NEURO 375 RETICULAR FORMATION PRACTICE TEST QUESTIONS AND ANSWERS 2024.

What is the reticular formation? - organized on a macroscopic level - loosely arranges cell bodies intermingles with bundles of axons - extends upwards to the level of the thalamus - extends downwards to be continuous with the spinal cord what are the distinct functions of the reticular formation 1. controlling arousal and consciousness - RAS - involved in sleep (especially REM) - biological clock) 2. Reticulospinal tract (help maintain tone and posture) 3. Involved in autonomic relays (lateral zone - cardiac, respiratory, viceral...) 4. Perception of pain (caudal raphe nuclei) what are the afferents to the reticular formation - ALL sensory pathways (general or special sensory) - cerebral cortex - basal ganglia - vestibular nuclei, visual pathway - Thalamus and hypothalamus what are the efferent projections of the reticular formation - reticulobulbar and reticulospinal - descending sympathetic and parasympathetic outflow of ANS - cerebellum - basal ganglia - Thalamic and hypothalamic nuclei what are the three zones of the reticular formation 1. Raphe nuclei (midline) 2. Medial zone 3. Lateral zone what are the nuclei of the reticular formation - raphe nuclei (serotonergic) - central group of nuclei (for descending reticulospinal and ascending central tegmental tracts) - cholinergic nuclei (for motor functions, consciousness and arousal) - Catecholinergic nuclei (substantia nigra = DA, locus coeruleus = NA pathway) - nuclei for cardiovascular centres - nuclei for viceral sensations raphe nuclei - project to limbic system - rostral projections = affects sleep patterns - caudal projections : - receive afferents from PAG - project to dorsal horn of spinal cord to release serotonin to interneurons, causing them to release endorphins (endogenous opiates) to nociceptors (blocks pain transmission) reticular activating system lovated in the RF medial zone - ascending fibres of the reticular formation - receives input from several centers - projects to the thalamus - thalamus projects to the cortex to promote arousal and CONSCIOUSNESS - damage to medial zone = unconsciousness Lateral zone of the reticular formation - controls the cardiorespiratory "reflex" - receives inputs from glossopharyngeal nerve (IX) about chemo or baroreception to NST - NTS projects to the reticular zone respiratory centres (lateral zone to modulate DMNV output to control breathing and heart rate) - reticular formation neurons involved in respiratory and cardiovascular control are intermingled within the medulla - lesion / tumor in lateral zone = unconsciousness or death resticulospinal tracts are the major alternative rout to pyramidal tracts by which spinal motor neurons are are controlled - both directly and via regulating the sensitivity of spinal reflex arcs - recieve projections from substantia nigra, basal ganglia, vestibular nuclei, somatosensory and motor cotices medial zone reticulospinal tract controles posture and balance via axial / core musculature lateral zone reticulospinal tracts inhibits limb muscularture during sleep Pontine (medial) reticulospinal tract - excitatory to leg extensors and arm flexors - eg. tells hamstrings to contract as you bend over so you dont fall forward medullary (lateral) reticulospinal tract - inhibits nearly ALL limb musclulature during