Sciatic Nerve

Directions: Label the neuromuscular (myoneural) junction. Then, read the case study below and answer the questions. Each question should be answered with FIVE or more sentences.

Encyclopedia of Nursing & Allied Health. Bioelectricity: Transmission of nerve impulses to muscle. Retrieved on 26 June 2011 from http://www.enotes.com/nursing-encyclopedia/bioelectricity

Extracellular recording electrodes were used to measure the compound action potentials (CAPs) in a cockroach leg nerve. CAPs are the summations of all present action potentials (APs) in the individual axons of the nerve. When an AP is conducted along an axon, sodium channels open and positively charged sodium ions enter the axon. Therefore the inside and the outside voltage changes. The voltage changes in the extracellular fluid were measured. A depolarisation of the axonal membrane causes a local negative charge in the extracellular fluid. The summation of all the voltage changes in the extracellular fluid at a specific position is measured by the recording electrodes.

The results in Figure 2. show that increasing the stimulus strength (V) from 0 to o.40V will result in an increase of Active Muscle force generated by the gastrocnemius muscle in the Buffo Marinus, confirming the hypothesis. The force generated plateaus when the stimulus is beyond o.40V.

Remove the cockroach from it habitat and submerge it in ice water for a few seconds to paralyze it. After the cockroach is paralyzed, using the surgical tools cut a leg (at the hip). The leg should be placed on the cork of the spike box, allowing a bit of the leg to overhang. The stimulation electrode should be placed on the femur and COXA then the electrodes should be connected to the output of the TENS electrical stimulator. Using the provided LabVIEW program, the onset stimulation delivered to the leg as well as its duration can be controlled. The stimulator should be turned on with the correct corresponding channels by turning the knob clockwise, the current intensity of the impulse increase further when the knob is turned clockwise. A

In this exercise, you examined the effect of increasing stimulus intensity on the nerve. What other stimulus parameter

nerve fibers, preventing them from releasing acetylcholine, a chemical that allows nerves to communicate with muscles and other nerves.”

The thickness of the spinal cord varies in thickness depending on the area of the vertebral column and parts of the body supplied. It swells out in both the areas of the cervical and lumber regions, where at these points it supports the large nerve supply to the limbs. Known as the cervical and lumbar enlargements. The cord itself consist of a deep cleft both at the back and the front, here it is almost completely divided into a right and left side like that of the cerebrum. If you were to view a section of the spinal cord which had been cut cross-sectionally you would be able to see a butterfly-shaped region, which would appear grey in colour and surrounded by white matter. Found on the outside of the cord, the white matter consist of bundles of nerve fibres called axons. The axons extend the length of the spinal cord supporting communication of the CNS. Each bundle of nerve fibres are responsible for specific types of information they can transmit ascending signals towards the brain and descending signals from the brain to neurons in various muscles and glands throughout the body. Found inside the spinal cord is the grey matter, this is the butterfly-shaped region containing four projectile shapes known as horns, the two which project forwards are known as the anterior horns(ventral) and the two facing backwards are referred to as the(dorsal)

4. In this exercise, you examined the effect of increasing stimulus intensity on the nerve. What other stimulus parameter might also affect the nerve's tendency to generate a CAP?

Sciatica is often characterized by one or a combination of the following symptoms: Constant pain in only one side of the buttock or leg (rarely can occur in both legs) Pain that is worse when sitting Leg pain that is often described as burning, tingling or searing (vs. a dull ache) Weakness, numbness or difficulty moving the leg or foot

Smooth muscle cells of the ileum spontaneously contract due to the presence of pacemaker cells, called Cajal cells (Widmaier et al., 2014d). However, these smooth muscle they are also innervated by autonomic nerves, which can be stimulated to change contraction rates by stimulating. Figure 1, shows the effect of nerve stimulation of 17volts on isolated ileum tissue. Stimulating sympathetic (sympathetic nerves was stimulated for this particular tissue), causes release of noradrenaline, which inhabits contraction of smooth muscle cells. Furthermore, according to table 1, there is a -58.83% change in contraction amplitude. It can be extrapolated that fewer smooth muscles are contracting. At lower voltages, a weaker response was observed, as voltage is increased a stronger response was observed. Increasing the voltage, means more neurons are being recruited (Widmaier et al., 2014b). In this particular experiment, stimulation of nerves around the mesenteric artery caused an inhibitory response, therefore at higher voltages, more smooth muscles are being inhibited.

Sciatica is often misunderstood as a diagnosis rather than a symptom. Characteristically, sciatic symptoms leg pain that radiates and follows the dermatomal outline associated with the distribution of the nerve itself. The sciatic nerve (largest nerve in the body) originates from the lateral sides of the lumbar spine and individually travels distally down the back of each leg, eventually dividing in the area near the popliteal fossa and traveling further down to each foot. When any type of outside pressure is distributed to the nerve throughout its course, it may cause a painful sensation. Pain associated with a nerve may have a wide array of presentations, such as sharp, aching, burning, numbness, tingling, weakness, or general discomfort. This type of pain

As the message arrives at the end of the nerves, the message is transmitted to the muscles. Before the message is transmitted to the muscles it has to pass the space between the end of the nerve and the muscle, and that space is called neuromuscular junction. The message is transmitted from the brain to the end of the nerve and from the nerve to the neuromuscular junction, and when the message arrives the chemical called neurotransmitters are released.

Very educational post. Looking at all the symptoms and the data given, I would also agree with your priority diagnosis of Sciatica. Here the patient is complaining of acute low back pain which is associated with pain and burning that radiates along the lateral thigh, leg, and foot. Sciatic pain is a sharp, burning pain that radiates down the posterior and lateral leg to the foot or ankle. This Sciatic pain could be related to herniated disk (Dains, Baumann, Scheibel, 2016). According to De Campos (2017), in 90% cases, sciatica is caused by a herniated disc with nerve root compression. Lumbar stenoses and tumors are less likely to cause this. Many people think that the worse the pain, the more likely something bad is going on. However, this

The compound action potential adds up all the action potentials that each individual neuron experiences in the sciatic nerve. Different stimulus amplitudes cause different neurons to fire an action potential; this is due to the fact that each neuron has a different threshold potential, or the minimum voltage the neuron needs to fire an action potential. The individual neuron action potential is an ‘all-or-nothing’ event, but the CAP, as a summation of different individual neurons, is not. The CAP amplitude will increase with larger stimulus potentials because more neurons with higher individual thresholds will be recruited. For this frog sciatic nerve, there are three fiber types, A, B, and C. A fibers are further divided, in the order of decreasing diameter, into α, β, γ, and δ fibers. There is an inverse relationship between the diameter of the nerve fiber and the threshold potential: the larger the diameter, the lower the threshold. Thus, as the largest fibers, the Aα neurons will be the first to be stimulated at a low stimulus potential, and the Aδ neuron fibers will be the last to be recruited. Because the sciatic nerve is mostly composed of A fibers, the recruitment of A-subtype nerve fibers are more readily distinguishable from the data. The minimum potential required to stimulate the Aα fibers was between 75 mV and 80 mV. Once the stimulus potential reached 90 mV, Aβ neurons were recruited and contributed to the increase in amplitude of the CAP. At a stimulus