Brainstem Flashcards
What do the cerebral peduncles contain?
The pyramidal and corticopontine tracks
Dorsal tegmentum of midbrain contains:
CN nuclei: 3, 4
White matter tracks
Substantial Nigra and Red Nucleus.
What makes up the tectal midbrain?
What are their functions?
Quadrigeminal plate: superior and inferior colliculus
Superior: visual processing
Inferior: auditory processing
What does the ventral pons contain?
Corticospinal, corticobulbar, corticopontine tracts.
What does the pons dorsal tegmentum contain?
Cranial nerve nuclei five, six, seven, eight, and the white matter tracks, and trapezoid body
What are the white matter tracks in the dorsal tegmentum of the pons?
MLF, ML, LL, STT, CTT
What does the ventral medulla contain?
Vascular ?
The pyramids and the olives.
Anterior spinal artery, and vertebral artery
What does the medulla dorsal tegmentum contain?
CN nuclei: 9, 10, 11, and 12
continuation of the white matter tracks
What are the white matter tracks in the medulla?
MLF, ML, STT, CTT, spino-cerebellar tract
What is the function of the periaqueductal gray matter in the midbrain?
Pain
emotion (including fear and anxiety vocalization)
cardiovascular control
What do the pyramidal tracks contain?
CST and CBT
What do the corticopontine tracks connect?
Cortex to pons to opposite cerebellum
allowing coordination of planned motor functions
What are the functions of the substantia Niagara?
Motor control and reward pathways
What does the red nucleus function in?
Motor coordination as part of the extrapyramidal system
What does the medial longitudinal fasciculus do?
It is the main central connection for the ocular motor nerve and it coordinates conjugate gaze
What does the medial lemniscus carry?
Proprioceptive, vibratory, and touch-pressure sense
What does the lateral lemniscus do?
It carries auditory information to the auditory cortex
What does the central tegmental tract contain?
Ascending fibers connecting the rostral nucleus solitarius to the thalamus and cortical taste area.
Nucleus Tractus Solitarius
What are inputs and outputs
- autonomic regulation, integrating sensory information from the viscera and coordinating reflexive responses.
Inputs
CN IX (Glossopharyngeal):
* Baroreceptor and chemoreceptor input from the carotid sinus and carotid body.
* Taste sensation from the posterior one-third of the tongue.
CN X (Vagus):
* Visceral afferent input from thoracic and abdominal organs (e.g., lungs, heart, gastrointestinal tract).
* Baroreceptor and chemoreceptor input from the aortic arch.
CN VII (Facial):
* Taste sensation from the anterior two-thirds of the tongue (via the chorda tympani).
2. Peripheral Chemoreceptors and Mechanoreceptors:
* Afferent fibers carrying information about changes in blood pressure, blood gas levels, gut distension, and other visceral stimuli.
Descending Inputs from Higher Brain Centers:
*Hypothalamus and limbic system
(modulation of autonomic responses based on emotional and homeostatic states).
Outputs of the Nucleus Solitarius
1. Parasympathetic Preganglionic Neurons:
* Sends projections to the dorsal motor nucleus of the vagus and nucleus ambiguus to modulate heart rate, respiratory rate, and gastrointestinal activity.
2. Brainstem Reflex Centers:
* Cardiovascular regulation:
* Projects to the rostral ventrolateral medulla (RVLM) and caudal ventrolateral medulla (CVLM) to modulate sympathetic and parasympathetic output for blood pressure control.
* Respiratory regulation:
* Swallowing and Gag Reflex:
3. Hypothalamus: 4. Cerebellum: 5. Thalamus and Cortex: * Sends ascending projections (via the parabrachial nucleus) to the thalamus and insular cortex, enabling conscious awareness of visceral sensations (e.g., nausea, pain, fullness).
Clinical Relevance
1. Dysfunction of the Nucleus Solitarius:
* Disorders such as autonomic dysreflexia, baroreflex failure, or sudden infant death syndrome (SIDS) can involve dysfunction of the NTS.
* Lesions in the medulla (e.g., lateral medullary syndrome) can disrupt inputs and outputs, leading to dysregulation of autonomic functions like blood pressure, swallowing, or respiratory rhythms.
2. Role in Reflex Arcs:
* The NTS integrates afferent signals in reflex arcs like the baroreceptor reflex, respiratory reflexes, and gastrointestinal reflexes, making it a central hub in autonomic homeostasis.
This integration of sensory inputs and motor/autonomic outputs highlights the nucleus solitarius as a cornerstone of homeostatic regulation in the central nervous system.
Superior and inferior olive functions
Inferior olive: balance and voluntary movements
Superior olive: sound localization and analysis
Location
The inferior olives: medulla
The superior olives: pons.
