BSI Lecture 62 Neuroanatomy 1 Flashcards
Define the CNS?
1) The central nervous system is made up of many neurons and glial cells.
2) It is protected by the skull and bony vertebrae.
3) It is made up of the brain and spinal cord.
Are there more neurons or glia in the body?
Glia, there are apparently ~ 10^11 neurons in the brain but 10^12 glia!
What are the primary brain vesicles?
1) Prosencephalon
2) Mesencephalon
3) Rhombencephalon
What are the secondary brain vesicles?
1) Telencephalon
2) Diencephalon
3) Mesencephalon
4) Metencephalon
5) Myelencephalon
What are the adult brain structures?
1) Cerebrum: Cerebral hemispheres (cortex, white matter, and basal nuclei)
2) Diencephalon: Thalamus, hypothalamus, epithalamus
3) Brain stem: midbrain
4) Brain stem: pons and cerebellum
5) Brain stem: medulla oblongata
6) Spinal cord
What are the adult neural canal regions?
1) Lateral Ventricles
2) Third Ventricle
3) Cerebral aqueduct
4) and 5) Fourth Ventricle
6) Central Canal
Where is the CSF carried?
In the 4 brain ventricles and the central canal
What is specific about cerebral cortices and cerebellum in regards to gray matter?
They have an additional outer gray layer composed of neurons that have migrated during development from the central gray matter, (guided by glia).
What are the 5 parts of the brain (4 of them are major)?
The telencephalon, (cerebral hemispheres and basal ganglia), the diencephalon, (thalamus, hypothalamus), mesencephalon, (“midbrain”), and met- and myelencephalon, (“brainstem:” pons and medulla oblongata)
What is the largest part of the brain and how much space does it take up?
The cerebrum (80%)
What does the cerebral cortex cover?
Parts of the diencephalon, midbrain, and part of the brainstem.
What are fissures?
Fissures are deep sulci that separate major divisions of the cerebral cortex
What are the 5 major lobes
frontal, parietal, occipital and temporal lobes plus the insula
What separates the frontal and parietal lobes?
The transverse central sulcus
What is the cerebral cortex responsible for?
Our “conscious mind” which includes self-awareness, the ability to initiate and control voluntary movement, communicate, remember, and understand.
What normally covers/hides the insula?
Parts of the frontal, parietal, and temporal lobes
_________ is an old non-invasive technique which has now been refined to specifically locate active regions plus it is very fast.
Electroencephalography, (EEG)
What are the three functional areas that the cerebral cortex can be divided into?
motor, sensory, and “associative”
All of the neurons in the CCs are really ______.
interneurons (totally within the CNS).
Where is the primary motor cortex localized?
Along the precentral gyrus of the frontal lobe. (Composed of large pyramidal neurons.
Where do the pyramidal tracts of the cortex decussate?
Under the brain stem so they can innervate muscles on the opposite side of the body.
What does the somatic sensory cortex allow?
a conscious awareness of general somatic senses via sensory afferent information from the spinal and cranial nerves.
Which special sense does not get processed by the thalamus, but instead goes straight to the limbic system?
Olfaction
What is special about the wiring of the somatic sensory cortex?
It allows us to determine spatial discrimination of a stimulus.
What happens if the somatic sensory cortex is damaged?
It destroys the ability to feel localized touch, pressure, and vibration of the skin. Pain and temperature perceptions are also lost, but we can still perceive them in a vague, poorly localized manner.
What is the somatosensory association areas responsible for?
Integrating different sensory inputs into a comprehensive understanding/appreciation of what is being felt. (memories)
What happens if the occipital lobe (primary visual cortex) is damaged?
A person would have no conscious awareness of what is being viewed; therefore, they would be functionally blind.
In 90-95% of people, what does the left side of the brain have more influence on?
Language, math, and logic
In 90-95% of people, what does the right side of the brain have more influence on?
Visual-spatial skills, communication, intuition, emotion, and artistic skills
What is the cerebral white matter mostly composed of?
Myelinated axons
What are the 3 types of connection/projection fibers that the cerebral white matter can be divided into?
1) Commissures
2) Association fibers
3) Projection fibers
What are commissures?
Commissural fibers that connect corresponding regions of the right and left hemispheres. (Corpus Callosum)
What are Association fibers?
Fibers that connect different regions in the same hemisphere
What are Projection fibers?
The inputs and outputs of the cerebral cortex.
What does the deep gray matter consist of?
The basal ganglia, the basal forebrain, and the claustrum
What is another name for the basal ganglia?
The Corpus striatum
What are the basal ganglia composed of?
The Caudate and Lentiform nuclei
What can the Lentiform nuclei be broken down into?
The Putamen and Globus pallidus
What are the basal ganglia responsible for?
They act as a neural calculator that works with the cortex in controlling movement and other functions
If there is a loss of dopaminergic projection from the pars compacta (Substantia nigra), what disease can occur?
Parkinson’s disease
If there is a loss of GABA’ergic projection, what disease can occur?
Huntington’s disease
What is the difference between Parkinson’s and Huntington’s disease?
The cause of Parkinson’s is unknown and Huntington’s is an inherited condition.
What are the cholinergic neurons of the basal ganglia responsible for?
Arousal, learning, memory, and motor control
What does Alzheimer’s disease destroy?
Cholinergic neurons
What happens if there is damage to the Basal ganglia?
Dyskinesia (bad movements)
What is the limbic system composed of?
The hippocampus, the dentate gyrus, and parts of the amygdala, hypothalamus, and thalamus
What is the limbic system called?
Our “emotional” brain or primitive brain
What is the limbic system responsible for?
Producing basic and essential “primitive” behaviors such as fear, rage, aggression, etc. It is also responsible for memory formation (emotional) but is not the sire of storage or retrieval.
What makes up the Diencephalon?
The thalamus, hypothalamus, and epithalamus
What is the thalamus separated by and how much of the diencephalon does it make up?
It is separated by the third ventricle and makes up about 80% of the diencephalon.
What makes up the hypothalamus?
12 major nuclei
What do the thalamic nuclei do?
They relay signals and process data so they can organize and adjust signals
Where is the hypothalamus located?
below the thalamus on the underside of the brain between the optic chiasma and mammillary bodies
Where is the pituitary located and what is its function?
It’s located below the hypothalamus and is responsible for releasing major hormones.
What is the hypothalamus the control center of?
It is the main visceral control center of the body and controls the autonomic nervous system. It is also involved in emotional responses in the limbic system.
What functions does the hypothalamus control?
1) Body’s thermostat: can initiate sweating or shivering
2) Initiates/motivates feeding and sexual behavior
3) Responsible for the timing of the sleep cycle
4) memory formation
What is the epithalamus composed of?
A tiny group of nuclei plus the pineal gland.
What does the pineal gland do?
It releases melatonin (which is formed from 5-HT) which prepares the body for sleep.
Where is the midbrain located and what does it contain?
It is located between the diencephalon and the pons. It contains the cerebral aqueduct.
What surrounds the cerebral aqueduct?
periaqueductal grey matter
What does periaqueductal grey matter do?
It is involved in the sympathetic division of the autonomic nervous system’s response to fear. It is the link between the amygdala and the sympathetic nervous system.
What other things does the midbrain do?
1) Helps mediate a response to visceral pain
2) controls eye movement because it contains the cell bodies cranial nerves 3 and 4
3) It also coordinates eye and ear reflexes
What is the function of the rostral part of the brainstem?
It serves as the site of attachment for the cerebellum, and it is the site of origin of several cranial nerve nuclei (5, 6, and 7)
What does the caudal part of the brainstem turn into?
The spinal cord after it leaves the foramen magnum
What does the medulla contain?
Then nuclei/origins of the last 5 cranial nerves (8-12)
What does the medulla have in common with the hypothalamus?
It contains nuclei that regulate vital, subconscious body functions such as heart rate, blood pressure, breathing rate, hiccuping, swallowing, coughing, and sneezing
What does general anesthetics, alcohol, tranquilizers, and sleep-inducing drugs do?
They depress RAS activity causing loss of consciousness
Where is the cerebellum located and how much of the total mass of the brain does it account for?
It is situated above the pons and makes up about 11% of the total mass of the brain
What does the cerebellum do?
It smooths and coordinates movements directed by other brain regions.
How do the cerebellum and cortex differ?
The cerebellum effects the same side of the body (ipsilateral)
What happens if the cerebellum is damaged?
It leads to lack of coordination. (Can’t touch nose with eyes closed, slurred speech, falling over, etc.)
What is the leading cause of accidental death in the United States? (~10^6)
Blows to the head
What is suspected to be the cause of autism?
Dysfunction of the prefrontal cortex and its connections to cortical and subcortical regions
How do most ADHD drugs work?
The increase NA and DA levels in the body.
