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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.
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 |
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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 |
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delts, shoulders front/ side/ rear head |
Moves upper arm upward to front, to side and backwards and over head. |
Latissimus dorsi |
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lats, outer back |
Pulls shoulders downward and to back. |
Rhomboids (below Trapezius) heads: Rhomboids minor, Rhomboids major |
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middle back |
Rhomboids take part in the adduction and downward rotation of scapula. |
Trapezius heads: upper fibers, middle fibers, lower fibers |
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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 |
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quads, front thigh |
Extends the leg from flexed position. |
Hamstrings heads: Biceps Femoris Long Head, Biceps Femoris Short Head, Semitendinosus, Semimembranosus |
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rear thigh |
Hamstrings flex the legs. |
Adductors heads: Adductor Brevis, Adductor Longus, Adductor Magnus |
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inner thigh |
Adductors move thigh inward. |
Abductors heads: Tensor Fasciae Latae |
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outer thigh |
Abductors move thigh outward. |
Calves
consist of: Gastrocnemius (upper heads), Soleus (lower head) |
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- |
Calves extend ankle so forefoot moves away from body. |
Gluteus maximus supported by: Gluteus medius, Gluteus minimus |
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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 |
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glutes, butt, rear hips |
Hip flexors move legs up. |
Rectus abdominis |
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abdominals, abs, waist, belly |
Abs are responsible for flexing lumbar spine. |
Obliques heads: External oblique, Internal Oblique |
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side waist |
Obliques flex lumbar spine to both sides and are involved in left and right rotation. |
Erector spinae heads: Iliocastalis, Longissimus, Spinalis |
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lower back |
Lower back extends and rotates spine. |
Biceps brachii heads: Long head, Short head |
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biceps, front arm |
Bicpes flexes elbow and rotates forearm to the inside. |
Triceps brachii heads: Long head, Lateral head, Medial head |
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triceps, rear arm |
Triceps extends elbow. |
Brachioradialis |
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forearm |
Brachioradialis is involved in flexing elbow. |
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