Function of the reticular formation

This activity, for example, allows for movements of the jaw, lips, and tongue that lead to the movements required for chewing and eating. Divisions of the Reticular Formation Traditionally, the nuclei are divided into three columns: Raphe nuclei medium column Magnocellular red nucleus medial zone Parvocellular reticular nucleus lateral zone Sagittal division reveals more morphological distinctions.

Neurotransmitters are produced in all of these areas and sent throughout the central nervous system to modulate sensory perception, motor activity, and behavioral responses.

The cholinergic neurons originate in the pedunculopontine nucleus and laterodorsal tegmental nuclues, while the noradrenergic neurons originate in the locus coeruleus. During sleep, neurons in the ARAS will have a much lower firing rate; conversely, they will have a higher activity level during the waking state.

reticular activating system anatomy

The original functional differentiation was a division of caudal and rostral, based on the observation that damage to the rostral reticular formation induces a hypersomnia in the cat brain. It is also an important part of the extra pyramidal tract.

Reticular activating system sleep

Activity in reticulospinal axons appears to play a role in modulating spinal reflex activity and may also modulate sensory input by regulating the gain at synapses within the spinal cord. The nuclei of cranial nerves V and VI are located in the pons. These fibers are mainly found in the reticulospinal tract , which extends from the reticular formation to help maintain posture, facilitate stereotyped movements like stepping, and modulate muscle tone to either aid or inhibit movement. The cerebellum compares input from muscles and joints with motor output from the cortex and relays subsequent adjustments to the cortex through the red nucleus and thalamus. The researchers proposed that a column of cells surrounding the midbrain reticular formation received input from all the ascending tracts of the brain stem and relayed these afferents to the cortex and therefore regulated wakefulness. In contrast, damage to the more caudal portion of the reticular formation produces insomnia in cats. It controls muscles of the pharynx, larynx and velum. The sensory fibers are located behind the motor fibers.

The reticulospinal tracts works with the other three pathways to give a coordinated control of movement, including delicate manipulations. Provided by: Boundless. It is also quite important to swallowing.

Of the numerous cell groups and tracts found throughout the reticular formation or connected to reticular formation neurons, some worth noting are nuclei involved in neurotransmitter production, nuclei associated with the cranial nervesdescending tracts involved in modulating sensory and motor functions, and ascending tracts integral to arousal and consciousness.

Additionally, facial paralysis due to a pyramidal lesion will not permit voluntary control of the muscles but these paralyzed muscles will respond to emotional expression.

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Reticular formation