Calculated decisions: Modified Mallampati classification.

The Modified Mallampati Classification stratifies predicted difficulty of endotracheal intubation based on anatomic features.

Morphology of the Musculus Uvulae In Vivo Using MRI and 3D Modeling Among Adults With Normal Anatomy and Preliminary Comparisons to Cleft Palate Anatomy.

PURPOSE: To investigate the musculus uvulae morphology in vivo in adults with normal velopharyngeal anatomy and to examine sex and race effects on the muscle morphology. We also sought to provide a preliminary comparison of musculus uvulae morphology in adults with normal velopharyngeal anatomy to adults with repaired cleft palate. METHODS: Three-dimensional magnetic resonance imaging data and Amira 5.5 Visualization Modeling software were used to evaluate the musculus uvulae in 70 participants without cleft palate and 6 participants with cleft palate. Muscle length, thickness, width, and volume were compared among participant groups. RESULTS: Analysis of covariance analysis did not yield statistically significant differences in musculus uvulae length, thickness, width, or volume by race or sex among participants without cleft palate when the effect of body size was accounted for. Two-sample t test revealed that the musculus uvulae in participants with repaired cleft palate is significantly shorter (P = .008, 13.65 mm vs 16.07 mm) and has less volume (P = .002, 51.08 mm3 vs 97.62 mm3) than participants without cleft palate. CONCLUSION: In adults with normal velopharyngeal anatomy, the musculus uvulae is a cylindrical oblong-shaped muscle lying on the nasal surface of the soft palate, with its greatest bulk located just nasal to the levator veli palatini muscle sling. In participants with repaired cleft palate, the musculus uvulae is substantially reduced in volume. This diminished muscle bulk located just at the point where the palate contacts the posterior pharyngeal wall may contribute to velopharyngeal insufficiency in children with repaired cleft palate.

Does the Pharyngeal Airway Recover After Sagittal Split Ramus Osteotomy for Mandibular Prognathism?

PURPOSE: Mandibular setback surgery can adversely affect the pharyngeal airway. The aim of this study was to investigate changes of the pharyngeal airway at specific intervals during a 12-month period after bilateral sagittal split ramus osteotomy (BSSO) for correction of mandibular prognathism. MATERIALS AND METHODS: This retrospective cohort study included patients with mandibular prognathism who underwent BSSO. The pharyngeal airway was measured at 3 different levels on lateral cephalograms: the uvula tip, the most inferior-anterior point on the body of the second cervical vertebra (low-C II), and a midanterior point on the body of the third cervical vertebra (mid-C III). The pharyngeal airway was measured preoperatively, immediately postoperatively, and 1, 3, 6, and 12 months postoperatively. The measurements at each level were compared. Multivariable analysis of variance was used to measure the changes in pharyngeal airway space over time. RESULTS: The study sample was composed of 30 patients (14 men and 16 women) who were diagnosed with mandibular prognathism. The pharyngeal airway at the uvular tip level was significantly reduced by 39% (P < .001) after surgery and was significantly improved by 26% (P < .01) from baseline at 1 month postoperatively. The pharyngeal airway at the low-C II level was significantly reduced by 27% (P < .001) after surgery and was significantly improved by 24% (P < .01) from baseline at 1 month postoperatively. The pharyngeal airway at the mid-C III level was significantly reduced by 23% (P < .001) after surgery and was improved by only 13% from baseline at 1 month postoperatively. Additional statistical changes were not noted on 3 and 6 months postoperative radiographs at all levels. The pharyngeal airway was decreased by 16, 19, and 8% from baseline at 12 months postoperatively, respectively. The upper airway length was significantly increased immediately after surgery (P < .001), but was incompletely recovered at 12 months postoperatively. CONCLUSION: The outcomes of this study indicate that the pharyngeal airway gradually recovers over time. An immediate postoperative reduction in pharyngeal airway space can induce or exacerbate obstructive sleep apnea symptoms; thus, any pre-existing symptoms should be screened and considered for surgical treatment planning.

Effect of posterior impaction and setback of the maxilla on retropalatal airway and velopharyngeal dimensions after two-jaw surgery in skeletal Class III patients.

OBJECTIVE: To evaluate the changes in retropalatal airway and velopharyngeal dimensions after posterior impaction (PI) only or PI and setback (PI/SB) of the maxilla in patients with skeletal Class III undergoing two-jaw surgery. MATERIALS AND METHODS: Subjects consisted of 60 Class III patients treated with two-jaw surgery. They were divided into two groups: group 1 (n  = 30; PI of the maxilla; mean  =  2.6 mm) and group 2 (n = 30; PI/SB of the maxilla; mean  =  2.8 mm and 1.8 mm, respectively). Using three dimensional computed tomography images taken 1month before surgery (T0) and at least 6 months after surgery (T1), retropalatal airway volume, minimum cross-sectional area, and lateral and anteroposterior (AP) dimensions of minimum cross-sectional area, soft palate angle, soft palate length, and pharyngeal depth were measured. A paired t-test and independent t-test were used for statistical analysis. RESULTS: Group 1 showed increase in retropalatal airway volume and minimum cross-sectional area (P < .01 and P < .05, respectively). Group 2 exhibited decrease in retropalatal airway volume, minimum cross-sectional area, and lateral and AP dimensions of minimum cross-sectional area (all P < .01). Although groups 1 and 2 showed an increase in soft palate length (P < .01 and P < .001, respectively), pharyngeal depth significantly increased only in group 1 (P < .01). Groups 1 and 2 were significantly different in retropalatal airway volume, minimum cross-sectional area, and AP dimension (P < .05, P < .001, and P < .05, respectively). CONCLUSION: Because the direction of surgical movement in the maxilla can determine the changes in the retropalatal airway and velopharyngeal dimensions, it is recommended that clinicians investigate whether patients suffer from sleep-related breathing disorders before performing PI/SB of the maxilla.

Obstructive sleep apnea: awakening the hidden truth.

Obstructive sleep apnea (OSA) is a common type of sleep apnea and is caused by obstruction of upper airway. Sleep apnea is clinically defined as frequent episodes of apnea, hypopnea and symptoms of functional impairment, which could be life-threatening and associated with extreme daytime hyper somnolence, dysfunction, discrements in health-related quality of life, automobile accidents, and cardiovascular morbidity and mortality. Etiopathogenic factors that contribute to OSA include reduced upper-airway dilator muscle activity during sleep, upper-airway anatomical features, ventilatory control insufficiency, lung volume, and rostral fluid shifts. The presence of risk factors such as age, gender and obesity increases the incidence of OSA. The repetitive nocturnal hypoxemia experienced by patients with OSA is associated with activation of a number of neural, humoral, thrombotic, metabolic, and inflammatory disease mechanisms, all of which have also been implicated in the pathophysiology of various systemic diseases. This article summarizes the etiopathogenesis, epidemiology, associated systemic diseases such as cardiovascular diseases, diabetes, and dental diseases with OSA and the influence of tongue on oropharyngeal airway in OSA patients.

Anatomical status of the human musculus uvulae and its functional implications.

In our ongoing series of anatomical studies to determine the three-dimensional architecture of the human velar muscles, we have previously reported on the palatopharyngeus. The present study deals with the musculus uvulae (MU), in which the positional relationships of its origin to the posterior nasal spine and the palatine aponeurosis, as well as the interrelation between its anatomical status and functions, have yet to be clarified. Macroscopic and microscopic examinations were performed on 25 and 2 cadavers, respectively. In the former, bilateral MUs and their adjacent structures were exposed mainly from the nasal aspect. In the latter, the soft palates embedded in paraffin were cut into frontal and sagittal sections and alternately processed with HE and Azan stains. The left and right MUs adjacent to each other were found to run longitudinally along the midline beneath the nasal aspect of velum. It was overlaid by glandular tissue that increased in amount as it coursed distally. After originating from the oral surface of palatine aponeurosis, it ran backward to cross above the sling formed by the levator veli palatini muscles of both sides and reached the tip of uvula with its muscle fibers intermingled with glandular tissue. Past studies have proposed three functions of MU to enhance the efficiency of velopharyngeal closure: space occupier, stiffness modifier, and velar extensor. All of the above-described anatomical characteristics of MU could be explained as being adapted for these functions. This implies that MU is actively responsible for maintaining the velopharyngeal closure efficiency.

Modeling the pharyngeal anatomical effects on breathing resistance and aerodynamically generated sound.

The objective of this study was to systematically assess the effects of pharyngeal anatomical details on breathing resistance and acoustic characteristics by means of computational modeling. A physiologically realistic nose-throat airway was reconstructed from medical images. Individual airway anatomy such as the uvula, pharynx, and larynx was then isolated for examination by gradually simplifying this image-based model geometry. Large eddy simulations with the FW-H acoustics model were used to simulate airflows and acoustic sound generation with constant flow inhalations in rigid-walled airway geometries. Results showed that pharyngeal anatomical details exerted a significant impact on breathing resistance and energy distribution of acoustic sound. The uvula constriction induced considerably increased levels of pressure drop and acoustic power in the pharynx, which could start and worsen snoring symptoms. Each source anatomy was observed to generate a unique spectrum with signature peak frequencies and energy distribution. Moreover, severe pharyngeal airway narrowing led to an upward shift of sound energy in the high-frequency range. Results indicated that computational aeroacoustic modeling appeared to be a practical tool to study breathing-related disorders. Specifically, high-frequency acoustic signals might disclose additional clues to the mechanism of apneic snoring and should be included in future acoustic studies.

Prevalence of snoring and high risk of obstructive sleep apnea syndrome in young male soldiers in Korea.

There are little information on prevalence of obstructive sleep apnea syndrome (OSAS) and clinical features in the young military population. The purpose of this study was to estimate the prevalence of snoring and high risk of OSAS in young male soldiers in Korea and to identify the risk factors of OSAS. A total of 665 participants (aged 20-23 yr) who visited the Armed Forces Ildong Hospital for regular physical examination were enrolled. All participants completed the Berlin Questionnaire and underwent a physical examination. The participants with high risk for OSAS completed portable sleep monitoring. The prevalence of snoring and high risk of OSAS in young male soldiers in Korea was 13.5% and 8.1%, respectively. The prevalence of high arched palate, tongue indentation, long uvula, large tonsil and retrognathia was significantly higher in the high risk OSAS group. High arched palate, long uvula or low lying soft palate, tonsil size III or IV, Epworth Sleepiness Scale score > 10 and obesity (BMI > 27 kg/m(2)) were found to independently predict OSAS. For early identification and treatment of young soldiers with OSAS in a military environment, a precise screening by questionnaire and physical examination is needed.

Prevalence of Snoring and High Risk of Obstructive Sleep Apnea Syndrome in Young Male Soldiers in Korea

There are little information on prevalence of obstructive sleep apnea syndrome (OSAS) and clinical features in the young military population. The purpose of this study was to estimate the prevalence of snoring and high risk of OSAS in young male soldiers in Korea and to identify the risk factors of OSAS. A total of 665 participants (aged 20-23 yr) who visited the Armed Forces Ildong Hospital for regular physical examination were enrolled. All participants completed the Berlin Questionnaire and underwent a physical examination. The participants with high risk for OSAS completed portable sleep monitoring. The prevalence of snoring and high risk of OSAS in young male soldiers in Korea was 13.5% and 8.1%, respectively. The prevalence of high arched palate, tongue indentation, long uvula, large tonsil and retrognathia was significantly higher in the high risk OSAS group. High arched palate, long uvula or low lying soft palate, tonsil size III or IV, Epworth Sleepiness Scale score > 10 and obesity (BMI > 27 kg/m2) were found to independently predict OSAS. For early identification and treatment of young soldiers with OSAS in a military environment, a precise screening by questionnaire and physical examination is needed.

Three-dimensional reconstruction of soft palate modeling from subject-specific magnetic resonance imaging data.

PURPOSE: The objectives of this study were to extract a computational three-dimensional (3D) soft palate model from a set of magnetic resonance imaging (MRI) data and to identify an approach that generates a patient-specific model in a computerized visual platform. METHODS: Multiple MRI slices of the head and neck region of a young, non-overweight Caucasian male volunteer were taken in the supine position with a passive oral appliance in place. The DICOM (Digital Imaging and Communications) MRI slices were registered into a high-resolution volumetric data set for manually segmentation to generate a surface mesh and, with additional editing, a volume mesh. For biomechanical dynamic simulation and for physical simulation of the anatomical structures, the volume mesh format and multiple landmarks of each muscle were imported into ArtiSynth, a 3D biomechanical modeling toolkit. RESULTS: The segmented soft palate complex consisted of five groups of muscles: levator veli palatini, tensor veli palatini, palatoglossus, palatopharyngeous and musculus uvulae. The palatine tonsil between the pharyngopalatine and glossopalatine arches was included in the segmentation. CONCLUSIONS: The same procedure was used to build up a generic reference model of the dentition, tongue, mandible and airway from a mixture of medical records (CT and dental casts) of the same subject. This manual segmentation method eliminated the common errors that occur from an automatic segmentation although it was more time-consuming. It remains a fundamental process for analyzing the dynamic interaction between anatomical components in the oral, pharyngeal, and laryngeal areas.

Gross anatomical study of the human palatopharyngeus muscle throughout its entire course from origin to insertion.

The palatopharyngeus (PP) extends throughout the entire length of the pharynx and probably plays an important role in deglutition, but its spatial distribution remains undefined in some respects. This study was designed to clarify the exact distribution of the PP indispensable for understanding its functions. Using 50 cadavers, the PP and its neighboring muscles were bilaterally exposed in both surfaces of the pharynx. The PP was composed of two divisions: longitudinal and transverse. It is already known that the longitudinal PP is divided into two fasciculi sandwiching the levator veli palatini (LVP) immediately after originating from the palatine aponeurosis. However, we newly discovered a fasciculus originating from the uvula, and further regarded the salpingopharyngeus as another fasciculus of origin. The four fasciculi united to descend through the palatopharyngeal arch and inserted into the thyroid cartilage and beneath the mucosa of the hypopharynx. The transverse PP occupied a location transitional between the PP and superior constrictor (SC), where it originated from the palatine aponeurosis and passed dorsally to encircle the pharyngeal isthmus and reach the pharyngeal raphe. Although whether it belongs to the PP or SC has remained controversial, we regarded it as a portion of the PP from the evolutionary perspective and proposed anatomical criteria for differentiating it from the SC. The wide distribution of the PP suggests that it acts not only to elevate the pharynx or depress the soft palate, but also as a nasopharyngeal sphincter when closing the pharyngeal isthmus.

Does the length of uvula affect the palatal implant outcome in the management of habitual snoring?

OBJECTIVES/HYPOTHESIS: To evaluate the impact of the uvular length on the efficacy of palatal implants in primary snoring. STUDY DESIGN: Prospective case series, tertiary hospital, snoring and respiratory sleep disorders center. METHODS: Forty subjects with inserted palatal implants and diagnoses of primary snoring were included. All met the inclusion criteria of age >18 years, body mass index <30, apnea-hypopnea index <5, tonsil grade <3, soft-palate length >25 mm, and Friedman tongue position <3 following clinical, endoscopic, and polysomnographic evaluation. Epworth sleepiness scale (ESS) and the snoring-intensity visual analogue scale (VAS) were recorded before and 9 months after the implant. Four subjects with extruded implants were excluded; the remaining 36 subjects were divided into two groups, Group I and Group II, with uvular lengths of ≤15 mm and >15 mm, respectively. The study assessed and compared subjective outcome measures including the partner's satisfaction (PS), partner's reported improvement (PRI), 50% VAS and ESS reduction, and subjective success (SS) defined as 50% VAS reduction. The Student t test, χ(2) test, and logistic regression models were used for statistical evaluation. RESULTS: SS (50% VAS reduction), PS, PRI, and 50% ESS reduction were significantly higher in Group I (P < .001, P = .0257, P = .027, P < .001). The overall SS, PRI, PS, and 50% ESS reduction were 33%, 78%, 50%, and 50%, respectively. The uvular length was found to be the determinant factor of SS (P = .005; odds ratio = 0.75), PRI (P = .039; odds ratio = 0.83), and 50% ESS reduction (P = .038; odds ratio: 0.84) following implant insertion through stepwise logistic regression analysis. CONCLUSIONS: Excess uvular length (>15 mm) is an important anatomic feature decreasing the efficacy of palatal implants in snoring, and additional measures, such as uvulectomy, should be considered simultaneously for better outcomes (level 4).

Modified Mallampati classification as a clinical predictor of peroral esophagogastroduodenoscopy tolerance.

BACKGROUND: Unsedated esophagogastroduodenoscopy (EGD) is simpler and safer than sedated EGD; however, approximately 40% of patients cannot tolerate it. Early identification of patients likely to poorly tolerate unsedated EGD is valuable for improving compliance. The modified Mallampati classification (MMC) has been used to evaluate difficult tracheal intubation and laryngoscope insertion. We tried to assess the efficacy of MMC to predict the tolerance of EGD in unsedated patients. METHODS: Two hundred patients who underwent an unsedated diagnostic EGD were recruited. They were stratified according to the view of the oropharynx as either MMC class I + II (good view) or class III + IV (poor view). EGD tolerance was assessed in three ways: gag reflex by endoscopist assessment, patient satisfaction by interview, and the degree of change in vital signs. RESULTS: MMC was significantly correlated to gag reflex (P < 0.001), patient satisfaction (P = 0.028), and a change of vital signs (P = 0.024). Patients in the poor view group had a 3.87-fold increased risk of gag reflex (P < 0.001), a 1.78-fold increased risk of unsatisfaction (P = 0.067), and a 1.96-fold increased risk of a change in vital signs (P = 0.025) compared to those in the good view group. CONCLUSIONS: MMC appears to be a clinically useful predictor of EGD tolerance. Patients with poor view of oropharynx by MMC criteria may be candidates for sedated or transnasal EGD.

Uvulo-glossopharyngeal dimensions in non-extraction, extraction with minimum anchorage, and extraction with maximum anchorage.

The aim of this study was to investigate upper respiratory airway dimensions in non-extraction and extraction subjects treated with minimum or maximum anchorage. Lateral cephalograms of 39 Class I subjects were divided into three groups (each containing 11 females and 2 males) according to treatment procedure: group 1, 13 patients treated with extraction of four premolars and minimum anchorage; group 2, 13 cases treated non-extraction with air-rotor stripping (ARS); and group 3, 13 bimaxillary protrusion subjects treated with extraction of four premolars and maximum anchorage. The mean ages of the patients were 18.1 ± 3.7, 17.8 ± 2.4, and 15.5 ± 0.88 years, respectively. Tongue, soft palate, hyoid position, and upper airway measurements were made on pre- and post-treatment lateral cephalograms and the differences between the mean measurements were tested using Wilcoxon signed-ranks test. Superior and middle airway space increased significantly (P < 0.05) in group 1. In group 2, none of the parameters showed a significant change, while in group 3, middle and inferior airway space decreased (P < 0.01). The findings show that extraction treatment using maximum anchorage has a reducing effect on the middle and inferior airway dimensions.

Organization of the pontocerebellar projection to the paramedian lobule and caudal vermis: a retrograde fluorescent tracer study in the rabbit.

Following paired injections of fluorescent tracers into the unilateral paramedian lobule (PML) and uvula (Uv) as well as the pyramis (Pr) and Uv, the distribution pattern of retrogradely labeled neurons in the pontine nuclei (PN) indicates a high degree of topographic organization in the pontocerebellar projection. This projection originates from neurons clustered in two groups located laterally and medially in relation to the course of the pyramidal tract fibers. The rostral part of the PN supplies the Uv, while its caudal part sends fibers to the PML and Pr. Neurons in defined regions of the individual PN project independently to the lobules under study, although there are also small regions in which neurons connected with the PML and Uv, and with the Pr and Uv, are intermingled. In spite of this, none of these neurons projects by axonal collaterals. The projection is bilateral, with an over two times contralateral dominance, and arises from the dorsolateral, paramedian, lateral, and peduncular PN. The PML and Uv receive profuse connections (45 and 43%, respectively), and the Pr receives moderate connections (12%). The involvement of the individual PN in the projection differs between the target lobules: the dorsolateral nucleus is the primary source of projection (45%), while the participation of the paramedian, lateral, and peduncular nuclei is successively smaller (25, 18, and 12%). This is the first report describing the organization of PML/Uv and Pr/Uv projections from rabbit PN. Comparisons with the same projections in other species are made and possible functions are discussed.

Microscopic relation of palatopharyngeus with levator veli palatini and superior constrictor.

The aim of this study was to elucidate microscopic relation between the levator veli palatini, palatopharyngeus (PP), and superior constrictor (SC) muscle in transverse, parasagittal, and coronal sections.In 10 Korean adult cadavers, the entire soft palate was removed, trimmed, and preserved in 10% neutral buffered formalin. Specimens were embedded in paraffin and sectioned at a thickness of 10 mum. Blocks were cut the course of levator veli palatini. Also, transverse, parasagittal, and coronal section were made, stained using Masson trichrome, and observed under light microscope.Levator veli palatini was inserted between mucous gland anteriorly and musculus uvulae posteriorly in the midline of the soft palate, where they interdigitated with those in the contralateral side. Palatopharyngeus originated from the palatine aponeurosis and posterior mucosa of the soft palate. Most of the fibers of the PP did not cross the midline in their origin; however, some fibers interdigitated across the midline. As PP went downward and crossed the levator, it divided into anterior fasciculus and posterior fasciculus. Anterior fasciculus was thick and went downward along the anterolateral side of the levator. Posterior fasciculus was thin and widely spread along the posteromedial side of levator. Below the levator, 2 fasciculi united and were inserted to the medial side of SC. There were close attachment between the PP and SC.A detailed understanding of the microscopic relationship between the levator veli palatini, PP, and SC muscle is desirable for performing pharyngeal flap surgeries.

La historia de la úvula / The history of the uvula

La doctrina humoral reinó en Medicina por más de veiticinco siglos y dentro de esta teoría, la úvula, fue un órgano de gran importancia, actuando como receptor y regulador del mucus cerebral y como moderador del aire inspirado. Sus afecciones fueron tratadas obsesivemente con gárgaras, toques, fumigaciones, cauterizaciones y procedimientos quirúrgicos hasta hace poco más de cien años. La importancia de la úvula perdió rerlevancia con el advenimiento del siglo XX, y es así que la encontramos opacamente mencionada en las primeras citas que mereció en la literatura especializada del Río de la Plata. Una enfermedad relativamente nueva y poco frecuente, la apoplejía de la úvula es objeto de atención especial. (AU)

Interexaminer agreement of Friedman tongue positions for staging of obstructive sleep apnea/hypopnea syndrome.

OBJECTIVE: To determine if strong interexaminer agreement exists in identifying Friedman tongue positions (FTPs) for staging of obstructive sleep apnea/hypopnea syndrome (OSAHS). STUDY DESIGN AND METHODS: Twenty-six digital video clips of oropharyngeal examinations were prepared to demonstrate FTPs I through IV. Specific parameters for each FTP were provided to 126 examiners (otolaryngology residents, attendings, and fellows). The video clips were then presented to the examiners to determine the FTP. Kappa statistical analysis was used to evaluate the degree of intergrader agreement or disagreement. RESULTS: A generalized kappa statistic of 0.8 is considered the upper limits of substantial agreement. Thus, the overall kappa value (0.82) as well as all the subgroup kappa values for attendings (0.84), fellows (0.87), and residents (0.84) represented "very good" agreement. CONCLUSION: The strong interexaminer correlation of FTP demonstrated by this study indicates that FTP may be a useful adjunct in describing hypopharyngeal anatomy in patients with OSAHS.

Topography of olivocerebellar projections to the uvula and paramedian lobule in the rabbit: comparison with other species.

The organization of projections from the inferior olive (IO) to the uvula of the vermis and the paramedian lobule (PML) of the same hemisphere in the rabbit cerebellar cortex was studied using retrograde tracers: Diamidino Yellow (DY) and Fast Blue (FB) dyes were injected unilaterally into these two targets in the same animals. The distribution patterns of DY- and FB-labeled neurons consistently detected in spatially separate regions of the contralateral IO subnuclei show that the IO-uvular and IO-PML projections display a distinct topography. The absence of double labeling indicates that no neurons project divergently to both the uvula and PML. The lateral and medial regions of the medial accessory olive and of the ventral lamina of the caudal principal olive project to the uvula and PML, respectively. Several neuronal groups at more rostral levels of the principal olive send fibers solely to the PML. The medial and lateral regions of the beta nucleus and the dorsomedial cell column supply the uvula and PML, respectively. Neurons in the dorsal cap and the ventrolateral outgrowth also tend to display this type of localization. Moreover, the caudal part of the dorsal accessory olive and the dorsal lamina of the principal olive project exclusively to the PML. The most caudal and rostral aspects of the IO do not participate in projection. Topographical relationships in the IO-uvular and IO-PML projections have not been previously demonstrated in the rabbit, and they are discussed in the context of inter-animal differences and cerebellar zonal organization. The possible functional significance of the connections is also discussed.