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Ch. 13 CNS
| Term | Definition | ||
|---|---|---|---|
| BRAIN | Control center for thoughts, memories, and behaviors | ||
| SPINAL CORD | The pathway for sensory nerve impulses traveling to the brain and motor nerve impulses traveling from the brain to skeletal muscles or other effectors ▪ Also controls some of the rapid reactions to environmental changes (reflexes) | ||
| BRAIN | ▪ Cerebrum - left and right hemispheres ▪ Diencephalon - includes thalamus and hypothalamus ▪ Brain stem - includes midbrain, pons, and medulla oblongata ▪ Cerebellum - posterior segment | ||
| SPINAL CORD | Extends inferiorly from brain stem to level of first or second lumbar vertebrae | ||
| PROTECTION OF CNS | ▪ Skeletal ▪ Meninges ▪ Cerebrospinal fluid | ||
| MENINGES | ▪ Dura mater ▪ Arachnoid mater ▪ Pia mater | ||
| DURA MATER | ▪ Strongest, dense, irregular connective tissue ▪ Adheres to periosteum of cranial bones ▪ Three extensions separate portions of brain ▪ Double layer forms dural sinuses ▪ Separated from spinal cord by epidural space | ||
| ARACHNOID MATER | ▪ Avascular web of delicate collagen and elastic fibers ▪ Separated from dura mater by subdural space | ||
| PIA MATER | ▪ Transparent, adheres tightly to surface of brain and spinal cord ▪ Separated from arachnoid by subarachnoid space | ||
| SKELETAL | -Skull - cranial bones form cavity - Vertebral column - vertebral foramina for canal | ||
| MENINGES | ▪ Three protective, connective tissue layers ▪ Cranial and spinal meninges continuous with each other | ||
| CEREBROSPINAL FLUID | - Fluid in space between meninges and inside cavities of brain and spinal cord - Buoyant, and shock-absorbing cushion | ||
| SPACES ASSOCIATED WITH MENINGES | -dural sinuses -subdural space -epidural space -subarachnoid space | ||
| Dural sinuses | brain only ▪ Blood from brain, delivers to internal jugular veins | ||
| Subdural space | brain and spinal cord ▪ Interstitial fluid | ||
| Epidural space | spinal cord only ▪ Fat and connective tissue ▪ Interstitial fluid | ||
| Subarachnoid space | brain and spinal cord ▪ Cerebrospinal fluid ▪ Along spinal cord only: denticulate ligaments extend laterally from pia mater to fuse with arachnoid mater to protect from sudden displacement of spinal cord | ||
| Blood brings continuous supply of | oxygen and glucose, and removes wastes and carbon dioxide | ||
| Blood flow to active areas of the brain increases during | higher levels of metabolic activity | ||
| Interruptions in blood flow have | very serious consequences (unconsciousness, stroke, death) | ||
| BLOOD FLOW TO BRAIN AND SPINAL CORD | ▪ Brain -Internal carotid and vertebral arteries - Dural sinuses and internal jugular veins ▪ Spinal cord - Posterior intercostal and lumbar arteries and veins | ||
| BLOOD-BRAIN BARRIER (BBB) | ▪ Created by tightly connected endothelial cells of CNS capillaries and astrocyte processes that press up against the capillaries ▪ Controls what can and cannot cross from blood into interstitial fluid of CNS tissues ▪ Glucose, oxygen, carbon dioxide, | most anesthetics, alcohol, and some other substances can cross ▪ Toxins, most antibiotics, and proteins cannot cross ▪ Protects CNS from harmful substances and pathogens | |
| BRAIN VENTRICLES Cerebrospinal fluid-filled cavities | ▪ Two lateral ventricles (right and left) ▪ Third ventricle - midline, superior to hypothalamus ▪ Fourth ventricle - between brain stem and cerebellum | ||
| CEREBROSPINAL FLUID (CSF) | Formed by choroid plexuses - capillary network in walls of ventricles | ||
| Functions of CSF | ▪ Mechanical protection - buoyancy and shock-absorption ▪ Chemical protection - maintain optimal ionic concentrations of interstitial fluid ▪ Circulation of nutrients - efficient exchange | ||
| ▪ Ependymal cells’ | tight junctions form blood-cerebrospinal fluid barrier that controls passage of substances from blood into CSF | ||
| CEREBROSPINAL FLUID CIRCULATION Ependymal cell | cilia move fluid between ventricles where formed ▪ Interventricular foramina - from lateral ventricles to third ventricle ▪ Cerebral aqueduct - from third to fourth ventricle | ▪ Median aperture and pair of lateral apertures - from fourth ventricle to subarachnoid space ▪ Some enters central canal of spinal cord | |
| CEREBROSPINAL FLUID CIRCULATION Arachnoid villi | ▪ Eventually fluid flows to subarachnoid space around brain ▪ Fingerlike extensions project into dural sinus for reabsorption into blood | ||
| CEREBRUM: FUNCTION | ▪ Interprets sensory impulses ▪ Controls muscular movements ▪ Functions in intellectual processes | ||
| CEREBRUM: SECTIONAL ANATOMY | ▪ Cortex ▪ Internal (medulla) ▪ Basal nuclei | ||
| Cortex | ▪ Outer rim of gray matter ▪ Gyri - folds of cortex ▪ Sulci - shallow grooves between gyri ▪ Fissures - deepest grooves, between major sections | ||
| Internal (medulla) | ▪ White matter - tracts of myelinated axons ▪ Propagate impulses for communication within CNS | ||
| Basal nuclei | ▪ Functional clusters of gray matter (neuronal cell bodies) deep within white matter | ||
| CEREBRUM Lobes named for superficial cranial bone | ▪ Frontal, parietal, temporal, and occipital ▪ Insula: deeper, within lateral fissure | ||
| CEREBRUM Fissures and sulci | ▪ Longitudinal fissure - between hemispheres ▪ Central sulcus - between frontal and parietal lobes ▪ Separates major gyri: precentral and postcentral gyrus ▪ Lateral sulcus - between frontal and temporal lobes | ▪ Parieto-occipital sulcus - between parietal and occipital lobe | |
| CEREBRUM: WHITE MATTER TRACTS | ▪ Association tracts ▪ Commissural tracts ▪ Projection tracts | ||
| ASSOCIATION TRACTS | Conduct impulses between gyri of the same hemisphere | ||
| COMMISSURAL TRACTS | ▪ Conduct impulses between gyri of different hemispheres ▪ Corpus callosum - largest fiber bundle in brain ▪ Anterior and posterior commissures | ||
| PROJECTION TRACTS | ▪ Conduct impulses between cerebrum and lower CNS regions | ||
| CEREBRUM: BASAL NUCLEI | Located deep in the cerebral white matter ▪ Globus pallidus ▪ Putamen ▪ Caudate nucleus | ||
| CEREBRUM: BASAL NUCLEI-FUNCTIONS | ▪ Help initiate and terminate movements ▪ Regulate muscle tone ▪ Control subconscious contractions of skeletal muscles ▪ Influence some cognitive processes | ||
| CEREBRUM: CORTEX FUNCTIONAL AREAS | ▪ Cortex ▪ Sensory areas ▪ Motor areas ▪ Association areas | ||
| CORTEX (gray matter with gyri/sulci) | can be divided into specialized functional areas | ||
| SENSORY AREAS | Allow perception (conscious awareness) of sensory information | ||
| MOTOR AREAS | Control the execution of voluntary movements | ||
| ASSOCIATION AREAS | Concerned with more complex integrative functions such as memory, personality traits, emotions, and intelligence | ||
| CEREBRAL CORTEX SENSORY AREAS | ▪ Primary somatosensory area (postcentral gyrus) ▪ Primary visual area ▪ Primary auditory area ▪ Primary gustatory area ▪ Primary olfactory area | ||
| Primary somatosensory area (postcentral gyrus) | Receives nerve impulses from somatic sensory receptors for touch, pressure, vibration, itch, tickle, temperature, pain, and proprioception and is involved in perception of these sensations | ||
| Primary visual area | Receives and perceives visual information | ||
| Primary auditory area | Receives and perceives sound information | ||
| Primary gustatory area | Receives and perceives taste information | ||
| Primary olfactory area | Receives and perceives smell information | ||
| CEREBRAL CORTEX MOTOR AREAS | ▪ Primary motor area (precentral gyrus) ▪ Broca’s area | ||
| Primary motor area (precentral gyrus) | ▪ Controls voluntary contractions of specific skeletal muscles or muscle groups on opposite side of body ▪ More cortical area devoted to muscles involved in skilled, complex, or delicate movement | ||
| Broca’s area | ▪ Controls muscles of larynx, pharynx, and mouth for production of speech ▪ Coordinates control of muscles for breathing to regulate proper flow of air | ||
| CEREBRAL CORTEX ASSOCIATION AREAS | ▪ Somatosensory association area ▪ Visual association area ▪ Auditory association area ▪ Wernicke’s area ▪ Common integrative area ▪ Prefrontal cortex ▪ Premotor area ▪ Frontal eye field area | ||
| Somatosensory association area | ▪ Permits you to evaluate an object by touch and to sense the relationship of one body part to another; also stores memories of past somatic sensory experiences | ||
| Visual association area | ▪ Utilizes past visual experiences for recognizing and evaluating what is seen | ||
| Auditory association area | ▪ Allows you to recognize a particular sound | ||
| Wernicke’s area | Interprets the meaning of speech by translating words into thoughts | ||
| Common integrative area | ▪ Integrates sensory interpretations from the association areas, allowing thoughts based on sensory input | ||
| Prefrontal cortex | ▪ Concerned with personality, intellect, complex learning abilities, judgment, reasoning, conscience, intuition, and development of abstract ideas | ||
| Premotor area | ▪ Controls sequential muscle contractions, and serves as a memory bank for complex movements | ||
| Frontal eye field area | ▪ Controls voluntary scanning movements of the eye | ||
| CEREBRUM: HEMISPHERIC LATERALIZATION | ▪ Subtle anatomical differences between two hemispheres, although variable in individuals ▪ Each has unique functions, in a division of labor ▪ Each receives sensory signals from and controls movements on the opposite side of the body | ▪ Left: more important for language, numerical and scientific skills, and reasoning | ▪ Right: more important for musical and artistic awareness, spatial and pattern perception, recognition of faces, emotional content of language, identifying odors, and generating mental images of sight, sound, taste, and smell |
| FUNCTIONAL DIFFERENCES BETWEEN THE 2 CEREBRAL HEMISPHERES-LEFT HEMISPHERE FUNCTIONS | -receives somatic sensory signals from and controls muscles on right side of body -reasoning -numerical and scientific skill -ability to use and understand sign language -spoken and written langauge | ||
| FUNCTIONAL DIFFERENCES BETWEEN THE 2 CEREBRAL HEMISPHERES-RIGHT HEMISPHERE FUNCTIONS | -receives somatic sensory signals from and controls muscles on left side of body -musical and artistic awareness -space and pattern perception -recognition of faces and emotional content of facial expressions | -generating emotional content of langauge -generating mental images to compare spacial relationships -identifying and discriminating among odors | |
| DIENCEPHALON: FUNCTION | ▪ Central core of brain tissue from brain stem to cerebrum, surrounding third ventricle ▪ Involved in variety of sensory and motor processing between higher and lower brain centers | ||
| DIENCEPHALON: SECTIONAL ANATOMY | ▪ Thalamus ▪ Hypothalamus ▪ Pineal gland | ||
| Thalamus | ▪ Paired oval masses of gray matter ▪ Intermediate mass connects right and left halves across third ventricle | ||
| Hypothalamus | ▪ Many gray matter nuclei inferior to thalamus, including mammillary bodies ▪ Stalk-like infundibulum connects to pituitary gland | ||
| Pineal gland | ▪ Pea-shaped protrusion posterior in midline of the third ventricle | ||
| DIENCEPHALON: THALAMUS | ▪ Relays and processes sensory impulses to the primary sensory areas of the cerebral cortex ▪ Transmits input from the cerebellum to the primary motor area of the cerebral cortex | ▪ Together with other brain areas, it functions in movement control, maintenance of consciousness, pain perception, memory, learning, and cognition | |
| DIENCEPHALON: HYPOTHALAMUS | ▪ One of the major regulators of homeostasis ▪ Control of autonomic nervous system (ANS) ▪ Production of hormones, especially related to pituitary gland ▪ Regulation of emotional and behavioral patterns | ▪ Regulation of eating and drinking ▪ Control of body temperature ▪ Regulation of circadian rhythms and states of consciousness | |
| DIENCEPHALON: PINEAL GLAND | ▪ Secretes the hormone melatonin ▪ More during darkness than in light ▪ Promotes sleepiness ▪ Appears to contribute to setting the body’s biological clock | ||
| BRAIN STEM: FUNCTION | ▪ Contain both tracts and nuclei ▪ Act as relay centers for processing and controlling involuntary reflexes for vision and hearing, and govern reflexes vital to life | ||
| BRAIN STEM: ANATOMY | ▪ Midbrain ▪ Pons ▪ Medulla oblongata | ||
| Midbrain | ▪ Divided anterior/posterior by cerebral aqueduct ▪ Axons from cerebellum and cerebral cortex form synapses with midbrain nuclei | ||
| Pons | ▪ Inferior to midbrain, anterior to cerebellum | ||
| Medulla oblongata | ▪ Inferior part, continuation with spinal cord ▪ Pyramids - bulges on anterior aspect ▪ Olive - swelling lateral to each pyramid | ||
| BRAIN STEM: MIDBRAIN | ▪ Cerebral peduncles ▪ Corpora quadrigemina ▪ Nuclei | ||
| Cerebral peduncles | ▪ Three paired, anterior tracts ▪ Motor axons (descending) conduct nerve impulses from motor areas of cerebrum to medulla, pons and spinal cord | ||
| Corpora quadrigemina | ▪ Superior colliculi - visual reflexes ▪ Inferior colliculi - auditory reflexes | ||
| Nuclei | Extend to basal nuclei and release dopamine ▪ Help control subconscious muscle activity | ||
| BRAIN STEM: PONS | ▪ Relays signals for voluntary movements from the cerebral cortex to the cerebellum ▪ Sensory (ascending) tracts ▪ Conduct impulses to higher brain areas ▪ Motor (descending) tracts ▪ Conduct impulses from higher brain areas toward the spinal cord | ▪ Pneumotaxic and apneustic areas ▪ Nuclei that work with the medullary rhythmicity area to help control breathing | |
| BRAIN STEM: MEDULLA OBLONGATA | ▪ Pyramids ▪ Motor tracts from cerebrum to spinal cord control voluntary movement of trunk and limbs ▪ Decussation (crossing over) of pyramids to opposite side before continuing to spinal cord | ▪ Cardiovascular center ▪ Controls heart rate and blood pressure ▪ Medullary rhythmicity area ▪ Adjusts basic rhythm of breathing ▪ Olive ▪ Relay motor impulses to cerebellum | |
| RETICULAR FORMATION | ▪ Broad region of brain stem and diencephalon ▪ White matter and gray matter form a netlike arrangement ▪ Reticular activating system (RAS) ▪ Sensory axons - visual, auditory, mental activities ▪ Helps arouse the body from sleep | ▪ Maintains attention and alertness (consciousness) ▪ Descending motor function ▪ Regulate posture ▪ Maintain muscle tone | |
| CEREBELLUM: FUNCTION | ▪ Highly folded surface that greatly increases surface area of outer gray matter cortex, allowing for greater number of neurons ▪ Evaluates, smoothes, and coordinates contractions of skeletal muscles; also maintains posture and balance | ||
| CEREBELLUM: ANATOMY | ▪ Vermis ▪ Cerebellar hemispheres ▪ Arbor vitae ▪ Cerebellar peduncles | ||
| Vermis | Central constricted area | ||
| Cerebellar hemispheres | Anterior, posterior, and flocculonodular lobes | ||
| Arbor vitae | Branching, white matter deep to cortex | ||
| Cerebellar peduncles | ▪ Three, paired tracts ▪ Superior: to midbrain and thalamus ▪ Middle: from pons and cerebral motor cortex ▪ Inferior: sensory information from medulla, pons, and spinal cord | ||
| LIMBIC SYSTEM | ▪ Broad region including parts of cerebrum and diencephalon ▪ Encircles upper brain stem and corpus callosum ▪ Primary role in emotional aspects of behavior ▪ Pain, pleasure, docility, rage, anger, affection ▪ Also role in memory and olfaction | ||
| SPINAL CORD: FUNCTIONS | ▪ Assist in maintaining homeostasis ▪ Nerve impulse propagation ▪ Ascending (sensory) or descending (motor) nerve impulse propagation | ▪ Information integration ▪ Spinal reflexes - fast, involuntary responses to stimuli processed in the gray matter of spinal cord | |
| SPINAL CORD: EXTERNAL ANATOMY | ▪ Oval in shape, slightly flattened anteriorly and posteriorly ▪ Two enlargements ▪ Conus medullaris ▪ Filum terminale | ||
| Two enlargements | ▪ Cervical - supplies nerves to/from upper limbs ▪ Lumbar - supplies nerves to/from lower limbs | ||
| Conus medullaris | ▪ Conical portion inferior to lumbar enlargement | ||
| Filum terminale | Extension of pia mater extending inferiorly to anchor spinal cord to coccyx | ||
| SPINAL CORD: SPINAL NERVE ROOTS | Connect spinal nerves to segment of cord ▪ Posterior root ▪ Posterior root gangli ▪ Anterior root ▪ Cauda equina | ||
| Posterior root | Contains sensory axons | ||
| Posterior root ganglion | Contains cell bodies of sensory neurons | ||
| Anterior root | Contains axons of motor neurons | ||
| Cauda equina | Collection of spinal nerve roots that hang inferiorly from spinal cord in the vertebral canal | ||
| SPINAL CORD: INTERNAL ANATOMY | Anterior median fissure and posterior median sulcus -Gray matter -White matter | ||
| Gray matter | H-shaped, deep ▪ Anterior, lateral and posterior horns ▪ Gray commissure connects right and left sides and surrounds central canal (cerebrospinal fluid-filled) | ||
| White matter | cortex ▪ Anterior, lateral, and posterior columns ▪ Ascending (sensory) tracts ▪ Descending (motor) tracts | ||
| SPINAL CORD TRACTS | Named for position and origin-destination -Ascending (sensory) -Descending (motor) | ||
| SPINAL CORD TRACTS-Ascending (sensory) | ▪ Spinothalamic tract - pain, warmth, coolness, itching, tickling, deep pressure, crude touch ▪ Posterior column - discriminative touch, light pressure, vibration, conscious proprioception | ||
| SPINAL CORD TRACTS-Descending (motor) | ▪ Direct pathways - cerebral cortex voluntary movement of skeletal muscles ▪ Indirect pathways - brain stem automatic movements of skeletal muscles |
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fieldslady80
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