CD 352 Exam 3 Review PDF

CD 352 Exam 3 Review Topic: Blood Supply & Protection Inner surface of the cranial vault divided into fossae. What is contained in each one? Anterior: frontal lobes Middle: temporal lobes Posterior: cerebellum and brainstem What are the 3 layers of tissue that cover the brain and spinal cord? Lis...

CD 352 Exam 3 Review Topic: Blood Supply & Protection Inner surface of the cranial vault divided into fossae. What is contained in each one? Anterior: frontal lobes Middle: temporal lobes Posterior: cerebellum and brainstem What are the 3 layers of tissue that cover the brain and spinal cord? List layers from deep to superficial. 1. Pia mater 2. Arachnoid mater 3. Dura mater Which layers divides the contents of the cranial cavity into difference cerebral subdivisions? What is a purpose of this? Dura mater: helps protect the brain by compartmentalizing it, limit spread of infections or hemorrhages What are the ventricles? The ventricles are a network of interconnected cavities within the brain that produce and contain cerebrospinal fluid How many do we have? Four Where are they located? (2) lateral in each cerebral hemisphere, 3rd midline between the two halves of the thalamus, and 4th between brainstem and the cerebellum How are they connected to one another? Lateral ventricles connect to the third ventricle via the interventricular foramina (Monro). The third ventricle connects to the fourth via the cerebral aqueduct (Sylvius) What does the vascular tissue found within them produce? The choroid plexus within the ventricles produce cerebrospinal fluid, helps protect and nourish the brain and spinal cord.  Using the images, consider what impairments a person may have if blood supply was disrupted to certain areas. Left MCA Superior Division: Motor: weakness or paralysis of the right face and arm (upper motor neuron) Sensory: sensory loss in the right face and arm Language/Cognition: Broca’s aphasia Other: possible right-sided neglect Left MCA Inferior Division: Motor: minimal or no motor deficits Sensory: sensory loss in the right face and arm Language/Cognition: Wernicke’s aphasia Other: right visual field deficit (homonymous hemianopia) Left MCA Stem: Motor: Severe weakness or paralysis of the right face, arm, and leg (hemiplegia) Sensory: sensory loss right face, arm, and leg Language/Cognition: global aphasia Other: right homonymous hemianopia Contribute(s) to the posterior blood supply: Vertebral arteries Contribute(s) to the anterior blood supply: Internal carotid arteries Feeds the parasylvian zone: Middle cerebral artery Occlusion of the basilar artery: Cause decrease blood supply to the cerebellar arteries Damage to the occipital pole and inferolateral surface of the hemispheres: Occlusion of the PCA (posterior cerebral artery) What is the circle of Willis? Where is it located? Vascular ring located at the base of the brainstem Topic: Neuronal Function Structural vs Functional Classes of nerve cells o Structural Classes Unipolar: 1 process extending from the cell body Bipolar: 2 processes (1 axon 1 dendrite) extending from the cell body Multipolar: multiple processes (1 axon multiple dendrites) extending from the cell body Pseudounipolar: 1 process that splits into two branches, functioning as a single axon o Functional Classes Sensory (Afferent): transmit sensory information from receptors to the CNS Motor (Efferent): Transmit motor commands from the CNS to muscles and glands Interneurons: connect sensory and motor neurons within the CNS Basic parts of a neuron Cell body: contains nucleus and organelles Axon: transmit electrical impulses Dendrites: receives signal What is myelin? Myelin is white, fatty substance that insulates the axons of neurons, rapid transmission of electrical impulses along the nerve cells What is a synapse? Junction between two neurons where communication occurs through the release and reception of neurotransmitters What is neuromuscular junction? Synapse between a motor neuron and a muscle fiber, motor transits signal to the muscle to induce contraction What is a neurotransmitter? Chemical messenger that transmits signals across a synapse from one neuron to another or a target cell What effect can a neurotransmitter have on a receiving neuron? Inhibitory: lowers likelihood of an action potential in receiving neuron Excitatory: increases the likelihood of an action potential in receiving neuron o Common Types: ▪ Acetylcholine (Ach): muscle contraction ▪ Dopamine: feelings of reward/pleasure; associated with some mental illnesses (schizophrenia); associated with Parkinson’s disease; may enhance impulsivity ▪ Norepinephrine: primary neurotrransmitter in the PNS; attention, vigilance; concentration ▪ Serotonin: important CNS neurotransmitter; sleep/arousal; happiness (“mood booster”) ▪ GABA: major inhibitory neurotransmitter; drug agent for epilepsy, anxiety; associated with Huntington’s chorea ▪ Glutamate: major excitatory neurotransmitter o What are the 2 most prevalent neurotransmitters? GABA and glutamate What is the purpose of a nerve cell? Transmit information from one location to another within the body What is normal functioning of a nerve cell dependent on? Volume of water content & electrical properties What does it mean when a neuron is at a steady state (i.e., at its resting potential)? Is the nerve firing impulses at this state? Neuron is not actively firing impulses, balanced and stable  What is required to change a neuron’s resting state? Adequate stimulus; strong enough to alter the balance across the neuron’s membrane Define depolarization, action potential, and hyperpolarization. Depolarization: The influx of positively charged ions into the neuron, which triggers an action potential. Action Potential: The electrical impulse that is generated and travels along the axon of the neuron. Hyperpolarization: The influx of negatively charged ions, making the inside of the cell more negative relative to the outside, which decreases the likelihood of generating an action potential. Review principles of neuronal operation: divergence and convergence Divergence: A single action potential can trigger multiple excitatory postsynaptic potentials (EPSPs) simultaneously, amplifying the activity of a single axon. Convergence: All neurons receive synaptic information from many other neurons, with multiple synapses occurring on one postsynaptic dendrite. Define diaschisis; sudden change in function in a portion of the brain that is connected to a damaged, but distant, brain area. What do we know about axonal regeneration? And overall injury to the nervous system? o Primary and secondary neuronal loss occurs following injury ▪ Secondary loss dependent on several variables o CNS axons do not spontaneously regenerate after injury o PNS axons readily regenerate What is MS vs PD, vs MG vs. ALS vs. CVA? Consider in terms of neuronal dysfunction. Multiple Sclerosis (MS): A sporadic, widespread disease caused by the degeneration of myelin on axons, affecting both sensory and motor neurons. Parkinson’s Disease (PD): A progressive disorder affecting the basal ganglia, associated with dopamine deficiency. Myasthenia Gravis (MG): A chronic autoimmune disorder associated with the degeneration of neuromuscular junctions, reducing the function of acetylcholine. Amyotrophic Lateral Sclerosis (ALS): A progressive neurodegenerative disease affecting motor neurons, leading to muscle weakness and atrophy. Cerebrovascular Accident (CVA): Also known as a stroke, it occurs when blood flow to a part of the brain is interrupted, leading to neuronal damage and loss of function. Topic: Neurosensory Organization What is the role of sensory information in context of speech, language, cognition, and/or swallowing? o Influences motor activity; required for execution of skilled motor acts (speech and swallowing) o Required for recognition and identification of stimuli that influences or precludes speech, language, cognition, and motor activity (speech and swallowing). What is a sensory receptor? A sensory receptor is a nerve ending that sends signals to the central nervous system (CNS) when stimulated. What are the 3 broad classes and where are they found. Exteroceptors: Found in the skin and sense external stimuli such as sight, smell, and cutaneous sensations. Proprioceptors: Located in muscles and joints, they sense deep somatic sensations related to body position and movement. Interceptors: Found in internal organs, they sense visceral pain, pressure, and distension. Where are afferent projections of sensory information first processed? Afferent projections of sensory information are first processed in the unimodal cortex (the primary sensory cortices). What are some different modalities of sensory input? Visual, auditory, and tactile (somatosensory) What system carries sensory impulses of pain and temperature, light touch and pressure, and tactile location from the periphery to the sensory cortex? anterolateral system What system conveys proprioceptive sensation of movement, posture, vibration, and stereognosis from the upper and lower extremities? DCML (Dorsal Column-Medial Lemniscus) system A patient who is not ability to determine, without looking, whether a joint of her arm is in flexion or extension is exhibiting a deficit in what type of sensory information? somatosensory information. What is an example of a special sense? Sight, hearing, taste, and smell What is the general anatomical organization of somatosensory system pathways: 1. Enter CNS 2. Cross midline 3. Project to cortex Regarding 2nd Order Neurons that make up the DCML and spinothalamic tracts: Located in the CNS Cross midline Gets the information from the spinal cord or brainstem to the thalamus True The 1st order neuron of a somatosensory pathway is a part of a spinal or cranial nerve. Sensory disorders resulting in an inability to interpret a sensory stimulus and recognize it are called agnosia They are typically the result of cerebral injury to the [association] areas of the brain. What is the internal capsule? Large bundle of fibers that is responsible for carrying almost all the information that travels to and from the cerebral cortex, major route. What type of information is transmitted via spinocerebellar tract? transmits information regarding unconscious proprioception (sensory info about position and movement of muscles and joints) Terms: Hypothesia: decreased tactile sensation Anesthesia: complete loss of sensation Kinesthesia: internal awareness of movement Hyperesthesia: abnormally increased tactile sensation Stereognosis: ability to perceive details by touch Astereognosis: inability to recognize common objects by touch Sensory Innervation of the Speech Mechanism: Face: mainly V/5 (Pain, temp, touch, proprioception) Tongue: V/5 (anterior 2/3 for general); IX/8 (posterior 1/3 for general and taste); VII/7 (anterior 2/3 for taste) Palate: IX/8 (general) Pharynx: IX/8 & X/10 Larynx: X/10 What part of the eye synapses with the 1st order neurons of the visual system? Rods and cones What type of cells are the 1st order neurons of the visual system? Bipolar Define Retina. a layer of tissue located at the back of the eye that converts light into neural signals What is the optic chiasm and what type of visual loss occurs if injured? Formed by the nerve fibers of the optic nerve. Point of decussation for some of the fibers. Injury results in loss of peripheral vision in both eyes. What cranial nerve is the optic nerve? Cranial Nerve II Define Optic tract: visual fibers in CNS that end at the thalamus Define Optic radiations: visual fibers that are projecting from the thalamus and terminate in visual cortices Where can damage be that may result in injury to optic radiations? Injury to the optic radiations can result from damage to the temporal lobe, parietal lobe, optic chiasm, or optic tracts. Define homonymous hemianopia. Where can damage be to occur this type of visual loss? Homonymous hemianopia is a visual field deficit characterized by the loss of half of the visual field on the same side of both eyes. This type of visual loss can occur due to damage to the optic tract, optic radiation, or occipital lobe. If a patient has complete blindness in one eye, where would injury have to be? Optic nerve What cranial nerve is the auditory nerve? Cranial Nerve VIII Basic auditory pathway: cochlea (sensory hair cells)→NTs stimulate CN VIII -> cochlear nucleus in brainstem → auditory cortex Majority of fibers decussate after synapses at cochlear nucleus, but some travel ipsilaterally Information coming in to left ear goes to right hemisphere primary auditory cortex and then must cross over to Wernicke’s area in left hemisphere for perceptual analysis and comprehension of language. What is the name of the primary auditory cortex? Heschl’s gyrus Topic: Motor System Organization & Disorders What are the 3 main neural structures/systems that “control” voluntary movement? 1. Pyramidal System 2. Extrapyramidal System 3. Cerebellum List anatomic levels of the motor system and example of a specific contribution each level makes to the final motor act: o Spinal Cord: Executes low-level demands that generate forces on muscles. o Brainstem: Organizes motor movements like reflexes and fine motor movements of the limbs and face. o Cerebellum: coordination, error detection and correction; ongoing unconscious monitoring of proprioception o Basal Ganglia: suppression of unwanted activity; posture, tone o Limbic System: Regulates conscious and unconscious patterns. o Internal Capsule/Corona Radiations: Major route for information traveling to and from the cerebral cortex. o Cortex (Primary and Association Areas): Initiates and plans voluntary movements. What tracts make up the Pyramidal System? Corticospinal, corticonuclear, and corticopontine tracts. The pyramidal system is also known as the direct activation pathway. Where do the tracts of the pyramidal system originate from? cerebral cortex. What is the main job of the pyramidal system? To activate the lower motor neurons.  What is an upper motor neuron vs a lower motor neuron? Illustrate this. Upper Motor Neuron (UMN): Nerve fibers that course from the cortex to the brainstem or spinal cord. Lower Motor Neuron (LMN): Nerve fibers that course from the CNS to the destination carrying motor information. Label the parts of a sample corticonuclear tract. Mark what is the UMN, LMN, circle the point of decussation, and include an example of the end target (effector). facial muscles involved in expressions, such as those controlled by the facial nerve (Cranial Nerve VII) Corticospinal fibers primarily provide unilateral innervation and is this type of innervation is provided to both (same or opposite side) of the body. What parts of the body do the corticospinal fibers control? Trunks, arms, and legs How does the corticonuclear tract differ from the corticospinal tract in terms of innervation? Corticonuclear tract provides both unilateral and bilateral innervation to muscles of head and neck vs primary unilateral to trunk, legs, and arms. False. All cranial nerve nuclei have bilateral innervation. False: portions of V, VII, and XII only have unilateral innervation. False: Cranial nerve nuclei receiving bilateral innervation get the same amount of innervation from both sides. False: nuclei receive varying amounts of innervation and therefore areas with less input from one side than the other may show weakness due to less compensation. Extrapyramidal system is also known as the indirect activation pathway. What is the primary function? Motor control to regulate reflexes and maintain posture and tone. What is this system made up of? Pathways interconnecting subcortical, cerebellar, and brainstem nuclei and then providing input to LMNS of the spinal cord and to some CN. Recognize vestibulospinal, rubrospinal, tectospinal and reticulospinal tracts as being pathways of the Indirect Activation Pathway. What type of information does the cerebellum need to carry out its role as a part of the motor system? Position sense, and copy of the motor plan What are some common signs of cerebellar damage? Ataxia: Lack of muscle coordination, leading to unsteady and clumsy movements. Dysmetria: Inability to judge the distance or range of a movement, resulting in overshooting or undershooting targets. Intention Tremor: Trembling that occurs during voluntary movement, often worsening as the movement nears its target. Dysdiadochokinesia: Difficulty performing rapid, alternating movements. Hypotonia: Reduced muscle tone, leading to floppy and weak muscles. Nystagmus: Involuntary, rapid eye movements. Gait Abnormalities: Unsteady walking, swaying, staggering, or falling. Speech Disturbances: Slurred or slow speech, known as dysarthria. Define Apraxia and Dysarthria. How to these two disorders differ from one another. Apraxia: A motor disorder caused by damage to the brain (specifically the posterior parietal cortex) in which the individual has difficulty with the motor planning to perform tasks or movements when asked. Dysarthria: A motor speech disorder resulting from neurological injury of the motor component of the motor-speech system, characterized by poor articulation of phonemes. Topic: Other (LH vs RH) True Left hemisphere is the dominant language hemisphere for most people. A person who is showing reduced spontaneous movements on the left side may be exhibiting: Hemiparesis Missing the overall theme of a picture scene, ignoring stimuli on the left-side of space, and incorrectly identifying objects/drawing due to visuospatial impairments are common characteristics of injury to the right hemisphere. A language disorder associated with left-hemisphere damage is called aphasia