Reticular Formation

StudyBlue printing of Reticular Formation html, body, div, span, applet, object, iframe, h1, h2, h3, h4, h5, h6, p, blockquote, pre, a, abbr, acronym, address, big, cite, code, del, dfn, em, font, img, ins, kbd, q, s, samp, small, strike, strong, sub, sup, tt, var, b, u, i, center, fieldset, form, label, legend, table, caption, tbody, tfoot, thead, tr, th, td { margin: 0; padding: 0; border: 0; outline: 0; font-size: 100%; background: transparent; } body { line-height: 1; } blockquote, q { quotes: none; } blockquote:before, blockquote:after, q:before, q:after { content: ''; content: none; } /* remember to define focus styles! */ :focus { outline: 0; } /* remember to highlight inserts somehow! */ ins { text-decoration: none; } del { text-decoration: line-through; } /* tables still need 'cellspacing="0"' in the markup */ table { border-collapse: collapse; border-spacing: 0; } /* end RESET */ .header { min-width:800px; } .logo { padding:6px 20px 2px 20px; margin:0; font-size:25px; font-weight:bold; color:#808285; position:relative; border-bottom: 1px solid #c5c5c5; } .logo-blue { color:#70adc4; } .logo-desc { font-weight:normal; font-size:19px; color:#cccccc; margin-top:50px; position:absolute; display: none; } .back-button { position:absolute; top:20px; right:20px; font-size:13px; line-height:25px; color:rgb(0,175,225); font-weight:normal; } .back-button a { color:rgb(0,175,225); } .instructions { padding:0; margin:0; width:100%; position:relative; color:rgb(100,100,100); } .step-holder { border-left:1px solid #ededed; margin-left:20px; } .steps { padding:15px 0; float:left; width:24%; border-right:1px solid #ededed; text-align:center; } .steps-01 { } .steps-02 { } .steps-03 { } .steps-04 { } .label { padding:5px 10px; } .print-button { } .print-button a { background-color:rgb(0,175,225); color:white; line-height: 19px; padding:9px 8px 5px 30px; font-size:14px; text-decoration:none; background-image: url(images/printer.png); background-repeat: no-repeat; background-position: 7px 50%; -moz-border-radius: 5px; -webkit-border-radius: 5px; } .print-button a:hover { background-color:black; } .theNote .content { width: 8.0in !important; margin: 5px auto; padding:20px; background-color:white; } .theNote .header { border-bottom: 1px dashed #C8C8C8; font-size: 17px; padding: 0 0 10px; line-height: 19px; color: #00ADE1; min-width:500px; } .theNote .body { font-size: 14px; line-height: 19px; padding: 10px 0; } .theNote{ padding:6px 0; clear:both; background-color: rgb(200,200,200); } .theNote h3{ color: rgb(100,100,100); } .theNote h1, .theNote h3{ background-color:white; padding:2px 20px; width:8.0in !important; margin: 0 auto; font-size: 15px; } .theNote h1{ padding-top: 10px; font-size: 15px; } .theNote h1:first-child{ font-size: 20px; } .theNote h3 { font-size: 14px; font-weight: normal; } #options { border: 3px double #ccc; padding: 5px 12px; margin: 10px 50px 10px 20px; float: left; } #info { border-top: 1px solid #ccc; padding-top: 5px; font-style: italic; } li { margin: 5px 10px 5px 25px; } ul li { list-style: disc; } ol li { list-style: decimal; } img { border: 0; } table { clear: both; width: 100%; border: 1px solid #c5c5c5; border-width: 1px 0; margin: 0; page-break-after: always; } table#page { page-break-after: auto; } td { text-align: center; font-size: 12px; border-bottom: 1px dashed #c5c5c5; height: 1.75in; width: 50%; padding-left: 15px; } .leftside { border-right: 1px solid #cccccc; padding: 0 15px 0 0; } .bottom td { border-bottom: none; } .clearfix { clear:both; line-height:1px; height:1px; } img { max-width:80%; max-height:150px; margin:20px; } @media print {.header { display: none; } .content .header{ display:inherit; } table { border: 1px dashed #bbb; border-width: 1px 0; } .theNote{ background-color:white; } } Occupies core of the entire brain stem tegmentum, extending from midbrain, pons to medullary region. As can be seen in the slide, the RF region in both pontine and medullary regions is in the tegmentum, and is surrounded by motor and sensory nuclei of the cranial nerves in the region, and also by ascending and descending tracts. It interacts with ascending and descending fibers by means of dendrites, and communicates from midbrain to medulla via long axonal projections. Modulation of the sensory perception under certain stress, pain is not realized - this is mediated by the reticular formation. This can occur at 2 regions. - at the spinal cord, interneurons release enkephalin, an opioid that inhibits terminal ends of primary sensory neurons and projection neurons, thereby inhibiting pain. - at the thalamus, similar inhibition, preventing the signal from reaching the cerebrum modulation of visceromotor function visceral function is controlled by the ANS, mostly mediated by the hypothalamus. the reticular formation can influence this system by: - integrating the sensory signals from the viscera with the signals from the hypothalamus - controlling visceral motor nuclei in the brain stem and spinal cord Vomiting Sensory receptors from gastric mucosa send fibers (CN X) to nucleus of solitary tract. From here, info goes to the vomiting center of RF. From here, efferents go to all other regions: - parasympath nuc of X, motor nuc of XII, nuc ambiguus, and also to spinal LMN of intermeidolateral nuc (ANS) each of which plays a role in mediating vomiting and associated functions. modulation of spinal motor neurons 2 reticulospinal tracts - pontine and medullary pontine RS (ventral funiculus) - EXCITE alpha and gamma motor neurons of extensor muscles medullary RS (Lateral funiculus) - INHIBIT alpha and gamma " " both via interneurons present in ventral horn affecting muscle tone and spinal reflexes (overall, stimulation of the gamma motor neuron can lead to the stimulation of the alpha motor neuron - therefore, intrafusal muscle contraction can lead to extrafusal muscle contraction and affects muscle tone) -stimulation of gamma motor neurons by pontine rs contracts intrafusal muscles in the extensor muscle. (if there was a signal from medullary rs, it would be inhibitory, and therefore opposite) -contraction of the intrafusal muscle leads to activation of the sensory receptors of muscle spindle, and the monosynaptic reflex pathway, leading to the activation of alpha motor neurons (or LMNs). - the alpha motor neurons in turn lead to the contraction of the extrafusal muscles, increasing muscle tone. of course, if the alpha motor neuron is directly innervated, it would lead to contraction, but here stimulation of gamma motor neurons itself leads to contraction.