Cerebellar peduncle

Midhrain and brainstem ventral tegmental area raphe nuclei superior cerebellar peduncle mesencephalic nucleus of trigeminal nerve substantia nigra nucleus coeruleus periaqueductal grey... 

Several types of abnormal movement are recognized. Tremor consists of a rhythmic oscillatory movement around a joint and is best characterized by its relation to activity. Tremor at rest is characteristic of parkinsonism, when it is often associated with rigidity and an impairment of voluntary activity. Tremor may occur during maintenance of sustained posture (postural tremor) or during movement (intention tremor). A conspicuous postural tremor is the cardinal feature of benign essential or familial tremor. Intention tremor occurs in patients with a lesion of the brain stem or cerebellum, especially when the superior cerebellar peduncle is involved it may also occur as a manifestation of toxicity from alcohol or certain other drugs. 

Fig. 1. Top Transverse sections through the human mesencephalon, as drawn by Theodor Meynert from preparations stained with gold and potassium chloride . Abbreviations (translated from the original legends in French) A, aqueduct Big.s., superior quadrigeminal tubercle Bri, geniculate body and its bundles Dcs, decussation of the superior cerebellar peduncle Krz.B., bundles of the anterior crossing, the X indicates the crossing L, posterior longitudinal bundle Lms, lemniscus after the decussation Pcbl, superior cerebellar...

PP, peripeduncular nucleus PR, prerubral field Reth, retroethmoid nucleus RMC, red nucleus, magnocellular RPC, red nucleus, parvocellular scp, superior cerebellar peduncle SNC, substantia nigra, compact part SNL, substantia nigra, lateral part SNR, substantia nigra, reticular part SPFPC, subparafascicular thalamic nucleus, parvocellular part SuML, supramammillary nucleus, lateral part VTA, ventral tegmental area VTM, ventral tuberomammillary nucleus ZID, zona incerta, dorsal part ZIV, zona incerta, ventral part 3, oculomotor nucleus 3n, oculomotor nerve or its root. Reproduced with permission from Paxinos and Watson (1998) and Paxinos et al. (1999). 

Blakemore WF (1973a) RemyeUnation of the superior cerebellar peduncle in the mouse following demyetination induced by feeding cuprizone. J Neurol Sci 20 73-83 Blakemore WF (1973b) Demyetination of the superior cerebellar peduncle in the mouse induced by cuprizone. J Neurol Sci 20 63-72... 

When Sprague-Dawley (CD) rats and B6C3F1 mice were exposed to nitrobenzene at 125 ppm daily for two weeks, damage to the hindbrain (cerebellar peduncle), including bilateral cerebellar perivascular hemorrhage and malacia (cell breakdown), was observed in 8/19 mice (both sexes) and in 14/19 rats (both sexes) (Medinsky and Irons 1985). No brain lesions were found in Fischer rats exposed to the same levels. The reason for these strain differences under similar conditions is not apparent. 

Neurological Effects. Neurotoxic symptoms reported in humans after inhalation exposure to nitrobenzene have included headache, confusion, vertigo and nausea (Ikeda and Kita 1964) effects in orally exposed persons have also included those symptoms as well as apnea and coma (Carter 1936 Leader 1932 Myslak et al. 1971). Studies in animals exposed via inhalation have shown morphological damage to the hindbrain (cerebellar peduncle) (Medinsky and Irons 1985). Damage to the brainstem, cerebellum and fourth ventricle was observed in orally exposed animals. Thus, it is possible that similar neurological changes may occur in humans as a result of nitrobenzene exposure. 

Fig. 99. Cerebellum of Macaca fascicularis. a. Anterior aspect, b. Ventral aspect, c. Caudal aspect, d. Dorsal aspect. Regions without cortex, where the white matter comes to the surface, are indicated with light hatching. Heavy hatching indicates cross section of the cerebellar peduncles, solid black indicates roof of the fourth ventricle in b. CrI = Crus I of the ansiform lobule CrII = crus II of the ansiform lobule FLO = flocculus fpl = posterolateral fissure PFLD = dorsal parafloculus PFLV = ventral paraflocculus PMD(cop) = paramedian lobule (copula pyramidis) SI = lobulus simplex.

The subdivision of Weidenreich-Ogawa received strong support from the localization of the fibers in the superior cerebellar peduncle. A small medial and a large lateral portion can be distinguished in this pathway in most mammals at its exit from the central nuclei (see in Fig. 102). Experiments in cat (Verhaart, 1956 Voogd, 1964) and rat (Haroian et ah, 1981) have shown that the medial part of the superior cerebellar peduncle takes its origin from the nuclei of the caudomedial group, mainly from the ipsilateral posterior interposed nucleus, and the lateral portion from the ipsilateral anterior interposed and lateral cerebellar nucleus. 

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