Reticular System Flashcards
sensory, motor, and autonomic functions
- sleep and wakefulness cycles
- consciousness
- and the regulation of emotional behavior.
reticular formation
represents a phylogenetically older region of the brain because it is found in the core of the brainstem of lower forms
reticular formation
- lateral third of the reticular formation contains small-sized cells
- receive afferent fibers from both neighboring regions of the brainstem as well as from distant structures
parvocellular regions
medial two thirds of the reticular formation contains different groups of large- sized cells
magnocellular regions
At least ___ distinct magnocellular regions in the pons and ___ large region in the medulla
two; one
produce serotonin that is distributed to wide regions of the brain and spinal cord
raphe nuclei
reticular formation receives inputs from ___ and ___ regions associated with sensory modalities as well as from structures associated with motor functions
brainstem; forebrain
pain and temperature signals are contained within the ___, which passes directly from the spinal cord to the contralateral ventral posterolateral nucleus of the thalamus
lateral spinothalamic tract
which sensory and other inputs to the reticular formation can modulate cortical neurons, cortical excitability, and states of consciousness
reticular activating system
received by a number of limbic structures (amygdala, hippocampal formation, and septal area)
secondary olfactory signals
receive significant inputs from two key regions associated with motor functions: the cerebellum and sensorimotor cortex
magnocellular nuclei
The reticular formation and ___ share reciprocal connections, which complete a circuit comprising feedback pathways between these two regions for the regulation of motor functions associated with each of these two structures
cerebellum
Cerebellar fibers that project to the reticular formation of the medulla and pons arise from the
fastigial nucleus
The fibers are both crossed and uncrossed and use the ___ (the pathway that passes just dorsal to the superior cerebellar peduncle).
uncinate fasciculus
terminate in the pons and medulla near cell groups that give rise to the reticulospinal tracts
corticoreticular fibers
influence both voluntary as well as reflex motor functions by acting on those neurons of the reticular formation that control extensor motoneuron activity
corticoreticular fibers
primary afferent fibers contained in cranial nerves
(CN) IX and X.
fibers arising from higher order autonomic integrative regions, which include the ___, as well as parts of the ___.
hypothalamus; limbic system
transmit both chemoreceptor and baroreceptor afferent signals to the brainstem.
glossopharyngeal and vagus nerves (CN IX and X)
signals arise from the aortic and carotid bodies
chemoreceptors
signals arise from the aortic arch and carotid sinus
baroreceptors
chemoreceptors and baroreceptors terminate in the
solitary nucleus
- Secondary neurons located in the solitary nucleus then project to the ___ and the ventrolateral medullary depressor areas located in the medullary reticular formation.
- this information is important for reflex regulation of blood pressure and respiration
nucleus ambiguus
of the brainstem reticular formation that provide basic mechanisms for the control of blood pressure, heart rate, and respiration
autonomic regions
These regions of hypothalamus project most heavily to the midbrain ___ and neighboring regions of the dorsal and lateral tegmental fields of the reticular formation
PAG
contains cells whose axons travel long distances
reticular formation
The reticular formation contains cells whose axons travel long distances. Some ascend to the ___, and others descend to the spinal cord or project to the ___
forebrain; cerebellum
efferent fibers that travel long distances arise from the ___ of the reticular formation, and those that travel only short distances as interneurons lie mainly in the ___ of the reticular formation.
medial two thirds; lateral third
The main dendritic branches of the neurons are oriented in a ___ perpendicular to the long axis of the brainstem
plane
Cells situated in the medial two thirds of the reticular formation of the medulla and pons give rise to ___ that travel for long distances in both directions
bifurcating axons
involve projections from the reticular formation to the intralaminar nuclei of the thalamus
first two mechanisms
involves direct projections from monoaminergic neurons of the reticular formation to the cerebral cortex
third mechanism
- low-frequency stimulation of nonspecific thalamic nuclei produces a distinctive cortical electrical pattern called a ___
- This response is characterized by a surface negative wave, which reaches a maximum amplitude rapidly and then slowly decreases in size.
recruiting response
The behavioral response noted from such stimulation of the nonspecific thalamus is that the patient has a
drowsy apperance
- highly important because it serves to change excitability levels of the cortex so that they will become more receptive to other sensory inputs that reach the cerebral cortex through the classical ascending sensory pathways.
arousal
- cortical desynchronization
- enables the individual to respond in an appropriate way that generates conscious awareness of these stimuli
beta rhythm
- high spinal transection
- the cortical arousal pattern is retained
encΓ©phale isolΓ© preparation
- one produces a transection rostral to the trigeminal nerve
- the EEG pattern that results is characteristic of a sleeping animal.
cerveau isolΓ© preparation
arise from different regions of the brainstem to supply the entire CNS, including the cerebral cortex, hypothalamus, and limbic system
monoaminergic neurons
give rise to serotonergic projections
raphe neurons
gives rise to noradrenergic projections
nucleus locus ceruleus
contains dopaminergic neurons that project to the entire forebrain with the exception of the neostriatum
ventral tegmental area
- fibers arising from the pons form the medial reticulospinal tract and issue from the ____ and ___
- pass in the ventral funiculus of the spinal cord
- facilitate both alpha and gamma motor neurons of extensors
nucleus reticularis pontis oralis and nucleus reticularis pontis caudalis
- fibers from the medulla arise from the ___, such as the nucleus gigantocellularis
- descend in the ventral funiculus as the lateral reticulospinal tract, where they also terminate on alpha and gamma motor neurons of extensors
magnocellular nuclei