1. Chapter 7
Muscular System

2. 3 Functions of Muscular System
Body heat to maintain body temperature
Body movement
Body form and shape to maintain posture

3. Types of Muscles Skeletal muscle Under voluntary (conscious) control
Striped or striated
Attached to bones
Provide limb movement
Contract quickly
Tire easily
Most of focus of this chapter!!

4. Types of Muscles 2. Smooth muscle Also called visceral muscle
Involuntary control
Controlled by autonomic nervous system
No striations
Not attached to bones
Act slowly
Peristalsis
Childbirth

5. Types of Muscles Cardiac muscle Found only in the heart Involuntary
Requires continuous supply of 02

6. Types of Muscle 4. Sphincter muscle
Not considered on of the major muscle types
Circular muscles
Esophagus
Stomach
Anus
Urethra

7. Characteristics of Muscles
Contractibility
Exclusive quality of muscle tissue
Reduces distance between parts

8. Characteristics of Muscles
Excitability or irritability
Ability to respond to a stimulus
and create an impulse

9. Characteristics of Muscles
Extensibility
Ability to be stretched

10. Characteristics of Muscles
Elasticity
Returns to original length
when relaxing

11. Muscle Attachments and Functions
Over 650 muscles in the body
Muscles must be attached to bones for leverage
Muscles only pull, never push
Attached to bone by tendons

12. Muscle Attachments and Functions
Muscles are attached at both ends
Attachments may be to bones, cartilage, ligaments, tendons, skin or to each other
Origin-least movable
Insertion-where
movement occurs

13. Muscle Functions Prime mover-moves in one direction
Antagonist-moves in opposite direction
Synergists-Help steady or stabilize joint activity

14. Sources of Energy and Heat
ATP (adenosine triphosphate)
Need oxygen, glucose, and other material to make
By-product is lactic acid
When muscle is stimulated releases ATP this
gives us heat

15. Contraction of Skeletal Muscle
Skeletal muscles must be
stimulated by nerve
impulses to contact
Excitability or irritability

16. Muscle Fatigue Caused by accumulation of lactic acid
Excess lactic acid causes fatigue and cramps
Need to repay oxygen debt

17. Muscle Tone Muscle tone Proper nutrition and regular exercise
Isotonic-contract and shorten
Isometric-tense the muscle
Atrophy and hypertrophy

18. Naming of Skeletal Muscles
Location
Size
Direction
Number of origins
Location of origin and insertion
Not all muscles are named by above method

19. Muscles 656 muscles 327 antagonistic muscles and two unpaired muscles
Orbicularis oris
Diaphragm

20. Muscles of the Head and Neck
Muscles of Facial Expression
1. Frontalis: raises the eyebrows and wrinkles the forehead
Orbicularis oris: used to close the mouth, form words,
and pucker the lips
3. Orbicularis oculi: used to wink, blink, squint
4. Buccinator: used to compress the cheek when whistling,
sucking, or blowing out air
5. Zygomaticus: used to raise the corner of mout when smiling

21. Muscles of the head & neck

22. Muscles of the head & neck
Muscles responsible for chewing movements
(mastication)
a. Temporalis: closes jaw
b. Masseter: closes jaw

23. Muscles of the head & neck
Sternocleidomastoid: flexes and
rotates the head
Trapezius: extends head, adducts,
elevates, and rotates scapula
(shrugging the shoulders)

24. Muscles of the trunk Erector spinae: extends the
vertebral column to maintain
erect posture
2. Latissimus dorsi: adducts
& rotates arm, lowers the
shoulder.
Important for swimming & rowing motions
The widest & strongest muscle in the back

25. Thoracic wall muscles Involved primarily in the process of breathing.
External intercostal muscles: inspiration
Internal intercostal muscles: forced expiration

26. Forms a partition between thorax and abdomen When diaphragm contracts: increases the volume of thoracic cavity and results in inspiration When diaphragm relaxes: decreases volume of thoracic cavity and forces air out during expiration
Diaphragm

27. Abdominal wall muscles
1. External oblique: compresses abdomen
2. Internal oblique: compresses abdomen
3. Transversus abdominis: compresses abdomen
Rectus abdominis: flexes vertebral column and
compresses abdomen (the 6-pack)

28. Pelvic floor muscles
Pelvic diaphragm: forms the floor of the pelvic cavity
Formed by the two levator ani muscles
Supports and maintains position of pelvic viscera
Urogenital diaphragm: fills the space within the pubic arch
Supports pelvic viscera and assists in function of genitalia

29. Upper extremity muscles
Serratus anterior: pulls
shoulder downward and forward
as in pushing something
2. Pectoralis major: adducts
and flexes arm across the chest

30. Upper extremity muscles
3. Deltoid: abducts the arm to a horizontal position
Common site for administering intramuscular (IM) injections
4. Rotator cuff
Group of four muscles that attach humerus to scapula
Form cap or cuff over humerus
Rotates arm

31. UPPER ARM MUSCLES Triceps brachii: extends the forearm
Biceps brachii: flexes and
supinates forearm

32. Muscles of the lower extremity
1. Gluteus maximus
Largest gluteal muscle
Extends thigh
2. Gluteus medius
Common site for
intramuscular injections
Abducts and rotates thigh
3. Gluteus minimus
Smallest and deepest

33. Muscles that move the leg
Quadriceps femoris: extends leg at the knee
Vastus lateralis
Vastus intermedius
Vastus medialis
Rectus femoris

34. Muscles that move the leg
Sartorius
Longest muscle in the body
Flexes thigh and flexes and
rotates leg
Hamstrings: flexes leg and extends thigh
a. Biceps femoris
b. Semimembranosus
c. Semitendinosus

35. Muscles that move the ankle and foot
1. Tibialis anterior: dorsiflexes foot
2. Peroneus: plantar flexes and everts foot
3. Gastrocnemius and soleus: plantar flexes foot
Have a common tendon: calcaneal tendon (Achilles tendon)
Allow you to stand on tiptoe

36. Skeletal Muscles