INTRODUCTIONHumans have over 650 muscles which differ in

size according to the jobs they do.

These muscles constitute 40% of our  body weight. The special function of muscle tissue is contraction. 

CONTRACTION: a shortening or tensing of a part or organ (especially of a muscle or muscle fiber)

TYPES OF MUSCLEVOLUNTARY/SKELETAL MUSCLE

INVOLUNTARY MUSCLE

CARDIAC MUSCLE

VOLUNTARY/SKELETAL MUSCLEMuscle that is under the control of the will and is

generally attached to the skeleton

Fast acting, Powerful, Eventually will tire

FOR EXAMPLE: Biceps and Deltoids

INVOLUNTARY MUSCLEMuscle whose activity is not under the control of the will;

it is supplied by the autonomic nervous system -The part of the vertebrate that supplies stimulation via motor nerves to the smooth and cardiac muscles (the involuntary muscles) and to the glands of the body

Slow actingWe do not have conscious controlWeak.

FOR EXAMPLE: Muscles of Digestive Tract/Bladder

CARDIAC MUSCLEA type of muscle with unique features only found in the

heart. The cardiac muscle is the muscle of the heart and medically is called the myocardium.

Own blood supply Does not tire Fast actingPowerful

FUNCTIONING OF A MUSCLEMuscle has only one function and that is to contract.

Muscles are attached to bones by tendons so when a muscle contracts it pulls on the bones that it is attached to and the result is movement of that bone.

The type of movement is determined by the joint at which the bone occurs.Because a muscle can only contract it can not move the bone back to its original position, i.e. it can not relax. So muscles usually work in pairs of opposites (Antagonistic pairs).

FUNCTIONING OF A MUSCLE(continued)

Although muscles are known individually by the particular anatomical name, they are also known collectively by the type of movement that their contraction creates. E.g. When the biceps contracts it bends the arm and pulls the hand up towards the shoulder. The movement that has occurred is flexion at the elbow.

– So the biceps is known as a “Flexor” muscle.The opposite movement is extension and the triceps is known as an

“Extensor” muscle

MUSCLE ATTACHMENTMuscles are attached to bones by tendons.

Tendons are fibrous straps that grow out of the bone and into the muscle. They are very strong and elastic, indeed the Achilles tendon is the strongest thing in the body.

ORIGIN AND INSERTIONA muscle is attached to at least two bones. These two attachments are different and are known by different names:

ORIGIN and INSERTIONThe origin is the point of attachment for the muscle to

the bone that it is anchored to. The point of insertion is the point of attachment for the muscle to the bone that it moves.

EX: The point of origin for the Biceps is the Scapula and the point of insertion is the radius i.e. it does not move the scapula but it does move the radius. 

DIFFERENT ROLES OF MUSCLE

Different muscles perform different functions…sometimes at different times

AGONIST (Prime Mover)

This is the muscle whose contraction and subsequent pull on the insertion tendon creates the movement

EX: the hamstrings when bending the leg to run.

ANTAGONIST

This is the muscle that is relatively passive during the movement, but that will become the prime mover when the body part is returned to its original position

EX: the quadriceps during the first part of the stride when running.

SYNERGISTThis is the muscle that helps to stabilize the body part that is being moved.

It is adjacent to the insertion tendon. EX: around the elbow during the bicep curl

(Biceps is the agonist, Triceps is antagonist).

FIXATORThis is the muscle that provides stability at the point

of origin for the working muscle, -

EX: The muscles of the shoulder and upper back during the bicep curl.

TYPES OF MUSCLE FIBERMuscle Fiber can be either:

SLOW TWITCH – (Type 1)

Endurance Fiber, works well with oxygen, aerobic Ex: Long Distance Runners

FAST TWITCH – (Type 2)

Power Fiber, Quick Bursts

anaerobic Ex. Sprinters, Power Lifters

Slow-TwitchSlow-twitch fibres contract slowly

and can be used for longer periods of time. Postural muscle of the back are composed of mostly slow-twitch muscle fibers. Athletes who run long

distances need more slow-twitch fibers in their legs. Slow-twitch

muscle fibers rely on oxygen as their main energy source.

Fast-TwitchFast-twitch fibers contract quickly and

provide strength and speed, though they also fatigue more quickly. Sprinters require short but intense bursts of

energy and therefore need more fast-twitch muscle fibers. Fast-twitch muscle fibers rely on ATP and glycogen as their

main energy source. As ATP sources can be rapidly depleted, lactic acid is a

by product of the breakdown of glycogen, fast-twitch fibers can only be

active for a short period of time..