Reading

Tests, Procedures, and Techniques

1:1 Electromyography Electromyography (e-lek' -trii-mi-OG-ra-fe; electro- = electricity; 1t1yo- = muscle; -graph = to write) or EMG is a test that measures the electrical activity (muscle action potentials) in resting and contracting muscles. Normally, resting muscle produces no electrical activity; a slight contraction produces some electrical activity; and a more forceful contraction produces increased electrical activity. In the procedure, a ground electrode is placed over the muscle to be tested to eliminate background electrical activity. Then, a fine needle attached by wires to a record­ ing instrument is inserted into the muscle. The electrical activity of the muscle is displayed as waves on an oscillo­ scope and heard through a loudspeaker.

EMG helps to determine if muscle weakness or paraly­ sis is due to a malfunction of the muscle itself or the nerves supplying the muscle. EMG is also used to diagnose cer­ tain muscle disorders, such as muscular dystrophy.

Resting muscle

Oscilloscop. e ~r.•., ,.

'\ 1; ' \ !

Recording need!e

\ .. I<.,,,,

Electromyography

!iii Intramuscular Injections

Contracting muscle

· .. ·1; .. 1. : '

; ./ . ' ·r-

An intramuscular (IM) injection penetrates the skin and subcutaneous tissue to enter the muscle itself. Intramuscular injections are preferred when prompt absorption is desired, when larger doses than can be given subcutaneously are indicated, or when the drug is too irritating to give subcu­ taneously. The common sites for intramuscular injections include the gluteus medius muscle of the buttock, lateral side of the thigh in the midportion of the vastus lateralis muscle, and the deltoid muscle of the, shoulder.

Muscles in these areas, especially the gluteal muscles in the buttock, are fairly thick, and absorption is promoted by their extensive blood supply. To avoid injury, intramuscu­ lar injections are given deep within the muscle, away from

Disorders Affecting the Muscular System 37

major nerves and blood vessels. Intramuscular injections have a faster speed of delive1y than oral medications, but are slower than intravenous infusions.

' r Intubation During Anesthesia VVhen general anesthesia is. administered during surge1y, a total relaxation of the muscles results. Once the various types of drugs. for anesthesia have been given (especially the paralytic agents), the patient's airway must be protect­ ed and the lungs ventilated because the muscles involved with respiration are among those paralyzed. Paralysis of the genioglossus muscle causes the tongue to fall posteri­ orly, which may obstruct the airway to the lungs. To avoid this, the mandible is either manually thrust forward and held in place (known as the "sniffing position"), or a tube is inserted from the lips through the laryngopharynx (infe­ rior portion of the throat) into the trachea (endotracheal intubation). People can also be intubated nasally (through the nose). cJ

Disorders Affecting the Muscular System

!.".' Bell's Palsy Bell's palsy, also known as facial paralysis, is a unilat­ eral paralysis of the muscles of facial expression. It is due to damage or disease of the facial (VII) nerve. Possible causes include inflammation of the facial nerve due to an ear infection, ear surgery that damages the facial nerve, or infection by the herpes simplex virus. The paralysis causes the entire side of the face.to droop in severe cases. The person cannot wrinkle the forehead, close the eye, or pucker the lips on the affected side. Drooling and dif­ ficulty in swallowing also occur. Eighty percent of patients recover completely within a few weeks to a few months. For others, paralysis is permanent. The symptoms of Bell's palsy mimic those of a stroke.

Li, Carpal Tunnel Syndrome The carpal tunnel is a narrow passageway formed ante­ riorly by the flexor retinaculum and posteriorly by the carpal bones. Through this tunnel pass the median nerve, the most superficial structure, and the long flexor tendons for the digits (see Figure 11.181). Structures within the carpal tunnel, especially the median nerve, are vulnerable to compression, and the resulting condition is called car­ pal tunnel syndrome. Compression of the median nerve leads to sensory changes over the lateral side of the hand and muscle weakness in the thenar eminence. This results in pain, numbness, and tingling of the fingers. The con­ dition may be caused by inflammation of the digital ten­ don sheaths, fluid retention, excessive exercise, infection, trauma, and/or repetitive activities that involve flexion of the wrist, such as keyboarding, cutting hair, or playing the piano. Treatment may involve the use of nonsteroidal

t

38 6 The Muscular System

anti-inflammatory drugs (such as ibuprofen or aspirin), wearing a wrist splint, corticosteroid injections, or surgery to cut the flexor retinaculun1 and release presssure on the median nerve.

uJ Compartment Syndrome Skeletal muscles in the limbs are organized into functional units called compartments. In a disorder. called compart­ ment syndrome, s01ne external or intt:rnal pressure constricts the structures within a compartment, resulting in damaged blood vessels and subsequent reduction of the blood supply (ischemia) to the strucmres within the compartment. Symptoms include pain, burning, pressure, pale skin, and paralysis. Common causes of compartment syndrome include crushing and penetrating injuries, con­ tusion (damage to subcutaneous tissues without the skin being broken), muscle strain (overstretching of a muscle), or an improperly fitted cast. The pressure increase in the compartment can have serious consequences, such as hem­ orrhage, tissue injury, and edema (buildup of interstitial fluid). Because deep fasciae (connective tissue coverings) that enclose the compartments are very strong, accumu­ lated blood and interstitial fluid cannot escape, and the increased pressure can literally choke off the blood flow and deprive nearby muscles and nerves of oxygen. One treatment option is fasciotomy (fash-e-OT-6-me), a sur­ gical procedure in which muscle fascia is cut to relieve the pressure. Without intervention, nerves can suffer damage, and muscles can develop scar tissue that results in perma­ nent shortening of the muscles, a condition called cont:rac­ t:ure. If left untreated, tissues may die and the limb may no longer be able to function. Once the syndrome has reached this stage, amputation may be the only treatment option.

11 Fibromyalgia Fibromyalgia (fi-br6-mi-AL-je-a; algia = painful condi­ tion) is a painful, nonarticular rheumatic disorder that usu­ ally appears between the ages of 25 and 50. An estimated 3 million people in the United States suffer from fibro­ myalgia, which is 15 times more common in women than in men. The disorder affects the fibrous connective tissue components of muscles, tendons, and ligaments. A strik­ ing sign is pain that results from gentle pressure at specific "tender points." Even without pressure, there is pain, ten­ derness, and stiffness of muscles, tendons, and surrounding soft tissues. Besides muscle pain, those with fibromyalgia report severe fatigue, poor sleep, headaches, depression, and inability to carry out their daily activities. Treatment consists of stress reduction, regular exercise, application of heat, gentle massage, physical therapy, medication for pain, and a low-dose antidepressant to help improve sleep.

• Impingement Syndrome One of the most common causes of shoulder pain and dys­ function in athletes is known as impingement syndrome, which is sometimes confused with another common com­ plaint, compartment syndrome. The repetitive movement

of tl1e arm over the head tl1at is common in baseball, over­ head racquet sports, lifting weights over tl1e head, spiking a volleyball, and swimming puts tl1ese atl1letes at risk. Impingement syndrome may also be caused by a direct blow or stretch injmy. Continual pinching of the supra­ spinatus tendon as a result of overhead motions causes it to become inflamed and results in pain. If movement is continued despite the pain, tl1e tendon may degenerate near tl1e attachment to tl1e humerus and ultimately may tear away from the bone (rotator cuff injury). Treatment consists of resting the injured tendons, strengthening the shoulder tl1rough exercise, massage therapy, and surgery if tl1e injury is particularly severe.

[J Inguinal Hernia A hernia is a protrusion of an organ through a structure that normally contains it, which creates a lump that can be seen or felt tl1rough the skin's surface. The inguinal region is a weak area in the abdominal wall. It is often the site of an inguinal hernia, a rupture or separation of a portion of tl1e inguinal area of tl1e abdominal wall resulting in tl1e protrusion of a part of the small intestine. A hernia is much more common in males than in females because the inguinal canals in males are larger to accommodate the spermatic cord and ilioinguinal nerve. Treatment of her­ nias most often involves surgery. The organ that protrudes is "tucked" back into the abdominal cavity and the defect in the abdominal muscles is repaired. In addition, a mesh is often applied to reinforce the area of weakness.

rr; Muscular Dystrophy The term muscular dystrophy (DIS-tr6-fe; dys- = diffi­ cult;-t:rophy = nourishment) refers to a group of inherited muscle-destroying diseases that cause progressive degen­ eration of skeletal muscle fibers. The most common form of muscular dystrophy is Duchenne muscular dystrophy (doo­ SHAN) or DMD. Because the mutated gene is on the X chromosome, and males have only one, DMD strikes boys almost exclusively. (Sex-linked in11eritance is described in Chapter 29.) Worldwide, about 1 in every 3500 male babies-21,000 in all-are born witlt DMD each year. The disorder usually becomes apparent between the ages of 2 and 5, when parents notice the child falls often and has difficulty running, jumping, and hopping. By age 12 most

,boys with DMD are unable to walk. Respiratory or cardiac 'failure usually causes death by age 20.

In DMD, the gene tl1at codes for the protein dystrophin is mutated, so little or no dystrophin is present in the sar­ colemma. Without the reinforcing effect of dystrophin, the sarcolemma tears easily during muscle contraction, causing muscle fibers to rupture and die. The dystrophin gene was discovere,din 1987, and by 1990 the first attempts were made to treat DMD patients with gene therapy. The muscles of three boys with DMD were injected with myoblasts bearing functional dystrophin genes, but only a few muscle fibers gained the ability to produce dystrophin. Similar clinical trials with additional patients have also failed. An alternative

approach to the problem is to find a way to induce muscle fibers to produce the protein utrophin, which is similar to dysu·ophin. Experiments with dystrophin-deficient mice suggest this approach may work.

CJ Myasthenia Gravis Myasthenia gravis (mi-as-THE-ne-a GRAV-is; mys­

,Jnuscle; aisthesis = sensation) is an autoimmune disease that causes chronic, progressive damage of the neuro­ muscular junction. The immune system inappropriately produces antibodies that bind to and block some ACh receptors, thereby decreasing the number of functional ACh receptors at the motor end plates of skeletal muscles. Because 7 5% of patients with myasthenia gravis have hyperplasia or tumors of the thymus, it is thought that thymic abnormalities cause the disorder. As the disease progresses, more ACh receptors are lost. Tims, muscles become increasingly weaker, fatigue more easily, and may eventnally cease to function.

Myasthenia gravis occurs in about I in 10,000 people and is more common in women, typically ages 20 to 40 at onset; men usually are ages 50 to 60 at onset. The muscles of the face and neck are most often affected. Initial symptoms inclnde weakness of the eye muscles, which may produce double vision, and weakness of the throat muscles that may produce difficulty in swallowing. Later, the person has difficulty chewing and talking. Eventnally the muscles of the limbs may become involved. Death may resnlt from paralysis of the respiratory mnscles, but often the disorder does not progress to this stage.

Anticholinesterase drugs such as pyridostigmine (Mestinon®) or neostigmine, the first line of treatment, act as inhibitors of acetylcholinesterase, the enzyme that breaks down ACh. Thus, the inhibitors raise the level of ACh that is available to bind with still-functional recep­ tors. More recently, steroid drugs such as prednisone have been nsed with success to reduce antibody levels. Another treatment is plasmapheresis, a procedure that removes the antibodies from the blood. Often, surgical removal of the thymus (thymectomy) is helpful.

• Plantar Fasciitis Plantar fasciitis (fas-e-1-tis) or painful heel syndrome is an inflammatory reaction due to chronic irritation of the plantar aponeurosis (fascia) at its origin on the cal­ caneus (heel bone). The aponeurosis becomes less elastic with age. This condition is also related to weight-bearing activities (walking, jogging, lifting heavy objects), improp­ erly constructed or fitting shoes, excess weight (puts pressure on the feet), and poor biomechanics (flat feet, high arches, and abnormalities in gait may cause uneven distribution of weight on the feet). Plantar fasciitis is the most common cause ·of heel pain in runners and arises in response to the repeated impac:t~oh-mutlng. Treatments include ice, deep heat, stretching exercises, weight loss, prosthetics (such as shoe inserts or heel lifts), steroid injections, and surgery.

Additional Clinical Considerations 39

i] Strabismus Strabismus (stra-BIZ-mus; st:rabismos = squinting) is a con­ dition in which tl1e two eyeballs are not properly aligned. This can be hereditaiy or it can be due to birtl1 injuries, poor attachments of the muscles, problems with the brain's control center, or localized disease. Strabismus can be constant or intermittent. In strabismus, each eye sends an image to a different area of tl1e brain a11d ·be-('ause tl1e brain usually ignores tl1e messages sent by one cif the eyes, tl1e ignored eye becomes weaker, hence "lazy eye1

' or amblyopia, develops. Rwe11wl strttbismus results when a lesion in the oculomotor (III) nerve causes tl1e eyeball to move laterally when at rest, and results in an inability to move tl1e eyeball medially and inferiorly. A lesion in tl1e abducens (VI) nerve results in intenzal strabismus, a condition in which tl1e eyeball moves medially when at rest and cannot move laterally.

Treaunent options for strabismus depend on tl1e spe­ cific type of problem and include surgery, visual therapy (reu·aining tl1e brain's control center), and orthoptics (eye muscle training to straighten the eyes).

[J Tenosynovitis Tenosynovitis (ten'-6-sin-6-Vl-tis) is an inflammation of the tendons, tendon sheaths, and synovial membranes sur­ rounding certain joints. The tendons most often affected are at the wrists, shoulders, elbows (resulting in tennis elbow), finger joints (resulting in trigger finger), ankles, and feet. The affected sheatl1S sometimes become visibly swol­ len because of fluid accumulation. Tenderness and pain are frequently associated with movement of tl1e body part. The condition often follows trauma, strain, or excessive exercise. Tenosynovitis of tl1e dorsum of the foot may be caused by tying shoelaces too tightly. Gymnasts are prone to developing tl1e condition as a result of chronic, repeti­ tive, and maximum hyperextension at the wrists. Other repetitive movements involving activities such as typing, haircutting, carpentry, and assembly line work can also result in tenosynovitis. ffl!J

Additional Clinical Considerations

1111 Aerobic Training Versus Strength Training Regular, repeated activities such as jogging or aerobic dancing increase the supply of oxygen-rich blood available to skeletal muscles for aerobic cellular respiration. By con­ trast, activities such as weight lifting rely more on anaero­ bic production of ATP through glycolysis. Such anaerobic activities stimulate synthesis of muscle proteins and result, over time, in increased muscle size (muscle hypertrophy). Athletes who engage in anaerobic training should have a diet that includes an adequate amount of proteins. This protein intake will allow the body to synthesize muscle proteins and to increase muscle mass. As a result, aero­ bic training builds endurance for prolonged activities; in contrast, anaerobic training builds muscle strength for

i.

'.'.,

'

" : :tn tr

'

' ' -

.

40 6 The Muscular System

short-term feats. Interval training is a workout regimen that incorporates both types of training-for example, alternating sprints with jogging.

r:J Anabolic Steroids The use of anabolic steroids by athletes has received wide­ spread attention. These steroid honnones, similar to testos­ terone, are taken to increase muscle size and thus strength during athletic contests. However, the large doses needed to produce an effect have damaging, sometimes even dev­ astating side effects, including liver cancer, kidney dam­ age, increased risk of heart disease, stunted growth, wide mood swings, increased acne, and increased irritability and aggression. Additionally, females who take anabolic steroids may experience atrophy of the breasts and uterus, menstrual irregnlarities, sterility, facial hair growth, and deepening of the voice. Males may experience diminished testosterone secretion, atrophy of the testes, sterility, and baldness.

• Back Injuries and Heavy Lifting Next to headaches, medical experts note that back prob­ lems are the most common medical complaint that lead people to seek treatment. Second only to the common cold as the greatest cause of lost workdays, back injuries cost U.S. industry $10-14 billion in workers' compensation costs and about 100 million lost workdays annually.

The four factors associated with increased risk of back injury are amount of force, repetition, posture, and stress applied to the backbone. Poor physical condition, poor pos­ ture, lack of exercise, and excessive body weight contribute to the number and severity of sprains and strains. Back pain caused by a muscle strain or ligament sprain will normally heal within a short time and may never cause further prob­ lems. However, if ligaments and muscles are weak, discs in the lower back can become weakened and may herniate (rupture) with excessive lifting or a sudden fall. After years of back abuse, or with aging, the discs may simply wear out and cause chronic pain. Degeneration of the spine due to aging is often misdiagnosed as a sprain or strain.

Full flexion at the waist, as in touching your toes, overstretches the erector spinae muscles. Muscles that are overstretched cannot contract effectively. Straightening up from such a position is therefore initiated by the hamstring muscles on the back of the thigh and the gluteus maximus muscles of the buttocks. The erector spinae muscles join in as the degree of flexion decreases. Improperly lifting a heavy weight, however, can strain the erector spinae muscles. The result can be painful muscle spasms, tearing of tendons an_d ligaments of the lower back, and herniating of interverte­ bral discs. The lumbar muscles are adapted for maintaining posture, not for lifting. This is why it is important to bend at the knees and use the powerful extensor muscles of the thighs and buttocks while lifting a heavy load.

ii!!I Creatine Supplementation Creatine is both synthesized in the body (in the liver, kid­ neys, and pancreas) and derived from foods sucl1 as milk,

red meat, and some fish. Adults need to synthesize and ingest a total of about 2 grams of creatine daily to make up for the urinary loss of creatinine, the breakdown product of creatine. Some studies have demonstrated improved per­ formance during explosive n1ovements1 such as sprinting. Other studies, however, have failed to find a performance­ enhancing effect of creatine supplementation. Moreover, ingestitig'Jxtra creatine decreases the body's own synthesis of creatine1 and it is not known whether natural synthesis recovers after long-term creatine supplementation. In addition, creatine supplementation can cause dehydra­ tion and may cause kidney dysfunction. Further research is needed to determine both the long-term safety and the value of creatine supplementation.

cJ Exercise-Induced Muscle Damage Comparison of electron micrographs of muscle tissue taken from athletes before and after intense exercise reveals considerable exercise-induced muscle dam­ age, including torn sarcolemmas in some muscle fibers, damaged myofibrils, and disrupted Z discs. Microscopic muscle damage after exercise also is indicated by increases in blood levels of proteins, such as myoglobin and the enzyme creatine kinase, that are normally confined within muscle fibers. From 12 to 48 hours after a period of stren­ uous exercise, skeletal muscles often become sore. Such delayed onset muscle soreness (DOMS) is accompanied by stiffness, tenderness, and swelling. Although the causes of DOMS are not completely understood, microscopic muscle damage appears to be a major factor. In response to exercise-induced muscle damage, muscle fibers undergo repair: New regions of sarcolemma are formed to replace torn sarcolemmas, and more muscle proteins (including those of the myofibrils) are synthesized in the sarcoplasm of the muscle fibers.

ill Groin Pull The five major muscles of the inner thigh function to move the legs medially. This muscle group is important in activities such as sprinting, hurdling, and horseback riding. A rupture or tear of one or more of these muscles can cause a groin p,µII. Groin pulls most often occur during sprint­ ing or twisting, or from kicking a solid, perhaps stationary object. Symptoms of a groin pull may be sudden, or may not surface until the day after tlfo injury, and include sharp pain in the inguinal region, swelling, bruising, or inabil­ ity to contract the muscles. As with most strain injuries, treatment involves RJCE therapy, which stands for Rest, Ice, Compression, and Elevation. Ice should be applied immediately, and the injured part should be elevated and rested. An elastic bandage should be applied, if possible, to compress the injured tissue.

111 Hypotonia and Hypertonia Hypotonia (hypo- = below) refers to decreased or lost muscle tone. Such muscles are said to be flaccid. Flaccid muscles are loose and appear flattened rather than rounded.

Certain disorders of the nervous system and disruptions in the balance of elecu·olytes (especially sodium, calcium, and, to a lesser extent, 111agnesium) may result in flaccid paralysis, which is characterized by loss of muscle tone, loss or reduction of tendon reflexes, and atrophy (wasting away) and degeneration of muscles.

Hypertonia (hyper- = above) refers to increased muscle tone and is expressed in two_._i,v,~ys: spasticity or rigid­ ity. Spasticity (spas-TIS-i-te) is chaiacterized by increased muscle tone (stiffness) associated with an increase in tendon reflexes and pathological reflexes (such as the Babinski sign, in which the great toe extends with or without fanning of the other toes in response to stroking the outer margin of the sole). Certain disorders of the nervous system and electro­ lyte disturbances such as those previously noted may result in spastic paralysis, partial paralysis in which the muscles exhibit spasticity. Rigidity refers to increased muscle tone in which reflexes are not affected, as occurs in tetanus.

!'1 Injury of Levator Ani and Urinary Stress Incontinence

During childbirth, the levator ani muscle supports the head of the fetus, and the muscle may be injured during a dif­ ficult childbirth or traumatized during an episiotomy (a cut made with surgical scissors to prevent or direct tearing of the perineum during the birth of a baby). The consequence of such injury may be urinary stress incontinence, that is, the leakage of urine whenever intra-abdominal pressure is increased-for example, during coughing. One way to treat urinary stress incontinence is to strengthen and tighten the muscles that support the pelvic viscera. This is accom­ plished by Kegel exercises, the alternate contraction and relaxation of muscles of the pelvic floor. To find the cor­ rect muscles, the person imagines that she is urinating and then contracts the muscles as if stopping in midstream. The muscles should be held for a count of three, then relaxed for a count of three. This should be done 5-10 times each hour-sitting, standing, and lying down. Kegel exercises are also .encouraged during pregnancy to strengthen the muscles for delivery.

il!l Muscular Atrophy and Hypertrophy Muscular atrophy (A-tr6-re; a- = without, -trophy =

nourishment) is a wasting away of muscles. Individual muscle fibers decrease in size because of progressive loss of myofibrils. Atrophy that occurs because muscles are not used is termed disuse atrophy. Bedridden individuals and people with casts experience disuse atrophy because the flow of nerve impulses (nerve action potentials) _to inactive skeletal muscle is greatly reduced. The condition is revers­ ible. If instead the nerve supply to a muscle is disrupted or cut, the muscle undergoes denervation atrophy. Over a period of 6 months tci 2 years, the• muscle shrinks to about one-fourth its original size, and the muscle fibers are irre­ versibly replaced by fibrous connective tissue.

Muscular hypertrophy is an increase in the diameter of muscle fibers due to increased production of myofibrils,

Additional Clinical Considerations 41

mitochondria, sarcoplasrnic reticulum, and other organ­ elles. It results from very forceful, repetitive muscular activity, such as strengtl1 training. Because hypertrophied muscles contain more myofibrils, they are capable of more forceful contractions.

:::1 Pulled Hamstrings and Charley Horse A strain or partial tear of the proximal hamstring muscles is referred to as pulled hamstrings or hamstring strains. Like pulled groins, they are common sports injuries in individuals who run ve1y hard and/or are required to perform quick starts and stops. Sometimes the violent muscular exertion required to perform a feat tears away a part of tl1e tendinous origins of the hamstrings, especially tl1e biceps femoris, from the ischial tuberosity. This is usually accompanied by a contusion (bruising), tearing of some of the muscle fibers, and mpture of blood ves­ sels, producing a hematoma (collection of blood) and sharp pain. Adequate training with good balance between the quadriceps femoris and hamstrings and stretching exercises before running or competing are important in preventing this injury.

The term charley horse (CHAR-le- h-6rs) is a slang term, and a popular name for a cramp or stiffness of muscles due to tearing of the muscle, followed by bleeding int6 the area. It is a conunon sports injury due to trauma or excessive activity and frequently occurs in tl1e quadriceps femoris muscle, especially among football players.

fiJ Rigor Mortis Afrer deatl1, cellular membranes become leaky. Calcium ions leak out of the sarcoplasmic reticulum into the cytosol and allow myosin heads to bind to actin. ATP synthesis ceases shortly afrer breathing stops, however, so the cross­ bridges cannot detach from actin. The resulting condition, in which muscles are in a state of rigidity (cannot contract or stretch), is called rigor morris (rigidity of death). Rigor mortis begins 3-4 hours after death and lasts about 24 hours; tl1en it disappears as proteolytic enzymes from lyso­ somes digest the crossbridges.

lilil Running Injuries Many individuals who jog or run sustain some type of run­ ning-related injury. Altl10ugh such injuries may be minor, some can be quite serious. Untreated or inappropriately treated minor injuries may become chronic. Among run­ ners, common sites of injury include the ankle, knee, calca­ neal (Achilles) tendon, hip, groin, foot, and back. Of these, the knee often is the most severely injured area.

Running injuries are frequently related to faulty train­ ing techniques. This may involve inlproper or lack of suf­ ficient warm-up routines1 running too much, or running too soon after an injury. Or it might involve extended run­ ning on hard and/or uneven surfaces. Poorly constructed or worn-out running shoes can also contribute to injury, as can any biomechanical problem (such as a fallen arch) aggravated by running.

42 6 The Muscular System

Most sports injuries should be treated initially with RICE therapy, which stands for Rest, Ice, Compression, and Elevation. Immediately apply ice, and rest and elevate the injured part. Then apply an elastic bandage, if pos­ sible, to compress the injured tissue. Continne using RICE for 2 to 3 days, and resist the temptation to apply heat, which may worsen the swelling. Follow-up treatment may include alternating moist heat and ice massage to enhance blood flow in the injured area. Sometimes it is helpful to take nonsteroidal anti-inflammatory drugs (NSAIDs) or to have local injections of corticosteroids. During the recovery period, it is in1portant to keep active, using an alternative fitness program that does not worsen the origi­ nal injury. This activity should be determined in consulta­ tion with a physician. Finally, careful exercise is needed to rehabilitate the injured area itself. Massage therapy may also be used to prevent or trerit many sports injuries.

• Shin Splint Syndrome Shin splint syndrome, or simply shin splints, refers to pain or soreness along the tibia, specifically the medial, dis­ tal two-tbirds. It may be caused by tendinitis of the anterior compartment muscles, especially the t:ibialis anterior muscle, inflammation of the periosteum (periostitis) around the tibia, or stress fractures of the tibia. The tendinitis usually occurs when poorly conditioned nnmers nm on hard or banked surfaces with poorly supportive running shoes. The condi­ tion may also occur with vigorous activity of the legs follow­ ing a period of relative inactivity or rwming in cold weather without proper warmup. The muscles in the anterior com­ partment (mainly the tibialis anterior) can be strengthened to balance the stronger posterior compartment muscles.

!/Ji Stretching The overall goal of stretching is to achieve normal range of motion of joints and mobility of soft tissues surrounding the joints. For most individuals, the best stretching routine involves static stretching, that is, slow sustained stretching that holds a muscle in a lengthened position. The muscles should be stretched to the point of slight discomfort (not pain) and held for about 30 seconds. Stretching should be done after warming up to increase the range of motion most effectively.

1. Improved physical pe,formance. A flexible joint has the ability to move through a greater range of motion, which improves performance.

2. Decreased risk of injury. Stretching decreases resis­ tance in various soft tissues so there is less likelihood of exceeding maximum tissue extensiblity during an activ­ ity (i.e., injuring the soft tissues).

3. Reduced muscle soreness. Stretching can reduce some of the muscle soreness that r~sults after exercise.

4. Improved posture. -Foor-posture-results from improper position of various parts of the body and the effects of gravity over a number of years. Stretching can help realign soft tissures to improve and maintain good posture. II

Medical Terminology

Cramp A painful spasmodic contraction is known as a cramp. Cramps may be caused by inadequate blood flow to muscles, overuse of a muscle, dehydration, injury, holding a position for prolonged periods, and low blood levels of electrolytes, such as potassium.

Fasciculation (fa-sik-ii-LA.-shun) An .-involuntary, brief twitch of an entire motor unit that is visible under "the skin; it occurs irregularly and is not associated with movement of the affected muscle. Fasciculations may be seen in multiple sclerosis or in amyotrophic lateral sclerosis (Lou Gehrig's disease).

Fibrillation (fi-bri-LA.-shun) A spontaneous contraction of a single muscle fiber that is not visible under the skin but can be recorded by electromyography. Fibrillations may signal destruction of motor neurons.

Muscle strain Tearing of a muscle because of forceful impact, accompanied by bleeding and severe pain. Also known as a charley horse or pulled muscle. It often occurs in contact sports and typically affects the quadriceps femoris muscle on the anterior surface of the thigh. The condition is treated by RICE therapy: rest (R), ice immediately after the injury (I), compres­ sion via a supportive wrap (C), and elevation of the limb (E).

Myalgia (mi-AL-je-a;-algia = painful condition) Pain in or associated with muscles.

Myoma (mi-0-ma; -oma = tumor) A tumor consisting of muscle tissue.

Myomalacia (mi'-6-ma-LA.-she-a;-malacia soft) Pathological softening of muscle tissue.

Myositis (mi' -6-SI-tis; -ttts inflammation o!) Inflammation of muscle fibers (cells).

Myotonia (mi' -6-TO-ne-a;-tonia = tension) Increased muscular excitability and contractility, with decreased power of relaxation; tonic spasm of the muscle.

Spasm A sudden involuntary contraction of a single muscle in a large group of muscles.

Tic A tic is a spasmodic twitching made involuntarily by muscles that are ordinarily under voluntary control. Twitching of the eyelid and facial muscles are examples of tics.

Tremor A tremor is a rhythmic, involuntary, purposeless contraction that produces a quivering or shaking move­ ment.

Volkmann's contracture (FOLK-manz kon-TRAK-tnr; contra- = against) Permanent shortening (contracture) of a muscle due to replacement of destroyed muscle fibers by fibrous connective tissue, which lacks exten­ sibility. Typically occurs in forearm flexor muscles. Destruction of muscle fibers may occur from interfer­ ence with circulation caused by a tight bandage, a piece of elasti~, or a cast.