RETICULAR FORMATION
RETICULAR FORMATION
- Grey matter present in core of brainstem.
- Neurons in this region form a network (reticulum) instead of well-defined tracts.
DIVISIONS:
- Functionally divided into,
- Lateral reticular formation
- Medial reticular formation
LATERAL RETICULAR FORMATION:
- Contains small local-circuit neurons forming “Reflex center” close to brainstem motor nuclei.
Centers included:
- Swallowing, coughing, sneezing, vasomotor & vomiting center – Located in medulla.
- Center for mastication co-ordination, lateral gaze movement & for emotional facial expressions – Located in pons.
MEDIAL RETICULAR FORMATION:
- Neurons usually have long & large axons which can be,
- Ascending
- Descending
SUBTYPES:
ASCENDING RETICULAR FORMATION:
- Also referred “Reticular Activating System (RAS)”.
- Long sensory ascending tracts (spinothalamic & dorsal column) give collateral to RAS.
- A non-specific system activated by any sensation.
- Stimulation causes “Sleep arousal”.
- On arousal from sleep, EEG pattern changes from high voltage slow δ-wave to high-frequency low voltage β-wave activity.
- This causes “δ-block”.
DESCENDING RETICULAR FORMATION:
Functions:
- Modulates pain.
- Controls motor function.
Exam Important
RETICULAR FORMATION
- Reticular Activating System (RAS) causes arousal from sleep producing “δ-block” where EEG pattern changes from high voltage slow δ-wave to high-frequency low voltage β-wave activity.
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