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Essentials of Human Anatomy

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Title: Essentials of Human Anatomy


1
Essentials of Human Anatomy Physiology
Elaine N. Marieb
Chapter 6The Muscular System
2
The Muscular System
  • Muscles are responsible for all types of body
    movement they contract or shorten and are the
    machines of the body
  • Three basic muscle types are found in the body
  • Skeletal muscle
  • Cardiac muscle
  • Smooth muscle

3
Characteristics of Muscles
  • Skeletal smooth 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

4
Skeletal Muscle Characteristics
  • Most are attached by tendons to bones
  • Cells are multinucleated
  • Striated have visible banding
  • Voluntary subject to conscious control
  • Cells are surrounded and bundled by connective
    tissue great force, but tires easily

5
Skeletal Muscle
6
Connective Tissue Wrappings ofSkeletal Muscle
  • Endomysium around a single muscle fiber
  • Perimysium around a fascicle (bundle) of fibers

7
Connective Tissue Wrappings ofSkeletal Muscle
  • Epimysium covers the entire skeletal muscle
  • Fascia on the outside of the epimysium

8
Skeletal Muscle Attachments
  • Epimysium blends into a connective tissue
    attachment
  • Tendon cord-like structure
  • Aponeuroses sheet-like structure
  • Sites of muscle attachment
  • Bones
  • Cartilages
  • Connective tissue coverings

9
Smooth Muscle Characteristics
  • No striations
  • Spindle-shaped cells
  • Single nucleus
  • Involuntary no conscious control
  • Found mainly in the walls of hollow organs
  • Slow, sustained contractions (tireless)

10
Smooth Muscle
11
Cardiac Muscle Characteristics
  • Has striations
  • Usually has a single nucleus
  • Joined to another muscle cell at an intercalated
    disc
  • Involuntary
  • Found only in the heart
  • Steady pace!

12
Cardiac Muscle
13
Muscle Functions
  • Produce movement
  • Maintain posture
  • Stabilize joints
  • Generate heat

14
Microscopic Anatomy of Skeletal Muscle
  • Cells are multinucleate
  • Nuclei are just beneath the specialized plasma
    membrane called ? Sarcolemma

15
Microscopic Anatomy of Skeletal Muscle
  • Myofibril
  • Bundles of myofilaments
  • Myofibrils are aligned to give distinct bands
    (striations)
  • I band light band
  • A band dark band

16
Microscopic Anatomy of Skeletal Muscle
  • Sarcomere
  • Contractile unit of a muscle fiber

17
Microscopic Anatomy of Skeletal Muscle
  • Organization of the sarcomere
  • Thick filaments Myosin filaments
  • Composed of the protein myosin
  • Contain ATPase enzymes
  • Extend the entire length of the dark A band

18
Microscopic Anatomy of Skeletal Muscle
  • Myosin filaments
  • Myosin heads
  • Create cross bridges

19
Microscopic Anatomy of Skeletal Muscle
  • Organization of the sarcomere
  • Thin filaments Actin filaments
  • Composed of the protein actin
  • Anchored to the Z disc

20
Microscopic Anatomy of SkeletalMuscle
  • Sarcoplasmic reticulum
  • Specialized smooth endoplasmic reticulum
  • Stores and releases calcium on demand when the
    muscle fiber is stimulated to contract

21
Skeletal Muscle Activity
  • Stimulation Contraction of Single Skeletal
    Muscle Cells
  • Irritability ability to receive and respond to
    a stimulus
  • Contractility ability to shorten when an
    adequate stimulus is received

22
Nerve Stimulus to Muscles
  • Skeletal muscles must be stimulated by a nerve to
    contract (motor neruron)
  • Motor unit
  • One neuron
  • Muscle cells stimulated by that neuron

23
Nerve Stimulus to Muscles
  • Neuromuscular junctions association site of
    nerve and muscle

24
Nerve Stimulus to Muscles
  • Synaptic cleft gap between nerve and muscle
  • Nerve and muscle do not make contact
  • Area between nerve and muscle is filled with
    interstitial fluid

25
Transmission of Nerve Impulse to Muscle
  • Neurotransmitter chemical released by nerve
    upon arrival of nerve impulse
  • The neurotransmitter for skeletal muscle is
    acetylcholine
  • Neurotransmitter attaches to receptors on the
    sarcolemma
  • Sarcolemma becomes permeable to sodium (Na)

26
Transmission of Nerve Impulse to Muscle
  • Sodium rushing into the cell generates an action
    potential
  • Once started, muscle contraction cannot be stopped

27
The Sliding Filament Theory of Muscle Contraction
  • Activation by nerve causes myosin heads
    (crossbridges) to attach to binding sites on the
    thin filament
  • Myosin heads then bind to the next site of the
    thin filament

28
The Sliding Filament Theory of Muscle Contraction
  • This continued action causes a sliding of the
    myosin along the actin
  • The result is that the muscle is shortened
    (contracted)

29
The Sliding Filament Theory
30
Contraction of a Skeletal Muscle
  • Muscle fiber contraction is all or none
  • Within a skeletal muscle, not all fibers may be
    stimulated during the same interval
  • Different combinations of muscle fiber
    contractions may give differing responses
  • Graded responses different degrees of skeletal
    muscle shortening, rapid stimulus constant
    contraction or tetanus

31
Muscle Response to Strong Stimuli
  • Muscle force depends upon the number of fibers
    stimulated
  • More fibers contracting results in greater muscle
    tension
  • Muscles can continue to contract unless they run
    out of energy

32
Energy for Muscle Contraction
  • Initially, muscles used stored ATP for energy
  • Bonds of ATP are broken to release energy
  • Only 4-6 seconds worth of ATP is stored by
    muscles
  • After this initial time, other pathways must be
    utilized to produce ATP

33
Energy for Muscle Contraction
  • Direct phosphorylation
  • Muscle cells contain creatine phosphate (CP)
  • CP is a high-energy molecule
  • After ATP is depleted, ADP is left
  • CP transfers energy to ADP, to regenerate ATP
  • CP supplies are exhausted in about 20 seconds

34
Energy for Muscle Contraction
  • Anaerobic glycolysis
  • Reaction that breaks down glucose without oxygen
  • Glucose is broken down to pyruvic acid to produce
    some ATP
  • Pyruvic acid is converted to lactic acid

35
Energy for Muscle Contraction
  • Anaerobic glycolysis (continued)
  • This reaction is not as efficient, but is fast
  • Huge amounts of glucose are needed
  • Lactic acid produces muscle fatigue

36
Energy for Muscle Contraction
  • Aerobic Respiration
  • Series of metabolic pathways that occur in the
    mitochondria
  • Glucose is broken down to carbon dioxide and
    water, releasing energy
  • This is a slower reaction that requires
    continuous oxygen

37
Muscle Fatigue and Oxygen Debt
  • When a muscle is fatigued, it is unable to
    contract
  • The common reason for muscle fatigue is oxygen
    debt
  • Oxygen must be repaid to tissue to remove
    oxygen debt
  • Oxygen is required to get rid of accumulated
    lactic acid
  • Increasing acidity (from lactic acid) and lack of
    ATP causes the muscle to contract less

38
Types of Muscle Contractions
  • Isotonic contractions
  • Myofilaments are able to slide past each other
    during contractions
  • The muscle shortens
  • Isometric contractions
  • Tension in the muscles increases
  • The muscle is unable to shorten

39
Muscle Tone
  • Some fibers are contracted even in a relaxed
    muscle
  • Different fibers contract at different times to
    provide muscle tone
  • The process of stimulating various fibers is
    under involuntary control

40
Effects of Exercise on Muscles
  • Results of increased muscle use
  • Increase in muscle size
  • Increase in muscle strength
  • Increase in muscle efficiency
  • Muscle becomes more fatigue resistant

41
Muscle Movements, Types, and NamesTextbook page
192 ?
42
Five Golden Rules of Skeletal Muscle Activity
  1. With a few exceptions, all muscles cross at least
    one joint
  2. Typically, the bulk of the muscle lies proximal
    to the joint crossed
  3. All muscles have at least 2 attachments ? origin
    insertion
  4. Muscles can only pull they never push
  5. During contraction, the muscle insertion moves
    toward the origin

43
Muscles and Body Movements
  • Movement is attained due to a muscle moving an
    attached bone

44
Muscles and Body Movements
  • Muscles are attached to bone, or to other
    connective tissue structures, at no less than two
    points
  • Origin attachment to the stationary bone
  • Insertion attachment to the movable bone

45
Types of Body Movements
  • Flexion- Decreases the angle of the joint and
    brings 2 bones closer together (Bending the knee
    or elbow)
  • Extension Opposite of flexion- increases the
    angle between 2 bones (Straightening the knee or
    elbow)
  • Hyperextension- Extension gt180 degrees (Tipping
    your head back so your chin points toward the
    ceiling)

46
(No Transcript)
47
Types of Body Movements
  • Rotation- Movement of a bone around its
    longitudinal axis Common with ball and socket
    joints ? describes the movement with the atlas
    around the dens of the axis (Shaking your head
    no)
  • Abduction Moving a limb away from the midline
    of the body Fanning movement of fingers, toes
  • Adduction Movement of a limb towards the body
    midline Opposite of abduction
  • Circumduction Combination of flexion,
    extension, abduction and adduction. Proximal end
    of limb is stationary, distal end moves in a
    circle ? Limb as a whole outlines a cone
  • See textbook page 195

48
Left Abduction moving the leg away from the
midline
Right Circumduction cone-shaped movement,
proximal end doesnt move, while distal end moves
in a circle.
Above Adduction- moving toward the midline
49
Special Movements
  • Dorsiflexion ? Lifting the foot so that its
    superior surface approaches the shin
  • Plantar flexion ? Pointing the toes
  • Inversion ? To invert the foot- turn the sole
    medially
  • Eversion ? To evert the foot- turn the sole
    laterally

50
Special Movements
  • Supination- Forearm rotates laterally so that the
    palm faces anteriorly, and the radius and ulna
    are parallel (Carry soup --gt soup-inating)
  • Pronation- Forearm rotates medially so the palm
    faces posteriorly (Face down)
  • Opposition- Action by which you move your thumb
    to touch the tips of the other fingers on the
    same hand
  • (See textbook page 195)

51
Interactions of Skeletal Muscles
  • Prime mover muscle with the major
    responsibility for a certain movement
  • Antagonist muscle that opposes or reverses a
    prime mover
  • When the prime mover is active its antagonist is
    stretched and relaxed
  • Synergist muscle that aids a prime mover in a
    movement and helps prevent rotation

52
Naming Skeletal Muscles
  • Direction of Muscle Fiber Rectus femoris
  • Relative Size- Gluteus maximus
  • Location Temporalis frontalis muscles
    Sterno- on the sternum
  • Number of Origins Biceps, triceps, quadriceps
  • Shape Deltoid (Triangular)
  • Action Flexor extensor adductor

53
Gross Anatomy of Skeletal Muscles
54
Head and Neck Muscles
55
Trunk Muscles
56
Deep Trunk and Arm Muscles
57
Muscles of the Pelvis, Hip, and Thigh
58
Muscles of the Lower Leg
59
Superficial Muscles Anterior
60
Superficial Muscles Posterior
61
Intramuscular Injections(vs. subcutaneous)
  • Muscle Injection Site LandmarkLandmarks
  • Deltoid Acromion of Scapula Acromion of
    Scapula
  • Vastus Lateralis ½ way betweenGreater
    Trochanter of Femur and Patellahalfway of
    between greater trochanter femur and
    patella
  • Gluteus Medius lIIiac Crest

62
Muscle Strain Website
  • What is a Muscle Strain?
  • A muscle strain is damage caused by
    over-stretching of muscle tissue. The muscle
    tissue becomes overloaded and reaches a breaking
    point where a tear or partial tear occurs.
  • GRADE 1 STRAIN There is damage to individual
    muscle fibers (less than 5 of fibers). This is a
    mild strain which requires 2 to 3 weeks rest.
  • GRADE 2 STRAIN There is more extensive damage,
    with more muscle fibers involved, but the muscle
    is not completely ruptured. The rest period
    required is usually between 3 and 6 weeks.
  • GRADE 3 STRAIN This is a complete rupture of a
    muscle. In a sports person this will usually
    require surgery to repair the muscle. The
    rehabilitation time is around 3 months.

63
Common Injuries
  • Hamstring pull/strain
  • tears of tendinous origins website
  • cause rigorous running/quick stop-start

64
Groin Pull
  • Strain of distal
  • abductors of iliac crest
  • website

65
  • Shin Splints
  • -pain in the Distal, medial 2/3 of shin
  • -Tendonitis of periosteum
  • -running on hard surfaces/
  • improper running shoes
  • website

66
Patello-Femoral Syndrome
  • Knee patello-femoral syndrome a.k.a. runners
    knee-lateral tracking of patella-result from
    over-running website

67
Plantar Faciitis - chronic irritation at origin
of Calcaneus- -painful-heel syndrome website
68
Treatments
  • RICE
  • Rest/Ice/Compression/Elevation
  • Anti-inflammatoryibuprofen (NSAIDS)
  • -non-steroidal anti-inflammatory drugs
  • Steroidal drugscortisone/hydrocortisone

69
Disorders relating to the Muscular System
  • Muscular Dystrophy inherited, muscle enlarge
    due to increased fat and connective tissue, but
    fibers degenerate and atrophy
  • Duchenne MD lacking a protein to maintain the
    sarcolemma
  • Myasthemia Gravis progressive weakness due to a
    shortage of acetylcholine receptors

70
Types of Ordinary Body Movements website
  • Abduction/Adduction (see slides)
  • Circumduction (see slides)
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