CH16 Brainstem Tracts 1 Flashcards
What types of vertical tracts are in the brainstem?
- sensory
- autonomic
- motor
vertical tracts: synapses or no?
- Some tracts continue through the brainstem without alteration
- Brainstem acts as a conduit
The brainstem is divided longitudinally into two sections:
- basilar
- tegmentum
Describe and name the additional longitudinal brainstem section (aside from the basilar and tegmentum)
Where is it?
TECTUM
- in the midbrain
- posterior to the tegmentum
The tectum includes structures involved in reflexive control of:
- intrinsic and extrinsic eye muscles
- movements in the head
important parts of the tectum
- pretectal area
- superior and inferior colliculi
(I think?)
Where is the basilar section of the brainstem? What does it primarily contain?
- anterior
- mostly motor
Which motor structures does the basilar section contain?
- descending axons from cerebral cortex
- motor nuclei
- pontocerebellar axons
Which descending tracts are in the basilar section?
- CST
- corticobulbar
- corticopontine
- corticoreticular
Which motor nuclei are in the basilar section?
- SN
- pontine nuclei
- inferior olivary nucleus
What is included in the reticular formation?
complex network
- reticular nuclei (and their connections)
- ascending/descending reticular pathways
What does the reticular formation do?
- Integrates sensory and cortical information
- Regulates somatic motor activity, autonomic function, and consciousness.
- Modulates nociceptive (pain) information.
What are the major reticular nuclei?
- ventral tegmental area (VTA)
- pedunculopontine nucleus (PPN)
- raphe nuclei
- locus ceruleus & medial reticular area
Most neurons that produce dopamine are located here
midbrain
What are the two production areas of dopamine in the midbrain?
- VTA (part of reticular formation)
- SNpc
What happens when the VTA is activated?
produces feelings of pleasure and reward
What nucleus does the VTA affect?
nucleus accumbens
Why is morphine habit forming?
inhibits inhibitory inputs to the VTA
Where is the PPN located?
caudal midbrain
Where do ascending axons from the PPN project?
- to the inferior part of the frontal cerebral cortex
- intralaminar nuclei of the thalamus
Through which connections does the PPN influence movement?
- Globus pallidus and subthalamic nucleus
- Limbic system
- Reticular areas that give rise to reticulospinal tracts
What NT (NM) does the VTA use?
dopamine
What NT (NM) does the PPN use?
acetylcholine
What NT (NM) do the raphe nuclei use?
serotonin
What NT (NM) does the locus ceruleus and medial reticular zone use?
norepinephrine (sometimes epi)
What does the ARAS regulate?
consciousness
consciousness
awareness of self and surroundings
What is the consciousness system?
governs alertness, sleep, and attention
What are the brainstem components of consciousness?
- reticular formation
- ARA
external medulla: What are the vertical bulges?
pyramids
Lateral to the pyramids are two small oval lumps, called
olives
Where does CN XII connect to the medulla?
between the pyramid and the olive
What does the inferior half of the medulla contain (canal)?
central canal that is continuous with the central canal of the spinal cord
anterior component of inferior medulla
descending axons of CST (form the pyramids)
What major nerve structures are found in the lower medulla?
cranial nerve structures
What happens to the central canal in the upper medulla?
widens to form part of the 4th ventricle
Positions of tracts in the rostral medulla compared to the caudal medulla
maintain approximately the same positions except that the medial longitudinal fasciculus is located more posteriorly
Where are most CN nuclei found in the rostral medulla?
clustered in the dorsal section
What functions does the medulla contribute to?
- controlling eye and head movements
- coordinating swallowing
- regulation of cardiovascular, respiratory, and visceral activity
