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The reticular formation,limbic system and basal ganglia I


The reticular formation

  • It’s a ‘diffuse net’ which is formed by nerve cells & fibers
  • It extends from the neuroaxis spinal cord through medulla,
  • pons, midbrain, subthalamus, hypothalamus & thalamus
  • (Spinal cord is relayed superiorly to the cerebral cortex)
  • Many afferent & efferent pathways project in & out of the RF from most parts of the CNS
  • The main pathways through the RF is poorly defined & difficult to trace using silver stains
  • Reticular formation can be divided into 3 columns : Median, Medial & Lateral columns
  • Functions of the reticular formation



    1. Control of skeletal muscles


      • Modulate muscle tone & reflex activities (Via reticulospinal & reticulo bulbar tracts)
      • Important in controlling muscles of facial expression when associated with emotions

    2. Control somatic & visceral sensation (Influence can be excitatory or inhibitory)
    3. Control of autonomic nervous system
    4. Control of endocrine nervous system (Hypothalamus & the pituitary)
    5. Influence on the biological clock (Rhythm)
    6. The reticular activating system (Arousal & level of consciousness are controlled by the RF)


Clinical note
  • When a person smiles for a joke, the motor control is provided by the RF on both side of the brain
  • The fibers from RF is separated from Cortico bulbar pathway (Supply for facial muscles)
  • If a patient suffer a stroke that involves Cortico bulbar fibers, has facial paralysis on the lower part of the face is still able to smile symmetrically

The limbic system

Limbic structures
Functions of the limbic system
  1. Sub callosal, cingulated & parahippocampal gyri
  2. Hippocampal formation
  3. Amygdaloid nucleus
  4. Mammillary bodies
  5. Anterior thalamic nucleus
  1. Influence the emotional behavior


    1. Reaction to fear & anger
    2. Emotions associated with sexual behavior

  2. Hippocampus is involved in converting short term memory to long term memory (If the hippocampus is damaged, patient is unable to store long term memory – Anterograde amnesia)


The basal ganglia & their connections

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The reticular formation,limbic system and basal ganglia I The reticular formation,limbic system and  basal ganglia I Reviewed by Radiology Madeeasy on August 10, 2010 Rating: 5
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