Ch. 15: Brain Stem Region Flashcards
What are the 3 divisions of the brainstem?
- Medulla
- Pons
- Midbrain
What are the 3 divisions on the brainstem?
- Base (basilar) - primarily motor tracts & function
- Tegmentum - primarily sensory tracts and function
- Tectum - reflexive control of eye movements and movements of the hard
What are the important structures on the ventral and dorsal Medulla?
- Ventral
- Pyramids
- Cranial nerve roots (9,10,11,12)
- Dorsal
- Sensory tracts - touch and proprioception
What are the important internal structures of Medulla?
- Basilar
- Corticospinal tracts: voluntary control of body - passess through
- Medial Lemniscus: conscious touch and proprioception - passes through
- Tegmentum
- Spinothalamic tracts: pain & temp from body
- Trigeminothalamic tracts: pain & temp from face
- Reticular Formation (5 broad categories)
- Autonomic “control” nuclei.
What are the important ventral and dorsal parts of the Pons?
- Ventral
- “Bulge” of pontine nuclei and pontocerebellar fibers
- Cranial nerve roots
- 5 (body of pons)
- 6,7,8 (border or pons and medulla)
- Dorsal
- Cerebellar peduncles - fiber bundles that connects to movement system (3 of them - 2 in, 1 out)
What are the important internal anatomy parts of the Pons?
- Basilar.
- Corticospinal tract.
- Pontine nuclei (origin of pontocerebellar fibers)
- Corticobrainstem tract.
- Tegmentum
- Medial lemniscus. (touch and proprioception)
- Spinothalamic tracts.
- Trigeminothalamic tracts.
- Reticular formation.
- Autonomic “control” nuclei.
What are the important ventral and dorsal external anatomy of the Midbrain?
- Ventral.
- Cerebral peduncles.
- Cranial nerve root (3)
- Dorsal.
- Superior colliculi.
- Inferior colliculi.
- Cranial nerve root (4)
What are the important internal anatomy of the Midbrain?
- Basilar.
- Cerebral peduncles.
- Substantia nigra.
- Tegmentum.
- Red nucleus.
- Pedunculopontine nucleus.
- Oculomotor complex (CN 3, 4).
- Periaqueductal gray.
- Tectum.
- Superior colliculi.
- Inferior colliculi.
What are the 5 function of the Reticular Formation?
- Projections can raise/lower arousal
- Provide autonomic control (Homeostasis)
- Vital centers of brain stem (ex: Jean’s class)
- Broadly control consciousness and sleep/wake
- Descending pain control system
- Nonspecific activating tracts - inc excitability to LMN in response to fight/flight stimulus
What can cause disorders of the brainstem region?
- Ischemia (stroke)
- Compression (growing tumor or inc CSF volume)
What are the differences between damage of a Vertical Tract vs Segmental
Ex: Damage to UMN or LMN contorlling muscles of fascial expression
-
Vertical tract (“above” brainstem) - opposite {B}
- Damage to cerebral cortex or corticobrainstem tract (vertical tract of facial function) rostral to the brainstem
- Corticobrainstem tract - UMN
- Presentation: Paresis or paralysis in “lower” 1/4 of contralateral side of face - can still close eyes and smile on one side, no smile on CONTRALATERAL side from injury
- Damage to cerebral cortex or corticobrainstem tract (vertical tract of facial function) rostral to the brainstem
-
Segmental (exiting brainstem) - Same side {A}
- Damage to CN VII (Facial) on one side of brainstem (either LMN cell body or LMN axon or both)
- CN VII - LMN of Facial function
- Presentation: Paresis or paralysis in entire ipsilateral 1/2 of face
- Damage to CN VII (Facial) on one side of brainstem (either LMN cell body or LMN axon or both)
What are the differences between damage of a Vertical Tract vs Segmental
Ex: Stroke in Anteromedial Medulla (vertebral artery)
-
Vertical tract (passing through brainstem)
- Corticspinal tract: Paralysis of arm/trunk/leg - Contralateral to damage
- Medial lemniscus: loss of touch from body - contralateral to damage
-
Segmental (exiting brainstem)
- Hypoglossal (CN 12 nucleus or nerve): Paralysis of tongue (ipsilateral to damage) → tongue points to same side of damage
- UMN comes from opposite side - brought down through corticobrainstem tract
What is the guiding principle for brainstem damage?
- Signs and sx to ipsilateral face and contralateral body
What is the result of unilateral brainstem damamge?
- Vertical tracts (body)
- Contralateral signs/sx
- (DC/ML, spinothalamic, corticospinal)
- Contralateral signs/sx
- Cranial nerve nuclei
- Ipsilateral signs/sx
- Cerebelluum
- Ipsilateral signs/sx
- Autonomic
- Ipsilateral signs/sx
Damage to what structures could cause disorders of vital function?
Damage to cardio and respiratory control centers in the medulla
