1. The Muscular System Lesson 1:24
The Muscular System
Lesson 1:

2. Lesson Objectives
Upon completion of this lesson, students should be able to …
Define and spell the terms to learn for this chapter.
Explain the functions of muscle.
Identify and discuss types of muscle tissue.
Describe the muscular system of the body.

3. Lesson Objectives Discuss the energy requirements for muscles.
Explain the structure of skeletal muscles.
List and discuss the three types of skeletal muscle movements.
Identify the major skeletal muscle groups of the body.

4. Muscle Characteristics
Bundles of parallel muscle tissue fibers
Fibers contract; they pull what they are attached to together
May move bones closer to make an opening narrower (as in sphincters)
Muscles contract when a message is sent from the brain via nerves
Point where a nerve contracts a muscle is myoneural junction 4

5. Muscle Characteristics
Human body has more than 400 muscles
Muscles make up more than 50% of body weight 5

6. Functions of the Muscular System
Contractibility
The cause of nearly all movement
Heat production
Helps maintain body temperature
Stability
Holds bones together
Tonicity
Maintains posture 6

7. Functions of the Muscular System7

8. Types of Muscles
Skeletal muscles: means by which the body can move voluntary, striated muscles.
Cardiac muscle: muscle that pumps blood to involuntary muscle.
Smooth muscle: involuntary, nonstriated, continuous, thin layer forming organs and other structures. 8

9. Types of Muscle Tissue 9

10. Critical Thinking Question
What categorizes a muscle tissue as voluntary or involuntary?

11. Types of Muscle Tissue
Can be categorized by either being voluntary or involuntary
Voluntary:
Allows the person to dictate movement
Involuntary:
Acts without conscious direction 11

12. Smooth Muscles Found in tissue in walls of hollow organs
Stomach
Walls of airways
Blood vessels
Responsible for movement of internal organs 12

13. Skeletal Muscles Attach to skeletal bones Allow for voluntary movement
Wrapped in layers of connective tissue
Fascia, tapers at the end to form tendon
Tendon inserts into the periosteum covering to attach muscle to bone
Are stimulated by motor neurons 13

14. Cardiac Muscle Myocardium Occurs in walls of heart
Allows for involuntary pumping action 14

15. Adenosine Triphosphate (ATP)
Type of chemical energy needed for sustained or repeated muscular contractions
Can be produced by either aerobic or anaerobic (without oxygen) means
Aerobic production of ATP
With oxygen, the body uses carbohydrates, fats, and proteins to produce energy
Provides more energy that is available to use and is required for endurance

16. Adenosine Triphosphate (ATP)
Anaerobic (without oxygen) production of ATP
Without oxygen, the body uses stored glucose (aka glycogen) which breaks down into lactic acid to produce energy
Provides for small bursts of energy rather than endurance

17. Adenosine Triphosphate (ATP)
Creatine phosphate production of ATP
Another method of acquiring muscular energy (ATP)
Done without the use of oxygen
Limited to skeletal muscles and is used for small bursts of energy

18. The Effects of Oxygen Debt
Occurs when skeletal muscles are used for more than 1 or 2 minutes
Lack of oxygen intake reduces body’s ability to produce energy aerobically causing anaerobic production
The body can only utilize this energy for about 60 seconds, depending on the individual, before severe fatigue sets in, making it very difficult to recover

19. The Effects of Oxygen Debt
Oxygen “owed” to body is the debt and can only be recovered by increased respiration which allows more oxygen into the bloodstream to reach the muscles

20. The Effects of Muscle Fatigue
Occurs as a result of accumulated lactic acid which decreases the muscle’s ability to contract and results in fatigue, sometimes cramps
Can also occur if blood supply to a muscle is stopped or interrupted

21. Coverings Composed of Connective Tissue
Fascia
Covers entire skeletal muscle
Separates muscles from one another
Epimysium
Thin covering on muscle
Attached to bones by tendons
Aponeurosis
Wide, thin, sheetlike tendon made up of fibrous connective tissue
Attaches muscles to other muscles

22. Coverings Composed of Connective Tissue
Perimysium
Comprised of connective tissue
Divides muscle into sections called fascicles
Endomysium
Surrounds individual muscle cell

23. Classification of Muscle Groups
Antagonist
A muscle that counteracts, or opposes, the action of another muscle
Prime mover, or agonist
A muscle that is the primary actor in a given movement. This is the muscle that produces the movement in muscle contraction.
Synergist
A muscle that acts with another muscle, most often a prime mover, to produce movement

24. Muscles of the Head Muscles for movement of the head:
Sternocleidomastoid – pulls head from to side to side and to the chest
Splenius capitis – rotates head and allows it to bend to the side
Muscles for facial expressions:
Frontalis – raises eyebrows
Orbicularis oris – puckers lips
Orbicularis oculi – closes eyes
Zygomaticus – pulls corners of the mouth up
Platysma – pulls corners of the mouth down

25. Muscles of the Head Muscles of the jaw (chewing):
masseter and temporalis – close the jaw

26. Arm and Forearm Muscle
Pectoralis major – pulls the arm across the chest, also rotates/adducts
Lattissimus dorsi – extension, adduction, and inward rotation of the arm
Deltoid – abduction/extension of the arm at the shoulder
Serratus anterior – pulls the scapula forward
Subscapularis – rotates the arm medially
Infraspinatus – rotates the arm laterally

27. Arm and Forearm Muscle
Biceps brachii – flexes the arm at the elbow, rotates hand laterally
Brachialis – flexes the arm at the elbow
Breachioradialis – flexes the forearm at the elbow

28. Arm and Forearm Muscle Triceps brachii – extends the arm at the elbow
Supinator – rotates the forearm laterally
Pronator teres – rotates the forearm medially

29. Muscles that Move the Wrist, Hand, and Fingers
Flexor carpi radialis and flexor carpi ulnaris – flex/abduct wrist
Palmaris longus – flexes wrist
Flexor digitorum profundus – flexes distal joints of fingers, not thumbs
Extensor carpi radialis longus and brevis – extends wrists, abducts hands
Extensor carpi ulnaris – extends wrists
Extensor digitorum – extends fingers, not thumbs

30. Respiratory Muscles Diaphragm External and internal intercostals
Separates thoracic cavity from abdominal cavity
Its contraction causes the process of inspiration
External and internal intercostals
Contraction expands and lowers ribs during breathing

31. Abdominal Muscles External and internal obliques Transversus abdminis
Compress the wall
Transversus abdminis
Also compresses the wall
Rectus abdominis
Flexes vertebral column, compresses abdominal wall

32. Muscles of the Pectoral Girdle
Trapezius
Raises arms, pulls shoulders downward
Pectoralis minor
Pulls scapula downward

33. Muscles in the Leg Psoas major – flexes thigh
Iliacus – also flexes thigh
Gluteus maximus – extends thigh
Vastus lateralis – extends knee

34. Muscles in the Ankle and Foot
Gastrocnemius
Flexes foot, aids in pushing body forward
Tibialis anterior
Causes dorsiflexion/inversion of the foot
Peroneus
Everts foot, helps bring about plantar flexion
Flexor and extensor digitorum longus
Flexes/extends toes, assists in other movements of the feet

35. Questions? 35