Lecture 3 Flashcards
Where is the brainstem located?
base of the cerebral hemispheres within posterior fossa of cranial cavity
What are the main components and regions of the brainstem?
COMPONENTS
1) Cranial nerve nuclei and related structures
2) Long tracts
- Descending Motor pathways
- Ascending Somatosensory and viscerosomatic pathways
3) Cerebellar connections & circuitry
4) Reticular Formation
REGIONS
1) Midbrain
- pontomesenphalic junction
2) Pons
- pontomedullary junction
3) Medulla
What is the function of brainstem?
- carries all information between brain and rest of nervous system
- pillar for our ability to be awake, aroused, and alive
What is the function of the reticular formation?
- general arousal/awareness (keeping brain on when needed)
- Reticular Activating System (RAS) - synapses with all major ascending tracts and functions in arousal from sleep
- Motor awareness
- autonomic regulation
Where is the reticular formation found, and where does it project to?
- extends through central core of medulla, pons, and midbrain
- projects to thalamus, cerebellum, spinal cord, and optic
What are some of the major functions of the midbrain?
Major associations include vision, hearing, motor control, sleep and wake cycles, alertness, and temperature regulation
What structures or landmarks can be found on the external surface of the midbrain?
CN 3 (oculomotor) and 4 (trochlear)
What are the 3 regions of the midbrain? How are they generally defined?
1) tectum (roof) - dorsal to cerebral aqueduct
2) tegmentum - middle and biggest region of midbrain
3) Basis pedunculi - most ventral and somatotopically organized
Identify the structures in the midbrain tectum
- superior (rostral) and inferior (caudal) colliculi
What is the function of the superior colliculi and where is it found?
- visual relay station
- found in midbrain rostral tectum
What is the function of the inferior colliculi and where is it found?
- auditory relay station - signal, frequency integration, and pitch discrimination
- found in midbrain caudal tectum
Identify the structures in the midbrain tegmentum
- substantia nigra
- reticular formation
Rostral
- ventral tegmental area (VTA)
- Red nuclei
- oculomotor nuclei
Caudal
- trochlear nuclei
- superior cerebellar peduncle
- raphe nuclei
What is the function of the ventral tegmental area (VTA) and where is it found?
- largest dopamine-producing neurons in brain
- play role in reward system w/ projection to limbic system and cortex
- found in midbrain rostral tegmentum
What is the function of the red nuclei and where is it found?
- motor coordination and control for flexor muscles
- found in midbrain rostral tegmentum
What is the function of the superior cerebellar peduncle and where is it found?
- relay station to cerebellum
- found in midbrain caudal tegmentum and rostral pons
What is the function of the raphe nuclei and where is it found?
- major serotonin-producing neurons
- found in midbrain caudal tegmentum and rostral pons
What is the function of the substantia nigra and where is it found?
- part of basal ganglia - involved in movement
- major dopamine-producing and storage area
- found in midbrain tegmentum
What are the 2 dopamine production and storage portions of midbrain?
substantia nigra and ventral tegmental area (VTA)
What are the primary highways in and out of our cerebellum?
cerebellar peduncles
What is the biggest region of the midbrain?
tegmentum
Identify the structures and their function found in the midbrain basis pedunculi
- crus cerebri - Large bundles of somatotopically-organized axons containing fibers from motor pathway
What structures make up the cerebral peduncles and what do they contain?
substantia nigra and basis pedunculi - contain large descending (motor) nerve tracts
What is the periaqueductal gray? What roles is it involved with?
- gray matter surrounding cerebral aqueduct
- involved with pain modulation (primarily: inhibition), autonomic regulation, emotion