1. Introduction to Medical Careers
Muscular System
Chapter 15

2. Objectives: Students will be able to…
Define 10 terms related to the muscular system
Describe the different types of muscles
Describe the functions of the muscular system
Describe the characteristics of a muscle
Describe the different parts of a muscle
Understand the sliding filament theory
Describe how muscles are named
Identify at least 15 different muscles in the body
Describe the different levers of the body
Describe a muscle strain

3. Vocabulary: Antagonist (p. 187) Atrophy (p. 191) Contraction (p. 186)
Contracture (p. 191)
Dystrophy (p. 191)
Myalgia (p. 191)
Paralysis (p. 192)
Posture (p. 186)
Prime mover (p. 187)
Range of motion (p. 191)
Sarcomere (p. 186)
Skeletal (p. 186)
Stimulus (p. 186)
Tonus (p. 186)
Visceral (p. 186)

4. Facts Over 600 muscles Three types Found in pairs (agonist/antagonist)
Skeletal (striated)
Visceral (smooth)
Cardiac (indistinctly striated)

5. Muscular System Types of Muscles Skeletal Cardiac Smooth or Visceral
A muscle having principally bony attachments.
Attach to bone; allows the body to move
Cardiac
The specialized muscle tissue of the heart; the myocardium
Involuntary control
Smooth or Visceral
Muscle tissue that contracts without conscious control or when stimulated
lines the organs, walls of blood vessels & in digestive system
found in the walls of the internal organs, such as the stomach, intestine, bladder, and blood vessels, excluding the heart.
Examples:
Walls of hollow organs – move food through digestive system
Eyes – changing pupil size
Skin – movement of hair

6. Functions Aid in movement Provide & maintain posture
Open & close body openings
Movement of blood, food & waste
Provide & maintain posture
Protect internal organs
Support
Produce heat

7. Unique Characteristics of Muscle Tissue
Irritability or excitability
Muscle’s ability to respond to a stimulus
Contractability
Ability to shorten forcefully when stimulated
Extensibility
Ability to stretch and lengthen
Elasticity
Ability to recoil to its resting length when relaxed

8. Skeletal Muscle Makes up more than 40% of a person’s body weight
Looks striated, or banded, under the microscope
Skeletal muscles have three parts:
Origin is one end of the muscle, attached to the less movable part of the bone
Insertion is the other end of the muscle, attached to the more movable part of the bone
The action is the movement that the muscle produces

9. Muscle Contraction
Muscles contract by what we call the sliding filament theory
Muscle cells use a form of glucose (glycogen) to produce energy used in conversion of ADP to ATP
Stimulus to contract a muscle occurs, ATP cycle provides energy to combine proteins actin & myosin into actomyosin
Calcium is necessary for the reaction to occur
Lactic acid is produced from the metabolism of glycogen is converted to water & CO2 with O2

11. Sliding Filament Theory

12. Types of Muscle Contraction
Isotonic: shortening that produces movement
Isometric: does not cause muscle shortening or movement
Spasms: involuntary, sudden and prolonged contraction
Convulsions: contractions of groups of muscles in an abnormal manner

13. Skeletal muscles Increase in size with exercise (hypertrophy)
Decrease without it (atrophy)
Attach to bones via tendons

14. Skeletal Muscles Cont. Fascia
Connective tissue that divides muscles from each other.
Connects skin to underlying tissues.

15. Skeletal Muscles Cont. Muscle Belly Thickest part of the muscle
Where action occurs

16. Named according to… Relation to bones Tibialis anterior Shape Deltoid
Action/Function
Wrist flexors
Abductor
Adductor
Size
Gluteus Maximus
Orientation
Rectus (straight)
Location
Pectoralis (chest)
Origin and insertion
Sternocleidomastoid (sternum & clavicle)

17. Muscles to know Deltoid 68 Biceps 65 Pectoralis major 67
Wrist flexors
Rectus abdominus 22
Diaphragm

18. Quadriceps group
Tibialis anterior 44

19. Triceps 68
Trapezius 13
Latissimus dorsi 67
Wrist extensors 60-62

20. Gluteus maximus 57
Hamstring Group
Soleus
Gastrocnemius 55

21. Muscular System - Levers
Muscle pulling on a bone works like a lever.
Skeletal muscles produce movement by contracting and exerting force on tendons, which in turn pull on bones.
When producing a body movement, the bones act as levers and the joints act as fulcrums.

23. Types of Levers First-class:
the fulcrum is between the effort and resistance.
There are only a few examples of this type in the human body.
Neck, elbow
examples: crowbar, seesaw, scissors

24. Types of Levers Second-class:
the resistance is between the fulcrum and the effort.
operates on the same principle as a wheelbarrow

25. Types of Levers Third-class:
the effort is between the fulcrum and the resistance.
Use is to gain speed in movement of the weight
Examples:
Shoveling

27. Muscle Strain “Pulled muscle”
Separation or overstretch of muscle fibers
S/S: pain, stiffness, bruising, redness
Care: RICE, crutches, surgery