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The Central Nervous System - Chapter 12 Lecture Notes
Central Nervous System (CNS)
Components and Early Development:
Refer to Figure 12.1 (pg. 431) for a brief overview.
Four Brain Regions:
(To be specified, likely cerebrum, diencephalon, brainstem, and cerebellum)
Gray Matter:
Composition and distribution within the CNS.
White Matter:
Composition and distribution within the CNS.
Ventricles:
Definition: Spaces within the brain filled with cerebrospinal fluid (CSF).
Location: Throughout the brain.
General organization.
Protection of the Brain (pg. 460)
Protective Structures:
Bones of the skull.
Cerebrospinal fluid (CSF).
Meninges.
Meninges
Definition: Protective membranes surrounding the brain and spinal cord.
Organization (layers):
Dura Mater:
Periosteal Layer: Outer layer attached to the skull.
Meningeal Layer: Inner layer.
Dural Septa: Extensions of the dura mater that divide the cranial cavity.
Falx Cerebri: Separates the two cerebral hemispheres.
Falx Cerebelli: Separates the two cerebellar hemispheres.
Tentorium Cerebelli: Separates the cerebrum from the cerebellum.
Arachnoid Mater:
Subdural Space: Space between the dura mater and arachnoid mater.
Subarachnoid Space: Space between the arachnoid mater and pia mater; contains CSF.
Arachnoid Granulations: Structures that allow CSF to pass into the dural sinuses.
Pia Mater: Innermost layer, tightly adhered to the surface of the brain and spinal cord.
Functions:
Protect the brain and spinal cord.
Provide a framework for blood vessels.
Contain cerebrospinal fluid.
Meningitis:
Inflammation of the meninges.
Cerebral Spinal Fluid (CSF)
Functions:
Cushions the brain and spinal cord.
Transports nutrients and waste products.
Helps maintain a stable chemical environment.
Composition:
Similar to blood plasma but with less protein and different ion concentrations.
Production:
Produced by the choroid plexus in the ventricles.
Blood Brain Barrier (BBB)
Organization:
Endothelial cells: Form the walls of capillaries in the brain; have tight junctions.
Tight junctions: Prevent most substances from passing between endothelial cells.
Basement membrane: Surrounds the capillaries.
Astrocytes: Help maintain the BBB.
Permeability:
Allows passage of: Lipid-soluble substances, gases (O2, CO2), some small molecules (e.g., glucose with the help of specific transporters).
Restricts passage of: Most large molecules, toxins, and drugs.
Cerebrum (Cerebral Hemispheres)
Location:
The largest part of the brain, located superiorly and anteriorly.
Fissures: Deep grooves that divide the cerebrum.
Longitudinal Fissure: Separates the left and right cerebral hemispheres.
Transverse Cerebral Fissure: Separates the cerebrum from the cerebellum.
Gyri: Elevated ridges on the surface of the cerebrum.
Precentral Gyrus: Located anterior to the central sulcus; contains the primary motor cortex.
Postcentral Gyrus: Located posterior to the central sulcus; contains the primary somatosensory cortex.
Sulci: Shallow grooves on the surface of the cerebrum.
Central Sulcus: Separates the frontal lobe from the parietal lobe.
Lateral Sulcus: Separates the temporal lobe from the frontal and parietal lobes.
Parieto-occipital Sulcus: Separates the parietal lobe from the occipital lobe.
Lobes: Major divisions of the cerebrum.
Frontal Lobe: Anterior part of the cerebrum; involved in motor control, planning, and higher-level cognitive functions.
Parietal Lobe: Located posterior to the frontal lobe; involved in somatosensory processing.
Occipital Lobe: Posterior part of the cerebrum; involved in visual processing.
Temporal Lobe: Located inferior to the frontal and parietal lobes; involved in auditory processing, memory, and language.
Insula: Located deep within the lateral sulcus; involved in taste, visceral sensation, and emotion.
General Regions:
Cerebral Cortex: Outer layer of gray matter.
White Matter: Located beneath the cerebral cortex; consists of myelinated axons.
Basal Nuclei (Basal Ganglia): Clusters of gray matter located deep within the white matter; involved in motor control, cognition, and emotion.
Cerebral Cortex
Composition:
Gray matter composed of neuron cell bodies, dendrites, and unmyelinated axons.
4 Cerebral Cortex Generalizations (pgs. 435-436): (To be specified)
Functional Areas:
Motor Areas:
Primary Motor Cortex:
Location: Precentral gyrus of the frontal lobe.
Function: Controls voluntary movements.
Pyramidal Cells: Large neurons in the primary motor cortex that project to the spinal cord.
Premotor Cortex:
Location: Anterior to the primary motor cortex in the frontal lobe.
Function: Plans and coordinates complex movements.
Broca’s Area:
Location: Frontal lobe, usually on the left side.
Function: Controls speech production.
Frontal Eye Field:
Location: Frontal lobe, anterior to the premotor cortex.
Function: Controls voluntary eye movements.
Sensory Areas:
Primary Somatosensory Cortex:
Location: Postcentral gyrus of the parietal lobe.
Function: Receives sensory information from the skin and proprioceptors.
Spatial Discrimination: Ability to identify the location of a stimulus.
Somatosensory Association Cortex:
Location: Posterior to the primary somatosensory cortex in the parietal lobe.
Function: Integrates sensory information to understand objects being felt.
Visual Areas:
Primary Visual Cortex:
Location: Occipital lobe.
Function: Receives visual information from the retinas.
Visual Association Area:
Location: Surrounds the primary visual cortex in the occipital lobe.
Function: Interprets visual stimuli.
Auditory Areas:
Primary Auditory Cortex:
Location: Temporal lobe.
Function: Receives auditory information from the inner ear.
Auditory Association Area:
Location: Surrounds the primary auditory cortex in the temporal lobe.
Function: Interprets auditory stimuli.
Primary Olfactory Cortex:
Location: Temporal lobe.
Function: Receives olfactory information from the olfactory receptors.
Gustatory Cortex:
Location: Insula.
Function: Receives taste information from the taste buds.
Visceral Sensory Area:
Location: Insula.
Function: Receives sensory information from the internal organs.
Multimodal Association Areas:
Anterior Association Area (Prefrontal Cortex):
Location: Frontal lobe.
Function: Involved in higher-level cognitive functions such as planning, decision-making, and working memory.
Posterior Association Cortex:
Location: Parietal, temporal, and occipital lobes.
Function: Integrates sensory information to create a coherent picture of the world.
Wernicke’s Area:
Involved in understanding language.
Homunculus:
A representation of the body surface on the primary motor and somatosensory cortices.
Shows the relative amount of cortical area devoted to different body parts.
Helps understand sensory input and motor output.
Cerebral White Matter
Definition:
Composed of myelinated axons.
Association Fibers:
Connect different parts of the same hemisphere.
Long Fibers: Connect different lobes within the same hemisphere.
Short Fibers: Connect adjacent gyri within the same hemisphere.
Commissural Fibers:
Connect corresponding areas of the two hemispheres.
Corpus Callosum: The largest commissure, connecting the cerebral hemispheres.
Anterior Commissures:
Posterior Commissures:
Projection Fibers:
Connect the cerebral cortex to lower brain regions and the spinal cord.
Internal Capsule:
*Corona Radiata:
Basal Nuclei (Basal Ganglia)
Areas:
Caudate Nucleus
Putamen
Globus Pallidus
Functions:
Motor control
Cognition
Emotion
Diencephalon
Location:
Located between the cerebrum and the brainstem.
Three Paired Structures:
Thalamus:
Location:
Functions:
Relay station for sensory information.
Involved in motor control and consciousness.
Nuclei: Lateral and Medial geniculate bodies.
Hypothalamus:
Location:
Functions:
Controls the autonomic nervous system.
Regulates body temperature, hunger, thirst, and sleep-wake cycles.
Mammillary Bodies:
Infundibulum:
Chief Homeostatic Roles:
Epithalamus:
Location:
Functions:
Contains the pineal gland and posterior commissure.
Pineal Gland: Secretes melatonin, which regulates sleep-wake cycles.
Posterior Commissure:
Brain Stem
Location:
Functions:
Midbrain:
Location:
Cerebral Peduncles:
Crus Cerebri:
Cerebral Aqueduct:
Periaqueductal Gray Matter:
Corpora Quadrigemina:
Superior Colliculi:
Inferior Colliculi:
Pons:
Conduction Tracts:
Longitudinal Tracts:
Transverse/Dorsal Tracts:
Middle Cerebellar Peduncles:
Cranial Nerves coming out of the Pons:
Function:
Medulla Oblongata:
Location:
Pyramids:
Decussation of the Pyramids:
Functions:
Cardiovascular Center:
Respiratory Centers:
Other Centers:
Cranial Nerves that come out of the Medulla Oblongata:
Cerebellum
Location:
Functions:
Vermis:
Posterior Lobe:
Anterior Lobe:
Cerebellar Cortex:
Arbor Vitae:
Folia:
Cerebellar Peduncles:
Superior Cerebellar Peduncles:
Middle Cerebellar Peduncles:
Inferior Cerebellar Peduncles:
Limbic System
Location:
Functions:
Amygdaloid Body:
Cingulate Gyrus:
Reticular Formation
Function:
Higher Mental Functions
Language:
Broca’s Area:
Wernicke’s Area:
How do they work together?
Memory:
Short Term Memory:
Long Term Memory:
Consciousness:
Selected Brain Injuries and Disorders
Traumatic Brain Injuries:
Concussion:
Contusion:
Subdural and Subarachnoid Hemorrhaging:
Cerebral Edema:
Cerebrovascular Accidents (Strokes):
Ischemia:
Transient Ischemic Attacks:
Degenerative Brain Disorders:
Alzheimer’s Disease:
Parkinson’s Disease:
Huntington Disease:
Spinal Cord
General Characteristics:
Conus Medullaris:
Filum Terminale:
Denticulate Ligaments:
Cervical Enlargement:
Lumbar Enlargement:
Cauda Equina:
Cross Section:
Ventral (anterior) Median Fissure:
Dorsal (posterior) Median Sulcus:
Central Canal:
Gray Matter:
Ventral Horns:
Ventral Roots:
Dorsal Horns:
Dorsal Root Ganglion:
Lateral Horns:
Gray Commissure:
White Matter:
Runs in 3 directions:
Ascending:
Descending:
Transverse:
White Columns (Funiculi):
Dorsal Funiculi:
Ventral Funiculi:
Lateral Funiculi:
White matter is composed of myelinated axons and connects different parts of the brain to each other and to the spinal cord.