M19: The Brain Part I - Cerebrum, Diencephalon, Cerebellum, and Brainstem Flashcards
What position is Rostral?
Towards the nose
What position is caudal?
towards the back of the head
What position is Ventral?
towards the front of the body
Anterior/Posterior ends
What position is dorsal?
the back of the body
Superior/Inferior ends of the body
Afferent
Incoming sensory information
Efferent
Outgoing motor information
Contralateral
opposite side
Ipsilateral
same side
What is the Telencephalon
aka cerebrum, the largest part of the brain
What is the Diencephalon?
Gray matter surrounded by the cerebral hemispheres
What makes up the diencephalon?
-All structures that end in -amus
-Composed of three paired structures:
—>Thalamus
—>Hypothalamus
—>Epithalamus
What is the Thalamus?
-a collection of nuclei that relay information between the cerebral cortex
and the spinal cord or brain stem
-does not just pass the information on, it also processes that information
—->For example, the portion of the thalamus that receives visual information
will influence what visual stimuli are important, or what receives attention
What is the Hypothalamus?
- the executive region in charge of the autonomic nervous system and the endocrine system through its regulation of the pituitary gland
-master control center of the endocrine system
-
What structure is the master control center of the endocrine system?
Hypothalamus
What is the function of the hypothalamus?
-Controls the release of regulatory hormones from the anterior pituitary gland
-Secretes specific hormones from the posterior pituitary gland
-Controls the stimulation and secretion activities of the adrenal medulla
Mesencephalon
midbrain
Metencephalon
region of the brain that differentiates into the pons and cerebellum
Myelencephalon
region of the brain composed of the medulla oblongata
Gray matter
cell bodies, dendrites, unmyelinated axons
- middle of spinal cord
Cortex
-covers the surface of the brain
-forms discrete internal clusters called cerebral nuclei
White matter
Myelinated axons (lipid substance)
What is the Cerebral Cortex ?
-Thin layer of gray matter on the outside of the cerebrum
-Tightly folded to fit within the limited space inside the skull, creating the sulci and gyri
What are the functional areas of the cerebral cortex?
-Cognition
-Motor areas
-Sensory areas
-Multimodal association areas
Cognition of the cerebral cortex
Mental processes such as awareness, knowledge, memory, perception, information
Motor areas of the cerebral cortex
Control voluntary motor functions
Sensory areas of the cerebral cortex
-Provide conscious awareness of sensation
-process incoming sensory information
Multimodal association areas of the cerebral cortex
-Integration and interpretation of sensory and
motor information → mixture of both sensory and motor information
Brodmann’s Areas
-German anatomist Korbinain Brodmann, 1909
—>Created the map based on cytoarchitectural differences in different brain regions
—> Areas numbered 1-52
What makes up area’s 1,2,3 of the brain?
primary somatosensory cortex
What makes up area 4 of the brain?
primary motor cortex
What makes up area 17 of the brain?
primary visual cortex
What makes up area 22 of the brain?
primary auditory cortex
What makes up areas 39 and 40 of the brain?
Wernicke’s area
What makes up areas 41 and 42 of the brain?
-primary auditory cortices in the superior temporal lobe.
-This is the first cortical area involved in processing hearing.
What makes up areas 44 and 45 of the brain?
Broca’s area: production of speech
Cytoarchitecture
-an extensive study of the microscopic anatomy of the cerebral cortex
-Found that the structure of the neurons in a given region of the cerebral cortex governs the function of that area of the cortex
-Cortex: 6 layers to cortex
-Not the same across the whole brain
Are the left and right cerebral hemispheres of the brain identical?
Anatomically mirror images, but differ functionally (hemispheric lateralization)
Median longitudinal fissure
divides the two cerebral hemispheres
Function of the right hemisphere?
visuospatial processes, imagination, music, and artistic skills
Function of the left hemisphere?
Analytical thinking and math skills generally, language centers are only located in the left hemisphere (with rare exceptions)
How are the cerebral hemispheres connected?
-Only connected by a few white matter pathways
—>Corpus Callosum, Anterior commissure, and Posterior commissure
What is the corpus callusum?
-the longest portion that connects the cerebral hemispheres
-Contains the default mode network, salience network, and central executive network
What is the default mode network in the corpus collusum?
-activates when not performing a task
—>Daydreaming, mind-wandering, thinking about others
What is the salience network in the corpus collusum?
switching between the default mode network and the central executive network
What is the central executive network in the corpus collusum?
engages your conscious brain to think and maintains attention on a prioritized task
—>Focusing on something
What is the Anterior commissure?
white matter fiber bundle that connects the two cerebral hemispheres of the brain concerned with the olfactory pathway, medial temporal area
What is the posterior commissure?
white matter that connect areas in the occipital lobes, primarily areas concerned with pupillary response and eye movement control.
Where is the frontal lobe located?
What area’s does it contain?
Anterior part of cerebral hemisphere
– forehead
Contains primary motor cortex (precentral gyrus), somatic motor association area (premotor
Cortex, prefrontal cortex, and broca’s area
What is the prefrontal cortex?
What does it contain?
-anterior portion of the frontal cortex
-contains Dorsolateral Prefrontal Cortex, Orbitofrontal Cortex, Anterior Cingulate Cortex
Dorsolateral Prefrontal Cortex function
-Executive (higher-cognitive) functions: lead to goal-directed behavior
—> Organization and planning
—> Managing behavior
—> High-level decision-making
—> Multitasking
-Working memory
Why are functions of the prefrontal cortex important?
- integral to the personality of
an individual, because it is largely responsible for what a person intends to
do and how they accomplish those plans
Working memory
taking in information and using it right away
Orbitofrontal Cortex function
-Modulating emotions
-Inhibition
-Adaptive learning, rewards, and emotion
-Explains why teenagers are emotional: amygdala develops first
Anterior Cingulate Cortex
-Motivational behavior
-Reward-based learning
—> Error detection
—> Outcome monitoring
-Pain processing
The Case of Phineas Cage:
-survived but personality changed drastically
-found that prefrontal cortex is not needed for life
Where does the cortical spinal tract begin?
primary motor cortex
Primary motor cortex location
precentral gyrus of the frontal lobe, anterior to the central sulcus
Primary motor cortex function
Voluntary motor activity
Primary motor cortex innervation
Neurons originating in this cortical region are the upper motor neurons
that travel to the spinal cord to synapse with lower motor neurons that
eventually innervate skeletal muscles
-Innervation can be diagrammed as a motor homunculus on the precentral gyrus
Motor homunculus
a topographic representation of the body parts and its correspondents along the precentral gyrus of the frontal lobe.
Premotor cortex function
aids in controlling movements of the core muscles to maintain posture during movement
Supplementary motor cortices function
hypothesized to be responsible for
planning and coordinating movement, manages sequential movements
that are based on prior experience (that is, learned movements)
What do premotor cortex and supplementary motor cortices do?
Process motor information,
plans and coordinates learned, skilled motor activities
Broca’s area function and location
controls muscle actions needed for speech (writing, signing, talking)
-Inferolateral portion of the frontal lobe in the left hemisphere only located on the left side, as only the left side of the brain is
involved in language
Broca’s Aphasia
Patient can understand spoken language but has difficulty communicating verbally
—>Knows what to say but can’t physically speak it
Where is the parietal lobe located and what structures does it contain?
-top of head
-Contains primary sensory cortex (postcentral gyrus), somatic sensory association area
Parietal lobe function?
Involved with general sensory functions: tactile sensation, proprioception, taste, language,
spatial orientation, and directing attention
Primary somatosensory cortex function
-receives general somatic sensory info from touch, pressure receptors
—> in charge of the initial processing of all tactile senses, including touch, pressure, tickle, pain, itch, and vibration
- Somatosensory receptors in the body are essentially mapped onto the somatosensory cortex, forming a somatosensory homunculus
Primary somatosensory cortex location
Housed by postcentral gyrus which is posterior to the central sulcus: primary sensory cortex
Somatosensory association cortex function
Integrates and interprets sensory information
Where is the temporal lobe located and what structures does it contain?
-temple, sides
-Located lateral aspect of the brain, near the ears
-Contains three parallel horizontal gyri on its lateral aspect: superior, middle, & inferior
-Auditory association area
-Auditory cortex
-Wernicke’s area
-Medial temporal lobe
What is the function of the temporal lobe?
Involved with hearing and smell, motor activity, higher-order thinking and personality
What structures does the medial temporal lobe contain?
- Hippocampus
-Amygdala
Hippocampus function
Essential in learning, storing memories, and forming long-term memory
Amygdala location and function
-Just anterior to the hippocampus in the medial-temporal lobe
-Connections with many sensory association areas
—-> Role in establishing associations between sensory input and emotions
——> critical for processing emotions and tying emotions to our sensations and our
current environment, especially fear
—–>Helps sort and code memories based on how they are emotionally perceived
———> important for regulating those emotions, along with part of the prefrontal cortex
-work with the hippocampus to tie emotions to memory
—->For example, when you are anxious or scared, the amygdala will send signals
to other parts of the brain to eventually trigger a fight-or-flight response.
-Involved in several aspects of emotion, especially fear
What is the location and function of the occipital lobe?
-Posterior region of the cortex
-responsible for processing visual information
What is the function of the Central Sulcus?
Separates the parietal lobe posteriorly and frontal lobe anteriorly from each other
What is the location and function of the lateral sulcus (Sylvian fissure)
-side of the head
-Separates the temporal lobe from the frontal and parietal lobes
What is the function of the Parieto-occipital sulcus?
Separates the occipital lobe from the parietal lobe on the medial aspect of each
hemisphere
Where is Wernicke’s area located?
Only located in the left hemisphere, overlaps the parietal and temporal lobe
Wernicke’s area function
-critical for the comprehension of language, understand speech
-Recognizing and comprehending written and spoken language
What is Wernicke’s Aphasia?
-Fluent speech
-Impaired repetition and comprehension
-Wordy but meaningless speech
-Can speak but doesn’t make sense
What is the Insula and what structures does it contain?
portion of the cerebral cortex folded deep in the lateral sulcus
contains primary gustatory cortex
Insula function
-emotion processing and arousal
-forwards the information to various structures associated with the limbic system.
Primary gustatory cortex
processes taste information
What is the limbic system?
-collection of structures involved in emotion, memory, and behavior
What are the structures of the limbic system?
Structures of limbic system form a ring around diencephalon
-Cingulate Gyrus
-Fornix
-Some thalamic nuclei
-Mammillary Body
-Amygdala
-Some hypothalamic nuclei
-Hippocampus
-Parahippocampal Gyrus
Functional grouping of the limbic system
-Structures collectively process and experience emotions
—> Establishing emotional states and related behavioral drives
-Affects memory formation, storage, and retrieval through the integration of past memories
of physical sensations with emotional states
-Link conscious, intellectual functions of cortex with unconscious and ANS functions of
other brain regions
What is the cerebral nuclei (basal ganglia)?
- A set of nuclei deep in the cerebrum involved in controlling aspects of movement, including the impulse to move
-Paired gray matter nuclei deep within the white matter
Major structures and function of the cerebral nuclei?
-Caudate nucleus
-Putamen
-Globus pallidus
-Control of posture and voluntary motor movements
-Coordinate & adjust pattern and rhythm of movement
-Control & integrate muscle tone
-Coordinate learned movement patterns
-Process, integrate, and relay info from cortex to thalamus
What is the Caudate nucleus?
long nucleus that follows the basic C-shape of the cerebrum from the frontal lobe, through the parietal and occipital lobes, into the temporal lobe
-controls movement
What is the putamen?
mostly deep in the anterior regions of the frontal and parietal lobel
-controls movement
What is the Globus pallidus?
a layered nucleus that lies just medial to the putamen in the cerebral nuclei
- controls movement
Pituitary gland location and structure
-Just inferior to the hypothalamus
-Anterior Lobe: Adenohypophysis
-Posterior Lobe: Neurohypophysis
Adenohypophysis
-anterior lobe of the pituitary gland
-made up of glandular tissue
-Controlled by releasing and inhibiting hormones from the hypothalamus
-Travel through the hypothalamohypophyseal portal system: allows hypothalamic hormones
to be transported to the anterior pituitary without first entering the systemic circulation
Hypothalamohypophyseal portal system
- Hypothalamic neurons secrete releasing or inhibiting hormones into the primary
capillary plexus - Hypothalamic hormones travel through portal veins to the anterior pituitary where
they stimulate or inhibit the release of hormones made in the anterior pituitary. - If stimulated, the anterior pituitary releases hormones into the secondary capillary
plexus and out into circulation. Inhibitory hormones inhibit release from the anterior
pituitary gland.
Neurohypophysis
-posterior lobe of the pituitary gland
-neural tissue
-Neural connection between the hypothalamus and the posterior pituitary
—-> Its axons make up the hypothalamohypophyseal tract
-Does not make hormones → stores and releases hormones made in the hypothalamus
How are hormones made in the hypothalamus?
- Hypothalamic neurons synthesize oxytocin or antidiuretic hormone.
- Hormones are transported via the axons of the hypothalamohypophyseal tract to the posterior pituitary.
- Hormones are stored in the posterior pituitary.
- When associated hypothalamic neurons fire, nerve impulses cause oxytocin or antidiuretic hormone to be released into the capillary bed
What is the cerebellum?
-“little brain,” and it accounts for approximately 10 percent of the mass of the brain
-covered in gyri and sulci like the cerebrum, though they appear more feathered or leaf-like,
which is why they are called the folia
-largely responsible for comparing information from the cerebrum with sensory feedback
from the periphery through the spinal cord
Cerebellum function
- Coordinates voluntary motor activity
—>Precision, timing, and error-correction
-Control of muscle tone and posture
-Motor learning and classical conditioning
—->Eye blink, visceromotor conditioning, vestibuloocular reflex
-Coordinates higher cognitive functions
—->Problem solving, abstraction, directed attention
-Coordinates emotional processing
-All functions are ipsilateral!!!
Cerebellum Structures
-Has anterior and posterior lobe, forming the majority of the structure
—>lobes are separated by the primary fissure
-Contains a smaller flocculonodular lobe anteriorly: composes midline
-Vermis: midline portion of the cerebellum between the two cerebellar hemispheres
-Has connections to portions of the brainstem, spinal cord, and cerebrum
-Duperior, middle, and inferior cerebellar peduncles contain white matter pathways
traveling to or from the cerebellum:
—> peduncles directly connect the cerebellum to parts of the brainstem, but the pathways will continue to or from these other regions of the CNS
Structures and function of the brainstem?
-Contains paired right and left structures
-Contains many autonomic centers and reflex centers required for survival
-Structures
—>Midbrain
—> Pons
—> Medulla Oblongata
-General functions include
—>Consciousness and awareness
—> Autonomic behaviors needed for survival
—> Auditory and visual reflexes
—> Motor and sensory innervation to the head and neck via the cranial nerves
Midbrain structure and function
-Most superior brainstem region, between the thalamus and pons
-Connected to cerebellum by cerebellar peduncles
-Contains tectum and reticular formation
-motor functions
—> Cerebral peduncles : primarily motor axons
—> Substantia nigra: neurons secrete dopamine
—–>Control of voluntary movements through connections to the basal ganglia
—> Red nucleus: Involuntary motor control, maintaining muscle tone and limb position
Tectum structure and function
-composed of four bumps known as the colliculi
-Together known as corpora quadrigemina
—->contains 2 pairs of sensory nuclei called corpora quadrigemina
-Visual reflexes: superior colliculi
-Auditory reflexes: inferior colliculi
Reticular formation structure and function
-A diffuse region of gray matter throughout the brain stem
-related to sleep and wakefulness, such as general brain activity and attention
-Arousal and consciousness
Pons structure and function
-Between the midbrain and medulla oblongata
-Anterior to cerebellum and 4th ventricle
-Contains corticospinal tract fibers
-the main connection between the cerebellum and the brain stem, particularly through
the middle cerebellar peduncle
-Process and relay of cerebellar commands
—–> Middle cerebellar peduncles
-Somatosensation: medial lemniscus
-Origin of four cranial nerves (nuclei)
-Regulation of breathing: autonomic nuclei in the pontine respiratory center
—> Regulate activity of respiratory rhythmicity center of the medulla oblongata
-Hearing: superior olivary nuclei receive auditory input and help localize sound
- Balance: nuclei that relay info from the cerebellum
- Sleep regulation
- Gray matter in the pons contains neurons receiving descending input from the
forebrain that is sent to the cerebellum as well as the pontine respiratory center
Medulla Oblongata structure and function
-Connects the brain with the spinal cord
-Many white matter tracts ascend or descend through it
-Origin of five cranial nerves (nuclei)
-Sensory nuclei from dorsal column medial lemniscus pathway
Motor information
—-> Pyramids: two vertical ridges on the anterior aspect of the medulla formed by the axons of the corticospinal tractcorticospinal tracts
—–> Pyramidal decussation: the area on the inferior aspect of the anterior medulla where the corticospinal tract fibers cross
—> Autonomic nuclei group to form
—–> Cardiovascular center: controls the smooth and cardiac muscle of the cardiovascular system through autonomic connections
———-> Adjust heart rate, strength of contraction, vasoconstriction/vasodilation
—–> Medullary respiratory center: communicates with the respiratory center of the pons to regulate breathing, sets the pace of breathing
—–> Other nuclei involved in coughing, sneezing, salivation, swallowing, gagging, and
vomiting
Infundibulum
Attaches pituitary gland to the hypothalamus
