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Muscular System

Muscular System. Muscles in Humans. There are approximately 650 muscles in the human body, each performing a unique role. Muscles are the driving force behind the musculoskeletal systems, enabling us to sit, stand, walk, talk and do anything else that requires movement.

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Muscular System

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  1. Muscular System

  2. Muscles in Humans • There are approximately 650 muscles in the human body, each performing a unique role. • Muscles are the driving force behind the musculoskeletal systems, enabling us to sit, stand, walk, talk and do anything else that requires movement. • They also keep our heart beating and help us breathe. • In order to function, they must be able to react to stimuli, contract, extend and return to their normal shape.

  3. 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

  4. 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

  5. Nervous system to muscles • Within the nervous system, nerve impulses travel from neuron to neuron along complex nerve pathways. The junction between the parts of two such neurons is called a "synapse.“ • If a sufficient amount of the substance (called "neurotransmitter") is released, the membrane is stimulated, and a nerve impulse is triggered

  6. Neuromuscular junction occurs when a nerve cell contacts a muscle 

  7. Comparison of Types of Muscle

  8. Types of Muscle, cont.

  9. Myofilaments • Muscle cells are unique because of the contractible protein fibers, called myofilaments, within them.  • the filaments of myofibrils constructed from proteins are of two types, thick and thin. • Thin filaments consist primarily of the protein actin. • Thick filaments consist primarily of the protein myosin. • Muscle contraction occurs because of the myosin filaments pull on actin filaments

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

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

  12. Characteristics of Cardiac Muscle • Has striations • Usually has a single nucleus • Joined to another cardiac muscle cell • Involuntary • Found only in the heart • Connects cytoplasm between 2 cells (Gap junction) Gap junctions are responsible for electrochemical and metabolic coupling. They allow Each heart muscle cell is coupled to its neighbors electrically by tiny holes, producing depolarization of the heart muscle

  13. 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 Skeletal Muscle

  14. Anatomy of a Muscle Cell • Each fiber is built up from smaller strands called myofibrils, and each myofibril contains interlaced filaments of muscle proteins.

  15. Naming Skeletal Muscles

  16. Direction of Muscle Fibers • Relative to the Midline • RECTUS = parallel to the midline • RectusAbdominus • TRANSVERSE = perpendicular to midline • TransverseAbdominus • OBLIQUE = diagonal to midline • External Oblique

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

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

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

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

  21. Origin & Insertion • Origin – attachment to an immoveable bone • Insertion – attachment to a movable bone • ILIOCOSTALIS= attaches to the ilium & ribs (costal = ribs)

  22. Action

  23. 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

  24. Head & Neck Muscles

  25. 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 Head & Neck Muscles

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

  27. 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 Key Muscles of Facial Expression

  28. Muscles of the Axial Skeleton

  29. Intrinsic Muscles Erector Spinae: maintain posture of back/extension Spinalis Longissimus Iliocostalis Oblique Muscles: rotation of the vertebrae Semispinalis Multifidus Rotatores Muscles of Quiet Respiration Diaphragm External Intercostals Internal Intercostals—deep breaths Abdominal Muscles External Obliques Internal Obliques Transverse Abdominus Rectus Abdominus Quadratus Lumborum Muscles of the Axial Skeleton

  30. Muscles of Scapular Stabilization • Trapezius: • Retraction (M) • Elevation (S) • Depression (I) • Upward Rotation (S, M) • Rhomboid—retraction • Levator Scapular—Elevation • Pectoralis Major—Protraction • Serratus Anterior—Protraction

  31. Anterior Muscles of Shoulder • Deltoid • Flexion (A, M)/Extension (P, M) • Abduction (M)/Adduction (A) • Internal (A) /External Rotation (P) • Pectoralis Major • Adduction • Flexion • Extension • Internal Rotation • Biceps Brachii—Flexion

  32. Posterior Muscles of Shoulder • Teres Major • Adduction • Extension • Internal Rotation • Latissimus Dorsi • Adduction • Extension • Internal Rotation • Triceps Brachii • Adduction • Extension

  33. Rotator Cuff Muscles (SITS) • Supraspinatus • Abduction • Infraspinatus • External Rotation • Teres Minor • External Rotation • Subscapularis • Internal Rotation

  34. Muscles of the Elbow/Forearm • Triceps Brachii—Extension • Bicep Brachii— • Flexion • Supination • Brachialis—Flexion • Brachioradialis— • Flexion • Pronation • Pronator Teres • Pronator Quadratus • Supinator Longus

  35. 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

  36. Muscles Of Hip:Anterior Muscles

  37. Medial/Adductor Muscles: Adductor Magnus Adductor Longus Adductor Brevis Gracilis Anterior Muscles Iliopsoas—Flexion Pectineus— Flexion Adduction Sartorius— Flexion Lateral Rotation Muscles of Hip:Anterior Muscles

  38. Muscles of Hip: Gluteal Muscles • Gluteus Maximus—Extension • Gluteus Medius—Abduction • Gluteus Minimus—Abduction • Tensor Fasciae Latae— • Flexion • Abduction ** Gluteus Minimus is under the Gluteus Medius

  39. 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

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

  41. 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

  42. Throwing Movement

  43. Running & Kicking

  44. Tendinitis • Inflammation of tendons and of tendon-muscle attachments • Many patients report stressful situations in their life in correlation with the beginnings of pain which may contribute to the symptoms. If the symptoms of tendinitis last for several months or longer it is probably tendinitis.

  45. Muscular Diseases • Muscular Dystrophy • Muscular Dystrophy (MD) is a group of genetic diseases that cause the muscle fibers to become easily damaged. • There are over one dozen different types, but the most common general symptoms are muscle weakness, lack of coordination and loss of mobility. • The most severe type, Duchenne's muscular dystrophy, can cause mental retardation and primarily affects young boys. • MD is diagnosed through genetic tests, muscle biopsies, blood tests that measure for high levels of creatine kinase and ultrasounds. • There is no cure for MD but it can be treated to reduce the severity with physical therapy, medication, surgery and special braces.

  46. Muscular Diseases • Compartment Syndrome • Compartment syndrome occurs when too much pressure builds up in and around the muscles. • It can result from crushing injuries, extended pressure on a blood vessel, swelling inside a cast or complications from surgery. • Symptoms include severe pain, a feeling of fullness or tightness in the muscle and a tingling sensation. • Numbness indicates cellular death and it may be difficult to restore full function once it reaches that point. Surgery to relieve the pressure is usually required.

  47. Fibromyalgia • is a medical disorder characterized by chronic widespread pain and allodynia, a heightened and painful response to pressure • Fibromyalgia is estimated to affect 2–4% of the population, with a female to male incidence ratio of approximately 9:1 • Fibromyalgia is considered a controversial diagnosis, due to lacking scientific consensus to its cause • Signs and symptoms: • Muscle spanms, weakness, nerve pain, muscles twitching, palpitations, bowel disturbances, sleep disturbances, short/long term memory, impaired speed performace, inability to multitask, anxiety, depression, RA, headaches, etc…

  48. Mitochondrial Myopathies • On biopsy, the muscle tissue of patients with this disease category usually demonstrate 'ragged red' muscle fibers. • These 'ragged red' fibers contain mild accumulations of glycogen and neutral lipids, and may show an increased reactivity for succinate dehydrogenase and a decreased activity for cytochrome c oxidase. • Examples of Mitochondrial myopathy include: • varying degrees of cognitive impairment and dementia • lactic acidosis (breakdown food) • strokes • transient ischemic attacks • hearing loss • Dysmotility (digestive muscles don’t work) • weight loss • cardiac conduction defects

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