Muscular System

Week 4 - Overview of Muscular System The body has over 600 muscles. These muscles function to allow a large range of movement, both consciously and unconsciously. The body’s health relies on subconscious movements, for example the diaphragm and intercostal muscles for breathing.

Functions of the Muscular System 1.Body Movement 2.Adequate Posture 3.Essential Bodily Functions

Body Movement All muscles that we constantly control are attached to our bones. The central nervous system sends a message to the relevant muscle. The muscle then pulls the bones to produce the desired movement.

Adequate Posture Muscles are continually in a state of ‘tone’ that affects their ability to help our body maintain an upright posture when awake and to function safely during sleep. People with poor muscle tone generally have poor posture and resultant aches and pains because gravity is defeating the muscles’ resistance. Muscles of the back influence muscle posture.

Essential Body Functions The involuntary muscles that we have no control over are continuously functioning and preserving our ongoing bodily needs whether we are awake or not. The heart is a muscle over which we generally have little control, and muscular effort also controls our digestive and breathing demands.

Structure of Muscles The middle of each muscle is normally the thickest part, this is known as the muscle belly. At the ends of each muscle is a tendon that attaches the muscle to bone that it is to move. Muscles are made up of 2 types of proteins that are able to contract and relax. Inside muscle is stored energy that can be used when desired. Muscles also have a rich supply of nerves and blood vessels, and like bones, they contain water which adds to their weight.

Muscles of the Body You will need to know: - Deltoids - Hamstrings - Quadriceps - Pectoralis Major - Biceps - Gluteals - Abdominals - Trapezius - Triceps - Gastrocnemius - Latissimus Dorsi

Week 5 – Names and Classifications of Muscles There are three different types of muscle in the body. They are skeletal, smooth and cardiac muscle. Each type of muscles has a different role to play within the body.

Skeletal Muscles These types of muscles are often called striated muscles because of their appearance. Skeletal muscles have a microscopic striped appearance. These muscles are voluntary muscles and work to produce movement of the limbs etc.

Skeletal Muscle cont… Skeletal muscles create movement by pulling on the muscles which they are attached to. Muscles can only pull not push, so they need to work in pairs to produce movement. For example, when the bicep pulls up, the tricep needs to relax or stretch to allow movement. Then, when the arm is pulled back down the bicep needs to relax while the tricep contracts. The same process occurs when you kick a football, the quadriceps pull and contract while the hamstring relax and lengthen.

Smooth Muscle Are found in the digestive system and the walls of other vital organs such as the bladder and blood vessels. These muscles are classed as involuntary as we have no conscious control over their movements. Smooth muscles help with the digestion of food. For example the oesophagus contracting to move food to the stomach.

Cardiac Muscle Is the muscle of the heart. It is also striated, like the skeletal muscle, but is involuntary, like smooth muscle. This is an effective combination for its demanding role for a persons health and wellbeing.

Connective Tissue…in detail Has an important role in both the skeletal and muscular system. It is classed as soft tissue as it does not have the rigidity that bone has and it does have the flexibility of soft tissue, as well as all the strength that collagen provides.

Cartilage This smooth, elastic tissue is found in different forms in the body. Hyaline cartilage coats the ends of bones in synovial joints. Discs of cartilage separate the vertebrae in the spine. Ribs attach to the sternum via cartilage. The hard part of the ear, and your nose are also cartilage.

Tendons As we already know, connect muscle to bone. They are inelastic and very strong to allow movement by muscles pulling through the joint and on the bones. The biceps muscle is an example of a muscle that works through two joints It has two tendonous origins at the scapular (allowing the humerus to flex away from the body) and the tendonous insertion into the radius in the forearm allows the forearm to flex upwards towards the humerus.

Muscle Fibres There are two muscle fibre types within the muscular system. These are called slow twitch fibres (red) and fast twitch fibres (white). Each is better suited to a different intensity of physical activity.

Fibre Types

Skeleton and Muscle Quiz the-skeletal-and-muscular- systems-video-quiz-video.htm Week 6

Week 7 - Muscular Contractions There are three types of muscular contractions: – Isotonic – Isokinetic and; – Isometric

Isotonic Contractions These contractions change the length of the muscle when creating a force. Muscle shortening = concentric contraction Muscle lengthening = eccentric contraction

Isokinetic Contractions These contractions allow the performer to work at a constant velocity against a weight or resistance that changes as the performer moves through the working muscles possible range of movement. These contractions are only possible with specialised equipment. Muscles are stronger or weaker depending on the degree of flexion around the joint. Isokinetic equipment is able to accommodate these differences and allow the muscle to work maximally at all degrees of flexion throughout the training movement

Isometric Contractions This contraction creates force but there is no change in the muscle length. This contraction produces the most amount of force for any contraction type and as such the muscle tires quickly. Eg, rugby scrum, balance in gymnastics.

Origin and Insertion to Create Movement The origin is the attachment that is closer (proximal) to the body. The insertion is further away (distal) from the midline of the body. The insertion is usually attached to the bone that moves the most when the muscle contracts.

Week 8 – Nervous Control of Muscles To enable the muscles to move, the brain must send electrical nervous messages to the muscle. These message travel through the spinal cord to the motor nerves which branch from the spinal cord to the appropriate muscle. Leaving the spinal cord, the nerve splits into motor neurons which then divide a number of times to attach to individual muscle fibres. When the neurons meets the muscle fibres there is a gap (called the neuromuscular junction or synaptic cleft) across which the nerve impulse has to jump.

Neurotransmitter Acetylcholine is the name of the neurotransmitter that helps the nerve impulse make that jump. The muscle will continue to contract for as long as the brain continues to send it messages and the relevant energy sources lasts.

Motor unit One motor neuron and the fibres that it controls is called a motor unit. When an electrical impulse tells the fibres to contract, all the fibres linked to this nerve contract totally. This is called the all or none principle. This does not mean that all of the fibres within one muscle are always contracted, just the ones connected to that particular motor neuron. For example, fewer motor neurons would be stimulated for picking up a can then to perform a bicep curl.

The Process of Muscular Contraction