Answer: <h3>Introduction to Muscular System</h3>
<p>The muscular system is the system of the human body that provides motor power for all movements of the body parts. The muscular system is composed of a special tissue called muscular tissue. Muscles have the ability to contract actively to provide force for movements of body parts. The muscular system is an important system of the human body because, without it, life will completely stop. Muscles produce not only those movements that are under the control of our will and that we can see and feel but also those movements that are responsible for activities like breathing, digestion of food, pumping blood, etc.</p>
<h3><br />Muscles</h3>
<p>Muscles are body tissue that provides the force for all body movements. They are made of special types of cells.</p>
<h4>Types</h4>
<p>i. Skeletal Muscles/ Voluntary Muscles<br />ii. Smooth/involuntary Muscles<br />iii. Cardiac Muscles</p>
<p><strong>i. Skeletal Muscles/Voluntary muscles</strong></p>
<p>Skeletal muscles form most of the human body weight. They are under the control of the human will and all body movements occurring by our will are produced by skeletal muscles. They are called skeletal muscles because they are almost found attached to the skeleton and produce movements in different parts of the skeleton.</p>
<p><br /><strong>ii. Smooth Muscles</strong></p>
<p>Smooth muscles form the soft body organs like stomach, intestine blood vessels, etc. They are not under the will of human beings and are responsible for unconscious body activities like digestion of food. They are called smooth muscles because when seen under the microscope, they do not have any striation in contrast to the other type of muscles.</p>
<p><br /><strong>iii. Cardiac Muscle</strong></p>
<p>Cardiac muscles are exclusively found in a human hearth and nowhere else. They are extremely strong and powerful muscles. They are not controls. A human will and are involuntary. The pumping of blood by human heart is because of the force provided by the contraction of cardiac muscles.</p>
<h4><br />Functions of Muscular System</h4>
<p>Muscular System has the following important functions in human body:<br /><strong>1) Movements of body parts</strong><br />Skeletal muscles are responsible for all voluntary movements of human body parts. They provide the force by contracting actively at the expense of the energy. In other words, an energy of food is converted into mechanical work.<br /><br /><strong>2) Stability and posture</strong><br />Skeletal muscles stabilize human skeleton and give a proper posture to human beings. Some joints of the human body are weak and they require the support of muscular system to achieve stability. Skeletal muscles are very important for such joints.</p>
<p><br /><strong>3) Heart Production</strong><br />A large share of body&rsquo;s energy is used by a muscular system. As a result of high metabolic rate, muscles produce a great amount of heat in the body. Heat produced by muscles is very important in cold climates.<br /><br /><strong>4) Circulation</strong><br />Cardiac muscles provide the main force for circulation of blood throughout the human body. The regular pumping of heat keeps the blood in motion and nutrients are readily available to every tissue of human body.<br /><br /><strong>5) Helps in Digestion</strong><br />Smooth muscles of organs like stomach and intestine help the digestive system in the process of digestion of food.</p>
<p>(Iqbal, 2010)</p>
<h4><br />Principles of Skeletal Muscles</h4>
<p>Muscles of the face, trunk, shoulders, and upper limbs, hips lower limbs, pelvis: The muscles of face are unique among groups of muscles in the body. While most muscles connects to move only bones, facial, mostly connects bones to skin. These muscles include zygomatic major and orbicularis oris. The neck muscle, including the sternocleidomastoid and the trapezious are responsible for gross motor movement in muscular system of head and neck. The muscle of abdomen, lower back, and pelvis are separated from those of the chest by the muscular wall of diaphragm, the critical breathing muscles. The muscles of lower back are erector spinae and quadratus lumborum muscles contract to extend and laterally bend the vertical column. The powerful muscles of hips and buttocks and pelvis actuate the flexible ball and socket hip joint.<br />(1999-2016)<br />Actions of the muscles in relation to forces: The principles of mechanisms are ; <br /><br />a. Lever is a rigid bar that moves about a fixed point known as the fulcrum; a small force is applied through a large distance and the other end of lever exerts a large force over a small distance.<br />b. Pulleys: can multiply forces at the expense of distance, the use of number of pulleys together, as in block and tackle provide a mechanical advantage equal to number of ropes excluding the pull rope.<br />c. Center of gravity: In human, the center of gravity is in pelvic cavity and for upright balance the line drawn from this point to the ground must fall somewhere the legs.<br />(2011)</p>
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<h4>Disorders of muscular system</h4>
<p>1. Atony: A state in which muscles are floppy lacking their normal elasticity.<br />2. Atrophy: generally, the wasting away of a normally developed organ or tissue due to degeneration of cells.<br />3. Cramp: it is prolonged painful involuntary contraction of skeletal muscles. It is sometime caused by imbalance of salts in the body.<br />4. Fibrositis: it is inflammation of fibrous connective tissue in muscles. It often affects the muscles of trunk and back.<br />5. Muscle fatigue: it is tiredness following prolonged or intense activity.<br />6. Myositis: it is inflammation of muscle fibrous and of a group of muscles disease in which inflammation and degeneration changes occurs.<br />7. Spasm: A sustained involuntary muscular contraction (which may occur either part of generalized disorders such as spastic paralysis or as a local response to another unconnected painful condition.<br />8. Spasticity: muscular hyper tonicity i.e. an increased in the state of readiness of muscle fibers to contracts an increased in partial contraction with an increased resistance to stretch.<br />9. Sprain: injury to a ligament caused by overstretching.<br />10. Strain: excessive stretching or working of a muscles resulting in pain and swelling of muscles.<br />(dis)</p>
<h4>Myasthenia gravis</h4>
<p>It is a neuromuscular disease that leads of fluctuation of muscle weakness and fatigue. Myasthenia is treated with medication such as acetyl cholinesterase inhibitors or immunosuppressant&rsquo;s and in selected cases. Thymectomy is a surgical management.</p>
<p><strong>Causes</strong></p>
<p>There will be transmission defects in nerve impulses to muscles. The neuromuscular junction is apparently affected acetylcholine, which produces muscles contraction under normal conditions no longer produces contraction necessary to muscle movement.</p>
<p><strong>Signs and symptoms</strong></p>
<ul>
<li>Myasthenia gravis is a painless weakness of specific muscles, not fatigue.</li>
<li>The muscle weakness becomes progressively worse during a period of physical activity and improves after periods of rests.</li>
<li>There may be eyelid drooping, difficulty swallowing (dysphagia), weakness of muscles that move the jaw, dysarthria, and hypophonia.</li>
</ul>
<p><strong>Diagnosis</strong></p>
<p><br />- Physical exam and history taking<br />- Blood test, serology can be done<br />- Edrophonium test<br />- Chest x-ray<br />- Pulmonary function test</p>
<p><strong>Management</strong></p>
<p><br />- Acetylcholine inhibitors can provide symptomatic benefit and may not fully remove a person weakness for myasthenia gravis<br />- Thymectomy is the surgical removal of the thymus gland.<br />(2016)</p>