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55 Cards in this Set

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what part of the brainstem has few histologically distinct nuclei thats critical for almost all motor and vegetative functions of the nervous system and regulation of arousal?
Reticular formation
where do the afferents of the reticular system come from?
sensory systems, cortex, hypothalamus, and thalamus
-integrative role of reticular formation
what are the three groupings that the reticular formation can be divided into?
midline raphe nuclei
medial columns
lateral columns
what are the functions of the midline raphe nuclei of the reticular formation?
primarily serotonergic
containing large neurons involving descending pain modulation, and in ascending activating systems
what are the functions of the medial columns of the reticular formation?
contains primarily large efferent neurons including those of reticulospinal tract
what is the function of the lateral columns of the reticular formation?
contains primarily parvocellular neurons that serve to relay somatic and visceral sensory information from ALS, trigeminal, and solitary nucleus to influence reticular formation efferent pathways
where are the visceral integrating centers found in the reticular formation?
caudal pontomedullary reticular formation
what is the function of the visceral integrating centers of the reticular formation?
control of heart beat, blood pressure, respiration, GI, gentiurinary control, reflexive behaviors
If the Pontomedullary reticular formation received bilateral damage what would be the prognosis of your paitent?
DEATH
where is the ascending reticular activating system located?
Rostral Pontomesencephalic reticular formation
If there is damage to the ascending reticular activating system what does this cause?
Irreversible coma because this system turns on the activity of the forebrain
what are the Cholinergic nuclei of the brainstem?
Pedunculopontine and laterodorsal tegmental nuclei
what are the Noradrenergic nuclei of the brainstem?
Locus Coerulus
Lateral Tegmental Area of Medulla
What are the Serotonergic nuclei of the brainstem?
rostral raphe nuclei
what region of the brainstem controls horizontal gaze?
PPRF in pons
what region of the brainstem controls vertical gaze?
rostral midbrain and pretectal area
where does modulation of pain occur?
midbrain: PAG
pons & medulla: raphe nuclei
what are the visceral integrating centers of the medulla?
LIFE SUPPORT
control blood pressure, heart rate, and respiration
Sensory input via IX, & X to solitary nucleus (GVA)
Effectors in dorsal motor nucleus of vagus, nucleus ambiguus, and spinal cord
where are the effectors of the visceral integrating centers located? what do they effect?
Effectors: dorsal motor nucleus of X, nucleus ambiguus, spinal cord
DMN X: GVE to heart, lungs, and gut to splenic flexure
what sensory information is relayed to solitary nucleus via IX and X?
Solitary nucleus is GVA
-sensation from chemoreceptors and baroreceptors of carotid body and aortic arch information
why is bilateral damage to the pontomedullary reticular formation life threatening?
lead to respiratory arrest because this is where the life support centers are located
-Tonsil herniation can result in uncompensated increase in intracranial pressure and compress these essential medullary centers
where does the pontine and medullary reticulospinal tract originate?
in pontine and medullary medial reticular nuclei
does the reticulospinal tract project contralateral or ipsilateral?
ipsilateral
what is the main function of the pontine and medullary reticulospinal tracts?
exert influence on LMN controlling proximal limb extensors and trunk
what tract is important for adjustments in posture and balance preceding and during voluntary movement, semi-automoatic movements involving coordination, and muscle tone?
Reticulospinal tract
why are hypertonicity and hyperreflexia observed following damage to UMN?
this is because of loss of descending control of the reticulospinal tract
If there is bilateral damage to the midbrain below the level of the red nucleus what will be observed in your patients?
DECERBRATE rigidity
this is due to unopposed activation of extensors by reticulospinal and vestibulospinal tracts
how does the reticular formation play a role in modulating brainstem reflexes?
it acts as a relay between the sensory input and the efferent limb
where do spinomesencephalic fibers project to?
PAG
where do the PAG neurons project to for modulation of pain?
raphe nuclei (raphe magnus) which is a serotonergic nuclei
where do the nucleus raphe magnus neurons project to for modulation of pain?
Nucleus raphe magnus is serotonergic and GABAnergic it projects to the spinal cord dorsal horn
where do raphe axons terminate? what is their function?
Raphe axons terminate on primary afferent terminals, interneurons, and second order neurons in the dorsal horn of spinal cord
-primarily inhibitory with regard to nociceptive afferent information
where do the chemoreceptors for blood oxygen, and pH of the lung project to? why?
directly and indirectly project through the solitary nucleus to medullary and pontine reticular nuclei controlling respiration
what are the nuclei of the dorsal respiratory group of involved in what part of respiration?
INSPIRATION
what are the subnuclei of the ventral respiratory group? when are they active?
Botzinger complex: expiration
Pre-Botzinger complex: inspiration
Rostral ventral respiratory group: inspiration
Caudal ventral respiratory group: expiration
what nuclei modulates respiration?
Medial parabrachial Kolliker Fuse area
if there is damage to medial parabrachial nucleus what does this cause?
Apneustic breathing
(match it to a lesion in our packet)
what lower motor neurons have inherent rhythms that drive resting patterns of respiration?
C3, C4, C5 give rise to phrenic nerve innervating the diaphragm
what brainstem nuclei must be coordinated for control of respiration?
XII: tongue
IX X: pharynx and larynx
XI: SCM & trapezius
VII: nares
what type of inputs mediate voluntary control over breathing and for regulation during talking, singing, playing a musical instrument?
Cortical inputs
in controlling blood pressure how is the information from the baroreceptors in the carotid sinus and aortic arch relayed to the brainstem?
CN IX & X carry sensory information from these receptors to solitary nucleus
solitary nucleus shares information with lateral parvocellular reticular nuclei in the lateral column
what activates baroreceptors in the aortic arch and carotid sinus?
increased blood pressure
what are chemoreceptors sensitive to?
oxygen, carbon dioxide, and blood pH
describe the baroreceptor reflex
1. PS neurons in inferior IX and nodose ganglia terminate in caudal solitary nucleus
2. solitary nucleus projects to control centers in medullary reticular formation and preganglionic neurons in nucleus ambiguus
3. Increased arterial pressure results in slowing of heart rate (X) and vasodilation (PS activation & sympathetics inhibition)
why does damage to the spinal cord result in spinal shock with reduced blood pressure?
lesioning of descending hypothalamospinal pathway
what type of drug is useful in controlling blood pressure?
Adrenergic antagonist
what part of the reticular formation controls GI and genitourinary function?
Pontine micturtion center
what type of coordination does coughing require?
coordination between nucleus ambiguus to prevent inspiration of irritant
what type of coordination does sneezing require?
involves coordination with n. ambiguus and facial n.
what are hiccups caused by?
involuntary inspiration caused by spasm of the diaphragm
what is the sound of a hiccup caused by?
rapid closing of vocal cords
what can cause intractable hiccups?
damage to medullary reticular formation
what is the pseudobulbar affect?
emotional incontinence
If a patient is suffering from pseudobulbar affect, what might be the symptoms and what caused this?
abnormal reflex activation of circuits for laughter and crying
-lesions of descending pathways or brainstem centers
True or False
The act of smiling is both voluntary and non-voluntary.
True
there is a reflexive smile and a voluntary smile
a patient may still be able to smile in response to a joke if they have a corticobulbar lesion contralateral voluntary paralysis of lower face because the facial nerve is still intact and muscles can be activated by the limbic pathways