Reticular formation Flashcards
What is the reticular formation?
Network of neurones from spinal cord to thalamus
What are the 3 zones in the reticular formation? Which nuclei will you find in each?
Median column (raphe nuclei)
Medial zone (magnocellular & gigantocellular nuclei)
Lateral zone (parvocellular reticular nuclei)
What are the functions of the neurones in each zone of the reticular formation?
Midline (raphe) contains serotonin (facilitatory or inhibitory)
Medial zone- motor output- source of long ascending and decsending projections
Lateral zone- sensory input- cranial nerve reflexes and visceral functions (gag reflex, respiration)
What is the over all function of the reticular formation?
Recives sensory and visceral information.
It acts as an important filter for the ANS. It Filters out unnecessary information – called habituation
Acts as a filter for all 5 senses, except smell.
What are the 4 main functions of RF?
- arousal responce
- Autonomic nervouse system control
- control of muscle tone and reflexes
- pain modulation
Name afferent and efferent conncetions for the RF
Afferent- cerebellum, cortex, thalamus, hypothalamus,
All senses except for smell pathways
Efferent- spinal cord, cortex, thalamus, hypothalamus, red nucleus substantial niagra
Which nucei is responsible for regulating posture? How does it do this?
Reticulo-spinal nuclei -
anticipates motor neuron reflexes to regulate posture before movement
Which parts of the RF control coordinated eye movements?
Paramedian pontine reticular formation (PPRF) – controls lateral eye reflex movements
Mesencephalic centres – controls vertical gaze
What is the lateral reflex? How is it controlled by the RF?
When one eye moves the other moves second, this happens so quickly it is un-noticed
The PPFR on the contralateral side respond through the medial longitudinal fasciculus (MLF) which combines CNIII, IV and VI to cause reflex movement on opposite eye.
What happens if the medial longitudinal fasciculus (MLF) is damaged?
Nystagmus- lost of co-ordinated eye movements- lateral eye reflex
Which visceral reflexes does the RF control? How does it do this
- Respiration,
- cardiovascular function,
- swallowing and vomiting, gag reflex
nucleus of the solitary tract (NST) is the main visceral sensory processing site.
reticulospinal tract carries the descending control to autonomic motor groups.
How does the RF control breathing?
Pontine Respiratory group- responsible for controlling breathing
Relays information to the medulla- controls movments of the muscles of expiration and there timing
Which part of the brain stem is responsible for control of respiration? What happens if it is damaged?
Medulla
cessation of ventilation
What is the afferent and efferent innervation for the gag reflex?
Afferent- carotid body via glossopharyngeal nerve (IX).
Efferent- Pharyngeal muscle via vagus nerve
What can disrupt the gag reflex?
damage/tumour at the jugular foramen.
