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The human body has more than 600 individual muscles. Although each muscle is a distinct structure, muscles act in groups to perform particular movements. This chapter focuses on the differences among three muscle tissue types, the structure of skeletal muscles, muscle actions, and the names of skeletal muscles.
CHAPTER 25 The Muscular System 25-2 Learning Outcomes (cont.) 25.1 Describe the functions of muscle 25.2 Compare the three types of muscle tissue including their locations and characteristics 25.3 Explain how muscle tissue generates energy 25.4 Describe the structure of a skeletal muscle 25-3 Learning Outcomes (cont.) 25.5 Recognize the terms origin and insertion 25.6 Identify the major skeletal muscles of the body, giving the action of each 25.7 Summarize the changes that occur to the muscular system as a person ages 25.8 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the muscular system 25-4 Introduction • Muscles contract and relax to cause movement • 600 individual muscles in the body You will focus on the differences among three muscle tissue types, the structure of skeletal muscles, muscle actions, and the names of skeletal muscles 25-5 Functions of Muscle • The ability to contract enables muscles to – Allow movement – Provide stability – Control body openings and passages – Warm the body 25-6 Functions of Muscle (cont.) • Skeletal muscles Attach to bones by tendons – Contractions result in movement – • Smooth muscle – contractions move organ contents • Cardiac muscle – contractions pump blood from the heart 25-7 Functions of Muscle (cont.) • Stability – Hold bones tightly together – Small muscles hold vertebrae together • Heat Production – Heat is released when muscles contract – Helps maintain a normal temperature 25-8 Control of Body Openings and Passages • Sphincters – Valve-like structures – Control movement in and out of passages 25-9 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 F Heat is released as muscles relax _ contract 25-10 Types of Muscle Tissue • Muscle cells or myocytes – muscle fibers – Sarcolemma – Sarcoplasm – Sarcoplasmic reticulum – Myofibrils • Long structures in sarcoplasm • Striations – arrangement of filaments Muscle structure 25-42 Leg Muscles • Iliopsoas major • Gluteus maximus • Gluteus medius and minimus • Adductor longus and magnus Skeletal muscles 25-43 Leg Muscles (cont.) • Biceps femoris, semitendinosus, and semimembranosus • Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius • Sartoris Skeletal muscles 25-44 Ankle, Foot, and Toe Muscles • Tibialis anterior • Extensor digitorum longus • Gastrocnemius • Soleus • Flexor digitorum longus Skeletal muscles 25-45 Apply Your Knowledge ANSWER: Matching: C raises the eyebrows F chewing B expand and lower ribs A Gluteus maximus B Intercostals C Frontalis E compress the abdominal wall D Quadriceps group A extends the thigh E Obliques D extends the leg at the knee F Masseter Bravo! 25-46 Aging and the Musculoskeletal System • Speed and strength of muscle contractions decrease • Aging – Decreased dexterity and gripping ability – Decreased mobility • Assistive devices helpful • Routine exercise 25-47 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 dystrophy Inherited disorder characterized by muscle weakness and a loss of muscle tissue Myasthenia gravis Autoimmune condition in which patients experience muscle weakness and loss of muscle tissue 25-48 Diseases and Disorders of the Muscular System (cont.) Disease Description Rhabdomyolysis Kidneys become damaged because of toxins released from muscle cells after serious muscle injuries Tendonitis Painful inflammation of a tendon and the tendon-muscle attachment to a bone Tetanus (lockjaw) Muscle spasms in the jaw, keck and facial muscles; high mortality rate 25-49 Diseases and Disorders of the Muscular System (cont.) Disease Description Torticollis (wryneck) A cervical deformity in which the head bends toward the affected side while the chin rotates to the opposite side Trichinosis An infection caused by parasites ingested by eating undercooked meat 25-50 Apply Your Knowledge What changes occur to the muscular system as a result of aging? ANSWER: Speed and strength of muscle contractions decrease with aging The aging process results in: • Decreased dexterity and gripping ability • Decreased mobility 25-51 Apply Your Knowledge ANSWER: True or False: Fibromyalgia F Botulism is a condition resulting in chronic pain in joints, muscles and tendons T Kidney damage due to toxins released by serious muscle injuries is the condition called rhabdomyolysis T Tetanus is caused by a toxin and causes muscle Torticollis spasms in the jaw, neck, and facial muscles F Lockjaw is caused by spasm or shortening of the sternocleidomastoid muscle 25-52 In Summary 25.1 The functions of muscles include movement, stability, control of body openings and passages, and the production of heat Valve- like muscular structures called sphincters control passage of substances into and out of organs like the stomach and bladder 25.2 The three types of muscle tissue are striated, voluntary skeletal muscle; smooth, involuntary visceral muscle; and specialized striated and involuntary cardiac muscle 25-53 In Summary (cont.) 25.3 There are three ways muscles create energy Creatine phosphate, aerobic respiration, and lactic acid production 25.4 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 25-54 In Summary (cont.) 25.5 The origin of a muscle is the attachment site of the muscle to the less moveable bone during muscle contraction The insertion of a muscle is the attachment site for the muscle to the more moveable bone during muscle contraction 25.6 The major muscles of the head and the upper extremity, major respiratory muscles, abdominal muscles, pectoral girdle muscles and those of the lower extremity are covered in this learning outcome 25-55 In Summary (cont.) 22.7 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 22.8 There are many common diseases and disorders of the muscular system with varied signs, symptoms, and treatments 25-56 End of Chapter 25 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 ... each 25. 7 Summarize the changes that occur to the muscular system as a person ages 25. 8 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the muscular system. .. energy 25. 4 Describe the structure of a skeletal muscle 25- 3 Learning Outcomes (cont.) 25. 5 Recognize the terms origin and insertion 25. 6 Identify the major skeletal muscles of the body, giving the. . .25- 2 Learning Outcomes (cont.) 25. 1 Describe the functions of muscle 25. 2 Compare the three types of muscle tissue including their locations and characteristics 25. 3 Explain how