Brainstem and reticular formation Flashcards
What are the tree functions of the brainstem?
conduit: info goes to cortex and spinal cord thru brainstem
cranial nerve: head’s version of spinal nn
integrative functions: complex motor patterns, cardiorespiratory control, reflexes
What does the STT detect?
pain and temp, some special touch
What does PCML pathway detect?
two point touch, vibration, pressure, conscious proprioception
What does corticospinal tract detect?
motor
What are the three areas of brainstem rostral to obex?
tegmenjtum = tissue ant to ventricle
tectum = post
stuff added onto ant surface
What structures are part of the medulla?
obex, pyramidal decussation, olive, cuneate tubercle, gracile tubercle, CNs IX, Xm XII
What structures are found in pons?
basal pons, middle cerebellar peduncle, CN V, VI, VII, VIII, superior cerebellar peduncle
Structures found in midbrain?
cerebral aqueduct, superior and inferior colliculus, CN II, IV, inferior brachium
Where does the caudal medulla extend?
caudal edge of pyramidal decussation to obex
Where does rostral medulla extend?
to lateral recess of 4th ventricle
Where does caudal pons extend?
lateral recess of 4th ventricle to middle cerebellar peduncle
Where does rostral pons extend?
top of middle cerebellar peduncle to vertebral aqueduct
What are the types of axons in a spinal n of the spinal cord?
- somatic sensory (paint, temp, mechanoreceptors)
- visceral sensory (GI, blood vessels)
- visceral motor (preganglionic autonomic)
- somatic motor (innervate skeletal mm)
What are the special CN functions?
special sensory = hearing, equilibrium
branchial motor = innervate mm derived from pharyngeal arches (larynx, pharynx, jaw, face)
How many different types of nerve fibers are in brainstem?
6
T/F No CN has all 6 types of axons
T
What is the central core of the brainstem?
reticular formation
Where does the reticular formation extend?
into cerebrum as hypothalamus
What is reticular formation important to regulate?
posture, some stereotypic motor behaviors, regulating internal environment, pain regulation, sleep and wakefulness, emotional tone
What are the longitudinal zones of the reticular formation?
- raphe nuclei
- medial zone
- lateral zone
What does the raphe nuclei zone produce?
serotonin
Where is the source of most ascending and descending projections of neurons?
medial zone
What does the medial zone do?
coordinates walking or running
Where is the lateral zone prominent?
rostral medulla and caudal pons
What is the lateral zone primarily involved in?
CN reflexes and visceral functions
What are the two reticulospinal tract? where are they?
medial = pons and lateral = medulla
Where does the lateral reticulospinal tract descend?
bilaterally in lateral funiculus
Where does medial reticulospinal tract descend?
ipsilateral near MLF and in ant funiculus
What is the major alternative to the corticospinal tract in regulating spinal motor neurons?
reticular formation - influences spinal motor neurons directly
What does reticular formation regulate?
spinal reflexes
Where does the reticulospinal tract receive input from?
cerebral cortex, basal ganglia, substantia nigra, etc
Which rhymes motor patterns does the brainstem reticular formation regulate?
gaze centers, mastication, locomotion (pons), heart rate, respiration, swallowing, vomiting
What are the gaze centers of reticular formation?
midbrain vertical gaze center and pontine horizontal
What are symptoms of sleep bruxism?
tooth grinding or clenching
- sounds, abnormal wear, jaw m discomfort
What happens to mm in sleep bruxism?
state of atonia, jaw mm co-contracted, mm of mastication all contracting at same time, increased tone in mm
What is the peripheral causes theory of bruxism?
malocclusion results in premature and one-sided contract, jaw movements continue in attempt to reach resting position
What is the central causes theory of bruxism?
sleep-related dysfunctions cause bruxism
- input to supratrige minal nucleus may be from basal ganglia, lateral hypothalamus and central nucleus of amygdala
where does PAG reticence pain info from?
spinomesencephalic fibers
Where does pain signal travel?
PAG to raphe -> posterior horn of spinal cord/ spinal V nucleus
What is one way opiates work to control pain?
activate PAG-raphe at multiple levels
How can raphe inhibit STT?
directly or indirectly by activating interneurons and can directly inhibit pain afferents
Where are centers controlling inspiration, expiration, breathing? heart rate and blood pressure?
pons and medulla
medulla
What projections work together to modulate cortical activity?
thalamic intralaminar nuclear projections to cortex and monoamine reticular projections
What results in prolonged coma?
bilateral damage to midbrain RF
What has a role in sleep-wakefulness cycle?
Ascending reticular activating system
What neurochemicals are in the brainstem? hypothalamus? telencephalon?
norepinephrine, dopamine, serotonin
histamine
acetylcholine
How does noradrenergic neurons function in the medulla?
solitary nucleus = memory enhancement
ventrolateral medulla = pain regulation
How do noadrenergic neurons in rostral pons function?
locus ceruleus = cortex (arousal) vigilance and attention
- active in attentive situations, moderate while awake and low when sleeping
What occurs when norepinephrine is released into trigeminal spinal nucleus and spinal cord?
suppress incoming pain signals
What is lost in patients with Parkinson’s disease?
locus ceruleus neurons
Where are dopamine neurons?
midbrain (substaita nigra and ventral segmental area)
What are the two components of schizophrenia?
social withdrawal and hallucinations
