Reticular Formation Anatomy

What is reticular formation

neuronal network, making tracts with polysynaptic connections, in brainstem

Reticular formation - function

muscle motor, somatic and visceral sensation, autonomic, endocrine, rhythms and consciousness

Lateral zone of nuclear groups

lateral third of tegmentum (medulla oblongata and pons), parvicellular

Intermediate zone of nuclear groups

middle third of brainstem, magnocellular

Median zone of nuclear groups - location

in median and paramedian of brainstem

Periqueductal and periventricular nuclei - location

around aqueduct and 4th ventricle

Role of non-specific thalamic nuclei

cortical diffuse projections of info via RAS (reticular activating system)

Intralaminary nuclei

in intermedullary lamina of thalamus, connects w/ limbic areas and reticular formation, makes RAS

Midline/paraventricular nuclei

thirdventricle, connects limbic and visceral functions

Reticular thalamic nucleus

in external medullary lamina, selective attention and projection monitoring function

Reciprocal connections of reticular formation with CNS makes :

self-control circuits/nervous impulse amplification systems

Lateral zone receive afferences from

somatosensitive, somatomotor, vegetative and reticular pathways

Spinal cord receive afferences from

spinoreticular tract and ascending pathways

Brainstem receives afferences from

nuclei of cranial nerves and quadrigemeinal colliculi

Cerebellum receives afferences from

precerebellar nuclear groups

Hypothalamus, pallidum, limbic system and cortex receive afferences from

central tegmental fascicle, mammilotegmental tract and median forebrain bundle

Direct fibers to cortex

extrathalamic reticulocortical fibers

Indirect fibers to cortex

reticulo-thalamo-cortical fibers

Reticular activating system

made of reticular efferences dispersed through cortex and limbic system, internal activation of cortex

Function of reticular activating system

controls excitability, sleep-wake cycle

Descending efferences of reticular neuron

groups into reticulospinal tract, somatosensitive, nociceptive and vegetative

Short descending efferences (reticulobulbar tract)

to nuclei of cranial nerves, for reflex coordination, eye movement, cardiovascular, respirator, deglutition

Ascending spinoreticular tract

in lat spinal cord, part of ant-lat spinothalamic system

Lateral reticulospinal/bulboreticulospinal tract

in bulbar magnocellular nuclei that descend in lat cord, ends in int spinal cord, controls respiration and cardiovascular reflexes

Medial reticulospinal/pontoreticulospinal tract

descends in ant cord, ends in interneurons of ant horn, controls neuron excitability and spinal voluntary and reflex movements