Oculomotor nucleus

There are a number of side-effects of opiates that are due to their actions on opiate receptors outside the central nervous system. Opiates constrict the pupils by acting on the oculomotor nucleus and cause constipation by activating a maintained contraction of the smooth muscle of the gut which reduces motility. This diminished propulsion coupled with opiates reducing secretion in the gut underlie the anti-diarrhoeal effect. Opiates contract sphincters throughout the gastrointestinal tract. Although these effects are predominantly peripheral in origin there are central contributions as well. Morphine can also release histamine from mast cells and this can produce irritation and broncho-spasm in extreme cases. Opiates have minimal cardiovascular effects at therapeutic doses. 

X2 NM 174873 Sensory and autonomic ganglia, dorsal and ventral horn of the spinal cord, thalamus, hypothalamus, preoptic area, red nucleus, oculomotor nucleus, locus coeruleus and dorsal motor nucleus of the vagus... 

Opioids elicit pupiiiary narrowing (miosis) by stimulating the parasympathetic portion (Edinger-Westphal nucleus) of the oculomotor nucleus. 

Fig. 6. (continued) thalamic nucleus VLps ventral lateral nucleus of the thalamus, pars postrema VPLc ventral posterolateral nucleus of the thalamus, caudal part III oculomotor nucleus. Scale bar 5 mm. 

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). 

Ml primary motor cortex 7-34, 81-89, 112-116 M2 secondary motor cortex 6-34, 80-86, 114-116 m5 motor root of the trigeminal nerve 46-59, 84-85, 90-97 MA3 medial accessory oculomotor nucleus 40-43, 79-80, 101-103 mcer middle cerebral artery 81 mch medial corticohypothalamic tract 21-22, 98-101 MCLH magnocellular nucleus of the lateral hypothalamus 31-33, 83, 94-95... 

Fig. 5. Drawing of the brainstem depicting neurons and pathways likely to use glutamate as a neurotransmitter. 1 = primary afferent inputs to the dorsal column nuclei (a), the solitary tract nucleus (b), and the cochlear nucleus (c) 2 = granule cell/parallel fibers in the dorsal cochlear nucleus 3 = calyces of Held in the medial nucleus of the trapezoid body 4 = cochlear nucleus inputs to the lateral superior olive 5 = input to the oculomotor nucleus from the ventral lateral vestibular nucleus 6 = input to the oculomotor nucleus from the abducens nucleus 7 = corticocollieular inputs 8 = spinal input to the periaqueductal gray 9 = inputs to the red nucleus and pontine nuclei from the cerebellar nuclei. For further details, see Section 3.3.

Similar to other projections from the cerebellar nuclei (except those to the inferior olive which are GABAergic), terminals of cerebellar origin in the red nucleus are enriched in Glu (Schwarz and Schmitz, 1997 Fig. 5). Enrichment of Glu has also been detected in terminals in the oculomotor nucleus originating from the abducens and ventral lateral vestibular nuclei (Nguyen and Spencer, 1999 Fig. 5). 

Nguyen LT, Spencer RF (1999) Abducens internuclear and ascending tract of Deiters inputs to medial rectus motoneurons in the cat oculomotor nucleus neurotransmitters. J Comp Neurol 4/7 73-86. 

Gacek RR (1977) Location of brain stem neurons projecting to the oculomotor nucleus in the cat. E.xp. Neurol, 57, 725-749. 

Simultaneously, the contralateral medial rectus muscle is stimulated by the contralateral Oculomotor Nucleus, and with the inhibition of the contralateral lateral rectus muscle via the Abducens Nucleus, a saccade occurs in the left eye. Thus the eyes move conjugately under the control of a single drive center. 

The ipsilateral FN stimulates the contralateral LLBN, EBN, and IBN. The contralateral EBN then stimulates the contralateral Abducens Nucleus. Further simulation of the contralateral IBN occurs from the contralateral LLBN. The contralateral IBN then inhibits the ipsilateral EBN, TN, and Abducens Nucleus, and contralateral Oculomotor Nucleus. With this inhibition, the stimulus to the agonist muscles ceases. 

The ipsilateral FN stimulation of the contralateral EBN allows for modest bursting in the contralateral EBN, which stimulates the contralateral Abducens Nucleus and Ipsilateral Oculomotor Nucleus. With... 

The burst firing in the ipsilateral IBN inhibits the contralateral EBN and abducens nucleus, and the ipsilateral oculomotor nucleus. 

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