Reticular formation - NEUR532 Flashcards
What is reticular formation?
Neurons and neuronal fibres make a netlike (reticular) appearance
What does the retiticular formation exclude?
- The cranial nerve nuclei
- Brain stem long tracts
- Visible grey matter masses
- the medial lemniscus and the nucleus ambiguous
What do ascending reticular formation fibres contributes to?
- Sort sensory stimulation
- Determines where to focus attention
- Circadian rhythm
- Direct and indirect connections with all levels of the CNS
What do descending pathways do?
- Movement of head & body (voluntary and involuntary)
- Facilitate and inhibit movements
- Respiration, blood pressure, heart rate
- Analgesic pathways
- ANS
Reticular formation key elements:
- Neuronal core of brainstem
- Connection point between spinal cord and diencephalon
- Complex
- Disorganised
- Primitive
Where does the reticular formation network extend from the spinal cord?
- Spinal cord to the thalamus
- Connections to the medulla oblongata, midbrain (mesencephalon), pons, diencephalon
Where are these neurons/axons/dendrites interspesed within the CNS?
- Between cranial nerve nuclei and brainstem racts
Where are the reticular formation nuclei found ?
- DEEP WITHIN THE BRAINSTEM
HOW MANY GROUPS OF NUCLEI CAN THE RETICULAR FORMATION BE DIVIDED INTO?
3
What are the 3 groups of reticular formation nuclei?
- Lateral
- Medial
- Median (raphe)
How many groups are found throughout the lateral group of reticular nuclei?
3
How many of cell groups within the lateral reticular neuclei are catecholamine based?
2 (noradrenergic cells A1 - A7)
- Exlucsed A3 in primates
- Adrenergic cels C1 & C2
- Cholingeric cells Ch5 and Ch6
Aggregations of neurons are thereby recognized and are
called nuclei. These include:
the precerebellar nuclei
2. the raphe nuclei
3. the central group of nuclei
4. the cholinergic and catecholamine cell groups,
5. the lateral parvocellular reticular area,
6. the parabrachial area, and
7. the superficial medullary neurons.
PRECEREBELLAR RETICULAR NUCLEI are made up of?
- The lateral reticular nucleus
- The paramedian reticular nucleus, and
- The pontine reticulotegmental nucleus
What’s the function of precerebellar nuclei?
Cooordination and muscle contraction
Describe 4 key elements of the raphe nuclei
- In or adjacent to the midline (raphe) of the brainstem
- Interspersed among bundles of decussating axons
- Many rache neurons synthesize and secrete serotonin
- Serotonin (5-hydroxytryptamine) is principal synapetic transmitter
Describe 4 key elements of the raphe nuclei
- In or adjacent to the midline (raphe) of the brainstem
- Interspersed among bundles of decussating axons
- Many rache neurons synthesize and secrete serotonin
- Serotonin (5-hydroxytryptamine) is principal synapetic transmitter
Describe 4 things about serotonergic raphe neurons
- Thin
- Unmyelinated
- Greatly branched
- Extensively distributed to the grey matter of the CNS
The connections of the medullary raphe nuclei with
the periaqueductal grey matter and the spinal
dorsal horn (and trigeminal sensory nuclei) are
important because….?
- The activity of this pathway can suppress the conscious awareness of pain
The more rostrally located raphe nuclei play a significant role in what?
Sleep
Central group of reticular nuclei includes what 2 nuclei?
- Paramedian pontine reticular formation (PPRF)
- Gigantocellular reticular nuclei
What is the paramedian pontine reticular formation (PPRF) involved in?
- Lateral movements of the eyes
Where does the central nuclei receive afferents from?
all the general and special sensory systems
* from the reticular formation of the midbrain
* the cholinergic reticular nuclei,
* the hypothalamus, and
* the premotor area of the cerebral cortex.
What do the log descending axons from the central groups constitute?
Reticulospinal tracts
What are reticulospinal tracts important for?
Motor pathways
Ascending axons from the central group of reticular nuclei travel in the…?
Central tegmental tract
What involvement of the ascending projections contribute?
- Maintaining consciousness
The reticulothalamic projection also provides an interaction with the corpus striatum, providing what function?
Motor and other functions
Which direction is rostral and caudal?
- Rostral towards the front of the head
- Caudal towards the occipital lobe
What neutoransmitter does cholinergic neurons use?
Acetylcholine
How many groups of cholinergic neurons are there?
2
What are the 2 cholinergic nuclei?
- Pedunculopontine nucleus (larger)
- Lateral dorsal tegmental nucleus