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There are 3 types of muscles in the body:


SKELETAL muscles are generally attached to the bones and creates movement at a joint. Controlled by the somatic portion of the nervous system which makes many of its functions voluntary or under our conscious control.

SMOOTH muscle lines the inside of blood vessels and organs, such as the stomach, and is also known as visceral muscle. It is the weakest type of muscle but has an essential role in moving food along the digestive tract and maintaining blood circulation through the blood vessels. Smooth muscle acts involuntarily, it is controlled by the autonomic nervous system. 

CARDIAC muscle, located only in the heart, pumps blood around the body. Cardiac muscle stimulates its own contractions that form our heartbeat. Signals from the nervous system control the rate of contraction. This type of muscle is strong and also acts involuntarily.


The main functions of the muscular system are: 


Mobility | Stability | Posture | Circulation | Respiration | Digestion | Urination | Childbirth | Vision |  Organ protection | Temperature regulation


What we usually think of as a working muscle is actually an organ made up of at least 4 different tissues : The muscle tissue itself has the ability to contract and create movement. The connective tissue communicates the power of that contraction to whatever the muscle is connected to; bones, organs or skin. The nerves tell the muscles to fire, for how long and what intensity. The blood vessels provide nourishment that allows the muscle tissue to become active. 



Taking a look at muscle tissue, it is surrounded both by multi-directional sheets of connective tissue, fascia, but also has fascial fibres running through and around each compartment and every muscle fibre. Think oranges. 

  • The integrity of muscle relies entirely on the fascia that surrounds it and holds it in place. 

  • Fascia facilitates muscular movement, providing surfaces that slide and glide easily on each other. This gives us full range of movement and easy coordination of our movement. For muscle to contract or stretch it needs to be free to change its shape.

  • Lack of movement causes our body to think it wants lack of movement, forming limiting trains of tension in the body. Fascia can dry out and lose its fluidity. Over use and injury also a problem. Fascia can become unhealthy; can stick together become clumpy, tight, and flaky, forming restrictions, adhesions, and distortions. Normal tissue fibers line up parallel to one another, scar tissue develops in a haphazard way, limiting movement. Yoga and other myofascial therapies work by reopening the tissues in question, restoring muscle function, connection with the sensory motor system and an easing of the biomechanics pull that caused the increased stress on that tissue in the first place. 

  • All the circulation in your body has to pass through these fibrous webs. Generally speaking, the denser the fibers and the drier the mucous, the less the fascial web allows molecules to flow through it: nourishment in one direction and waste in the other. Yoga helps both stretch and ease the fiber webbing, as well as hydrate the gel, making it more permeable.

  • Gives muscles their ability to transmit force to the tendons and thus to the bones resulting in a movement around the joints. 

  • Makes the body more efficient in maintaining tension. As the muscle fascia swells during contraction and presses against nearby muscles, these neighbouring muscle groups are pre-tensed, making them more effective and efficient. Tension is created and maintained not only by individual muscles doing their thing, but by the whole system of fascia




CONTRACTIBILITY - ability to shorten.

EXTENSIBILITY - ability to lengthen. 

ELASTICITY - ability to return to its normal tone.

ELECTRICAL EXCITABILITY - responds to nerve impulses.

Muscle actions :


Concentric Contraction:  The muscles shortens whilst contracting.

Eccentric (Contraction) Activation: The muscle is activated, trying to contract but is getting longer. (returning arm length after a bicep curl)

Isometric (Contraction) Activation: The muscle tries to contract but is held at a constant length. (holding a bicep curl)


Primary body movements :


  • Flexion 

  • Extension  

  • Rotation 

  • Abduction 

  • Adduction

  • Lateral Flexion

Muscles work in pairs :


Muscles pull in one direction. AGONIST is the prime mover of a joint and ANTAGONIST its opposite muscle. When you consciously signal a muscle to contract, the brain simultaneously signals its antagonist muscle to relax, a phenomenon known as reciprocal inhibition which allows movement. Engaging your quadriceps in the forward fold will signal the relaxing of the hamstrings. 

muscular STRENGTH



Flexibility is not only determined by the actual physical length of the muscle or of the muscle fibers that compose that muscle. The resting length of the muscle, its tone, and the amounts it will lengthen are all set by the proprioceptive nerve endings in the muscle. This setting is established in the nervous system through previous experiences regarding what is appropriate, safe, and functional. The amount of strength that muscle has is more dependent on its physical properties, including the actual number of muscle fibers. Muscle strength is also a product of the way that the nervous system recruits fibers and organises the surrounding muscles and kinetic chains. When the nervous system is inefficient in the way it recruits and organises muscles, it diminishes the functional strength of a muscle by creating a situation where the muscle has to exert effort to overcome resistance from other muscles in the body. 


Increasing flexibility and strength is the process of re-educating the nervous system through conscious attention and practice as much as it is about stretching and repetitions.


major muscles



In practice we cannot isolate individual muscles, that make up a muscle group, so we will be grouping them into functional groups. In teaching it’s not important to recite every tiny individual muscle that make up a group. Whether you’re doing it right or wrong isn’t based on how it looks, it’s are you feeling it in the appropriate areas. 




Sternocleidomastoid - Flex and side bend head

Scalenes - Flex and rotate head. Raises ribs.

Pecs : Pectoralis Major - Horizontal adduction, adduct, flex and inwardly rotate arm. Pectoralis Minor - Draw scapula forward and down.

Psoas Major and Minor - Flex hip. Psoas is a major stabiliser of the lower back, working in conjunction with the QL

Iliacus - Flex Hip

Obliques Internal, External and Transverse - Rotate, flex and side bend trunk. Support viscera and assist exhalation.

Rectus Abdominus - Flex trunk.




Levator Scapula - Raise scapula or rotate and side bend head. 

Rhomboids - Brace and rotate scapula and pull it towards spine

Serratus Anterior - Pull scapula forward (protract) and rotate it.

Quadratus Lumborum - Unilaterally : side bend trunk and Bilaterally : extends lower back. A major stabiliser of the lower back, working in conjunction with Iliacus and Psoas

Trapezius - Stabilise the scapula. Pull scapula towards the spine, some elevation, rotation and adduction. Upper part can also extend and rotate neck.

Latissimus Dorsi - Adducts, draw back (extend) and inwardly rotate arm.

Deep Spinal Muscles - Intervertebral movements: Extension, side bending and rotation. 

The Spinal Erectors -  a set of muscles that extend and side bend spine.

Splenius Cervices - Extend and side bend spine and rotate head. Splenius Capitus - Extend and rotate head. 




Rotator Cuff muscles - Maintain joint stability by holding the head of the humerus in the glenhoid cavity of the scapula.

Teres Major - Adduct, extend and inwardly rotate arm. 




Triceps Brachii - Extend elbow. Long head : slight adduction of shoulder. 

Posterior Forearm Muscles - Extend elbow, wrist thumb and fingers.  Spread fingers. Supinate forearm.



Deltoids : Anterior Deltoid - Draw arm foreword, inwardly rotate and abduct arm. Medial Deltoid - Abduct arm. Posterior Deltoid - Draw arm back and abduct arm.

Biceps Brachii - Strong flexor and supinator of forearm. Help abduct (long head) and adduct ( short head) the shoulder. 

Brachialis - Flex elbow.  

Anterior Forearm Muscles - Flex wrist, thumb and fingers. Pronate and flex forearm.  




Glutes : Gluteus Maximus - Extend and outwardly rotate hip, extend trunk. Proximal part : slight abduction. Distal part : slight adduction. Gluteus Medius & Minimus - Anterior: Flex and inwardly rotate hip. Posterior: Extended and outwardly rotate hip. (Glutes have an attachment into the IT Band which is a thick band of fascia that runs all the way down to the outside of the knee — so if you are doing a Glute stretch you might feel it all the way down the side of the leg.)

Piriformis , Obturator Internus, Gemellis Superior and Inferior - Outwardly rotate and abduct hip. 

Obturator Externus & Quadratus Femoris - Outwardly rotate hip.

Hamstrings: Biceps Femoris - Flex knee, outwardly rotate it when flexed, and extend hip. Semimembranosus & Semitendinosus - Flex knee, inwardly rotate it when flexed, and extend hip.

Calf Muscles : Gastrocnemius & Soleus : Plantaflex foot and flex knee. 

Tibialis Posterior - Plantaflex and invert foot. 





Quadriceps : Rectus Femoris - Flex hip and extend knee. Vastus Lateralis, Vastus Intermedius, Vastus Medialis - Extend knee.

Sartorius : Flex hip and knee, outwardly rotate and abduct hip. Inwardly rotate knee.

Inner Thigh Muscles :  Adductor Magnus, Brevis, Longus - Adduct leg and slight outward rotation. Pectineus - Adduct and flex hip and slight inward rotation. Gracilis - Adduct leg and flex knee. 

Tensor Fascia Lata : Abduct hip and slight flexion and inward rotation. 

Tibialis Anterior : Dorsiflex foot and slight supination. 

Peroneals - Pronates foot and assist plantaflexion.  

Major Muscles
Muscle contraction
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