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Ch. 12 - 13 defs
Study Question Definitions from Chapters 12 -13
| Question | Answer |
|---|---|
| Afferent | ascending, typically sensory, towards the central nervous system |
| Association fibers | myelinated fibers that provide communication between regions of the same hemisphere (e.g. connect the superior temporal gyrus with the middle temporal gyrus within the left hemisphere) |
| short association fibers | connect neurons of one gyrus to the next, traversing fissures |
| long association fibers | interconnect the lobes of the brain within the same hemisphere |
| Autonomic nervous system | governs involuntary activities of the visceral muscles (also, viscera), including glandular secretions heart function, digestive function, and so forth |
| Axon | transmit information away from the soma (cell body) |
| Basal ganglia | a group of nuclei (cell bodies) with functional unity involved in background movement and initiation of movement patterns |
| Five parts of the basal ganglia | includes the caudate nucleus, the putamnen, the globus pallidus, the claustrum, and the amygdaloid nucleus |
| Brainstem | consists of the medulla oblongata, pons and midbrain; origination of cranial nerves |
| Central nervous system (CNS) | includes the brain (cerebrum, cerebellum, subcortical structures, brainstem), and spinal cord; most structures housed within bone (skull or vertebral column) |
| Cerebral cortex | (also, cerebrum) the seat of consciousness in the brain (sensory information that does not reach the level of the cerebrum does not reach consciousness); source of voluntary movement |
| Cerebellum | source of motor coordination; information from peripheral sensors is coordinated with the motor plan of the cerebrum to provide body with ability to make finely tuned motor gestures; output modified by the basal ganglia; largest part of the hindbrain |
| Cerebrospinal fluid (CSF) | provides a cushion for the delicate and dense neural tissue as well as some nutrient delivery and waste removal, flows through ventricles of the brain; produced by the choroids plexus |
| Choroid plexus | structures within the ventricles that produce cerebrospinal fluid |
| Commissural fibers | myelinated fibers that connect a region of the brain with the corresponding region in the other hemisphere; e.g. the fibers of the corpus callosum |
| Conduction velocity | how fast a motor neuron can conduct an impulse |
| Contralateral innervation | each hemisphere of the brain controls motor function in the opposite side of the body; e.g. a command arising from the left hemisphere to move the thumb will cause the thumb of the right hand to twitch |
| Corpus callosum | provides communication concerning sensation and memory among the two hemispheres by means of myelinated fibers; four major regions |
| Corticobulbar tract | originates in the frontal lobe of the cerebrum and terminates in the brainstem; activates muscles served by cranial nerves |
| Corticobulbar tract function | axons branch and decussate at various levels of the brainstem, synapsing with nuclei of cranial nerves to provide bilateral innervation to many muscles of the face, neck, pharynx, and larynx |
| Corticospinal tract | originates in frontal lobe of cerebellum, terminates in spinal cord; activates skeletal muscle of extremities; fibers descend to medulla and undergo pyramidal decussation, where 75-90% of fibers cross to descend as lateral corticospinal tract in funiculus |
| Deep sensation | e.g. muscle tension, muscle length, joint position sense, muscle pain, pressure, and vibration |
| Demyelination | is a process that removes the myelin sheath from a myelinated axon; many diseases cause demyelination of the myelinated fibers in the brain result in dysfunction in the areas served |
| Dendrite | within a neuron, transmit information towards the soma (cell body) |
| Dermatone | a nerve that serves a region of sensory afferent spinal nerves that innervate a particular region of the body |
| Diencephalon | includes the thalamus, epithalamus, hypothalamus, and subthalamus |
| Efferent | descending, typically motor, away from the central nervous system |
| Excitation | stimulation that causes an increase of activity of the tissue stimulated |
| Fissure | a deeper, more pronounced sulcus (e.g. fissure of Roland = central sulcus) |
| Genu | “bend” part of the corpus callosum through which fibers connecting the anterior frontal lobes of both hemispheres run |
| Glial cells | (also, glia) support tissue, nutrients to neurons, comprise myelin |
| Gyri | the raised portions of the brain |
| Hematoma | a pooling of blood, typically arising from breakage of a blood vessel (e.g. subdural hematoma |
| Hippocampal formation | part of the rhinecephalon, strongly implicated in memory function, communicates with the hypothalamus (related to visceral function and emotion) and to portions of the temporal lobe associated with memory function |
| Hypothalamus | part of diencephalon; divided into three regions- preoptic, mammillary and tuberal regions; regulates reproductive behavior & phys, desire/perception of need for food or water, perception of satiation, control of digestive processes, & metabolic functions |
| Inhibition | stimulation of a neuron which will reduce its activity |
| Interneuron | provide communication between other neurons, do not exit the CNS |
| Kinesthetic sense | (also, kinesthesia) sense of the body in motion |
| Lower motor neuron (LMN) | the final neuron in the efferent chain; consists of the dendrites and soma within the spinal cord, as well as the axon and components that communicate with the muscle fiber |
| Medulla oblongata | contains the glossopharyngeal, vagus, hypoglossal, and spinal accessory nerves; the contains pyramidal decussation (the point at which motor commands originating in one hemisphere of the cerebral cortex cross to serve the opposite side of the body) |
| Midbrain | contains the optic nerve, optic tract |
| Motor neuron | efferent in nature |
| Myelin sheath | a white fatty wrapping around the axon, speeds neural conduction (areas between myelinated segments are nodes of Ranvier) |
| Nerves | (also, tracts) neural pathways through which motor commands are conveyed to the periphery for execution, or through which information concerning the status of the body and its environment (sensory input) are conveyed to the brain for evaluation |
| Neurons | (also, nerve cells) communicating tissue, function is to transmit information |
| Neurotransmitters | compounds that are responsible for activating the next neuron in a chain of neurons; a substance that is released from the terminal end bouton of an axon and causes either excitation or inhibition of another neuron or excitation of a muscle fiber |
| Parasympathetic system | (also, craniosacral system) responds to sympathetic system expenditure of energy by conserving energy |
| Peripheral nervous system (PNS) | 12 pairs of cranial nerves, 31 pairs of spinal nerves, and sensory receptors; mostly outside bone |
| Pons | contains the trigeminal, abducens, facial, and vestibulocochlear nerves, and the basal sulcus |
| Postsynaptic neuron | in a synapse, the following neuron that is receiving stimulation from the presynaptic neuron |
| Presynaptic neuron | in a synapse, the initial neuron that stimulates the following postsynaptic neuron |
| Projection fibers | myelinated fibers that comprise the tracts running to and from the cortex to the brainstem and the spinal cords; connect the cortex with distant location |
| Proprioceptors | sensors that monitor change in a body’s position or the position of its parts, and these include muscle and joint sensors, such as muscle spindles and Golgi tendon organs (including vestibular sense) |
| Pyramidal decussation | occurs in the lower medulla, the corticospinal tract splits so that about 75-90% of fibers descend as the lateral corticospinal tract |
| Receptor sites | locations on the postsynaptic neuron (typically the dendrite) where neurotransmitter released in the synaptic cleft will stimulate the postsynaptic neuron |
| Reticular activating system | arises from the thalamus, is the functional system responsible for arousing the cortex, and perhaps for focusing cortical regions to heightened awareness |
| Sensory neuron | afferent in nature |
| Somatic nervous system | involves all aspects of bodily function that are under conscious, voluntary control, including control of all skeletal or somatic muscles; includes paired sympathetic trunk ganglia, plexuses (networks of nerves), and ganglia outside CNS |
| Somatic sense | sensation related to pain, thermal sensation (temperature sense), and mechanical stimulation |
| Substantia nigra | located between the crus cerebri and tegmentum; a dark brown mass of cells that manufactures dopamine, a neurotransmitter essential for normal movement |
| Sulci | the “valleys” of the brain, deeper sulci are fissures |
| Superficial sensation | sensation arising from stimulation of the surface of the body (e.g. temperature, pain, touch) |
| Sympathetic system | (also, thoracolumbar system) part of the autonomic system, responds to stimulation through energy expenditure |
| Synapse | the union of two neurons, where communication between two neurons occurs; to make a neurochemical connection |
| Thalamus | thalami are the largest structures of the diencephalons and are the final, common relay for sensory information directed toward the cerebral cortex; all sensation (except olfaction) passes through the thalamus |
| Upper motor neuron (UMN) | have their cell bodies rostral to the segment at which the spinal nerve originates; efferent fibers descending from upper brain levels; bring commands from the upper brain levels that activate or inhibit muscle |
| Ventricular system | consists of ventricles (spaces through which cerebrospinal fluid flows); four cavities- the right lateral ventricle, the left lateral ventricle, the 3rd ventricle, and the 4th ventricle; within each ventricle is a choroids plexus, which produces CSF |
Created by:
sullivancl
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