Muscular system
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MUSCULAR SYSTEM - PowerPoint PPT Presentation

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MUSCULAR SYSTEM. “the power system”. FACTS: . Nearly half our weight comes from muscle tissue. There are 650 different muscles in the human body. Muscles give us form and shape. Muscles produce most of our body heat. THREE MAIN FUNCTIONS. Responsible for all body movement.

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“the power system”


  • Nearly half our weight comes from muscle tissue.

  • There are 650 different muscles in the human body.

  • Muscles give us form and shape.

  • Muscles produce most of our body heat.


  • Responsible for all body movement.

  • Responsible for body form and shape (posture)

  • Responsible for body heat and maintaining body temperature.

Types of muscles

  • Skeletal

  • Smooth

  • Cardiac

  • Sphincter

Skeletal Muscle

  • Attached to bone

  • Striated (striped) appearance


  • Contract quickly, fatigue easily, can’t maintain contraction for long period of time

Skeletal Muscles

  • Each skeletal muscle cell contains many nuclei

  • Muscle cells are known as muscle fibers

  • Cell membrane is call sarcolemma

  • Cytoplasm is called sarcoplasm

Smooth Muscle

  • Visceral (organ) muscle

  • Found in walls of digestive system, uterus and blood vessels

  • Cells small and spindle-shaped


  • Controlled by autonomic nervous system

  • Act slowly, do not tire easily, can remain contracted for long time

Cardiac Muscle

  • Found only in the heart

  • Striated and branched

  • Involuntary

  • Cells are fused – when one contracts, they all contract


  • special circular muscles in openings of esophagus and stomach, stomach and small intestine, anus, urethra and mouth.


  • CONTRACTIBILITY – the ability of a muscle to reduce the distance between the parts of its contents or the space it surrounds.

  • EXCITEABILITY (IRRITABILITY) – the ability to respond to certain stimuli by producing impulses.


  • EXTENSIBILITY – the ability to be stretched.

  • ELASTICITY – ability of muscle to return to its original length when relaxing.

Naming Muscles

  • Location:

    • frontalis-forehead

  • Size:

    • gluteus maximus

  • Direction of fibers:

  • external abdominal oblique

  • Number of origins:

    • Biceps-two headed muscle in humerus

  • Location of origin and Insertion: sternocleidomastoid- origin in sternum

Naming muscles

  • Action flexor:

    • flexor carpiulnaris- flexes the wrist

  • Extensor:

    • extensor carpiulnaris- extends the wrist

  • Levator and Depressor:

    • depressor angulioris-depresses the corner of the mouth, raises or lowers body parts


  • Muscles move bones by pulling on them.

  •  As a muscle contracts, it pulls the insertion bone closer to the origin bone. Movement occurs at the joint between the origin and the insertion. 

  • Rule: A muscle’s insertion bone moves toward its origin bone.

  • Groups of muscles usually contract to produce a single movement.

Muscle Contraction

  • Sarcolemma: muscle cell membrane

  • Synaptic Cleft: gap between the axon and the muscle cell.

Muscle Contraction

  • MOTOR UNIT – a motor neuron plus all the muscle fibers it stimulates.

  • NEUROMUSCULAR JUNCTION – the junction between the motor neuron’s fiber which transmits the impulse – and the muscle cell membrane.

  • ACETYLCHOLINE – chemical neurotransmitter, diffuses across the synaptic cleft (carries impulse across synaptic cleft)

  • MUSCLE FATIGUE – caused by the accumulation of lactic acid in the muscles.

  • OXYGEN DEBT – after exercise, the amount of oxygen needed by the muscle to change lactic acid back to glucose.

  • MUSCLE TONE - When muscles are slightly contracted and ready to pull.

Muscle Efficiency

  • Improves:

    -Coordination of all muscles involved

    -Respiratory and circulatory system to supply needs of active muscular system

    -Elimination of excess fat

    -Joint movement involved with that muscle activity

Muscle Strength

  • Strength (capacity to do work) is increased with training

  • Muscle size increase due to change in the sarcoplasm (cytoplasm found in the individual skeletal muscle fibers) Not the increase in the number of muscle fiber cells

Muscle Attachments

  • Tendons: non-elastic cords that attach muscles to bones

  • Bones are connected at joints


  • Dome-shaped muscle that separates the abdominal and thoracic cavities, aids in breathing

Disorders and Related Terminology

  • ATROPHY – wasting away of muscle due to lack of use.

  • If we fail to exercise our muscles weaken and become flaccid ex. Quadriplegics, elderly on bedrest, extremity in a cast, etc.

  • Massage of these muscles is essential in providing the proper physiotherapy or a general sense of comfort and well-being to a patient, also prevents atrophy in debilitated patients

  • HYPERTROPHY – an increase in the size of the muscle cell.

  • when over exercise the size of the muscle fibers increase due to a change in the sarcoplasm (not due to an increase in number of muscle fiber cells)

  • STRAIN – tear in the muscle resulting from excessive use. Bleeding inside the muscle can result in pain and swelling. Ice packs will help stop bleeding and reduce swelling.

    • RICE : rest, ice, compression, elevation

  • Rehabilitation: retaining of injured or unused muscles

  • MYALGIA – muscle pain

  • TENDONITIS – inflammation of a tendon

  • MUSCLE SPASM (cramp) – sustained contraction of the muscle, usually because of overuse.


  • Or wry neck, may be due to an inflammation of the trapezius and/or

  • Sternocleidomastoid muscle

La belleza perece en la vida pero es inmortal en el arte.

Leonardo Da Vinci

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