Reticular Formation

Question 1

What are all levels of the CNS interconnected directly or indirectly by way of…?

Answer 1

Reticular Formation

Question 2

Nuclei of the Reticular formation have a role in:

Answer 2

• regulating muscle tone for POSTURAL CONTROL DURING voluntary and reflexive movement
• modulating the sense of pain
• regulating arousal, sleep, and attention
• coordinating autonomic respiratory and cardiac function

Question 3

Describe the general organization of the Reticular Formation:

Answer 3

1) Central division (lateral & Medial zone) - Largest Division
2) Raphe Nuclei (Midline Zone) - this column of neurons along the midline of the brainstem
3) Miscellaneous Nuclei - paramedian pontine RF (PPRF)

Question 4

Describe the central division of the Reticular formation:

Answer 4

a continuous but diffuse column of neurons, begins as a continuation of the central gray interneuron network of the spinal cord Lamina X) and ends in the midbrain. It consists of a large MEDIAL ZONE (efferent) and small LATERAL ZONE (afferent).

Question 5

Describe the Lateral Zone of the Central Division:

Answer 5

• consists of neurons with large dendrites that receive collateral input from all sensory and motor information carried by cranial nerves, Spinal sensory pathways, and Corticospinal corticobulbar and corticopontine pathways.
• Sensory and cortical inputs are integrated in this area.
• The lateral zone relays information to the Medial Zone. It also projects to the Cerebellum, Thalamus (central median nucleus) and spinal cord.

Question 6

Describe the Medial Zone of the Centra Division:

Answer 6

gives rise to the major efferent pathways from the reticular formation:

1) Vital Function Regulation:
2) Somatic motor Activity Regulation (consists of Medial and Lateral Reticulospinal tract)

Question 7

Describe the Vital Function of Regulation of the Medial Zone of Central Division:

Answer 7

Nuclei of the medial zone receive input from:

• Lateral Zone
• Variety of peripheral receptors, including the Carotid body relayed through the solitary nucleus
• hypothalamus
• Prefrontal Cortex

Their role is to regulate vital cardiac and respiratory function through output to pre-ganglionic sympathetic neurons in the lateral horn of the thoracic spinal cord and preganglionic parasympathetic neurons associated with the vagus nerve (cardiac), and to the spinal cord for somatic control of motor neurons in the spinal cord that regulate inhalation and expiration.
Some patients with lesions to the brainstem that involve these regulatory centers have abnormal respiratory patterns or difficulty regulating blood pressure with hypertension. Additional reticular nuclei regulate swallowing and vomiting.

Question 8

Describe the Somatic Motor Activity Regulation of the Medial Zone of Central Division:

Answer 8

Nuclei in the pons and the medulla receive input from:

• the cortex (corticoreticular pathway),
• Cerebellum
• Vestibular nuclei, and
• Somatosensory areas via the Lateral Zone

Their role is to influence Lower motor neurons for the purpose of regulating POSTURAL, REFLEXIVE, and VOLUNTARY MUSCLE CONTROL. Fibers descend in two separate pathways. both pathways descend ipsilaterally, but then can synapse on interneurons both ipsilaterally and contralaterally. Thus, this influence can be seen bilaterally

Consists of Medial (pontine) and Lateral (medulla) reticulospinal tracts.