Y khoa, dược - The muscular system

22The Muscular System22-2Learning Outcomes22.1 List the functions of muscle. 22.2 List the three types of muscle tissue and describe the locations and characteristics of each.22.3 Describe how visceral (smooth) muscle produces peristalsis.22.4 Explain how muscle tissue generates energy. 22-3Learning Outcomes (cont.)22.5 Describe the structure of a skeletal muscle.22.6 Define the terms origin and insertion.22.7 List and define the various types of body movements produced by skeletal muscles.22.8 List and identify the major skeletal muscles of the body, giving the action of each. 22-4Learning Outcomes (cont.)22.9 Explain the differences between strain and sprain injuries.22.10 Describe the changes that occur to the muscular system as a person ages.22.11 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the muscular system.22-5Introduction Bones and joints do not produce movementThe human body has more than 600 individual musclesMuscles cause bones and supported structures to move by alternating between contraction and relaxationYou will focus on the differences among three muscle tissue types, the structure of skeletal muscles, muscle actions, and the names of skeletal muscles. 22-6Functions of Muscle Muscle has the ability to contract, permitting muscles to perform various functionsFunctions:MovementStabilityControl of body openings and passages Heat productionClick for Larger View22-7Skeletal Muscle22-8MovementSkeletal muscles Attached to bones by tendonsCross joints so when they contract, bones they attach to moveSmooth muscleFound on organ walls Contractions produce movement of organ contentsCardiac muscle Produces atrial and ventricular contractions This pumps blood from the heart into the blood vessels22-9StabilityHold bones tightly together Stabilize jointsSmall muscles hold vertebrae together Stabilize the spinal column22-10Control of Body Openings and PassagesSphincters Valve-like structures formed by muscles Control movement of substances in and out of passagesExample:A urethral sphincter prevents or allows urination22-11Heat ProductionHeat is released with muscle contractionHelps the body maintain a normal temperatureMoving your body can make you warmer if you are cold22-12Apply Your KnowledgeTrue or False:___ Skeletal muscles are attached to bones by ligaments.___ Contractions of smooth muscle produce movement of organ contents.___ Cardiac muscle produces atrial and ventricular contractions.___ Sphincters control movement of substances out of passages.___ Heat is released as muscles relax.tendonsin and outcontractTTFFFANSWER:RIGHT!22-13Types of Muscle Tissue Muscle cellsMyocytes called muscle fibersSarcolemma – cell membraneSarcoplasm – cytoplasm of cellMyofibrils – long structures in sarcoplasmArrangement of filaments in myofibrils produces striations22-14Types of Muscle Tissue (cont.)Muscle GroupMajor LocationMajor FunctionMode of ControlSkeletal MuscleAttached to bones and skin of the faceProduces body movements and facial expressionsVoluntarySmooth MuscleWalls of hollow organs, blood vessels, and irisMoves contents through organs; vasoconstrictionInvoluntary Cardiac MuscleWall of the heartPumps blood through heartInvoluntary22-15Skeletal MuscleMuscle fibers respond to the neurotransmitter acetylcholineCauses skeletal muscle to contractFollowing contraction, muscles release the enzyme acetylcholinesteraseBreaks down acetylcholineAllows muscle to relax22-16Smooth MuscleMultiunit smooth muscleIn the iris of the eye and walls of blood vesselsResponds to neurotransmitters and hormonesVisceral smooth muscleIn walls of hollow organsResponds to neurotransmitters ANDStimulate each other to contract so that muscle fibers contract and relax together in a rhythmic motion – peristalsis22-17Smooth Muscle (cont.) Peristalsis – rhythmic contraction that pushes substances through tubes of the bodyNeurotransmitters for smooth muscle contraction AcetylcholineNorepinephrine Will cause or inhibit contractions, depending on smooth muscle type 22-18Cardiac MuscleIntercalated discsConnect groups of cardiac muscleAllow the fibers in the groups to contract and relax togetherAllows heart to work as a pumpSelf-exciting – does not need nerve stimulation to contractNerves speed up or slow down contraction22-19Cardiac Muscle (cont.)NeurotransmittersAcetylcholine – slows heart rateNorepinephrine – speeds up rate22-20Apply Your KnowledgeMatch the following:___ Self-exciting A. Skeletal muscle___ Contract in response to B. Smooth muscle  acetylcholine C. Cardiac muscle ___ Stimulate each other to  contract___ Peristalsis___ Slowed by acetylcholine___ Voluntary movementCAABBVery Good!CANSWER:22-21Production of Energy for Muscle ATP (adenosine triphosphate) A type of chemical energyNeeded for sustained or repeated muscle contractions Muscle cells must have three ways to store or make ATP Creatine phosphate Rapid production of energyAerobic respiration Uses body’s store of glucose Lactic acid production Small amounts of ATPATP = energy22-22Oxygen DebtDevelops when skeletal muscles are used strenuously for several minutes and cells are low in oxygenLactic acid which builds upPyruvic acidConverts toMuscle fatigueTo liver for conversion to glucose, requiring more energy and oxygen to make ATPOxygen debt22-23Muscle FatigueCondition in which a muscle has lost its ability to contract CausesAccumulation of lactic acid Interruption of the blood supply to a muscle A motor neuron loses its ability to release acetylcholine onto muscle fibers 22-24Apply Your KnowledgeMatch the following:___ Rapid production of energy A. Lactic acid___ Needed for sustained or B. Pyruvic acid repeated muscle contractions C. ATP___ Uses body’s store of glucose D. Aerobic ___ Muscle fatigue respiration ___ With strenuous exercise, E. Creatineconverts to lactic acid phosphate CADBEANSWER:Yippee!22-25Structure of Skeletal MusclesSkeletal muscles The major components of the muscular systemComposition Connective tissueSkeletal muscle tissue Blood vessels Nerves22-26Connective Tissue CoveringsFascia Covers entire skeletal muscles Separates them from each otherTendonA tough, cord-like structure made of fibrous connective tissueConnects muscles to bonesAponeurosis A tough, sheet-like structure made of fibrous connective tissue Attaches muscles to other muscles22-27Connective Tissue Coverings (cont.)Epimysium A thin covering that is just below the fascia of a muscle and surrounds the entire musclePerimysium Connective tissue that divides a muscle into sections called fasciclesEndomysium Covering of connective tissue that surrounds individual muscle cells22-28Apply Your KnowledgeMatch the following:__ Thin covering under the fascia that surrounds the muscle __ Separates muscles from each other__ Connects muscles to bones__ Divides a muscle into sections called fascicles __ Surrounds individual muscle cells__ Attaches muscles to other musclesTendonPerimysium AponeurosisEpimysiumFasciaEndomysiumEABFCDANSWER:Excellent!22-29Attachments and Actions of Skeletal Muscles Actions depend largely on what the muscles are attached toAttachment sitesOrigin – an attachment site for a less movable boneInsertion – an attachment site for a more movable bone22-30Attachments and Actions (cont.)Movement usually produced by a group of musclesPrime mover (agonist) – muscle responsible for most of the movementSynergists – muscles that help the prime mover by stabilizing jointsAntagonist – muscle that produces movement opposite to prime moverRelaxes when prime mover contracts22-31Body Movements Flexion – bending a body part Extension – straightening a body part Hyperextension – extending a body part past the normal anatomical position Dorsiflexion – pointing the toes up Plantar flexion – pointing the toes downAbduction – moving a body part away from the anatomical position Adduction – moving a body part toward the anatomical position Figure of Body Movements22-32Body Movements (cont.)Back22-33Body Movements (cont.)Circumduction – moving a body part in a circle Pronation – turning the palm of the hand downSupination – turningthe palm of the hand up 22-34Body Movements (cont.)Inversion – turning the sole of the foot medially Eversion – turning the sole of the foot laterally Retraction – moving a body part posteriorly Protraction – moving a body part anteriorly22-35Body Movements (cont.)Elevation – lifting a body part; for example, elevating the shoulders as in a shrugging expressionDepression – lowering a body part; for example, lowering the shoulders22-36Apply Your KnowledgeANSWER: Move the patient’s leg away from its position in the anatomical position. The doctor has asked you to abduct the patient’s leg so he can see the patient’s wound. In order to position the patient correctly, what will you have to do?Correct!22-37Major Skeletal Muscles The muscle name indicates LocationSizeActionShape ORNumber of attachments of the muscleAs you study muscles, you will find it easier to remember them if you think about what the name describes.22-38Muscles of the HeadSternocleidomastoid Pulls the head to oneside Pulls the head to the chestFrontalis Raises the eyebrowsSplenius capitisRotates the head Allows it to bend to the sideOrbicularis oris Allows the lips to pucker 22-39Muscles of the Head (cont.)Orbicularis oculi Allows the eyes to close Zygomaticus Pulls the corners of the mouth upPlatysma Pulls the corners of the mouth downMasseter and temporalis Close the jaw22-40Arm MusclesPectoralis major Pulls the arm across the chest Rotates and adducts the armsLatissimus dorsi Extends and adducts the arm and rotates the arm inwardly22-41Arm Muscles (cont.)DeltoidAbducts and extends the arm at the shoulder Subscapularis Rotates the arm mediallyInfraspinatus Rotates the arm laterally22-42Arm Muscles (cont.)Biceps brachii Flexes the arm at the elbow Rotates the hand laterallyBrachialis Flexes the arm at the elbowBrachioradialis Flexes the forearm at the elbow22-43Arm Muscles (cont.)Triceps brachii Extends the arm at the elbowSupinator Rotates the forearm laterally (supination)Pronator teres Rotates the forearm medially (pronation)22-44Wrist, Hand, and Finger MusclesFlexor carpi radialis and flexor carpi ulnaris Flex and abduct the wristPalmaris longus Flexes the wristFlexor digitorum profundus Flexes the distal joints of the fingers, but not the thumb22-45Wrist, Hand, and Finger Muscles (cont.)Extensor carpi radialis longus and brevis Extend the wrist and abduct the handExtensor carpi ulnaris Extends the wristExtensor digitorum Extends the fingers, but not the thumb22-46Respiratory MusclesDiaphragm Separates the thoracic cavity from the abdominal cavityIts contraction causes inspiration External and internal intercostals Expand and lower the ribs during breathing 22-47Abdominal MusclesExternal and internal obliques Compress the abdominal wallTransverse abdominis Also compresses the abdominal wallRectus abdominisFlexes the vertebral columnCompresses the abdominal wallClick for View of Abdominal Muscles22-48Abdominal Muscles (cont.)22-49Pectoral GirdleTrapezius Raises the arms Pulls the shoulders downwardPectoralis minor Pulls the scapula downwardRaises the ribsClick for View of Pectoral Girdle Muscles22-50Leg MusclesIliopsoas majorFlexes the thighGluteus maximus Extends the thighGluteus medius and minimus Abduct the thighs Rotate them medially22-51Leg Muscles (cont.)Adductor longus and magnus Adduct the thighs Rotate them laterallyBiceps femoris, semitendinosus, and semimembranosus Known as the hamstring groupFlex the leg at the knee Extend the leg at the thigh22-52Leg Muscles (cont.)Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius Extend the leg at the kneeSartorius Flexes the leg at the knee and thigh Abducts the thigh, rotating the thigh laterally but rotating the lower leg medially22-53Ankle, Foot, and Toe MusclesTibialis anterior Inverts the foot and points the foot up (dorsiflexion)Extensor digitorum longus Extends the toes and points the foot upGastrocnemiusFlexes the foot and flexes the leg at the knee22-54Ankle, Foot, and Toe Muscles (cont.)Soleus Flexes the footFlexor digitorum longusFlexes the foot and toes22-55Apply Your KnowledgeANSWER: You would look at the back of his leg, and the muscles involved would be the biceps femoris, semitendinosus, and semimembranosus. These three muscles are known as the hamstring group. Your patient complains of hurting his hamstring when running today. You would look at what part of the leg, and what muscles would be involved?Bravo!22-56Muscle Strains and SprainsStrains – injuries due to over-stretched muscles or tendonsSprains – more serious injuries that result in tears to tendons, ligaments, and/or cartilage of jointsRICE is recommended treatment for eitherRestIceCompressionElevation22-57Muscle Strains and Sprains (cont.)PreventionWarm up muscles A few minutes before an intense activity raises muscle temperature and makes muscle more pliableStretching Improves muscle performance and should always be done after the warm-up or after exercising Cooling down or slowing down Before completely stopping prevents pooling of blood in the legs and helps remove lactic acid from muscles 22-58Aging and the Musculoskeletal SystemContractions become slower and not as strongDexterity and gripping ability decreaseMobility may decreaseAssistive devices helpfulRoutine exerciseSwimmingPhysical therapy22-59Diseases and Disorders of the Muscular SystemDiseaseDescriptionBotulismAffects the gastrointestinal tract and various muscle groups FibromyalgiaFairly common condition that causes chronic pain primarily in joints, muscles, and tendonsMuscular dystrophyInherited disorder characterized by muscle weakness and a loss of muscle tissueMyasthenia gravisAutoimmune condition in which patients experience muscle weakness22-60Diseases and Disorders of the Muscular System (cont.)DiseaseDescriptionRhabdomyolysisA condition in which the kidneys become damaged after serious muscle injuriesTetanus (lockjaw)Painful inflammation of a tendon and the tendon-muscle attachment to a boneTorticollis (wryneck)Acquired or congenital; spasm or shortening of the sternocleidomastoid muscle; head bends to affected side and chin rotates to opposite sideTrichinosisAn infection caused by parasites (worms)22-61Apply Your KnowledgeANSWER: Muscular dystrophy is an inherited disorder characterized by muscle weakness and a loss of muscle tissue. The doctor has told your patient that his son has muscular dystrophy disorder. What is muscular dystrophy?Good Job!22-62In Summary22.1 The functions of muscles include movement, stability, control of body openings and passages, and the production of heat.22.2 The three types of muscle tissue are striated voluntary skeletal muscle, smooth involuntary visceral muscle, and specialized striated and involuntary cardiac muscle. 22.3 Peristalsis is the rhythmic contraction produced by smooth muscle to push substances through various tubes in the body. 22-63In Summary (cont.)22.4 Muscles create energy in three ways. Creatine phosphate is a rapid method for muscles to create energy, aerobic respiration uses stored glucose to produce ATP in the Krebs cycle, and lactic acid production occurs when a cell is low in oxygen and coverts pyruvic acid to lactic acid. 22.5 Skeletal muscle is composed of connective tissues, skeletal muscle tissue, blood vessels, and nerves. The coverings of skeletal muscles include fascia, tendon, aponeurosis, epimysium, perimysium, and endomysium.22-64In Summary (cont.)22.6 The origin of a muscle is the attachment site of the muscle to the less movable bone during muscle contraction. The insertion of a muscle is the attachment site for the muscle to the more movable bone during muscle contraction.22.7 The body movements produced by skeletal muscles include flexion, extension, hyperextension, dorsiflexion, plantar flexion, abduction, adduction, rotation, circumduction, pronation, supination, inversion, eversion, retraction, protraction, elevation, and depression.22-65In Summary (cont.)22.8 The major muscles of the head are sternocleidomastoid, splenius capitis, frontalis, orbicularis oris and oculi, zygomaticus, platysma, masseter, and temporalis. The upper extremity muscles include pectoralis major, latissimus dorsi, deltoid, subscapularis, biceps brachii, brachialis, brachioradialis, triceps brachii, supinator and pronator teres, flexor carpi radialis and ulnaris, plamaris longus, flexor digitorum profundus, extensor carpi radialis longus and brevis, and extensor digitorum. The major respiratory muscles are the diaphragm and the external and internal intercostals. 22-66In Summary (cont.)22.8 (cont.) The abdominal muscles include external and internal obliques, transverse abdominis, and rectus abdominis. The pectoral girdle muscles include trapezius and pectoralis minor. The muscles of the lower extremity include iliopsoas major; gluteus maximus, medius, and minimus; adductor longus and magnus; biceps femoris; semitendinosus and semimembranosus; rectus femoris; vastus lateralis, medius, and intermedius; sartorius; tibialis anterior; extensor digitorum longus; gastrocnemius; soleus; and flexor digitorum longus.22-67In Summary (cont.)22.9 Strain injuries involve injuries to muscles and/or tendons. Sprains are more serious injuries that result in tears to tendons, ligaments, and/or the cartilage of joints. 22.10 The common diseases of aging include arthritis, fractures, osteoporosis, and muscular decline. Aging causes a decline in strength and speed of muscle contractions. Dexterity and gripping abilities lessen and mobility often decreases related to skeletal and muscular decline.22-68In Summary (cont.)22.11 The diseases of the muscular system, as well as their symptoms and treatments, vary widely and are discussed in the Pathophysiology section of this chapter. Some of the common diseases discussed include botulism, fibromyalgia, muscular dystrophy, myasthenia gravis, tendonitis, tetanus, and torticollis.22-69Everyone has a ‘risk muscle.’ You keep it in shape by trying new things. If you don’t, it atrophies. Make a point of using it at least once a day.~Roger von OechEnd of Chapter 22