1. The Muscular System
Chapters 9 & 10

2. The Muscular System

4. Muscular System Functions
The muscular system moves the body.
The body has over 600 muscles.
Some muscles are called voluntary, that means that you choose to use them. How active you are depends on how much use they get!
Some muscles are called involuntary because they work without you thinking about them. These are muscles like the heart and digestive system.

5. Did you know that ?
more than 50% of body weight is muscle !
And muscle is made up of proteins and water

6. Info About Muscles Only body tissue able to contract
create movement by flexing and extending joints
Body energy converters (many muscle cells contain many mitochondria)

7. Muscular System Muscles are responsible for all types of body movement
3 basic muscle types are found in the body
Skeletal muscle
Cardiac muscle
Smooth muscle

8. Characteristics of Muscles
Muscle cells are elongated (muscle cell = muscle fiber)
Contraction of muscles is due to the movement of microfilaments
All muscles share some terminology
Prefix myo refers to muscle
Prefix mys refers to muscle
Prefix sarco refers to flesh

9. Comparison of Types of Muscle

10. Comparison of Types of Muscle

11. Types of Muscle, cont.

12. Three types of muscle
Skeletal
Cardiac
Smooth

13. Skeletal Muscle Characteristics
Most attach to bones by tendon
Cells are multinucleate
Striated—have visible binding
Voluntary
Cells surrounded & bundled by connective tissue

14. Skeletal Muscle Most are attached by tendons to bones
Cells have more than one nucleus (multinucleated)
Striated- have stripes, banding
Voluntary- subject to conscious control
Tendons are mostly made of collagen fibers
Found in the limbs
Produce movement, maintain posture, generate heat, stabilize joints

15. Skeletal Muscle Characteristics
Most are attached by tendons to bones

16. Smooth Muscle Characteristics
Has no striations
Spindle-shaped cells
Single Nucleus
Involuntary—no conscious control
Found mainly in the walls of hollow organs

17. Characteristics of Cardiac Muscle
Has striations
Usually has a single nucleus
Joined to another cardiac muscle cell
Involuntary
Found only in the heart

18. Skeletal Muscle Functions of Skeletal Muscle Produce Movement
Maintain posture
Stabilize joints
Generate Heat
Sites of Muscle Attachment
Bones
Cartilage
Connective tissue coverings
Muscle Fibers blend into a connective tissue attachment
Tendon—cordlike structure
Aponeurosis—sheet-like structure
Properties of Muscle
Irritability – ability to receive and respond to a stimulus
Contractibility – ability to shorten when an adequate stimulus is received
Extensibility – ability to lengthen when an adequate stimulus is received
Elasticity – ability to return to normal shape

19. Anatomy of a Muscle Cell

20. Microscopic Anatomy of Skeletal Muscle
Cells are multinucleate
Nuclei are just beneath the sarcolemma
Sarcolemma – specialized plasma membrane
Sarcoplasmic reticulum – specialized smooth endoplasmic reticulum

21. Microscopic Anatomy of Skeletal Muscle
Sarcomere
Contractile unit of a muscle fiber
Myofibril
Bundles of myofilaments
Myofibrils are aligned to give distinct bands
I band =
light band
A band = dark band

22. Microscopic Anatomy of Skeletal Muscle
Sarcomere
Contractile unit of a muscle fiber

23. Nerve Stimulus to Muscles
Skeletal muscles must be stimulated by a nerve to contract
Motor unit
One neuron
Muscle cells stimulated by that neuron
Release of neurotransmitter called acetylcholine (ACh)

24. Sliding Filament Theory
Sarcomere Shortening Animation

25. Nerve Stimulus to Muscles
Muscle twitch- a single, brief, jerky contraction that occurs as a result of certain nervous conditions (“eye jump”)

26. Muscle Tone and Fatigue
If we exercise our muscles strenuously for a long time, muscle fatigue occurs. Muscle fatigue is when the muscle is unable to contract even though it is being stimulated.
Muscle fatigue is believed to be related to oxygen debt, therefore it leads to more rapid breathing.
Muscle Tone is a state of partially being contracted at all times.

27. ** Violent muscle contractions require much oxygen. **
If oxygen is not available muscle fatigue will set in.
"Muscle fatigue"-- results from oxygen debt -- lactic acid accumulates in skeletal muscles
rest restores the oxygen balance
“Lactic acidosis” – it is more or less a muscle cramp for the entire body or a certain muscle.

28. Naming Skeletal Muscles

29. Origin vs. Insertion
The muscles origin is attached to the immovable bone.
At its other end, the insertion is attached to the movable bone. Insertion moves toward the origin.
Ex: When you flex your bicep, the muscle’s insertion moves toward the origin. So the origin of your bicep is near your shoulder and the insertion is on the top of your forearm.

30. Muscle Attachments Insertion Origin
Muscles attach in at least two places in the body. *The origin is the attachment that moves the least. *The insertion is the attachment that moves the most. This diagram illustrates the origin and insertion of one of the neck muscles. Note the origin is on the clavicle and sternum. The insertion is on the skull. When the muscle contracts it will shorten the distance between the origin and insertion. The head will move when this muscle contracts. Remember the insertion is the end of the muscle that moves the most. Since the head moves the attachment on the head is called the insertion. The origin is generally on a larger body part will move the least. The chest does not move when this muscle contract. The bones in the chest are therefore the origin.
Origin

31. Direction of Muscle Fibers
Relative to the Midline
RECTUS = parallel to the midline
Rectus Abdominus
TRANSVERSE = perpendicular to midline
Transverse Abdominus
OBLIQUE = diagonal to midline
External Oblique

32. Location Structure near which muscle is found
FRONTALIS = near FRONTAL bone
OCCIPITALIS = near OCCIPITAL bone

33. Size Relative Size of Muscle MAXIMUS = largest MEDIUS = middle
Gluteus Maximus
MEDIUS = middle
Gluteus Medius
MINIMUS = smallest
Gluteus Minimus
LONGUS = longest
Fibularis Longus
BREVIS = short
Fibularis Brevis
TERTIUS = shortest
Fibularis Tertius

34. Number of Origins Number of tendons of origin BICEPS = Two
Biceps Brachii
Biceps Femoris
TRICEPS = Three
Triceps Brachii
QUADRICEPS = Four
Quadriceps Femoris

35. Shapes of Muscles Triangular- shoulder, neck Spindle- arms, legs
Flat- diaphragm, forehead
Circular- mouth, anus

36. Shape Relative Shape of the Muscle DELTOID = triangular shape Δ
TRAPEZIUS = trapezoid shape  SERRATUS = saw-toothed ♒
RHOMBOIDEUS = rhomboid shape 
TERES = round ○

37. Origin & Insertion Origin – attachment to an immoveable bone
Insertion – attachment to a movable bone
ILIO COSTALIS= attaches to the ilium & ribs (costal = ribs)

38. Types of Movement Allowed By Muscles
Gliding Movements (moving hand)
Angular Movements
Flexion
Extension
Dorsiflexion and Plantar Flexion of the foot
Abduction
Adduction
Circumduction (arms in circle)

39. Types of Movement Allowed By Muscles
Rotation
Special Movements
Supination and Pronation
Inversion and Eversion
Elevation and Depression
Opposition

40. Types of Musculo-Skeletal Movement
Flexion
You will need to know the action or movement performed for each of the muscles we study. The first type of movement is called flexion. Note the lower leg is being flexed in this diagram. During flexion the angle of joint is decreased. As the knee is flexed, the angle between the lower leg and the thigh is decreased. Flexion of the upper arm is also illustrated in this diagram. Here the angle between the arm and the frontal plane is decreased.

41. Extension
Extension is the opposite of flexion. In extension the angle of a joint is increased. Extension of the lower leg causes an increased angle between the lower leg and the thigh.

42. Hyperextension
Flexion and extension also apply to the neck. When a joint is extended past the anatomical position the movement is called hyperextension.

43. Abduction, Adduction & Circumduction
Abduction refers to moving away from the median plane of the body. Adduction is the opposite movement to abduction. It is moving toward the medial plane. Circumduction refers to inscribing a circle while moving a limb.

44. Rotation
Rotation is turning a bone on its own axis. Moving the head back and forth to indicate “no” is an example of rotation. Note the difference between medial and lateral rotation. In lateral rotation the limb is rotated the lateral side of the body. Medial rotation rotates the limb toward the medial side of the body.

45. More Types of Movement……
Inversion- turn sole of foot medially
Eversion- turn sole of foot laterally
Pronation- palm facing down
Supination- palm facing up
Opposition- thumb touches tips of fingers on the same hand

46. Action NAME ACTION EXAMPLE FLEXOR EXTENSOR ABDUCTOR ADDUCTOR LEVATOR
Decrease angle at a joint
Flexor Carpi Radialis
EXTENSOR
Increase angle at a joint
Extensor Carpi Ulnaris
ABDUCTOR
Move bone away from midline
Abductor Pollicis Longus
ADDUCTOR
Move bone toward midline
Adductor Longus
LEVATOR
Produce upward movement
Levator Scapulae
DEPRESSOR
Produce downward movement
Depressor Labii Inferioris
SUPINATOR
Turn palm upward/anterior
Supinator
PRONATOR
Turn palm downward/posterior
Pronator Teres

47. Types of Muscle--Actions
Prime mover (Agonist) – muscle with the major responsibility for a certain movement
Antagonist – muscle that opposes or reverses a prime mover
Synergist – muscle that aids a prime mover in a movement and helps prevent rotation
Fixator – stabilizes the origin of a prime mover

48. Sternocleidomastoideus
Flexes and Rotates Head
The first muscle we will learn is the sternocleidomastoideus. It is sometime called the sternocleitomastoid. It is the same neck muscle shown on the previous slide. * This muscle has two origins. The first origin is on the sternum manubrium. The second origin is on the clavicle. *The insertion is on the mastoid process of the skull. *Contraction of both sternocleidomastoideus muscles will flex the head. If just on of the muscles contracts, the head will rotate.

49. Masseter Elevate Mandible
The masseter is one of major chewing muscles. *The origin of the masseter is on the zygomatic arch. *The insertion is on the mandible. *Contraction of the masseter will elevate the jaw.

50. Elevate & Retract Mandible
Temporalis
Elevate & Retract Mandible
The temporalis is another chewing muscle. Note how it attaches on the side of skull. *It also elevates the mandible. Also note I did not give the origin and insertion of this muscle. You will only need to know the origin and insertion of a few of the muscles in this unit.

51. Extend Head, Adduct, Elevate or Depress Scapula
Trapezius
Extend Head, Adduct, Elevate or Depress Scapula
The trapezius is a large muscle in the upper back. It attaches to the skull, shoulder and vertebrae of the back. *When this muscle contracts it will cause the head to extend. It will also move the scapula. The direction the scapula moves depends on which part of the trapezius contracts. The trapezius may adduct elevate or depress the scapula.

52. Extend, Adduct & Rotate Arm Medially
Latissimus Dorsi
Extend, Adduct & Rotate Arm Medially
The latissimus dorsi is a large muscle in the back. It is often referred to as a lat. *It has origins on the vertebrae, ilium ribs and scapula. *The insertion is on the humerus. When it contracts it moves the humerus. *It can extend, adduct and rotate the arm medially. This is the main muscle used in movement such as pounding a nail with a hammer.

53. Abduct, Flex & Extend Arm
Deltoid
Abduct, Flex & Extend Arm
The deltoid covers the shoulder and has the shape of a delta. *It has origins on the scapula and clavicle. *The deltoid inserts on the deltoid tuberosity of the humerus. *Contraction of the deltoid will adduct the arm. If only the anterior fibers of the muscle contract it will flex the arm. Contraction of the posterior fibers will extend the arm.

54. Flexes, adducts & rotates arm medially
Pectoralis Major
Flexes, adducts & rotates arm medially
The pectoralis major is a large muscle in the pectoral region of the body. *It has origins on the clavicle and sternum. *The insertion is on the greater tubercle of the humerus. *Contraction of the pectoralis major will flex the arm. It will also adduct and rotate the arm medially. The pectoralis major is used in movements such a climbing, throwing and doing pushups.

55. Biceps Brachii Flexes Elbow Joint
The biceps brachii is located on the anterior side of the upper arm. It is often just called the biceps. There is a biceps femoris in the leg we will study shortly. *The biceps has two origins. One origin is on the corocoid process and the other on the Glenoid cavity of the scapula. The “bi” in biceps refers to the two origins. *It inserts on the radial tuberosity. *Contraction of the biceps will cause flexing at the elbow joint.

56. Triceps Brachii Extend Elbow Joint
The triceps is on the back of the upper arm. *It has three origins. Two origins are on the back of the humerus and one on the scapula. *The triceps inserts on the olecranon. *Movement of the triceps will extend the elbow joint.

57. Rectus Abdominus Flexes Abdomen
Rectus abdominus is a long muscle in the abdomen. *The muscle originates on the pubis. *It inserts on the xiphoid process of the sternum and also on cartilage of the ribs. *When rectus abdominus contracts it will flex the abdomen.

58. External Oblique Compress Abdomen
Another muscle in the abdomen is the external oblique. It has muscle fibers that run in an oblique direction across the abdomen. *Contraction of the external oblique will compress the abdomen.

59. External Intercostals
Elevate ribs
There are two groups of muscles that run between the ribs. The first are the external intercostals. *They will elevate the ribs.

60. Internal Intercostals
Depress ribs
The internal intercostals are also located between the ribs. *They will depress the ribs.

61. Diaphragm Inspiration
This is an inferior view of the diaphragm. This muscle separates the abdominal cavity from the thoracic cavity. *When it contracts it will cause inspiration.

62. Forearm Muscles Flexor carpi—Flexes wrist Extensor carpi—Extends wrist
Flexor digitorum—Flexes fingers
Extensor digitorum—Extends fingers
Pronator—Pronates
Supinator—Supinates
There are several muscles in the forearm that have important movements. *The flexor carpi are used to flex the wrist. *Extensor carpi extend the wrist. *Flexor digitorum flexes the fingers. *Extensor digitorum extends the fingers. *The pronator pronates. *A supinator muscle will supinate.

63. Extends & Rotates Thigh Laterally
Gluteus Maximus
Extends & Rotates Thigh Laterally
The large muscle on the posterior side of the body at the top of each leg is the gluteus maximus. *The gluteus maximus originates on the ilium, sacrum and coccyx. *It inserts on the gluteal tuberosity of the femur. *This muscle will extend and rotate the thigh laterally.

64. Flexes Thigh, Extends Lower Leg
Rectus Femoris
Flexes Thigh, Extends Lower Leg
Rectus femoris is located on the anterior side of the thigh. *It originates on the ilium. *The insertion is on the patella and the tibial tuberosity. *When rectus femoris contracts it will flex the thigh and extend the lower leg.

65. Adducts and Flexes Thigh
Gracilis
Adducts and Flexes Thigh
The gracilis is on the medial side of the thigh. *It adducts and flexes the thigh.

66. Flexes Thigh, & Rotates Thigh Laterally
Sartorius
Flexes Thigh, & Rotates Thigh Laterally
Sartorius is a long, strap like muscle. *It originates on the anterior superior iliac spine of the ilium. *The insertion is on the medial side of the tibia. * Contraction of the sartorius flexes the thigh and rotates the thigh laterally. This is the muscle used when crossing the legs to sit on the floor.

67. Extends Thigh & Flexes Lower Leg
Biceps Femoris
Extends Thigh & Flexes Lower Leg
Biceps femoris is one of the hamstring muscles. *The origin is on the ischial tuberosity. *Biceps femoris inserts on the tibia and fibula. This muscle extends the thigh and flexes the lower leg.

68. Plantar Flexes Foot & Flex Lower Leg
Gastrocnemius
Plantar Flexes Foot & Flex Lower Leg
Gastrocnemius is commonly called the calf muscle. *It originates on the distal end of the femur. *The insertion is on the calcaneus bone of the foot. *It will cause plantar flexion of the foot and also flex the lower leg.

69. Dorsiflexes and Inverts Foot
Tibialis Anterior
Dorsiflexes and Inverts Foot
Tibialis anterior is located on the anterior side of the tibia. *It will dorsiflex and invert the foot.

70. Head & Neck Muscles

71. Head & Neck Muscles Frontalis: elevate eyebrows 
Orbicularis Oculi: close eyelid 
Zygomaticus: draw angle of lip upward 
Buccinator: draws cheeks against teeth
Orbicularis Oris: closes mouth 
Platysma: draws lower lip down & back 
Cranial Aponeurosis: connects frontalis to occipitalis
Temporalis: elevates mandible
Occipitalis: draws scalp back
Masseter: elevates mandible
Sternocleidomastoid:
Flexes head
Draws head toward shoulder

72. Muscles of Mastication
Masseter: elevates mandible
Temporalis: elevates mandible
Medial pterygoid: elevates mandible
Lateral pterygoid: depresses mandible

73. Key Muscles of Facial Expression
Smiling Muscles
Orbicularis Oculi
Nasalis
Levator Labii Superioris
Levator Anguli Superioris
Zygomaticus
Risorius
Frowning Muscles
Frontalis
Orbicularis Oris
Depressor Anguli Oris
Depressor Labii Inferioris
Mentalis
Platysma

74. Anterior Muscles of Shoulder
Deltoid
Flexion/Extension
Abduction/Adduction
Rotation
Pectoralis Major
Adduction
Flexion
Extension
Biceps Brachii—Flexion

75. Posterior Muscles of Shoulder
Latissimus Dorsi
Adduction
Extension
Internal Rotation
Triceps Brachii

76. Muscles of the Elbow/Forearm
Triceps Brachii—Extension
Bicep Brachii—
Flexion
Supination
Brachialis—Flexion
Brachioradialis—
Pronation

77. Muscles of the Wrist & Hand
Flexor Carpi Ulnaris
Flexor Carpi Radialis
Flexor Digitorum
Extensor Carpi Ulnaris
Extensor Carpi Radialis
Extensor Digitorum
Anterior (Palmar) View
Posterior (Dorsal) View

78. Muscles Of Hip: Anterior Muscles

79. Muscles of Hip: Gluteal Muscles
Gluteus Maximus—Extension
Gluteus Medius—Abduction
Gluteus Minimus—Abduction
** Gluteus Minimus is under the Gluteus Medius

80. Muscles of Anterior Thigh
“Quadriceps”
Rectus Femoris—
Hip flexion
Knee extension
Vastus Lateralis—knee extension
Vastus Medialis—knee extension
Vastus Intermedius—knee extension
Sartorius—
Hip & Knee Flexion
Lateral Hip Rotation
**Vastus Intermedius is beneath Rectus Femoris

81. Muscles of Posterior Thigh
“Hamstrings”
Responsible for Knee Flexion & Hip Extension
Semimembranosus
Semitendinosus
Biceps Femoris
Gastrocnemius
Knee Flexion

82. Muscles of the Lower Leg
Anterior Compartment
Tibialis Anterior—Dorsiflexion & inversion
Extensor Digitorum Longus
Fibularis Tertius—dorsiflexion & eversion
Posterior Compartment
Gastrocnemius—plantarflexion, knee flexion
Soleus—plantarflexion
Lateral Compartment
Fibularis Longus—plantarflexion & eversion
Fibularis Brevis—plantarflexion & eversion

83. Throwing Movement

84. Running & Kicking

85. 5 Golden Rules of Skeletal Muscle Activity
All muscles cross at least one joint
Typically, the bulk of the muscle lies proximal to the joint crossed
During contraction, the muscle insertion moves toward the origin
All muscles have at least two attachments:
Origin – attachment at least moveable bone
Insertion – attachment onto the moveable bone
Muscles can only pull, they never push. This means that most muscles must work in pairs. Muscles are arranged on the skeleton in such a way that whatever one muscle can do, another can do in reverse.

86. Pushing the Limits strength video

87. Developmental Aspects of the Muscular System
At birth, a baby’s muscular movement is uncoordinated and largely reflexive.
Men are stronger due to having a 42% muscle mass compared a 36% muscle in women. The hormone testosterone influences this effect
As we age, the amount of connective tissue of skeletal muscle increases, the number of muscle fibers decrease---as a result the muscles become more weak.