1. OT 110 Anatomy & Physiology for OTA Week 6: The Muscular System
Caryn M. Masterson, MS, OTR/L
x. 6105

3. Muscle Facts There are more than 600 muscles in the body
Muscles make up about 40% of total body weight
The strongest muscles in the body pound for pound, are the muscles that you chew with - called the masseters
Humans are born with all of the muscle fibers they will ever have. They don't grow new fibers, they just grow thicker.
Muscles cannot push, they can only pull. The reason the arm can push is muscles in the back of the arm pulling on the elbow
The strongest muscle in the human body is the tongue

4. Muscle Types Three basic muscle types that are found in the body
Skeletal muscle
Cardiac muscle
Smooth muscle

5. Size, Shape, and Directional Classifications
Muscles are further classified by their shape, size and direction, according to the NIH.
Size Examples
Gluteus Maximus
Gluteus Medius
Gluteus Minimus
Shape Examples
Deltoid
Rhomboid
Direction Examples
Rectus Abdominis
Transverse Abdominis

7. Microscopic anatomy of skeletal muscle
Sarcomere—contractile unit of a muscle fiber
Organization of the sarcomere
Myofilaments produce banding (striped) pattern
Thick filaments  myosin filaments
Thin filaments  actin filaments (each actin filament is surrounded by 3 myosin filaments
Composed of the protein myosin
Contain ATPase enzymes
Possess myosin heads
Heads are known as cross bridges when they link thick and thin filaments during contraction

8. Microscopic Anatomy Cont’d
Thin filaments  actin filaments
Composed of the contractile protein actin
Actin is anchored to the Z disc
At rest, within the A band there is a zone that lacks actin filaments
Called the H zone
Sarcoplasmic reticulum (SR)
Specialized smooth endoplasmic reticulum
Stores and releases calcium
Surrounds the myofibril

9. Segment of a muscle fiber
Sarcolemma—specialized plasma membrane
Myofibrils—long organelles inside muscle cell
Light (I) bands and dark (A) bands give the muscle its striped appearance
Banding pattern
I band  light band
Contains only thin filaments
Z disc is a midline interruption
A band  dark band
Contains the entire length of the thick filaments
H zone is a lighter central area
M line is in center of H zone

12. Characteristics of muscle
Skeletal and smooth muscle cells are elongated (muscle cell  muscle fiber) Contraction and shortening of muscles is due to the movement of microfilaments All muscles share some terminology Prefixes myo and mys refer to “muscle” Prefix sarco refers to “flesh”

14. Connective tissue wrappings of the muscular system
Cells are surrounded and bundled by connective tissue
Endomysium—encloses a single muscle fiber
Perimysium—wraps around a fascicle (bundle) of muscle fibers
Epimysium—covers the entire skeletal muscle
Fascia—on the outside of the epimysium

19. 3 Sites of Muscle Attachments
Bones
Cartilages
Connective tissue coverings

20. Skeletal muscle attachments
Epimysium blends into a connective tissue attachment
Tendons—cordlike structures
Mostly collagen fibers
Often cross a joint because of their toughness and small size
Aponeuroses—sheet-like structures
Attach muscles indirectly to bones, cartilages, or connective tissue coverings

21. Anatomy of a tendon

26. Hand Anatomy Video

27. Smooth muscle characteristics
Lacks striations
Spindle-shaped cells
Single nucleus
Involuntary—no conscious control
Found mainly in the walls of hollow visceral organs (such as stomach, urinary bladder, respiratory passages)

29. Cardiac muscle characteristics
Striations
Usually has a single nucleus
Branching cells
Joined to another muscle cell at an intercalated disc
Involuntary
Found only in the walls of the heart

31. Physical properties of muscles
Irritability (also called responsiveness)—ability to receive and respond to a stimulus
Contractility—ability to shorten when an adequate stimulus is received
Extensibility—ability of muscle cells to be stretched
Elasticity—ability to recoil and resume resting length after stretching

32. Motor Neuron Tract

33. The nerve stimulus and action potential
Skeletal muscles must be stimulated by a motor neuron (nerve cell) to contract
Motor unit—one motor neuron and all the skeletal muscle cells stimulated by that neuron
Neuromuscular junction
Association site of axon terminal of the motor neuron and sarcolemma of a muscle
Neurotransmitter
Chemical released by nerve upon arrival of nerve impulse in the axon terminal
Acetylcholine (ACh) is the neurotransmitter that stimulates skeletal muscle
Synaptic cleft
Gap between nerve and muscle
Nerve and muscle do not make contact
Filled with interstitial fluid

34. Transmission of Nerve Impulse to Muscle
When a nerve impulse reaches the axon terminal of the motor neuron,
Calcium channels open, and calcium ions enter the axon terminal
Calcium ion entry causes some synaptic vesicles to release acetylcholine (ACh)
ACh diffuses across the synaptic cleft and attaches to receptors on the sarcolemma of the muscle cell
If enough ACh is released, the sarcolemma becomes temporarily more permeable to sodium (Na)

35. Transmission of nerve impulse
Sodium rushes into the cell, and potassium leaves the cell
Depolarization opens more sodium channels that allow sodium ions to enter the cell
Once started, the action potential cannot be stopped, and contraction occurs
Acetylcholinesterase (AChE) breaks down acetylcholine into acetic acid and choline
AChE ends muscle contraction

36. Transmission of Nerve Impulse to Muscle
Cell returns to its resting state when:
Potassium ions diffuse out of the cell
Sodium-potassium pump moves sodium and potassium ions back to their original positions

37. Motor Neuron

39. Muscle Fibers Explained
VIDEO

40. Muscle innervation

41. Contraction of 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

42. Mechanism of Muscle Contraction: The Sliding Filament Theory
Calcium binds to regulatory proteins on thin filaments and exposes myosin-binding sites, allowing the myosin heads on the thick filaments to attach
The attached heads pivot, sliding the thin filaments toward the center of the sarcomere, and contraction occurs
ATP provides the energy for the sliding process, which continues as long as ionic calcium is present
Graded responses can be produced by changing:
The frequency of muscle stimulation
The number of muscle cells being stimulated at one time

43. Types of graded responses
Twitch
Single, brief contraction
Not a normal muscle function
Summing of contractions
One contraction is immediately followed by another
Because stimulations are more frequent, the muscle does not completely return to a resting state
The effects are “summed” (added)
Unfused (incomplete) tetanus
Some relaxation occurs between contractions, but nerve stimuli arrive at an even faster rate than during summing of contractions
Unless the muscle contraction is smooth and sustained, it is said to be in unfused tetanus
Fused (complete) tetanus
No evidence of relaxation before the following contractions
Frequency of stimulations does not allow for relaxation between contractions
The result is a smooth and sustained muscle contraction

44. Types of muscle contraction

45. Types of muscle contraction
Isotonic
Isometric
Isokinetic

46. Isotonic Muscle Contraction
Isotonic contractions are those which cause the muscle to change length as it contracts and causes movement of a body part. There are two types of Isotonic contraction:

47. Concentric Vs. Eccentric Muscle Contractions
VIDEO
VIDEO

48. Types of Isotonic Contractions
Concentric
Eccentric
For example, when kicking a football, the Quadriceps muscle contracts concentrically to straighten the knee and the Hamstrings contract eccentrically to decelerate the motion of the lower limb. This type on contraction puts a lot of strain through the muscle and is commonly involved in muscle injuries.

50. Concentric Contractions
Concentric contractions are those which cause the muscle to shorten as it contracts. An example is bending the elbow from straight to fully flexed, causing a concentric contraction of the Biceps Brachii muscle. Concentric contractions are the most common type of muscle contraction and occur frequently in daily and sporting activities.

51. Eccentric Contractions
Eccentric contractions are the opposite of concentric and occur when the muscle lengthens as it contracts. This is less common and usually involves the control or deceleration of a movement being initiated by the eccentric muscles agonist.

52. Concentric vs. Eccentric Muscle Contractions

53. Isometric vs. Isotonic contractions
VIDEO

54. Isometric Muscle Contraction
Isometric contractions occur when there is no change in the length of the contracting muscle.

55. Isokinetic Muscle Contraction
Isokinetic contractions are similar to isotonic in that the muscle changes length during the contraction, where they differ is that Isokinetic contractions produce movements of a constant speed.

56. Muscle Response to Strong Stimuli
Muscle force depends upon the number of fibers stimulated
Contraction of more fibers results in greater muscle tension
Muscles can continue to contract unless they run out of energy

57. Muscle Fatigue and Oxygen Deficit/Debt
If muscle activity is strenuous and prolonged, muscle fatigue occurs because:
Because so many of your muscles are working together during a workout, your body needs to transport oxygen to all of them to make sure that they can continue to move properly. Without oxygen, they will fatigue quickly and eventually force you to stop to catch your breath
Ionic imbalances occur
Lactic acid accumulates in the muscle
Energy (ATP) supply decreases
After exercise, the oxygen deficit is repaid by rapid, deep breathing

58. Muscle Fatigue

59. Muscle Recovery
Steady breathing begins to replenish the oxygen in your body, which helps to refill the myoglobin oxygen stores in your muscles.
When you down a protein shake or even a Snickers bar, oxygen is used to convert this food into glucose, to refill your body’s glycogen supplies.
Then the combination of glycogen and oxygen works to restore ATP levels in your body, which has been depleted completely.
Finally, you’ve got all of the built up lactic acid in the kidneys and liver to deal with. Oxygen is required to break this acid down in order to convert it to pyruvic acid, which is then broken down into ATP. Water assists with breaking down lactic acid and flushing the kidneys.

60. Muscle Recovery

61. Muscle tone Muscle tone keeps muscles healthy and ready to react
Result of a staggered series of nerve impulses delivered to different cells within the muscle
Hypotonia: Decreased muscle tone and strength that results in floppiness. Hypotonia is a common finding with cerebral palsy and other neuromuscular disorders. Untreated hypotonia can lead to hip dislocation and other problems. Treatment is via physical therapy. In some cases, braces may be needed to permit a full range of movement in patients with hypotonia.
Hypertonia: Increased tightness of muscle tone and reduced capacity of the muscle to stretch caused by damage to the motor nerve pathways in the central nervous system. Untreated hypertonia can lead to loss of function and deformity.

62. Baby with
Hypotonicity or
Hypotonia

63. Child with
Hypertonicity Or
Hypertonia

64. Types of Exercise Aerobic exercise:
exercise that increases the need for oxygen such as dance, cardiopulmonary exercise, running, biking, jogging- exercise intended to strengthen the circulatory system
Anaerobic exercise:
physical activity, which instigates a metabolism that does not depend on oxygen. Examples include isotonics, in which the muscles contract against an object of resistance with movement (e.g., weight lifting); isometrics, in which muscles contract against resistance but without movement; and calisthenics (e.g., sit-ups and knee-bends), which increase flexibility and improve joint mobility.

65. Effect of Exercise on Muscles
Exercise increases muscle size, strength, and endurance
Aerobic (endurance) exercise (biking, jogging) results in stronger, more flexible muscles with greater resistance to fatigue
Makes body metabolism more efficient
Improves digestion, coordination
Resistance (isometric) exercise (weight lifting) increases muscle size and strength

67. Muscle disease
Muscle disease, any of the diseases and disorders that affect the human muscle system. Diseases and disorders that result from direct abnormalities of the muscles are called primary muscle diseases; those that can be traced as symptoms or manifestations of disorders of nerves or other systems are not properly classified as primary muscle diseases. Because muscles and nerves (neurons) supplying muscle operate as a functional unit, disease of both systems results in muscular atrophy (wasting) and paralysis.

68. Muscle disease article

69. Muscle System Diseases
Muscular Dystrophy
Cerebral Palsy
Fibrodysplasia Ossificans Progressiva
Dermatomyosistitis
Compartment Syndrome
Myesthenia Gravis
Amyotrophic Lateral Sclerosis
Mitochondrial Myopathies
Rhabdomyolysis
Polymyositis
Fibromyalgia
Myotonia
Myofascial Pain Syndrome
Rotator Cuff Tear
Muscle Cramps
Sprains and Strains
Talipes (flat feet)
Tendonitis

70. Neuromuscular diseases
Spinal muscular atrophies:
Amyotrophic lateral sclerosis (ALS), or motor neuron disease
Infantile progressive spinal muscular atrophy
Intermediate spinal muscular atrophy
Juvenile spinal muscular atrophy
Adult spinal muscular atrophy
Inflammatory myopathies:
Dermatomyositis
Polymyositis
Inclusion body myositis
Diseases of peripheral nerve:
Charcot-Marie tooth disease
Dejerine-Sottas disease
Friedreich's ataxia
Diseases of the neuromuscular junction:
Myasthenia gravis
Lambert-Eaton syndrome
Botulism
Metabolic diseases of the muscle:
Acid maltase deficiency
Carnitine deficiency
Carnitine palmityl transferase deficiency
Debrancher enzyme deficiency
Lactate dehydrogenase deficiency
Mitochondrial myopathy
Myoadenylate deaminase deficiency
Phosphorylase deficiency
Phosphofructokinase deficiency
Phosphoglycerate kinase deficiency
Less common myopathies:
Central core disease
Hyperthyroid myopathy
Myotonia congenita
Myotubular myopathy
Nemaline myopathy
Paramyotonia congenita
Periodic paralysis-hypokalemic-hyperkalemic

71. What is a metabolic muscle disease?
Muscles require a lot of energy to work properly, and metabolic diseases of muscle interfere with chemical reactions involved in drawing energy from food. When energy levels become too low, muscle weakness and exercise intolerance with muscle pain or cramps may occur.

72. Metabolic muscular diseases
Metabolic diseases of muscle were first recognized in the second half of the 20th century. Each of these disorders is caused by a different genetic defect that impairs the body's metabolism, the collection of chemical changes that occur within cells during normal functioning. They are caused by defects in the enzymes that control chemical reactions used to break down food. Enzyme defects are caused by flaws in the genes that govern production of the enzymes.
Normally, fuel molecules derived from food must be broken down further inside each cell before they can be used by the cells’ mitochondria to make energy. (The mitochondria inside each cell could be called the cell’s “engines.”) Metabolic muscle diseases are caused by problems in the way certain fuel molecules are processed before they enter the mitochondria, or by the inability to get fuel molecules into mitochondria.
Muscles require a lot of energy to work properly, and metabolic diseases of muscle interfere with chemical reactions involved in drawing energy from food. When energy levels become too low, muscle weakness and exercise intolerance with muscle pain or cramps may occur.

73. Types of metabolic muscle diseases
Acid maltase deficiency
Muscle phosphorylase deficiency
Debrancher enzyme deficiency
Phosphofructokinase deficiency
Phosphoglycerate kinase deficiency
Phosphoglycerate mutase deficiency
Lactate dehydrogenase deficiency
Carnitine palymityl transferase deficiency
Carnitine deficiency
Myoadenylate deaminase deficiency

74. Sprains, strains, and other soft tissue injuries
The most common soft tissues injured are muscles, tendons, and ligaments. These injuries often occur during sports and exercise activities, but sometimes simple everyday activities can cause an injury.
Soft-tissue injuries fall into two basic categories: acute injuries and overuse injuries.
Acute injuries are caused by a sudden trauma, such as a fall, twist, or blow to the body. Examples of an acute injury include sprains, strains, and contusions.
Overuse injuries occur gradually over time, when an athletic or other activity is repeated so often, areas of the body do not have enough time to heal between occurrences. Tendinitis and bursitis are common soft-tissue overuse injuries.

75. Sprains
A sprain is a stretch and/or tear of a ligament, which is a strong band of connective tissue that connect the end of one bone with another. The areas of your body that are most vulnerable to sprains are your ankles, knees, and wrists.
While the intensity varies, pain, bruising, swelling, and inflammation are common to all categories of sprains.

76. Strain
A strain is an injury to a muscle and/or tendons. Tendons are fibrous cords of tissue that attach muscles to the bone. Strains often occur in your foot, leg (typically the hamstring) or back.
Similar to sprains, a strain may be a simple stretch in your muscle or tendon, or it may be a partial or complete tear in the muscle-and-tendon combination.
Typical symptoms of a strain include pain, muscle spasm, muscle weakness, swelling, inflammation, and cramping.

77. Muscle Soreness
Muscle Soreness Video

78. Contusion
A contusion is a bruise caused by a direct blow or repeated blows, crushing underlying muscle fibers and connective tissue without breaking the skin.

79. Soft Tissue Injuries
Tendinitis is an inflammation or irritation of a tendon or the covering of a tendon (called a sheath) caused by a series of small stresses that repeatedly aggravate the tendon.
Bursitis: Bursitis is inflammation of a bursa. Repeated small stresses and overuse can cause the bursa in the shoulder, elbow, hip, knee or ankle to swell. Many people experience bursitis in association with tendinitis.

80. Muscles
PRACTICE GAME
CAT CADAVER

81. Case Studies (Group Project)
Occupational Profile
Analysis of Occupational Performance
Occupations
Performance Patterns
Performance Skills
Client Factors
Contexts and Environments
Theory and Evidence
Intervention Plan and Goals
Situations
Discharge Planning

82. Origins vs. Insertions Explained (Quickly)
VIDEO

83. Introduction to Origins, Insertions, and Actions
VIDEO
CHART

84. Tendons What are tendons?
The skeleton of human body comprise of around 206 bones. Tendons are the main connective tissues which hold the whole skeletal frame together.
In tandem with muscles and ligaments tendons help in the mechanics of movement and provide form and function to our body. They are also called sinews and perform the main function of connecting the muscles to the You do not have access to view this node.  

85. Composition of Tendons
Tendons comprise of regular, dense connective tissue which consists of collagen fibers which are densely packed bundles. These fibers are placed parallel to each other in the direction of pull on the tendon. The major components of tendons are:
Collagen fibers are more or less elastic but have very few blood vessels due to which they have the elasticity property. But this property results in longer recovery in case of tendon strain.
Fibroblasts are typical cells that are known to regenerate or reproduce the collagen fibers. The cell regeneration is a slow process as there is low vascularity in the tendon tissue as compared to soft You do not have access to view this node

86. What is a tendon?
VIDEO

87. Function of Tendons
Tendons connect a person's muscles to their bones. Tendons are tough and flexible bands of fibrous tissue that attach a person's skeletal muscles to their bones. Tendons; in essence, enable a person to move. They may be thought of as intermediaries between muscles and bones; for example, the Achilles tendon which connects a person's muscles of their calf to their heel bone. The tendon is vulnerable to tendonitis and tearing.

88. Structure of a tendon

89. Differences between ligaments and tendons
Ligaments and tendons are both fibrous, connective tissues. The difference is that tendons attach muscles to bones or other tissues while ligaments attach bones to each other.
The tendon is primarily responsible for moving a bone while the ligament is primarily responsible for holding joints together and providing stability of the joint.
However, both structures are critical in making your joints move correctly and fluidly. When you injure a joint, it is very common to injure both ligaments and tendons.

90. Composition of Tendons
Tendons comprise of regular, dense connective tissue which consists of collagen fibers which are densely packed bundles. These fibers are placed parallel to each other in the direction of pull on the tendon. The major components of tendons are:
Collagen fibers are more or less elastic but have very few blood vessels due to which they have the elasticity property. But this property results in longer recovery in case of tendon strain.
Fibroblasts are typical cells that are known to regenerate or reproduce the collagen fibers. The cell regeneration is a slow process as there is low vascularity in the tendon tissue as compared to soft You do not have access to view this node
Composition of Tendons

91. http://study.com/academy/lesson/what-is-a-tendon-anatomy-definition-quiz.html VIDEO
What is a tendon?

92. Tendons connect a person's muscles to their bones
Tendons connect a person's muscles to their bones. Tendons are tough and flexible bands of fibrous tissue that attach a person's skeletal muscles to their bones. Tendons; in essence, enable a person to move. They may be thought of as intermediaries between muscles and bones; for example, the Achilles tendon which connects a person's muscles of their calf to their heel bone. The tendon is vulnerable to tendonitis and tearing.
Function of Tendons

93. Structure of a tendon

94. Differences between ligaments and tendons
Ligaments and tendons are both fibrous, connective tissues. The difference is that tendons attach muscles to bones or other tissues while ligaments attach bones to each other. The tendon is primarily responsible for moving a bone while the ligament is primarily responsible for holding joints together and providing stability of the joint. However, both structures are critical in making your joints move correctly and fluidly. When you injure a joint, it is very common to injure both ligaments and tendons.
Differences between ligaments and tendons

95. Ligaments vs. Tendons Video

96. References http://www.innovateus.net/health/what-are-tendons

98.
N. Lowenstien & P. Halloran (2015). Case studies through the healthcare continuum: A workbook for the occupational therapy student. Slack, inc.;Thorofare, NJ.
Occupational Therapy Practice Framework – 3rd Edition. American Journal of Occupational Therapy, March/April 2014, Vol. 68, S1-S48. doi: /ajot