Ner 19: Reticular Formation

Front 1

7 major functional groups of the reticular formation

Back 1

1) Cranial Nerve
2) Voluntary movements
3) ANS
4) Slow pain
5) Diffuse modulating systems
6) Respiration
7) Sleep, arousal, wakefullness

Front 2

Top 4 afferent connections to reticular formation

Back 2

1) Spinal cord - via spinoreticular projections which ascend in anterolateral fasiculus and terminate medially in medulla and pons
2) Cranial nerves - From secnonday sensory nuclei of CN trigem, auditory, vestibular, glossopharyngeal, and vagus.
3) Cerebellum - Impulses regarding equilibrium and posture arise from vesibular part of cerebellum and terminate in medulla.
4) Forebrain - Impulses descending from hypothalamus, thalamus, and basal ganglia terminate in midbrain. Cerebral cortex sensorimotor areas project to pons, medulla.

Front 3

Output of RF at caudal medulla through CNs

Back 3

1) Swallowing
2) Coughing
3) Gagging
4) Vomiting
5) Respiration
6) Cardiovasc reflexes

Front 4

Output of RF at pns/rostral medulla through CNs

Back 4

1) equilibrium
2) facial movements
3) horizontal gaze
4) mastication
5) blinking
6) auditory reflexes

Front 5

Output of RF at midbrain through CNs

Back 5

1) pupilary reflex
2) Ocular reflex
3) auditory reflex

Front 6

RF efferent tract effecting voluntary movements

Back 6

Impulses descend via reticulospinal tracts and influence axial and limb muscles.

Front 7

RF efferent tract effecting ANS

Back 7

Impulses from hypothalamus descend in medial reticular formation. Some synapse on para nuclei in RF. Others continue down spinal cord via lateral reticulospinal tract.

Front 8

Spainal lamina locations of fast pain vs slow pain

Back 8

Fast pain - More dorsal; lamina 1
Slow pain - More ventral 4-8

Front 9

Fast vs slow pain synapse locations in thalamus

Back 9

Fast - VPL of lateral thalamus
Slow - Medial part of thalamus (intralaminar and medial nuclei)

Front 10

TENS (trans electrical nerve stimulation fibers)

Back 10

Selective stimulation of larger touch fibers to treat chronic pain.

Front 11

Exogenous Pain Modulation

Back 11

Large cutaneous afferent nerve fibers for touch, when stimulated, send off collateral branches which synapse on interneurons in the substantia gelatinosa and other areas in the dorsal horn. These interneurons inhibit pain neurons.

Front 12

Endogenous Pain Modulation

Back 12

Neurons in periaquaductal gray of rostral midbrain and periventricular gray of adjacent diencephalon, when stimulated (by electrical signals or opiates), produce analgesia. Neurons in the aforementioned nuclei synapse on neurons of nucleus raphe magnus and surrounding reticular formation at the level of pontomedullary junction. These neurons then synapse on interneurons in substantia gelatinosa which inhibit pain.

Front 13

Locus Ceruleus

Back 13

Noradrenergic diffuse modulating system.
Located laterally in floor of forth ventricle in rostral pons. Axons distributed to entire cerebral cortex, thalamus, hypothalamus, cerebellum, midbrain, and spinal cord.
Increases brain responsiveness, speeding up info processing. Involved in regulation of attention, cortical arousal, sleep-wake, learning, memory, mood.

Front 14

Raphe Nuclei

Back 14

Serotonergic diffuse modulating system.
Medullary projections go to spinal cord to modulate slow pain. Pontine/midbrain projections go to thalamus, limbic nuclei, and cerebral cortex.
Involved in sleep/wake cycle, mood, emotion, aggression.

Front 15

Ventral trigeminal Area and Substantia Nigra

Back 15

Dopaminergic diffuse modulating system.
Substantia nigra projects to striatum, VTA projects to prefrontal cortex and limbic nuclei. VTA associated with reward and pleasure.

Front 16

Brainstem and forebrain diffuse modulating system

Back 16

Cholinergic
Pontine and midbrain nuclei project to thalamus - regulate excitability of sensory relay neurons.
Basal nucleus of meyhert project to cerebral cortex and regulate cortical excitability, memory, and learning. Degeneration of basal nucleus occurs in Alzheimers disease.

Front 17

RF contribution to respiration

Back 17

Respiratory center of RF located in ventrolateral medullary RF at level of caudal 4th ventricle. Chemo receptors in carotid artery and aorta which sense CO2 and O2, and carry info to solitary nucleus which then projects to RF. Sends reticulospinal fibers to phrenic nucleus at C3 and C4 and LMNs at T1-10 that innervate intercostals. bilateral lessions of this center in RF will lead to respiratory arrest.

Front 18

ARAS (ascending reticular activating system)

Back 18

Ascends from RF to cortex, is able to activate or inactivate the cortex and is responsible for consciousness. Damage can leads to coma.

Front 19

What 4 nuclei form the diffuse modulating system and what are their NTs?

Back 19

locus ceruleus - Nori
raphe - seritonin
ventral tegmental - dopamine
basal nucleus of meynert - Ach

Front 20

Lesion to what induces insomnia?

Back 20

Anterior hypothalmus

Front 21

Whats the first sign of an uncal herniation?

Back 21

Ipsilateral dilated pupils