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OT 110 Anatomy & Physiology for OTA Week 6: The Muscular System
Caryn M. Masterson, MS, OTR/L x. 6105
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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
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Muscle Types Three basic muscle types that are found in the body
Skeletal muscle Cardiac muscle Smooth muscle
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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
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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
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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
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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
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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”
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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
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3 Sites of Muscle Attachments
Bones Cartilages Connective tissue coverings
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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
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Anatomy of a tendon
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Hand Anatomy Video
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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)
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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
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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
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Motor Neuron Tract
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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
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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)
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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
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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
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Motor Neuron
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Muscle Fibers Explained
VIDEO
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Muscle innervation
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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
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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
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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
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Types of muscle contraction
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Types of muscle contraction
Isotonic Isometric Isokinetic
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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:
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Concentric Vs. Eccentric Muscle Contractions
VIDEO VIDEO
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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.
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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.
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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.
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Concentric vs. Eccentric Muscle Contractions
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Isometric vs. Isotonic contractions
VIDEO
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Isometric Muscle Contraction
Isometric contractions occur when there is no change in the length of the contracting muscle.
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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.
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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
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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
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Muscle Fatigue
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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.
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Muscle Recovery
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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.
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Baby with Hypotonicity or Hypotonia
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Child with Hypertonicity Or Hypertonia
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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.
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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
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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.
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Muscle disease article
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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
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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
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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.
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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.
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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
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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.
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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.
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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.
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Muscle Soreness Muscle Soreness Video
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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.
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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.
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Muscles PRACTICE GAME CAT CADAVER
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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
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Origins vs. Insertions Explained (Quickly)
VIDEO
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Introduction to Origins, Insertions, and Actions
VIDEO CHART
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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.
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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
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What is a tendon? VIDEO
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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.
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Structure of a tendon
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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.
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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
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http://study.com/academy/lesson/what-is-a-tendon-anatomy-definition-quiz.html VIDEO
What is a tendon?
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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
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Structure of a tendon
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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
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Ligaments vs. Tendons Video
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References http://www.innovateus.net/health/what-are-tendons
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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
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