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Measuring the Conduction Velocity of Median Motor Nerve Axons

Measuring the Conduction Velocity of Median Motor Nerve Axons. Introduction Electromyograhy (EMG) is a technique used to measure “changes in electrical potential that result from the conduction of action potentials along motor units during muscle contraction”1. EMG activity (measured in mV) is linearly related to the force produced by muscles2 and so it is used as a diagnostic procedure to assess pathology affecting the anterior horn cell, plexus, nerve roots, neuromuscular junction, peripheral nerve, and the muscle3. Recordings are made with an electrode which is either inserted directly into the muscle (needle electrode) or applied to the skin (extracellular electromyography using surface electrodes)4 and electrical activity picked up by the electrodes is displayed on an oscilloscope screen in the form of waves (EMG)5. An audio-amplifier is also used so that the activity can be heard as well as seen5. This set-up is known as an electromyography machine (fig 1). From the waveform output (graph), conduction velocity, amplitude (which depends on the synchrony and number of action potentials) and duration of action potentials (reflecting the degree of temporal dispersion) are key measurements for the diagnosis of neuromuscular disorders3. Electrical signals can be measured using a monopolar arrangement (i.e. measuring at only one site) or a bipolar electrode arrangement (i.e. measuring at two different sites) coupled with a differential amplifier to “increase the amplitude of the difference signal between the two recording electrodes with respect to the reference electrode”6. Working of an EMG machine All these recordings are made after a stimulating bar, having an anode (positively charged) and cathode (negatively charged) at a fixed distance, is placed on the subject and stimulates the selected nerve3. The nerve depolarizes (is stimulated) underneath the cathode, and the resulting action potential travels along the nerve in the customary physiological direction (orthodromically) and opposite to the physiological direction (antidromically)3. It is recorded using the two recording electrodes from the EMG machine which are attached to the muscle fibre3 using an electrode paste for low-impedance electrode contact7. These measure the electromagnetic field (EMF) that is generated by action potentials7. The potential voltage difference between the two separate electrodes can be calculated in order to provide information about the ability of that muscle to respond to stimulation7. To calculate nerve conduction velocity from an electromyogram the distance from the centre of the cathode also needs to be recorded. In this experiment the nerve conduction velocity of the median motor nerve axons innervating the abductor pollicis brevis (APB) or thumb abductor muscles, as well as other muscles in the arm, forearm and hand was determined using extracellular (surface) electromyography. The median nerve was stimulated at the wrist and elbow and the electrical activity was recorded using electrode stickers and an isolated stimulator. Since the muscle was stimulated by depolarization of the median nerve at two distinct locations bipolar EMG was performed. Onset latency (explained below) and time taken from delivery of stimulus to recording in the EMG electrodes were measured and the nerve conduction velocity calculated. The procedure used has been described below along with calculations involved in determining the nerve conduction velocity of median axons innervating the APB. Afterwards, the subject’s median motor nerve conduction velocity has been compared to the average velocity range. Protocol and set-up To measure nerve conduction velocity of the median motor nerve the Evoked EMG and Nerve conduction velocity protocol from Kuracloud was followed8. An isolated stimulator and disposable ECG electrode stickers (recording electrodes) were used to collect the data inputted into the Kuracloud system. The recording electrodes were attached to the thumb and the ‘earth strap’ secured around the forearm as depicted in fig 1 and fig 2. Checking equipment Prior to beginning the experiment, the equipment was checked to ensure it was functioning correctly. The subject was asked to press their thumb and ring finger together as hard as they could, to see if any signal would be generated if the muscle was contracted. Two graphs were produced. Since no electrical activity was detected in the absence of muscle contraction, there was a flat line. Voluntary contraction resulted in voluntary an asynchronous burst of activity/staggered line around a constant voltage). Since electrical activity was detected only once muscle contraction began, it was concluded that the equipment was working correctly. Measuring nerve conduction First, the median nerve was located by dipping a bar in water and firmly pressing it on the subject’s wrist near their tendons of abductor pollicis longus. This was done to ensure the nerve was stimulated and the electrode did not move around during stimulation (fig 2). Pulses of 3.6mA were emitted from the stimulating bar on pressing “start”. At this point the subject experienced light tingling in their hand and all fingers. The amplitude was increased in order to produce a clear contraction of the APB muscle alone. The electrode was also moved laterally until only the thumb was twitching. The final position was marked on the subject’s skin with a pen (fig 3). Electrical activity from the APB muscle was recorded at the chosen amplitude and position (fig 4). The median nerve was also stimulated at the elbow as is done in bipolar EMGs. This eliminates electromagnetic noise that can interfere with the displayed wave. Other precautions to minimise noise included not having the mains cable and recording cable touch each other or any other bioelectric bodies. For this second recording the stimulating bar was placed on the lateral side of the tendon of the biceps bacchhii and the amplitude of ‘pulse’ was set to 11.2mA. Stronger external force was applied here as the nerve is deeper in this tissue. Once again, the electrode was shifted slightly until a clear stimulation of the subject’s APB muscle was observed i.e. the thumb twitched. The position was marked, and an electromyogram recorded (fig 5). Fig 3: Points of stimulation marked on subject’s right arm with a pen. Fig 4: Electromyograph of median motor nerve stimulated at the wrist. Start of action potential marked with orange line. Data analysis and Results Fig 5: Electromyograph of median motor nerve stimulated at the elbow. Nerve conduction velocity Evoked EMG readings at the wrist “The time interval between the stimulus at 0ms (can be confirmed by presence of stimulus artefact at 0ms) and the initiation of an evoked potential is known as onset latency”9. This is also the time it takes the impulse to travel from the stimulation point at the wrist to the recording electrode7 and “it reflects conduction speed along the fastest fibres”9. At the wrist it was recorded as 4.90ms. The point selected on the electromyogram can be seen (fig 4). Additionally, the maximum amplitude of the subject’s response to median nerve stimulation at the wrist was recorded as 7.07mV in the Kuracloud program. Motor axon loss, a conduction block or incorrect electrode placement can result in low-amplitude of compound muscle action potential, apart from temporal dispersion (mentioned above). Evoked EMG readings at the elbow The onset latency of the subject’s median nerve stimulated at the elbow was recorded as 9.8ms and the amplitude was noted as 4.57mV (fig5) in Kuracloud. Calculating nerve conduction velocity An electromyogram shows the response of a particular muscle following nerve stimulation. This means that nerve latency and amplitude vary according to the point of nerve stimulation. Onset latency increases when the stimulation occurs farther away from the targeted muscle. However certain times do not change with stimulation location: the time taken for the current to reach the electrode and from there to stimulate the nerve, action potential propagation, time taken for neurotransmitters to be released, and the time for the electrical signal from the movement to be picked up by the equipment are the same at all stimulation locations. The distance between the marked stimulation sites (elbow and wrist), measured to be 320mm, was needed to calculate the median nerve conduction velocity of the subject. The nerve conduction velocity, calculated by diving the distance between the two sites by the difference in onset latencies at the elbow and wrist, was found to be 65.31m/s (see Table 1). Table 1: Showing latencies at different points, which were used to calculate conduction velocity. Discussion The electromyograms (fig 4, fig 5) show the depolarisation and repolarisation of APB muscle fibres as the muscle contracts and the thumb ‘twitches’ following stimulation from an electrode. From this the subject’s median motor nerve conduction velocity was determined to be 65.31m/s. While this value varies between individuals, the accepted range for the normal median motor nerve conduction in healthy individuals is49.48m/s – 66.92m/s10. There might be slight variation in this figure due to age or height, which are negatively associated with nerve conduction velocity10,11 , but not due to gender11. Variation may also occur because of temperature or compression7. The subject in this experiment was 165cm tall, 19 years old and tested in a room of approximately 22⁰C. Low temperatures decrease nerve conduction velocity. The subject did not note any feeling of compression, and so it is thought that this did not affect the results. Given the subject’s profile, their nerve conduction velocity appears to be higher than the mean velocity of others in their age group (see ‘Young adult’ under ‘Age group’ in Table 2), however it is still considered to be in the global normal range mentioned above. It would be valuable to compare this value to that of other subjects tested under the same conditions (same temperature) to accurately assess if their conduction velocity is notably different from the group mean. Further trials also need to be conducted to determine if this result is consistent. It is important to note, that the ‘normal range’ values may have been taken at a different temperature as most nerve conduction velocity studies are carried out at 33⁰C – 34⁰C12. Hence, it is recommended that during future trials, the subject be maintained at this temperature to ensure comparable results. If the subject’s results are consistently high it is likely that their nerves are well myelinated and the diameters of their axons larger than average, such that leakage is prevented, and resistance is decreased within axons. Table 2: Showing normal conduction velocity in axons of median motor nerves10. Nerve conduction tests are traditionally used to non-quantitively13 test for demyelination (caused by Guillan-Barrè syndrome) or axon loss (due to Friedrich’s ataxia) in large diameter axons, rather than the suspected pathology of the subject. This experiment tests the subjects median motor nerve; however, a variety of other peripheral nerves can also be tested: Sural sensory nerve, medial plantar nerve and the Ulnar sensory nerve14,15(for ‘normal’ velocities of different nerves see Table3). Table 3: Showing normal nerve conduction velocities of different nerves in healthy individuals In Guillan – Barrè syndrome (GBS) the body’s immune system attacks parts of the peripheral nervous system and damages the myelin sheath surrounding axons. As a result, axons are exposed to damage16 and saltatory conduction is prevented, slowing down nerve conduction velocity. This causes muscle weakness and possible sensation changes as damaged nerves might pass on abnormal sensory signals from the body16. Studies have shown GBS to result in decreased amplitude and nerve conduction velocity17. This fall in amplitude is characteristic of a sub-type of GBS: acute motor axonal neuropathy, which is characterized by the immune system attacking the node of Ranvier instead of the Schwann cells making up the myelin sheath17. Friedrich’s ataxia is an inherited disease which causes progressive nervous system damage which results in impaired muscle coordination18. The degradation of neuronal cell bodies and axons can be detected by a significant decrease in amplitude identified during nerve conduction studies. The nerve conduction velocity remains unchanged19. References 1 Hess, U. (2009). Facial EMG. In E. Harmon-JonesMeasuring the Conduction Velocity of Median Motor Nerve Axons
project management.

This week, you will submit the next three parts of the course-length project. The deliverables for Week 3 are:The communications plan: Determine stakeholders from the requirements determination section. Add a new stakeholder and determine the following information for him or her:Information needThe messages to be communicatedThe timing and frequency of communicationThe person responsible for communicationThe medium for communicationRisk assessment: Determine potential risks that can prevent the project’s objectives from being met on time and within the budget. Develop a risk mitigation plan to manage the risks. The plan should have a severity ranking for each risk. For the most severe risk, develop a risk mitigation strategy that includes risk triggers and the team members responsible for responding to the risk.The organization and human resources plan: Prepare an organizational structure for the project and identify the skills required to perform the work effectively and efficiently. Identify project team members and define their functions, responsibilities, qualifications, and capabilities. Explain where each team member fits into the organizational structure, including the details of the stage of the project where the team member will be assigned. Create a responsibility assignment matrix (RAM).Provide a summary of the key information you have learned in the project so far. What seem to be the most important ideas? What ideas are you still finding challenging? What practical ways can you apply what you are learning?Submission Details:Submit your answers in a 6- to 8-page Microsoft Word document, using APA style.Name your document SU_PMC6601_W3_LastName_FirstInitial.docHHave included the previous files for continuity.
project management

Ball State University Racial Oppression Case Discussion.

Jim is an 18-year-old white student living away from home for the first time. He and his girlfriend were hanging out at the park when they noticed a car pull into the empty parking lot. No one got out of the car for nearly an hour, and it was getting dark. Jim and his girlfriend had planned to stay a while longer, but the car made them feel nervous.As they left the park, they passed nearby the car, and Jim knocked on the window to see if the occupants needed any help. As the window rolled down, Jim noticed that the men were black. He said, “Hey, what’s up? What are you guys doing here?” One of the men was insulted, became angry, and stated that they had every right to be in the parking lot. He claimed that Jim was racially profiling them. He has gone to the campus mediation center to report the incident and is demanding that Jim formally apologize.Jim is very upset because he feels he is being unfairly called a racist.Imagine that you are a residence hall counselor on campus, and the student described in the incident has come to you to ask for advice.What sort of advice would you give to the student?Explain why your advice represents the best course of action for the student to follow
Ball State University Racial Oppression Case Discussion

Sports and Leisure, writing homework help

Sports and Leisure, writing homework help.

MUST HAVE ACCESS TO WATCH A MOVIE ONLINEI need you to submit a 350-400 word summary (12-point font, 1-inch margins) on ALL THE READINGS AND VIDEOS BELOW. As you summarize the readings and the video, make sure to speak about how they relate to each other or if they are different in any way. MAKE SURE TO INCLUDE ALL READINGS AND VIDEOS IN THE ESSAY. MAKE SURE TO CITE ALL WORK FROM THE READINGS http://www.nytimes.com/2007/11/11/opinion/11lewis….http://www.nytimes.com/2013/01/17/education/top-pu…http://www.washingtonexaminer.com/money-for-colleg…Watch “Schooled: the Price of College Sports”After you are done with the essay I need you to write 1 discussion question pertaining to the readings and the videos. This question will be for my classmates to answer.
Sports and Leisure, writing homework help

Intervention Design For the final paper, you will write an intervention paper for your conflict. You have already mapped your conflict and analyzed it theoretically in previous assignments. In this pa

python assignment help You have already mapped your conflict and analyzed it theoretically in previous assignments. In this paper, you will (1) evaluate the origins and the stage of the conflict and (2) will make suggestions to solve this conflict. 1. First, discuss previous interventions done by the conflicting parties or 3rd parties to manage, prevent, or resolve the conflict based on your previous research.  2. Then, discuss critically how these interventions impacted the whole conflict process and then, make your suggestions to bring the parties or the situation to a more positive conclusion.  3. Based on your previous mapping and analysis in the midterm paper, briefly discuss how the theories explain the conflict at hand and its dynamics while discussing the origins, and the stage of the conflict. Don’t go at length for this section as you have already submitted an assignment about theories.  4. Then suggest appropriate conflict intervention methods and design an intervention that you think will be more constructive and sustainable for the parties. Please do not forget to discuss why the method(s) you offered is the most appropriate one. Paper  • The paper should be between 10-15 pages double-spaced, 0.5’ margins, pages numbered, and proper formatting.  • Your paper should have an introduction and a conclusion.  • Make sure to use proper citation (in-text and a reference list).  • All Citation styles are accepted as long as they are conventional and used consistently throughout the paper.  • Feel free to use graphs and visuals, including a legend (explanation of the symbols) and a paragraph at least explaining the graph.  • Do not forget that you must use only in-course materials in your paper except the content directly related to your conflict case. For instance, when you discuss a theory, you should discuss it with reference to your in-course materials. When you talk about certain incidents in the conflict, you will need to refer to outside sources. Note I have attached the Theoretical paper that you must read before doing this assignment since it is connected. Please make sure it is not plagiarized since the paper is gonna go through safe-assign. Don’t worry about in-course material citation, but do cite the rest of the references in MLA format.

Biology 1114 Research Project Report Instructions You will turn in both a worksheet and a research paper. Point total

Biology 1114 Research Project Report Instructions You will turn in both a worksheet and a research paper. Point total for research paper: 90 points Point total for worksheet: 10 points Your paper will be written in the format of a scientific journal article and include the following parts: Title (2 points): The title of a scientific paper is specific and tells the reader everything he/she needs to know in order to decide if this paper is relevant to his or her own work. Abstract (8 points): This is a summary of the entire project, all in about one paragraph. It includes the results, so you can’t write it until you are done with the project. Introduction (15 points): Talk about the species of beetle we will be using. Discuss its ecological niche presently as well as what it likely was before humans began storing grain. How does Tribolium confusum interact with other species in its environment including humans. You will need to include the food habits, life history, and rates of reproduction for this beetle. You will also need to determine the acceptable ranges of temperature, humidity, and how this beetle reacts to light. Cite your references by naming the authors with their publication years such as (Jones, 2004). This section should be relatively short and to the point. At the end of the introduction, tell what the hypotheses are (both null and alternative). Give a prediction of the results. Methods (15 points): Describe the experimental methods, tell what was measured and how. Tell when it was measured. List all your equipment and the steps you used to setup and complete the experiment. The idea of a methods section is to be detailed enough that someone else could perform the experiment from your descriiption. DO NOT INCLUDE ANY RESULTS IN THIS SECTION. Results (15 points): Here is where you will present your experimental data in the form of tables and/or graphs. In this section you provide your results, but you do not yet draw conclusions from them. That effort is left for your last section. You must also test your results using a statistical test and make sure you report these results and the methods you used to obtain them. Conclusions (15 points): This is where you discuss your results and draw conclusions (i.e. what might have caused any differences observed in the containers. Also, in this section you accept or reject your hypotheses. This is where you discuss the possibility of experimental errors. Writing Style (5 points): The writing style in a scientific paper is described as “detached third person.” You are not offering opinions or comment. Avoid words such as I, you, we, because you are merely collecting and reporting facts. Spelling, grammar, and the organization of your ideas will be parts of your grade on this paper, so please pay attention to your writing. Seek help (from me, other students, the writing center on campus) if you are unsure about how to write in a scientific style. Avoid using bullets! If English is not your first language, please contact a tutor at the writing center tutors! References (15 points): You must include a reference page. You can consult the Internet and you must include citations with website addresses and the date you consulted them if you do. You must also have three other sources, and all must be peer-reviewed journal articles. If you have any questions about whether or not a source is peer-reviewed please ask me. You should cite papers within the text. Any paper that is in your reference section must be cited somewhere in the text. Newspapers and magazines are not acceptable references for this paper. Anything cited in the text must also be in the references. Use the APA reference style (there are many examples online, such as, http://www.liu.edu/CWIS/CWP/library/workshop/citapa.htm). Here are some examples of citing a reference within the text of a scientific paper:

ACT 348 Middle East College Important Role of Auditing Discussion

ACT 348 Middle East College Important Role of Auditing Discussion.

Assignment Questions1. Greenbloom Garden Centers is a small, privately held corporation that has two stores in Orlando, Florida. The Greenbloom family owns 100 percent of the company’s stock, and family members manage the operations. Sales at the company’s stores have been growing rapidly, and there appears to be a market for the company’s sales concept— providing bulk garden equipment and supplies at low prices. The controller prepares the company’s financial statements, which are not audited. The company has no debt but is considering expanding to other cities in Florida. Such expansion may require long-term borrowings and is likely to reduce the family’s day-to-day involvement in all of the company’s operations. The family does not intend to sell stock in the company.Required:Discuss the factors that may make an audit necessary and potentially valuable for the company. Be sure to consider the concept of information risk.2. Many companies post their financial statements and auditor’s report on their home pages, generally under a heading labeled “investor relations” or “financial statements.” The audited financial statements are also available on the website www.msm.gov.om. You are required to select audited financial statements of any two companies (in two different sectors) listed in the MSM and comment on the audit report.The answer should include;- The type of audit report- The different sections in the audit report- The basis of opinion- A summary of major observations in the audit report.*** Words count = 1900 words.*** In-Text Citations and References using APA style.*** I’ve uploaded file named “Assessment Booklet”. (Might help)
ACT 348 Middle East College Important Role of Auditing Discussion