Muscular System PDF - McKay McGraw-Hill

26-1 Chapter 24 The Muscular System PowerPoint® presentation to accompany: Click to add text Medical Assisting Third Edition Booth, Whicker, Wyman, Pugh, Thompson...

26-1 Chapter 24 The Muscular System PowerPoint® presentation to accompany: Click to add text Medical Assisting Third Edition Booth, Whicker, Wyman, Pugh, Thompson McKay © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-2 Learning Outcomes 26.1 List the functions of muscle. 26.2 List the three types of muscle tissue and describe the locations and characteristics of each. 26.3 Describe how visceral (smooth) muscle produces peristalsis. 26.4 Explain how muscle tissue generates energy. © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-3 Learning Outcomes (cont.) 26.5 Describe the structure of a skeletal muscle. 26.6 Define the terms origin and insertion. 26.7 List and define the various types of body movements produced by skeletal muscles. 26.8 List and identify the major skeletal muscles of the body, and giving the action of each. © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-4 Learning Outcomes (cont.) 26.9 Explain the differences between strain and sprain injuries. 26.10 Describe the changes that occur to the muscular system as a person ages. 26.11 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the muscular system. © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-5 Introduction  Bones and joints do not Muscles cause bones and produce movement supported structures to  The human body has move by alternating more than 600 between contraction and individual muscles relaxation You will focus on the differences among three muscle tissue types, the structure of skeletal muscles, muscle actions, and the names of skeletal muscles. © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-6 Functions of Muscle Muscle has the ability to Functions: contract, permitting Movement muscles to perform Stability various functions Control of body openings and passages Heat production Click for Larger View Click for Larger View © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-7 Skeletal Muscle © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-8 Functions of Muscle: Movement  Skeletal muscles ◼ Attached to bones by tendons ◼ Cross joints so when they contract, bones they attach to move  Smooth muscle ◼ Found on organ walls ◼ Contractions produce movement of organ contents  Cardiac muscle ◼ Produces atrial and ventricular contractions ◼ This pumps blood from the heart into the blood vessels © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-9 Functions of Muscle: Stability  Hold bones tightly together ◼ Stabilize joints  Small muscles hold vertebrae together ◼ Stabilize the spinal column © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-10 Functions of Muscle: Control of Body Openings and Passages  Sphincters ◼ Valve-like structures formed by muscles ◼ Control movement of substances in and out of passages ◼ Example:  A urethral sphincter prevents or allows urination © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-11 Functions of Muscle: Heat Production  Heat is released with muscle contraction ◼ Helps the body maintain a normal temperature ◼ Moving your body can make you warmer if you are cold © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-12 Apply Your Knowledge True or False: ANSWER: tendons F Skeletal muscles are attached to bones by ligaments. ___ __ T Contractions of smooth muscle produce movement of organ contents. T Cardiac muscle produces atrial and ventricular contractions. ___ in and out F Sphincters control movement of substances out of passages. ___ RIGHT! F Heat is released as muscles relax. ___ contract © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-13 Types of Muscle Tissue  Muscle cells ◼ Myocytes called muscle fibers ◼ Sarcolemma – cell membrane ◼ Sarcoplasm – cytoplasm of cell ◼ Myofibrils – long structures in sarcoplasm  Arrangement of filaments in myofibrils produces striations © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-14 Types of Muscle Tissue (cont.) Muscle Major Major Mode of Group Location Function Control Skeletal Attached to Produces body Voluntary Muscle bones and skin of movements and the face facial expressions Smooth Walls of hollow Moves contents Involuntary Muscle organs, blood through organs; vessels, and iris vasoconstriction Cardiac Wall of the heart Pumps blood Involuntary Muscle through heart © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-15 Types of Muscle Tissue: Skeletal Muscle  Muscle fibers respond to the neurotransmitter acetylcholine ◼ Causes skeletal muscle to contract  Following contraction, muscles release the enzyme acetylcholinesterase ◼ Breaks down acetylcholine ◼ Allows muscle to relax © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-16 Types of Muscle Tissue: Smooth Muscle  Multiunit smooth muscle ◼ In the iris of the eye and walls of blood vessels ◼ Responds to neurotransmitters and hormones  Visceral smooth muscle ◼ In walls of hollow organs ◼ Responds to neurotransmitters AND ◼ Stimulate each other to contract so that muscle fibers contract and relax together in a rhythmic motion – peristalsis © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-17 Types of Muscle Tissue: Smooth Muscle (cont.)  Peristalsis – rhythmic contraction that pushes substances through tubes of the body  Neurotransmitters for smooth muscle contraction ◼ Acetylcholine ◼ Norepinephrine ◼ Will cause or inhibit contractions, depending on smooth muscle type © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-18 Types of Muscle Tissue: Cardiac Muscle  Intercalated discs ◼ Connect groups of cardiac muscle ◼ Allow the fibers in the groups to contract and relax together  Allows heart to work as a pump  Self-exciting – does not need nerve stimulation to contract ◼ Nerves speed up or slow down contraction © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-19 Type of Muscle Tissue: Cardiac Muscle (cont.)  Neurotransmitters ◼ Acetylcholine – slows heart rate ◼ Norepinephrine – speeds up rate © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-20 Apply Your Knowledge Match the following: ANSWER: C Self-exciting ___ A. Skeletal muscle A Contract in response to ___ B. Smooth muscle acetylcholine C. Cardiac muscle B Stimulate each other to ___ contract B Peristalsis ___ Very C Slowed by acetylcholine ___ Good! ___ A Voluntary movement © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-21 Production of Energy for Muscle  ATP (adenosine Muscle cells must have triphosphate) three ways to store or ◼ A type of chemical make ATP energy Creatine phosphate ◼ Needed for sustained Rapid production of energy or repeated muscle Aerobic respiration contractions Uses body’s store of glucose Lactic acid production ATP = energy Small amounts of ATP © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-22 Production of Energy: Oxygen Debt  Develops when skeletal muscles are used strenuously for several minutes and cells are low in oxygen Converts Pyruvic acid Lactic acid to which builds up To liver for conversion to Muscle fatigue glucose, requiring more energy and oxygen to make ATP Oxygen debt © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-23 Production of Energy: Muscle Fatigue  Condition in which a muscle has lost its ability to contract  Causes ◼ Accumulation of lactic acid ◼ Interruption of the blood supply to a muscle ◼ A motor neuron loses its ability to release acetylcholine onto muscle fibers © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-24 Apply Your Knowledge Match the following: ANSWER: ___ E Rapid production energy A. Lactic acid ___ C Needed for sustained or B. Pyruvic acid repeated muscle contractions C. ATP ___ D Uses body’s store of glucose D. Aerobic A Muscle fatigue ___ B respiration ___ With strenuous exercise, E. Creatine Yippee! converts to lactic acid phosphate © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-25 Structure of Skeletal Muscles  Skeletal muscles ◼ The major components of the muscular system  Composition ◼ Connective tissue ◼ Skeletal muscle tissue ◼ Blood vessels ◼ Nerves © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-26 Structure: Connective Tissue Coverings  Fascia Aponeurosis ◼ Covers entire skeletal A tough, sheet-like muscles structure made of ◼ Separates them from fibrous connective each other tissue Attaches muscles to other muscles  Tendon ◼ A tough, cord-like structure made of fibrous connective tissue ◼ Connects muscles to bones © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-27 Structure: Connective Tissue Coverings (cont.)  Epimysium ◼ A thin covering that is just below the fascia of a muscle and surrounds the entire muscle  Perimysium ◼ Connective tissue that divides a muscle into sections called fascicles  Endomysium ◼ Covering of connective tissue that surrounds individual muscle cells © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-28 Apply Your Knowledge Match the following: D A. Tendon __ Thin covering under the fascia that surrounds the muscle B. Perimysium E __ Separates muscles from each other C. Aponeurosis A __ Connects muscles to bones D. Epimysium B __ Divides a muscle into sections E. Fascia called fascicles F. Endomysium F __ Surrounds individual muscle cells C __ Attaches muscles to other muscles ANSWER: © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-29 Attachments and Actions of Skeletal Muscles  Actions depend largely on what the muscles are attached to  Attachment sites ◼ Origin – an attachment site for a less movable bone ◼ Insertion – an attachment site for a more moveable bone © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-30 Attachments and Actions (cont.)  Movement usually produced by a group of muscles ◼ Prime mover – muscle responsible for most of the movement ◼ Synergists – muscles that help the prime mover by stabilizing joints ◼ Antagonist (agonist) – produces movement opposite to prime mover  Relaxes when prime mover contracts © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-31 Attachments and Actions: Body Movements (cont.) Circumduction – moving a Inversion – turning the sole of body part in a circle the foot medially Pronation – turning the palm Eversion – turning the sole of the foot laterally of the hand down Retraction – moving a body Supination – turning the palm part posteriorly of the hand up Protraction – moving a body part anteriorly © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-32 Attachments and Actions: Body Movements Flexion – bending a body Plantar flexion – pointing part the toes down Extension – straightening a Abduction – moving a body body part part away from the anatomical position Hyperextension – extending a body part past the normal anatomical Adduction – moving a body position part toward the anatomical position Dorsiflexion – pointing the toes up © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-33 Attachments and Actions: Body Movements (cont.) Elevation – lifting a body part; for example, elevating the shoulders as in a shrugging expression Depression – lowering a body part; for example, lowering the shoulders © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-34 Apply Your Knowledge 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? ANSWER: Move the patient’s leg away from its position in the anatomical position. Correct! © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-35 Major Skeletal Muscles  The muscle name As you study muscles, you indicates will find it easier to ◼ Location remember them if you ◼ Size think about what the ◼ Action name describes. ◼ Shape OR ◼ Number of attachments of the muscle © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-36 Major Skeletal Muscles: The Head  Sternocleidomastoid Splenius capitis ◼ Pulls the head to one Rotates the head side Allows it to bend to the side ◼ Pulls the head to the Orbicularis oris chest Allows the lips to pucker  Frontalis ◼ Raises the eyebrows © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-37 Major Skeletal Muscles: The Head (cont.)  Orbicularis oculi Platysma ◼ Allows the eyes to Pulls the corners of the close mouth down  Zygomaticus Masseter and temporalis ◼ Pulls the corners of the Close the jaw mouth up © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-38 Major Skeletal Muscles: Upper Arm  Pectoralis major ◼ Pulls the arm across the chest ◼ Rotates and adducts the arms  Latissimus dorsi ◼ Extends and adducts the arm and rotates the arm inwardly © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-39 Major Skeletal Muscles: Upper Arm (cont.)  Deltoid ◼ Abducts and extends the arm at the shoulder  Subscapularis ◼ Rotates the arm medially  Infraspinatus ◼ Rotates the arm laterally © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-40 Major Skeletal Muscles: Forearm  Biceps brachii ◼ Flexes the arm at the elbow ◼ Rotates the hand laterally  Brachialis ◼ Flexes the arm at the elbow  Brachioradialis ◼ Flexes the forearm at the elbow © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-41 Major Skeletal Muscles: Forearm (cont.)  Triceps brachii ◼ Extends the arm at the elbow  Supinator ◼ Rotates the forearm laterally (supination)  Pronator teres ◼ Rotates the forearm medially (pronation) © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-42 Major Skeletal Muscles: Wrist, Hand, and Fingers  Flexor carpi radialis and flexor carpi ulnaris ◼ Flex and abduct the wrist  Palmaris longus ◼ Flexes the wrist  Flexor digitorum profundus ◼ Flexes the distal joints of the fingers, but not the thumb © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-43 Major Skeletal Muscles: Wrist, Hand, and Fingers (cont.)  Extensor carpi radialis longus and brevis ◼ Extend the wrist and abduct the hand  Extensor carpi ulnaris ◼ Extends the wrist  Extensor digitorum ◼ Extends the fingers, but not the thumb © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-44 Major Skeletal Muscles: Respiratory  Diaphragm ◼ Separates the thoracic cavity from the abdominal cavity ◼ Its contraction causes inspiration  External and internal intercostals ◼ Expand and lower the ribs during breathing © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-45 Major Skeletal Muscles: Abdominal  External and internal obliques ◼ Compress the abdominal wall  Transverse abdominis ◼ Also compresses the abdominal wall  Rectus abdominis ◼ Flexes the vertebral column ◼ Compresses the abdominal wall Click for View of Abdominal Muscles Click for View of Abdominal Muscles © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-46 Abdominal Muscles (cont.) © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-47 Major Skeletal Muscles: Pectoral Girdle  Trapezius ◼ Raises the arms ◼ Pulls the shoulders downward  Pectoralis minor ◼ Pulls the scapula downward ◼ Raises the ribs Click for View of Pectoral Girdle Muscles Click for View of Pectoral Girdle Muscles © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-48 Major Skeletal Muscles: Leg  Psoas major and iliacus ◼ Flexes the thigh  Gluteus maximus ◼ Extends the thigh  Gluteus medius and minimus ◼ Abduct the thighs ◼ Rotate them medially © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-49 Major Skeletal Muscles: Leg (cont.)  Adductor longus and magnus ◼ Adduct the thighs ◼ Rotate them laterally  Biceps femoris, semitendinosus, and semimembranosus ◼ Known as the hamstring group ◼ Flex the leg at the knee ◼ Extend the leg at the thigh © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-50 Major Skeletal Muscles: Leg (cont.)  Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius ◼ Extend the leg at the knee  Sartorius ◼ Flexes the leg at the knee and thigh ◼ Abducts the thigh, rotating the thigh laterally but rotating the lower leg medially © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-51 Major Skeletal Muscles: Ankle, Foot, and Toes  Tibialis anterior ◼ Inverts the foot and point the foot up (dorsiflexion)  Extensor digitorum longus ◼ Extends the toes and point the foot up  Gastrocnemius ◼ Flexes the foot and flexes the leg at the knee © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-52 Major Skeletal Muscles: Ankle, Foot, and Toes (cont.)  Soleus ◼ Flexes the foot  Flexor digitorum longus ◼ Flexes the foot and toes © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-53 Apply Your Knowledge 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? ANSWER: 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. Bravo! © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-54 Muscle Strains and Sprains  Strains – injuries due to over-stretched muscles or tendons  Sprains – more serious injuries that result in tears to tendons, ligaments, and/or cartilage of joints  RICE is recommended treatment for either ◼ Rest ◼ Ice ◼ Compression ◼ Elevation © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-55 Muscle Strains and Sprains (cont.)  Prevention ◼ Warm up muscles  A few minutes before an intense activity raises muscle temperature and makes muscle more pliable ◼ Stretching  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 © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-56 Aging and the Musculoskeletal System  Contractions become slower and not as strong ◼ Dexterity and gripping ability decrease ◼ Mobility may decrease  Assistive devices helpful  Routine exercise ◼ Swimming ◼ Physical therapy © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-57 Diseases and Disorders of the Muscular System Disease Description Botulism Affects the gastrointestinal tract and various muscle groups Fibromyalgia Fairly common condition that causes chronic pain primarily in joints, muscles, and tendons Muscular Inherited disorder characterized by muscle Dystrophy weakness and a loss of muscle tissue Myasthenia gravis Autoimmune condition in which patients experience muscle weakness © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-58 Diseases and Disorders of the Muscular System (cont.) Disease Description Rhabdomyolysis A condition in which the kidneys become damaged after serious muscle injuries Tendonitis Painful inflammation of a tendon and the (lockjaw) tendon-muscle attachment to a bone Torticollis Acquired or congenital; spasm or shortening of (wryneck) the sternocleidomastoid muscle; head bends to affected side and chin rotates to opposite side Trichinosis An infection caused by parasites (worms) © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-59 24.8 Common Diseases and Disorders of the Muscular System Botulism − poisoning caused by toxins produced by Clostridium botulinum bacteria. − Etiology – typically through contaminated food or water. Bulging or dented cans such as vegetables, natural honey*. − S/s – dysphagia, dysphasia, (know the difference! - use McKays method to remember), may progress to difficulty breathing − Tx - Rx meds, IV prn © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-60 Fibromyalgia ⚫ A chronic common rheumatologic syndrome/condition causing pain, stiffness, and tenderness of the muscles, tendons, and joints. It is also characterized by restless sleep, tiredness, fatigue, anxiety, depression, and disturbances in bowel functions. ⚫ Etiology – unknown ⚫ S/s – generalized malaise, discomfort ⚫ Tx: Rx med's, exercise, therapies (PT), stress management techniques © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-61 Muscular Dystrophy ⚫ A progressive generalized muscle disease ⚫ Etiology – defective or specifically absent glycoproteins in the muscle membrane ⚫ Tx: Rx med's, exercise, therapies (PT), surgery, may progress to potentially life threatening status as disease progresses © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-62 Myasthenia Gravis ⚫ A chronic autoimmune neuromuscular disease that causes weakness in the skeletal muscles, which are responsible for breathing and moving parts of the body, including the arms and legs ⚫ Etiology – autoimmune ⚫ Tx: Rx med's, therapies (PT) to slow progression, surgery, may progress to potentially life threatening status as disease progresses, may need to adjust lifestyle habits © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-63 Rhabdomyolysis ⚫ A breakdown of muscle tissue that releases a damaging protein into the blood ⚫ Etiology – commonly: trauma, other: drugs, viral, infection, genetics, autoimmune, other ⚫ S/s – arrhythmia, myalgia, dark urine, n/v ⚫ Tx: Rx med's, therapies (PT) to slow progression, surgery, may progress to potentially life threatening status as disease progresses, may need to adjust lifestyle habits © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-64 Tendonitis ⚫ Inflammation of a tendon ⚫ Etiology – commonly: trauma or repetitive movements ⚫ S/s – pain and/or swelling with tenderness localized over a tendon ⚫ Tx: NSAIDs, RICE, corticosteroid injections, Rx med's, therapies (PT) © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-65 Tetanus ⚫ A serious bacterial infection that affects the nerves and causes painful muscle spasms and can lead to death once respiratory or cardiac muscles are involved. Commonly seen with lockjaw and muscle rigidity. ⚫ Etiology – Contact with the bacteria, although usually associated with scraping against metal or rusted object, can be through other avenues of contamination (door knobs, etc). ⚫ S/s – pyrexia, HTN, tachycardia, diaphoresis, dysphagia, dyspnea/apnea ⚫ Tx: NO CURE, penicillin may help, Tdap vaccine to PREVENT! © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-66 Torticollis ⚫ A rare condition in which the neck muscles contract, causing the head to twist to one side. Usually in infants. ⚫ Etiology – believed to be either inherited or due to parents not moving baby around equally. ⚫ S/s – stiff neck musculature ⚫ Tx: P.T., massage, stretching, possibly Botox injections? © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-67 Trichinosis ⚫ Sometimes called trichinellosis ⚫ Etiology – consuming the larva and/or adult roundworm parasite from eating undercooked or improperly cooked meats #sushi ⚫ S/s – may be asymptomatic, otherwise: diarrhea, abdominal p!, N/V, pyrexia, myalgia, conjuctivitis, photophobia, possibly others. ⚫ Tx: May not need to be tx'd, otherwise: NSAIDs, rx meds, corticosteroids © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-68 Apply Your Knowledge The doctor has told your patient that his son has muscular dystrophy disorder. What is muscular dystrophy? ANSWER: Muscular dystrophy is an inherited disorder characterized by muscle weakness and a loss of muscle tissue. Good Job! © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-69 In Summary  Skeletal muscles Smooth muscles ◼ Voluntary control Involuntary control ◼ Produce movement in Control body openings and conjunction with passages skeletal system Cardiac muscles ◼ Help stabilize joints Involuntary control ◼ Participate in heat Responsible for pumping production action of the heart © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-70 In Summary (cont.)  Medical assistants must understand the muscular system to ◼ Give IM injections ◼ Prepare patients for massage therapy ◼ Demonstrate ambulatory techniques ◼ Assist in care and prevention of muscular disorders © 2009 The McGraw-Hill Companies, Inc. All rights reserved  26-71 End of Chapter 26 End of Chapter Everyone 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 Oech © 2009 The McGraw-Hill Companies, Inc. All rights reserved