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muscles
muscle types
In principle that´s what all training is about. More or less every physical activity performed on a certain level puts effort on our muscles. We have more than 600 of them waiting to be activated. Muscle are categorized in three different types:
  • Smooth muscle is part of the walls of organs like stomach.
  • Cardiac muscle can only be found in the heart.
  • Skeletal muscle is anchored to the bones by tendons.
  • muscle anatomy
    A muscle is made of a lot of muscle cells, so called called muscle fibers. They are called fibers because of their size. A single cell or fiber has a diameter of 0,1mm and a lenght up to 30cm. Many fibers are wrapped together to bundles called fascicles. The fascicles itself are also bound together to make up the muscle.

    muscle
    tendon
    Tendons connect muscles to bones or muscles to muscles. They have the shape of bands and are very tension-resistant.
    blood vessel
    It provides the muscle with blood, carrying oxygen, nutrients and other vital substancies.
    muscle fiber
    A muscle fiber is a cell consting of a nucleus, sarcoplasmic reticulums, mitochondrions (wich are responsible for muscle growth) and myofibrils (the contractile elements), wich contain sarcomeres made of actin and myosin.
    endomysium
    The endomysium is a tissue that wrappes a single muscle fiber.
    fascicle
    A fascicle is a bundle of several muscle fibers.
    perimysium
    Another tissue that covers the fasciles.
    epimysium
    It groups the fascicles to form the muscle.
    muscle fibers
    Muscle fibers can be separated into two types, depending on their attributes.

     
    slow twitch, type I
    fast twitch, type II
    function
    slow, persistent
    fast contraction
    contractile speed
    slow
    fast
    color
    red
    white
    mitochondria
    high quantity
    low quantity
    myoglobin
    high quantity
    low quantity
    capillary densitiy
    high
    lower
    oxygen transport
    high
    low
    lactic acid production
    lower
    higher

    The type II fibers are subdivided into three categories with contractile speeds situated between type I and type II. Basically it´s enough to know the main fibers.
    The red and white color is caused by the amount of capillaries inside the muscle. Red muscles carry more blood than white ones. That´s why certain animals have red and others have white meat.
    Every muscle owns fibers of each type. The arrangement is based on your genetics and the muscle´s function.
    muscle maps
    Let´s have a closer look at the main skeletal muscles, because they are interesting for training purpose. It makes little sense to know all of them. The following table names the most important muscles, their anatomical and common names and most evident function.
    The names already tell a lot about muscles. Most of them are not just one piece of muscle, but constist of other muscles, so called heads. The Quadriceps consists of four (=quad) heads, Triceps of course three (=tri ) and Biceps (bi=two).
    Heads are attached to the bones through tendons, wich enables us to move our joint(s) included and therefore to move our body.

    muscle
    illustration
    other names
    basic functions
    Pectoralis major/minor
    heads:
    Clavicular head,
    Sternal head
    chest
    chest, pecs, pectorals
    Moves the arms towards away from torso and together towards and across chest from the sides.
    Deltoids
    heads:
    Anterior head,
    Lateral head,
    Posterior head
    delts
    delts, shoulders front/ side/ rear head
    Moves upper arm upward to front, to side and backwards and over head.
    Latissimus dorsi
    lats
    lats, outer back
    Pulls shoulders downward and to back.
    Rhomboids
    (below Trapezius)
    heads:
    Rhomboids minor,
    Rhomboids major
    rhomboids
    middle back
    Rhomboids take part in the adduction and downward rotation of scapula.
    Trapezius
    heads:
    upper fibers,
    middle fibers,
    lower fibers
    traps
    traps, middle back (lower fibers)
    Upper traps elevate scapula and extend cervical spine.

    Middle fibers elevate and adduct scapula.

    Lower traps extend thoracic spine and adduct, rotate or depress scapula.
    Quadriceps
    heads:
    Rectus femoris
    Vastus lateralis
    Vastus Intermedius
    Vastus Medialis
    quads
    quads,
    front thigh
    Extends the leg from flexed position.
    Hamstrings
    heads:
    Biceps Femoris Long Head,
    Biceps Femoris Short Head,
    Semitendinosus,
    Semimembranosus
    hamstrings
    rear thigh
    Hamstrings flex the legs.
    Adductors
    heads:
    Adductor Brevis,
    Adductor Longus,
    Adductor Magnus
    adductors
    inner thigh
    Adductors move thigh inward.
    Abductors
    heads:
    Tensor Fasciae Latae
    abductors
    outer thigh
    Abductors move thigh outward.
    Calves
    consist of:
    Gastrocnemius (upper heads),
    Soleus (lower head)
    calves
    -
    Calves extend ankle so forefoot moves away from body.
    Gluteus maximus
    supported by:
    Gluteus medius,
    Gluteus minimus
    "glutes"
    glutes, butt, rear hips
    Glutes are involved in hip abduction and adduction. It´s main function is to move thigh to rear by extending hips.
    Hip flexors
    Muscles:
    Iliopsoas,Sartorius
    Tensor Fasciae Latae,
    Pectineus
    hip flexors
    glutes, butt, rear hips
    Hip flexors move legs up.
    Rectus abdominis
    abs
    abdominals, abs, waist, belly
    Abs are responsible for flexing lumbar spine.
    Obliques
    heads:
    External oblique,
    Internal Oblique
    obliques
    side waist
    Obliques flex lumbar spine to both sides and are involved in left and right rotation.
    Erector spinae
    heads:
    Iliocastalis,
    Longissimus,
    Spinalis
    lower back
    lower back
    Lower back extends and rotates spine.
    Biceps brachii
    heads:
    Long head,
    Short head
    biceps
    biceps,
    front arm
    Bicpes flexes elbow and rotates forearm to the inside.
    Triceps brachii
    heads:
    Long head,
    Lateral head,
    Medial head
    triceps
    triceps,
    rear arm
    Triceps extends elbow.
    Brachioradialis
    lower arm
    forearm
    Brachioradialis is involved in flexing elbow.
       
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