic 75 mg clomipramine amex, and many of their neurons give rise to similar cells referred to as columns or nuclei Chapter 2 Spinal Cord: Topography and Functional Levels 23 (Fig quality 10mg clomipramine. For example, Myelin-stained transverse sections of the four the substantia gelatinosa and the proper sensory major regions of the spinal cord can be distin- nucleus, which are related to pain impulses from guished from each other most readily by the size all spinal nerves, extend throughout the length and shape of the respective gray matter (Figs. Because of the large size of the lower dorsal nucleus and the intermediolateral nucleus, limbs, the lumbar and sacral segments have mas- which are related to the cerebellar and auto- sive posterior and anterior horns. In lumbar seg- nomic systems, respectively, exist only in certain ments, the anterior horn has a distinct medial spinal cord segments. In addition, the Laminae rim of white matter surrounding the sacral gray The spinal gray matter can also be divided into matter is much thinner than that in the lumbar laminae or layers based on layerings of morpho- spinal cord. Laminae The posterior horn in both thoracic and cervi- provide a more precise identifcation of areas cal segments is narrow compared with lumbar and within the spinal gray matter and are very use- sacral segments. However, owing to the muscular ful in describing the locations of the origins or volume of the upper limbs, the cervical anterior terminations of the functional paths. Ten lami- horn is much larger than the thoracic, which nae make up the spinal gray matter, and, in mainly supplies the relatively small intercostal general, they are numbered from posterior to and subcostal muscles. Nevertheless, Lamina X is in the commissural area surrounding because the white matter contains axons trans- the central canal. Posterior median sulcus Posterior funiculus Posterior horn Substantia Intermediate gelatinosa zone Central canal Lateral horn Lateral funiculus Anterior horn Anterior funiculus Anterior median fissure Figure 2-7 Transverse section of thoracic spinal cord. Note the slim anterior and posterior horns and lateral horn indenting the lateral funiculus. Chapter 2 Spinal Cord: Topography and Functional Levels 25 Gracile tract Posterior median sulcus Posterior funiculus Cuneate tract Posterior intermediate sulcus Posterior horn Substantia gelatinosa Intermediate zone Lateral funiculus Anterior horn Anterior funiculus Anterior median fissure Figure 2-8 Transverse section of cervical enlargement. Note the slim posterior horn, the large anterior horn, and the division of the huge posterior funiculus. This is the anatomi- Injury to the spinal cord can be two fundamen- cal basis underlying sacral sparing (See Fig. Acute spi- nal cord injury can result from trauma or stroke, while chronic injury can result from infections, Chapter Review infammation, tumors, genetic disorders, and com- pression. Traumatic injury with momentary or Questions prolonged compression of the spinal cord has an immediate onset of clinical signs that vary depend- 2-1. What are the contents of the spinal ing upon the specifc tracts and neurons/nuclei epidural space? At what three intervertebral articulations are bination of trauma and vascular interruption comes dislocations most likely to occur and what with contusions to the spinal cord. What are the distinguishing characteristics white matter is more resistant to hypoxia than the of transverse spinal cord sections at sacral, gray matter. Each of the following concerning the cauda anatomical landmarks for: equina is true except one: a. The disparity between spinal cord levels spinal cord and vertebral levels in adults is due to b. Differential growth or elongation of the of the cord spinal cord compared to the vertebral c. The diminished size of the caudal spinal eral white matter may remain functional cord compared to rostral levels. It also contains the long tracts that transmit somatosensory impulses from all parts of the body to the forebrain, as well as motor impulses for vol- untary movements that originate in the forebrain. Damage to the brainstem is manifested by somatosensory or motor dysfunctions or both, accompanied by abnormalities in cranial nerve functions. The level of damage in a brainstem lesion can usually be determined by cranial nerve malfunction. Because of the vital nature of many functional centers located in the brainstem, especially at more caudal levels, brainstem lesions are frequently fatal. The brainstem is the stalk-like part of the brain The brainstem is covered posteriorly by the that is located in the posterior cranial fossa. It cerebellum to which it is connected by huge consists of the medulla oblongata, pons, and masses of nerve fbers that form the three pairs of midbrain (Fig. Its anterior surface is closely continuous with the spinal cord at the foramen related to the clivus, the downward sloping basal magnum, and the midbrain is continuous with surface of the posterior cranial fossa between the the forebrain at the tentorial notch, the opening dorsum sellae and foramen magnum (Fig. The posterior surface of its rostral stance, the brainstem is thrust downward as part is anatomically related to the cerebellum to the overlying mass of the cerebellum herni- which it is connected by the inferior cerebellar ates through the foramen magnum against the peduncles. Pressure on cardiovascular The caudal half of the medulla contains a and respiratory centers in the medulla quickly prolongation of the central canal of the spinal results in death. Corpus callosum Cerebral Fornix hemisphere Septum pellucidum Diencephalon Third ventricle Middle cranial Midbrain fossa Cerebral aqueduct Anterior cranial Cerebellum fossa Fourth ventricle Drosum sellae Pons Posterior cranial fossa Medulla Clivus Posterior margin of foramen magnum Spinal cord Figure 3-2 Magnetic resonance image of median view of right half of brain. Chapter 3 Brainstem: Topography and Functional Levels 29 of the medulla forms the caudal or medullary part are necessary to distinguish the subdivisions and of the foor of the fourth ventricle, the cerebrospi- their functional levels, these alone are described nal fuid–flled cavity between the cerebellum and here. Lateral to the rostral Pons part of each pyramid is a prominent elevation, The pons extends from the medulla to the mid- the olive. The sul- the cerebellum to which it is attached by the cus posterior to the olive is the postolivary sulcus, middle cerebellar peduncles or brachii pontis. Because these rootlets eventually join and are distributed with the vagus nerve, the so-called cranial part of the accessory nerve is considered Midbrain by many to be a misnomer. The midbrain lies between the pons and the fore- brain and is located in the tentorial notch. It is Pons the shortest part of the brainstem and contains The anterior portion of the pons is the basilar part. An tomedullary junction, near the lateral border of imaginary line passing from side to side through the pyramid. As stated in the Preface, before describing the clini- cally important functional paths, it is imperative for Midbrain the reader to become familiar with the distinguish- ing characteristics of the subdivisions of the brain The anterior surface of the midbrain is formed by and their functionally important levels. Fourth Ventricle The foor of the fourth ventricle can be divided into medullary and pontine parts by drawing an Posterior Surface imaginary horizontal line between the lateral recesses, which are found at the widest point of Medulla the fourth ventricle. The caudal tip of the fourth The posterior surface of the closed or caudal half ventricle lies between the gracile tubercles and is of the medulla contains the gracile tubercles called the obex. In most brains, the rostral part of on either side of the posterior median sulcus the medullary foor contains a variable number of (Fig. Lateral to each gracile tubercle and white strands called the striae medullares, which extending slightly more rostral is the cuneate extend laterally from the median sulcus toward tubercle. The median sulcus divides the foor of the Cerebellar Peduncles fourth ventricle into symmetric halves. Each half is The cut surfaces of the cerebellar peduncles further subdivided into medial and lateral parts by are at the lateral aspects of the pons and in the the superior and inferior foveae, small depressions roof of the fourth ventricle. At its infer- and indicate the boundary between motor struc- omedial part is the inferior cerebellar peduncle tures, which are medial, and sensory structures, or restiform body, which connects the medulla to which are lateral.
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