1. Medical Assisting Chapter 26
PowerPoint® to accompany
Medical Assisting Chapter 26
Second Edition
Ramutkowski  Booth  Pugh  Thompson  Whicker
Chapter 26
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2. The Muscular System Objectives 26-1 List the functions of muscle.
26-2 Explain how muscle tissue generates energy.
List the three types of muscle tissue and describe
the locations and characteristics of each.
Describe how smooth muscle produces peristalsis.
Describe the structure of a skeletal muscle.

3. The Muscular System Objectives (cont.)
26-7 List and define the various types of body
movements produced by skeletal muscles.
26-8 Define the terms origin and insertion.
26-9 List the major skeletal muscles of the body and give the action of each.
26-10 Describe various disorders and diseases of the muscular system.

4. Introduction Bones and joints do not themselves produce movement.
The human body has more than 600 individual muscles
By alternating between contraction and relaxation, muscles cause bones and supported structures to move.
You will focus on the differences among three muscle tissue types, the structure of skeletal muscles, muscle actions, and the names of skeletal muscles.

5. Functions of Muscle Click for Larger View
Muscle has the ability to contract, and this contraction allows muscles to perform various functions.
Functions:
Movement
Stability
Control of body openings and passages
Heat production
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6. Skeletal Muscle

7. Functions of Muscle Movement:
Skeletal muscles are attached to bones which allow you to walk or wave your hand.
Smooth muscle is found on organ walls such as the intestine. Contractions produces movement of food through the intestine.
Cardiac muscle produces the pumping of the blood in the heart.

8. Functions of Muscle Stability:
Muscles hold your bones together to stabilize joints.
Small muscles hold your vertebrae together to stabilize your spinal column.

9. Functions of Muscle Controlling of openings and passages:
Muscles form valve like structures called sphincters
Sphincters control movement of substances in and out of passages.
A urethral sphincter prevents or allows urination

10. Functions of Muscle Heat production:
When muscles contract heat is released
This helps the body maintain a normal temperature
Moving your body can make you warmer if you are cold.

11. 3 Types of Muscle Tissue Muscle Group Major Location Major Function
Mode of Control
Skeletal Muscle
Attached to bones and skin of the face
Produces body movements and facial expressions
Voluntary
Smooth Muscle
Walls of hollow organs, blood vessels, and iris
Moves contents through organs; vasoconstriction
Involuntary
Cardiac Muscle
Wall of the heart
Pumps blood through heart

12. Peristalsis
Rhythmic contraction that pushes substances through tubes of the body.
Muscle fibers in visceral smooth muscle respond to neurotransmitters but they also stimulate each other to contract.
The muscle fibers tend to contract and relax together.
This type of muscle produces an action called peristalsis.

13. Production of Energy for Muscle
ATP (adenosine triphosphate), a type of chemical energy, is needed for sustained or repeated muscle contractions.
Muscle cells must have three ways to store or make this substance:
Creatine phosphate
Aerobic respiration of glucose
Lactic acid production

14. Oxygen Debt
Oxygen debt develops when skeletal muscles are used strenuously for a minute or two and:
supplies in the muscle are low
the aerobic respiration of glucose can no longer be used to produce ATP.
This process accounts for why you still burn energy after you exercise. 

15. Muscle Fatigue
Condition in which a muscle has lost its ability to contract
Develops due to an accumulation of lactic acid
Occurs when the blood supply to a muscle is interrupted
A motor neuron loses its ability to release acetylcholine onto muscle fibers
Cramps or painful involuntary contractions of muscles, can accompany muscle fatigue

16. Apply Your Knowledge
What causes bones to move?

17. Apply Your Knowledge -Answer
What causes bones to move?
Bones move by alternating between contraction and relaxation; muscles cause bones and supported structures to move.

18. Structure of Skeletal Muscles
Skeletal muscles are the major organs that make up the muscular system
Consists of connective tissues, skeletal muscle tissue, blood vessels, and nerves
When body movements are produced, not just one muscle is involved, but a group of muscles contract

19. Connective Tissue Coverings
Fascia - covers entire skeletal muscles and separates them from each other. 
Tendon - a tough, cord-like structure made of fibrous connective tissue that connects muscles to bones.
Aponeurosis - a tough, sheet-like structure made of fibrous connective tissue that attaches muscles to other muscles.
Epimysium - a thin covering that is just deep (underneath) to the fascia of a muscle that surrounds the entire muscle.
Perimysium - connective tissue divides a muscle into sections called fascicles.
Endomysium - covering of connective tissue surrounds individual muscle cells.

20. Attachments and Actions of Skeletal Muscles
Actions of skeletal muscles depend largely on what the skeletal muscles are attached
Insertion - an attachment site that moves when a muscle contracts.
Origin - an attachment site that does not move when a muscle contracts

21. Body 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 down
Abduction – Moving a body part away from its position in the anatomical position
Adduction – Moving a body part toward its position in the anatomical position

22. Body Movements (cont.)
Circumduction- Moving a body part in a circle; for example, moving your arm in a circular motion
Pronation – Turning the palm of the hand down
Supination – Turning the palm of the hand up
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 anteriorly

23. 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

24. 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?

25. Apply Your Knowledge - Answer
The doctor has asked you to abduct the patient’s leg, so he can see the patients wound. In order to position the patient correctly what will you have to do?
Moving the patient’s leg away from its position in the anatomical position.

26. Major Skeletal Muscles
The muscle name indicates the location, size, action, shape, or number of attachments of the muscle.
As you study muscles, you will find it easier to remember them if you think about what the name describes.

27. Muscles of the Head
Sternocleidomastoid - pulls the head to one side and also pulls the head to the chest
Splenius capitis - rotates the head and allows it to bend to the side
Frontalis - raises the eyebrows
Orbicularis oris - allows the lips to pucker
Orbicularis oculi - allows the eyes to close
Zygomaticus - pulls the corners of the mouth up
Platysma - pulls the corners of the mouth down
Masseter and temporalis - close the jaw

28. Arm Muscles
Pectoralis major - pulls the arm across the chest; it also rotates and adducts the arms
Latissimus dorsi - acts to extend, adduct, and rotate the arm inwardly
Deltoid - acts to abduct and extend the arm at the shoulder
Subscapularis - rotates the arm medially
Infraspinatus - rotates the arm laterally

29. Forearm Muscles
Biceps brachii - flexes the arm at the elbow and rotates the hand laterally
Brachialis - flexes the arm at the elbow
Brachioradialis - flexes the forearm at the elbow
Triceps brachii - extends the arm at the elbow
Supinator - rotates the forearm laterally (supination)
Pronator teres - rotates the forearm medially (pronation)

30. Muscles of the Wrist, Hand and Fingers
Flexor carpi radialis and flexor carpi ulnaris - act to flex and abduct the wrist.
Palmaris longus - acts to flex the wrist.
Flexor digitorum profundus - acts to flex the distal joints of the fingers but not the thumb.
Extensor carpi radialis longus and brevis - act to extend the wrist and abduct the hand.
Extensor carpi ulnaris - acts to extend the wrist.
Extensor digitorum - acts to extend the fingers but not the thumb.

31. Respiratory Muscles
Diaphragm - separates the thoracic cavity from the abdominal cavity; its contraction causes inspiration.
External and internal intercostals - muscles expand and lower the ribs during breathing.

32. Apply Your Knowledge
A patient has arrived in the office complaining of pain when she raises her arm. What muscle would be involved in this action?

33. Apply Your Knowledge -Answer
A patient has arrived in the office complaining of pain when she raises her arm. What muscle would be involved in this action?
The deltoid muscle acts to abduct and extend the arm at the shoulder.

34. Abdominal Muscles
External and internal obliques - compress the abdominal wall.
Transverse abdominis - also compresses the abdominal wall.
Rectus abdominis - acts to flex the vertebral column and compress the abdominal wall.
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35. Abdominal Muscles (cont.)

36. Muscles of the Pectoral Girdle
Trapezius - muscle raises the arms and pulls the shoulders downward.
Pectoralis minor - muscle pulls the scapula downward and raises the ribs.

37. Leg Muscles Psoas major & iliacus - flexes the thigh.
Gluteus maximus - extends the thigh.
Gluteus medius and minimus - abduct the thighs and rotate them medially.
Adductor longus and magnus - muscles adduct the thighs and rotate them laterally.
Biceps femoris, semitendinosus, and semimembranosus - three muscles are known as the hamstring group. They act to flex the leg at the knee and extend the leg at the thigh.

38. Leg Muscles (cont.)
Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius - act to extend the leg at the knee.
Sartorius - flexes the leg at the knee and thigh and abducts the thigh, rotating the thigh laterally but rotating the lower leg medially.

39. Muscles of the Ankle, Foot, and Toes
Tibialis anterior - acts to invert the foot and point the foot up (dorsiflexion).
Extensor digitorum longus - acts to extend the toes and point the foot up.
Gastrocnemius - acts to flex the foot and flex the leg at the knee.
Soleus - also acts to flex the foot.
Flexor digitorum longus - acts to flex the foot and toes.

40. 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?

41. Apply Your Knowledge -Answer
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?
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.

42. Muscle Strains and Sprains
Warm Up – Warming up muscles for just a few minutes before an intense activity raises muscle temperature.
Stretch – Stretching improves muscle performance and should always be done after the warm up or after exercising.
Cool Down – Slowing down the exercise before completely stopping prevents dizziness and fainting.

43. Diseases and Disorders of the Muscular System
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 - patients experience muscle weakness

44. Diseases and Disorders of the Muscular System
Rhabdomyolysis - a condition in which the kidneys have been damaged related to serious muscle injuries
Tetanus - commonly called lockjaw
Trichinosis - an infection caused by parasites (worms)

45. Apply Your Knowledge
The doctor has told your patient that his son has muscular dystrophy disorder. What is muscular dystrophy?

46. Apply Your Knowledge -Answer
The doctor has told your patient that his son has muscular dystrophy disorder. What is Muscular dystrophy?
Muscular dystrophy is an inherited disorder characterized by muscle weakness and a loss of muscle tissue.

47. Medical Assistant Summary
Skeletal muscle works in conjunction with the skeletal system to produce movement.
You must understand the muscular system in order to give muscular injections, prepare patients for massage therapy, demonstrate ambulatory techniques, and assist in the care of sprains and strains.

48. End of Chapter
End of Chapter