Overview of CNS Flashcards
What are the components of the CNS?
Cerebrum, brainstem, cerebellum and spinal cord
What are the components of the peripheral nervous system?
Cranial and spinal nerves that have processes extending from the brain and spinal cord to all parts of the body.
What are the names of the projections that receive information and the ones that transmit information?
The projections that receive information are termed dendrites, while the main projection that transmits information is the axon.
Gray Matter in the CNS (description)
Gray matter areas of the cerebrum are areas where neuronal cell bodies (somas) reside and where synapses between neurons occur. Groups of cell bodies are called often called a cortex, ganglia, nuclei, or horn.
What are some important examples of gray matter?
1) the 2-3 mm thick external layers of the cerebral cortex 2) basal ganglia: caudate, putamen and globus pallidus 3) ventral and dorsal horns of the spinal cord
White matter (general description)
White matter areas of the central nervous system are composed largely of myelinated axons or fiber tracts.
What are additional terms for a bundle of myelinated axons (WHITE matter) in the CNS?
Tract Lemniscus Fasciculus Funiculus Column Peduncle Capsule Callosum Radiation
Among others, three important white matter areas include:
- corpus callosum (largest bundle of commissural fibers connecting left and right hemispheres; seen in mid-sagittal view or transverse view) Disruption of this fiber tract produces a “split brain” syndrome. 2. optic radiations (association fibers that form the final relay pathway for transmission of visual signals from the lateral geniculate nucleus to the primary visual cortex) 3. internal capsule (projection fibers that descend from brain to brainstem and spinal cord or ascend from the lower centers to the cerebral cortex). The internal capsule has an anterior limb, genu and posterior limb. 4. cerebral peduncles, pyramids, and white matter tracts of the spinal cord
Components of the Cerebrum (CNS)
Cerebrum -Telencephalon Cerebral Cortex (hemispheres) Caudate Putamen Globus Pallidus -Diencephalon Thalamus Hypothalamus
Components of the Brainstem (CNS)
Brainstem -Midbrain -Pons -Medulla
Cerebral Cortex (description)
-The outer shell is about 3 mm thick, composed of gray matter, which is primarily neuronal cell bodies No myelin The cortical surface is highly convoluted, which increases its surface area. The cortex is the most complicated integrating area of the nervous system, and is required for processing of incoming (afferent) information into meaningful perception, and for the ultimate refinement of control over outgoing (efferent) information. The cortex is also the site of long-term memory storage and is responsible for our ability to learn motor skills.
What are the 5 lobes of the cerebrum?
Frontal, Parietal, Temporal, Occipital and Insular lobes (some anatomists divide the cerebrum into 6 lobes with the Limbic Lobe being the 6th
Frontal lobe: Primary motor cortex (functional system 1 of 4)
(M1); origin of the corticospinal, corticobulbar and corticopontine tracts.
Frontal lobe: Supplementary motor area (functional system 2 of 4)
(SMA; M2) is more active when a sequence of movements is remembered and self-determined or internally referenced. SMA receives input from the basal ganglia.
Frontal lobe: Premotor cortex (functional system 3 of 4)
The premotor complex is used in visually guided, externally referenced motor tasks. Gets input from the cerebellum which helps program the motor cortex for execution of a movement. Functions in reaching, precision grip and prehension.
Frontal lobe: Pre-frontal cortex (functional system 4 of 4)
The Pre-frontal cortex is one of the most complex parts of the brain. It integrates all judgment, behavior, imagination and emotion into a person’s unique identity or personality. Damage to this area causes disturbances of these features and alters personality, i.e. Phineas Gage.
Parietal lobe functional systems
The Parietal lobe contains the primary somatosensory cortex and somatosensory association areas. The association areas of the parietal, temporal and occipital lobes are areas that interpret sensory input and give it meaning.
Temporal lobe functional systems
Temporal lobe contains the primary auditory cortex and auditory association areas. In addition, structures in and around the medial temporal lobe play roles in olfaction, emotion, and memory, i.e. HM.
Occipital lobe functional systems
The Occipital lobe contains the primary visual cortex and visual association areas.
Insula or insular lobe functional systems
Insula or insular lobe (contains part of the limbic system, which is involved in the control of behavior and emotions). Functionally, it plays a role in diverse functions including emotions, homeostasis, perception, motor control, self-awareness, cognitive functioning, and interpersonal experience.
Gyri (singular, gyrus)
are the convoluted folds in the cortex of the cerebral hemispheres.
Sulci (singular, sulcus) and fissures
are grooves between the gyri, with fissures being the deeper of the two. Sulci and fissures are formed as a result of massive growth of the telencephalon during embryonic development.
Major sulci/fissures of the cortex: Longitudinatl fissure
Longitudinal fissure: separates left and right cerebral hemispheres (also called the interhemispheric fissure).
Major sulci/fissures of the cortex: Central sulcus
Central sulcus (or Fissure of Rolando): separates frontal and parietal lobes.
Major sulci/fissures of the cortex: Lateral fissure
Lateral fissure (or Fissure of Sylvius): separates temporal lobe below from frontal and parietal lobes above.
Major sulci/fissures of the cortex: Parieto-occipital sulcus
Parieto-occipital sulcus: separates the parietal lobe from the occipital lobe.
Major sulci/fissures of the cortex: Calcarine sulcus
Calcarine sulcus: divides the primary visual cortex into two regions: the cuneus (above the sulcus) and the lingual gyrus (below the sulcus). These regions can be seen from the mid-sagittal surface of the brain.
Some important (gyri) of the cerebral cortex include: Post Central Gyrus
primary somatosensory cortex
Some important (gyri) of the cerebral cortex include: Precentral Gyrus
primary motor cortex
Motor and sensory cortex: the homunculus
Sensory evoked potentials (i.e., cortical responses to tactile stimulation) and direct stimulation of the postcentral gyrus have been used to map the representation of the body surface (the sensory homunculus).
The homunculus and respective representations
Body areas with greater representation in the cortex have proportionally greater sensory innervation in the periphery (e.g., face & tongue vs. lower extremity). A similar motor map exists in the precentral gyrus. Areas with larger representation, have relatively greater motor innervation and finer motor control (the motor homunculus).
Some important (gyri) of the cerebral cortex include: Cuneus and Lingual Gyri
primary visual cortex
Some important (gyri) of the cerebral cortex include: Superior Temporal Gyrus
primary auditory cortex
Some important (gyri) of the cerebral cortex include: Posterior Inferior Frontal Gyrus
Broca’s area: speech center that coordinates movement of the larynx and mouth to produce speech. A lesion in this area can produce severe speech deficits (Broca’s or “expressive” aphasia) ranging from complete muteness to non-fluent (“choppy”) language production; difficulty word finding.