Muscles • Every movement of your body depends on muscles. There are three different types of muscles: • INVOLUNTARY MUSCLE (SMOOTH) - is found in the body’s internal organs. It performs its function without any conscious control, but usually quite slowly.
VOLUNTARY OR SKELETAL MUSCLE (also known as ‘striped’ or ‘striated’ muscle) - mainly found attached to the skeleton, capable of rapid contraction which cause skeletal movement. It is under our conscious control. • CARDIAC MUSCLE - is only found in the heart and is also involuntary. It never stops working until we die. It pumps blood from our heart around the body.
Voluntary Muscle - How They Perform In Detail • FRONT • DELTOIDS - create abduction at the shoulder and raise your arm sideways, e.g. swimming arm action. • PECTORALS - create adduction at the shoulder across the chest, e.g press ups. • BICEPS - allows flexion at the elbow, e.g. chin-ups. • ABDOMINALS - allow you to flex your trunk, e.g. sit -ups. • QUADRICEPS - makes extension of the leg possible at the knee, e.g. squats, kicking.
BACK • TRAPEZIUS - allows rotation of the shoulders, e.g. cricket bowling action. • LATISSIMUS - adduction at the shoulder behind your back, e.g. rope climb. • TRICEPS - creates extension at the elbow, e.g. press-ups, throwing. • GLUTEALS - allow extension, abduction and adduction at the hip (gluteus maximus is the biggest Gluteal). E.g. squats, jumping. • HAMSTRINGS - these allow flexion of the knee, e.g. sprinting (leg action recovery) • GASTROCNEMIUS - allows you to stand on your tiptoes, by creating extension at the ankle, e.g. sprinting (start).
Muscle Attachment • voluntary muscles are attached to your skeleton by TENDONS, usually across a synovial joint. These are fibrous and INELASTIC. • the point where the muscle tendon attaches to the fixed or stationary bone is called the ORIGIN. • the point where the muscle tendon attaches to the moving bone is called the INSERTION. • as muscles contract they shorten. This makes the joint move. • WHEN A MUSCLE CONTRACTS THE INSERTION MOVES TOWARDS THEORIGIN.
HOW MUSCLES WORK • muscles can only create movement in one direction - by becoming shorter. This means that you need two muscles at every joint to allow movement in two directions. • Therefore MUSCLES WORK IN PAIRS. For example, when your biceps CONTRACTit makes your elbow flex pulling your forearm up. To allow your elbow to extend, you need your triceps to CONTRACTand pull your arm back down. Meaning the biceps are RELAXING.
All muscles have fast and slow twitch fibres or a mixture of the two. The proportions are inherited. • FAST TWITCH FIBRES • produce powerful contractions very quickly (explosive) • these fibres become fatigued in a short time • great for sprinting and fast bowling • SLOW TWITCH FIBRES • produce less powerful, slower contractions. • become fatigued less quickly. • ideal for endurance events. E.g. marathon running.