Body & Mind Training Center

Saddle: Flexion/Extension/Adduction/Abduction/Circumduction


CMC joint of the thumb





Saddle joint





Condyloid : Flexion/Extension/Adduction/Abduction/Circumduction


Wrist/MCP & MTP joints





Condyloid joint





Gliding : Gliding movements


Intercarpal joints





Gliding joint

Types of Muscle :


There are three types of muscle found in the human body:

Skeletal Muscle
Smooth Muscle
Cardiac Muscle (heart muscle




Skeletal muscle :

Skeletal Muscles are those which attach to bones and have the main function of contracting to facilitate movement of our skeletons. They are also sometimes known as striated muscles due to their appearance. The cause of this 'stripy' appearance is the bands of Actin and Myosin which form the Sarcomere, found within the Myofibrils.

Skeletal muscles are also sometimes called voluntary muscles, because we have direct control over them through nervous impulses from our brains sending messages to the muscle. Contractions can vary to produce powerful, fast movements or small precision actions. Skeletal muscles also have the ability to stretch or contract and still return to their original shape.


Skeletal muscle fibre type :

Not all fibres within Skeletal muscles are the same. Different fibre types contract at different speeds, are suited to different types of activity and vary in colour depending on their Myoglobin (an oxygen carrying protein) content.


Smooth muscle :

Smooth muscle is also sometimes known as Involuntary muscle due to our inability to control its movements, or Unstriated as it does not have the stripy appearance of Skeletal muscle. Smooth muscle is found in the walls of hollow organs such as the Stomach, Oesophagus, Bronchi and in the walls of blood vessels. This muscle type is stimulated by involuntary neurogenic impulses and has slow, rhythmical contractions used in controlling internal organs, for example, moving food along the Oesophagus or contricting blood vessels during Vasoconstriction.


Cardiac muscle (heart muscle :

This type of muscle is found solely in the walls of the heart. It has similarities with skeletal muscles in that it is striated and with smooth muscles in that its contractions are not under conscious control. However this type of muscle is highly specialised. It is under the control of the autonomic nervous system, however, even without a nervous imput contractions can occur due to cells called pacemaker cells. Cardiac muscle is highly resistant to fatigue due to the presence of a large number of mitochondria, myoglobin and a good blood supply allowing continuous aerobic metabolism.

Skeletal Muscle Cell Structure :


Although skeletal muscle cells come in different shapes and sizes the main structure of a skeletal muscle cell remains the same.


Muscle Anatomy:

If you were to take one whole muscle and cut through it, you would find the muscle is covered in a layer of connective muscle tissue known as the Epimysium. The Epimysium protects the muscle from friction against other muscles and bones.
It also continues at the end of the muscle to form (along with other connective tissues) the muscles tendon. Looking at the cross section of the muscle you can see bundles of fibres / fibers, known as Fasciculi, which are surrounded by another connective tissue, called the Perimysium. Each Fasciculi contains anywhere between 10 and 100 muscle fibres, depending on the muscle in question.




A large strong muscle, such as thoses forming your Quadriceps would have a large number of fibers within each bundle. A smaller muscle used for precision movement, such as those in the hand would contain far fewer fibres per Fasciculi.

Looking at each muscle fiber in detail, you can see they too are covered in a fibrous connective tissue, known as Endomysium which insulates each muscle fiber. Muscle fibers can range from 10 to 80 micrometers in diameter and may be up to 35cm long.



Beneath the Endomysium and surrounding the muscle fibre is the Sarcolemma which is the fibres cell membrane and beneath this is the Sarcoplasm, which is the cells cytoplasm, a gelatinous fluid which fills most cells.

This contains Glycogen and Fats for energy and also Mitochondria which are the cells powerhouses, inside which the cells energy is produced.

Each muscle fiber itself contains cylindrical organelles known as Myofibrils. Each muscle fiber contains hundreds to thousands of Myofibrils. These are bundles of Actin and Myosin proteins which run the length of the muscle fiber and are important in muscle contraction.

Surrounding the Myofibril there is a network of tubules and channels called the Sarcoplasmic Reticulum in which Calcium is stored which is important in muscle contraction. Transverse tubules pass inwards from the Sacrolemma throughout the Myofibril, through which nerve impulses travel.

Each Myofibril can then be broken down into functional repeating segments called Sarcomeres.

Muscle Fiber Types :


Within skeletal muscle there are three types of fiber:

Type I

Type I fibers are also known as slow twitch fibers. They are red in colour due to the presence of large volumes of myoglobin and so oxygen and high numbers of Mitochondria. Due to this fact they are very resistant to fatigue and are capable of producing repeated low-level contractions by producing large amounts of ATP through an aerobic metabolic cycle.

For this reason the muscles containing mainly type I fibers are often postural muscles such as those in the neck and spine due to their endurance capabilities Also, athletes such as marathon runners have a high number of this type of fiber, partly through genetics, partly through training.


Type II a

Type IIa fibers are also sometimes known as fast oxidative fibres and are a hybrid of type I and II fibers. These fibers contain a large number of mitochondria and Myoglobin, hence their red colour. They manufacture and split ATP at a fast rate by utilising both aerobic and anaerobic metabolism and so produce fast, strong muscle contractions, although they are more prone to fatigue than type I fibers. Resistance training can turn type IIb fibers into type IIa due to an increase in the ability to utilise the oxidative cycle.


Type II b

Often known as fast glycolytic fibers they are white in colour due to a low level of myoglobin and also contain few mitochondria. They produce ATP at a slow rate by anaerobic metabolism and break it down very quicky. This results in short, fast bursts of power and rapid fatigue. As mentioned above, this type of fiber can be turned into type IIa fibers by resistance training. This is a positive change due to the increased fatigue resistance of type IIa fibers. These fibers are found in large quantities in the muscles of the arms.

Shapes of Muscles


What are the different shapes of muscle ?

There are 5 different muscle shapes within the human body:

Circular
Convergent
Parallel
Pennate
Fusiform


Circular Muscles :

These muscles appear circular in shape and are normally sphincter muscles which surround an opening such as the mouth, surrounded by Obicularis Oris and Obicularis Oculi surrounding the eyes


Convergent Muscles :

These are muscles where the origin (the attachment to a fixed bone, usually the proximal attachment) is wider than the point of insertion. This fibre arrangement allows for maximum force production. An example is Pectoralis Major. Convergent muscles are also sometimes known as triangular muscles.





Parallel Muscles :

Parallel muscles have fibres which, as the name suggests, run parallel to each other and are sometimes called strap muscles.

They are normally long muscles which cause large movements, are not very strong but have good endurance. Examples include Sartorius and Sternocleidomastoid. Some textbooks include Fusiform muscles in the parallel group.






Pennate Muscles :

Pennate muscles have a large number of muscle fibres per unit and so are very strong, but tire easily. They can be divided into:

Unipennate: These muscles have their fibres arranged to insert in a diagonal direction onto the tendon, which allows great strength. Examples include the Lumbricals (deep hand muscles) and Extensor Digitorum Longus (wrist and finger extensor)
Bipennate: Bipennate muscles have two rows of muscle fibres, facing in opposite diagonal directions,with a central tendon, like a feather. This allows even greater power but less range of motion. An example is the Rectus Femoris




Multipennate: As the name suggests Multipennate muscles have multiple rows of diagonal fibres, with a central tendon which branches into two or more tendons. An example is the Deltoid muscle which has three sections, anterior, posterior and middle.


Fusiform Muscles

Sometimes included in the parallel muscle group, these muscles are more spindle shaped, with the muscle belly being wider than the origin and insertion. Examples are Biceps Brachii and Psoas major

Types of Muscle Contraction :


Muscle Contractions can be divided into:

Isotonic (meaning same tension)
Isometric (meaning same distance or not moving)
Isokinetic (meaning same speed)


Isotonic Contractions :

Isotonic contractions are those which cause the muscle to change length as it contracts and causes movement of a body part. There are two types of Isotonic contraction:


Concentric :

Concentric contractions are those which cause the muscle to shorten as it contracts. An example is bending the elbow from straight to fully flexed, causing a concentric contraction of the Biceps Brachii muscle. Concentric contractions are the most common type of muscle contraction and occur frequently in daily and sporting activities.


Eccentric :

Eccentric contractions are the opposite of concentric and occur when the muscle lengthens as it contracts. This is less common and usually involves the control or deceleration of a movement being initiated by the eccentric muscles agonist.

For example, when kicking a football, the Quadriceps muscle contracts concentrically to straighten the knee and the Hamstrings contract eccentrically to decelerate the motion of the lower limb. This type on contraction puts a lot of strain through the muscle and is commonly involved in muscle injuries


Isometric Contractions :

Isometric contractions occur when there is no change in the length of the contracting muscle. This occurs when carrying an object in front of you as the weight of the object is pulling your arms down but your muscles are contracting to hold the object at the same level. Another example is when you grip something , such as a tennis racket. There is no movement in the joints of the hand, but the muscles are contracting to provide a force sufficient enough to keep a steady hold on the racket.

The amount of force a muscle is able to produce during an isometric contraction depends on the length of the muscle at the point of contraction. Each muscle has an optimum length at which the maximum isometric force can be produced.


Isokinetic Contractions :

Isokinetic contractions are similar to isotonic in that the muscle changes length during the contraction, where they differ is that Isokinetic contractions produce movements of a constant speed. To measure this a special piece of equipment known as an Isokinetic Dynamometer is required. Examples of using isokinetic contractions in day-to-day and sporting activites are rare. The best is breast stroke in swimming, where the water provides a constant, even resistance to the movement of adduction.