Muscles

Function of Muscle

1. Muscle tissue is responsible for all body movements. This includes body motion as in walking (Skeletal Muscle) but also organ movement (smooth muscle) such as dilation of blood vessels or heart contraction (Cardiac Muscle).

2. Muscles support the functions of most our systems that keep us alive: ie – respiration, digestion, blood circulation …

3. Heating of body, muscle contractions give off heat and help maintain body temperature. Shivering warms the body when muscles in the skin contract reflexively due to cold.

Muscle TissueSkeletal, Cardiac and Smooth

Cardiac Muscle

• Found only in the heart. Able to contract independently of the brain but requires signals from the brain to beat in correct sinus rhythm.

Anatomy of a Skeletal MuscleSkeletal muscle attaches to bone and moves our skeleton

Skeletal muscle is called voluntary muscle as it requires a conscious command from the brain in order to move

Smooth Muscle tissue is found in the organs and vessels of the body. Smooth muscle is called an involuntary muscle because it requires no

conscious signal from the brain to do its function and movements.

How Many??

• There are over 600 different muscles in our body. Some are very large for gross motor movement (kicking a ball) and some very tiny fine motor control (blinking).

Tendon vs LigamentTendon – attaches muscle to boneLigament – attaches bone to bone

Properties of Muscle Fibre

Conductivity – can transmit an electrical or neural impulseContractibility – ability to shorten in lengthExtensibility – able to extend and become longer over time (flexibility training/stretching)Elasticity – able to be stretched and return to normal lengthIrritability – ability to respond to a stimulus (nerve impulse)

Muscle Fibers

• Muscle Fibers are about the diameter of a human hair, they can contract about ½ their length and can lift about 1000 times their weight.

• Muscle Fibers are malleable. When stimulated by an electrical impulse they contract but need to be pulled back by another force to return to their original length.

Motor UnitA motor unit consists of the nerve (neuron) and all the fibers connected to it. When a neuron is stimulated all of its fibers will contract completely. This is called the All or None Principal. The number of motor units stimulated the stronger the muscle contraction and vice versa.

Gross Motor MovementsBig muscles with small # of motor units but each motor unit controls larger numbers of

muscle fibers

Fine Motor

• Small muscles with lots of motor units to control them but each motor unit controls fewer numbers of muscle fibers.

Eccentric, Concentric and IsometricContractions

Muscle Strength

• Muscles can adapt to use. Muscle fibres get thicker and stronger if they are exercised regularly over time.

Micro Tears, Overload, Rest and RecoveryStrength Training

• During weight resistance training we try to overload a muscle. This means work it beyond its normal strength

• Overloading results in micro tears in the muscle fibers. Tiny lesions in the fibers open up.

• During rest and recovery over the next 24 hours the tears heal and make the fiber a bit larger in diameter and as a result stronger

• Over time repeated training will result in larger fibers and bigger, stronger muscles.

Muscle Concepts• Transient Hypertrophy – Muscle temporarily get larger during exercise due to

increased blood flow. This lasts only for 30 minutes or so after exercise. Does not increase strength.

• Chronic Hypertrophy – Muscle fibers diameters get bigger as they adapt to repeated exercise training. As fibers get larger the muscle gets bigger and stronger over time.

• Muscle Atrophy - Muscle fiber diameters get smaller over time as a result of lack of use or training. Results in loss of strength.

• Hyperplasia – An unproven theory that increases in strength due to exercise actually result in muscle fibers splitting and increasing in number to account for increased strength.

• Voluntary Muscle – muscles that we consciously control like leg muscles for walking

• Involuntary Muscle – muscles that function without conscious control like our organs – blood vessels, stomach, heart…

Transient Hypertrophy the muscle increases size from increased blood flow, temporary (30 min) and no strength gain

Chronic Hypertrophy – muscle gets larger and stronger from training

Muscle Atrophy – muscle shrinks from disuse

Voluntary and involuntarymuscle

• Voluntary like writing

• Involuntary like pupil dilation

Naming Muscles

• Location: Tibialis Anterior muscle• Shape: Trapezius• Action: Extensor Digitorum• Direction of Fibres: Tranversus Abdominus• Attachment Points: Sternocleidomastoid• Number of Heads: Biceps, Triceps

Location: Tibialis Anterior muscle

Shape: Trapezius

Action: Extensor Digitorum

Direction of Fibres: Tranversus Abdominus

Attachment Points: Sternocleidomastoid

Number of Heads: Biceps, Triceps

Muscle PairsAgonist and Antagonist

• Example – Muscles work in pairs to counteract each other’s movement. Example: the bicep is called the agonist (primary mover) and the tricep is the antagonist (returns the arm to its original position.

Tendons, Origin and Insertion

• Tendons connect the muscle to bone.• Origin is the connection we call an anchor, it does not move

during the contraction• Insertion is the connection that moves a bone during the

contraction.• www.getbodysmart.com/ap/muscularsystem/menu/menu.html

Muscle Strain and TearsSymptoms: Pain, Weakness & Function

Muscle Strains/Tears

Treatment of muscle injury

Rest – it takes time for the muscle to repairIce – helps reduce the swelling and painCompression – helps hold muscle in line and

reduce the pain and swelling

Return to action when function is no longer impaired.

Returning too soon may result in re injury