Reticular Formation & Movement Flashcards
What are some functions of the reticular formation?
Input from all sensory modalities, motor (postural adjustments, pattern generator, etc.), forebrain modulation (sleep, cortical arousal), visceral fxn, pain modulation
What is the function of reticular formation in midbrain and rostral pons?
Modulate forebrain
What is the function of the RF in caudal pons and medulla?
Modulate motor/visceral function
Where is the RF?
Poorly differentiated, in the tegmentum of brainstem
What are the 5 descending motor tracts to cord?
CST, rubrospinal tract (red nuc), pontine reticulospinal, medullary reticulospinal, lateral vestibulospinal
What are the 5 brainstem motor areas?
Red nuc (rostral midbrain), mesencephalic motor area (PPtN, caudal mid, rost pons), pontine motor area (caudal pons, MPRF), medullary motor area (rost med), vestibular complex (rost med)
What does the red nucleus do?
Flexes elbows
What does the PPtN/mes motor area do? Where does it project? What other functions is it involved with?
Posture, basic motor programs like walking; NOT to cord, modulates pontine and medullary motor areas; ACh and glut neurons linked to cortical arousal, REM sleep
What does the pontine motor area do?
Desc pontine reticulospinal motor fibers, extensors, also overlaps area linked to REM sleep, called MPRF (medial pons RF)
What does the medullary motor area do?
Med retic tract for posture, basic motor programs like walking
What does the vestibular complex/lateral vestibulospinal tract do?
Extends elbow/knee, plantar flexion of ankle - “fights gravity”
What is constraint-induced movement therapy?
Force person with spastic paralysis upper limb to use it, improves fxn perhaps due to rubrospinal latent function
What modulates the MRF and PRF?
Mesencephalic motor area/PPtN, MRF by cortex also
What modulates the vestibular complex?
Vestibular and spinal cerebellum
What modulates the red nucleus?
Pontocerebellum, and cortex (inhibits)
What is decerebrate rigidity? Decorticate rigidity?
Decerebrate: extensor rigidity/posturing
Decorticate: flexor rigidity/posturing
What does midbrain damage inferior to the red nucleus cause?
Extensor rigidity because of unopposed lateral vestibulospinal tract
What does damage superior to red nucleus cause?
Disinhibited elbow flexion because red nuc not inhibited by cortex, knee extension (lat vestibulospinal)
Does flexor or extensor rigidity indicate a better outcome for coma?
Flexor because no brainstem involvement
What are other brainstem signs in coma?
Mid: lose CN 3 (fixed dilated pupil, no consensual light reflex)
Pons: lose 5/7 (no jaw-jerk or corneal reflex)
Med: lose 9/10 (no gag, tracheal cough, lose breathing)
What are RF viscerosensory functions?
Solitary nuc: cardiovascular, resp, GI, liver, gustation
What are cardiovascular control areas of RF?
Medullary pressor area (glutamate, adrenergic, maintains symp tone, tonically active), depressor area (GABA, noradrenergic), baroreceptor response
Where is the medullary pressor area? How does it control sympathetic tone?
Rostral anterolateral medulla, overlaps ALQ; projects to ACh pregang symp in IML column, which fires postgang NE neurons to heart/vessels
Where is the medullary depressor area? How does it control sympathetic tone?
Caudal anterolateral medulla, overlaps ALQ; inhibits pressor area with GABA, inhibiting firing of IML column
Describe the baroreceptor reflex pathway.
CN 9/10 viscerosensory input aortic/carotid stretch receptors -> sol nuc -> GABA in depressor -> inhibits pressor. Sol nuc ALSO -> DMNX and ambig to increase PSNS
What are the respiratory cell groups in the medulla?
Posterior/dorsal area and anterior/ventral groups
Where is the post resp area? Where does it receive input from, and what is it for?
Distinct part of solitary nucleus; input from pulmonary stretch receptors (CN X), pace maker system for breathing
Where are the anterior respiratory cell groups? What do they do?
Anterolateral caudal medulla near depressor group over ALQ; inspiration group (to phrenic) and expiration group (to thoracic/lumbar LMN)
