C12 9-12 Flashcards
What is the cerebral white matter made of?
Tracts that connect areas of the cerebral cortex to each other or to other parts of the CNS.
Where is Cerebral/central white matter found?
White matter of the brain between the cortex and nuclei (cerebral medulla)
What type of fibers are found in the cerebral white matter?
commisure, association fiber, projection fiber.
Commissure
Connect corresponding grey areas of the two hemispheres and allow the two hemispheres to function as a coordinated whole.
What is the largest commisure?
Corpus callosum - lies superior to the lateral ventricles deep within the longitudinal fissure (less prominent are the anterior and posterior commissures)
Association fiber
Connect areas of the cortex within the same hemisphere. Short associatioin fibers connect adjacent gyri, long fibers connect different cortical lobes.
Projection fiber
Connect the cerebrum to other parts of the brain and spinal cord.
The projection fibers form the internal capsule.
Where are the basal nuclei found?
Deep within the cerebral white matter
Three nuclei: globus pallidus, putamen, caudate.
What are the major functions of the basal (cerebral) nuclei?
- inhibit muscle tone
- inhibit unwanted muscle movement
- start/stop movement.
Also: help initiate and terminate some cognitive processes - attention, memory, planning.
Input/output of basal nuclei
input - from the cerebral cortex
output - to motor areas of the cortex via the thalamus.
What structures are closely associated with the basal nuclei?
Substantia nigra (plays a role in controlling basal nuclei) of the midbrain and subthalmic nuclei of the diencephalon.
What are some disorders associated with the Basal Nuclei?
Parkinson’s disease, obsessive-compulsive, schizophrenia, chronic anxiety.
-dysfunctions of circuits between the basal nuclei and limbic system.
Location of the diencephalon?
Central core of the forebrain, surrounded by the cerebral hemispheres
Divisions of the diencephalon?
Thalamus, hypothalmus, epithalmus
In which ways does the Thalamus relay information?
- most sensory impulses (not olfaction)
* *spinal cord and brain stem —> primary sensory areas of the cerebral cortex** - motor functions
* *cerebellum and basal nuclei —> primary motor cortex** - between different areas of cerebrum (maintenance of consciousness.)
Why is the thalamus an “executive secretary?”
It acts as an information filter, screening out most sensory info that arrives at the thalamus and fwding only a small portion to the cerebrum.
(i.e., filters out sounds and sights when you are studying)
What portion of the diencephalon does the thalamus occupy?
80%
What is the function of the hypothalmus?
- Regulates ANS activity (SWEET HAT)
- Serves as a relay station for reflexes related to smell and with the limbic system emotional and behavioural patterns.
Hypothalmus - SWEET HAT
Sleep Wake (circadian)
Emotional brain Hq (limbic system)
Endocrine Hq
Thirst
Hunger - Autonomic Hq - Thermostat
Epithalamus function
- Includes the pineal gland which secretes melatonin and helps regulate day/night/circadian rhythms.
- Includes the habenular nuclei which help relay signals from the limbic system to the midbrain and are involved in visceral and emotional responses to odors.
Three major regions of the brainstem? (the mesencephalon)
Midbrain, Pons, Medulla oblongata
What does the midbrain include?
cerebral peduncles
, substantia nigra,
Tegumentum,
tectum
What does the pons include?
Conduction pathways, Pontine sleep center, Pontine respiratory center
What does the Medulla Oblongata include?
Pyramids, cranial nerve nuclei, part of reticular formation,
cardiac center, vasomotor center, medullary respiratory center,
nuclei that are involved in coughing, sneezing, salivation, swallowing, gagging, vomiting.
