The muscular system

The Muscular System Muscles work in conjunction with the skeleton to help us move and perform basic functions Most muscles are arranged in pairs called “antagonistic” – they work as opposites of each other Muscles are never completely at rest There are approx700 muscles in the body Muscle makes up 1/5th of a persons total body weight

Functions of a muscle Movement Maintain posture Produce heat Contract after stimulation from either – Chemical, Mechanical, Electrical or heat source Muscles are approx. 70% water and 25% solids (the most important are proteins Actin & Myosin)

Muscle groups Muscles are often grouped together and named by a system according to: Function – flexors/extensors Attachment – sterno-cleido mastoid Shape – trapezius Formation – biceps/triceps Position - intercostals

How a muscle works Muscles have the following points of attachment: Origin – bone to which they are attached and don’t move Insertion – bone to which muscle attach and does move In order to contract, muscle fibres need adequate supplies of blood, oxygen, nutrients and waste removal systems

How a muscle works Discuss in pairs the origin and insertion of each of the following muscles; Biceps Gastrocnemius Hamstrings

How a muscle works Energy is brought to the muscles via the blood stream It is stored as glycogen until needed When required the glycogen combines with oxygen from the blood starting off a chemical chain reaction The result is energy and waste being produced

Types of muscle tissue Voluntary (striated) Under conscious control Contain collagen and elastin fibres Make up approx 40% of body weight Each fibre is linked to the CNS Fatigues easily if overused Reactions are quick and immediate

Types of muscle tissue Involuntary (smooth, visceral) Not under conscious control Found in the walls of internal organs (stomach, bowel) & Respiratory system Doesn’t fatigue Contraction is slower but more even

Types of muscle tissue Cardiac Only found in the heart Not under conscious control Doesn’t fatigue Strongest type of muscle tissue Self regulating contraction

Muscle contraction Muscles contract (shorten) to exert a force when stimulated by the CNS The motor nerve carries the impulse to a motor neuron in the muscle fibres The more fibres that are stimulated the shorter the muscle will become & therefore the stronger the contraction

Types of muscle contraction Concentric Muscle actively shortens & thickens Origin & insertion move closer together Produces heat in the muscles Can be used in all ranges of movement Try this yourself

Types of muscle contraction Eccentric Muscles lengthen Origin & insertion move further away (against gravity) Heat is produced Used in all ranges of movement Try this yourself

Types of muscle contraction Isometric Muscles contract becoming harder but stay the same length Sometimes known as static contraction Isotonic Muscles move against constant resistance This is how muscles work in weight training Try these!

Muscle tone State of partial contraction of muscle Linked to the maintanence of posture etc Always present in some fibres (even at rest) Weakest during sleep Only lost when the motor nerve supply is interrupted Poor tone indicated undersized muscles which fatigue easily. Contractions are slow & weak Excessive tone indicates tense muscles due to over development

How would you measure the tone of your clients muscles? Muscle tone How would you measure the tone of your clients muscles?

Effects of temperature Warm – faster contractions due to the chemical process being quicker. tone is reduced as temperature rises as more of the fibres relax Cold – chemical process slows down so does contraction speed Involuntary increase in muscle tone eventually results in “shivering”

Muscle fatigue Caused by an inadequate blood supply Due to over worked muscles – contractions slow & weaken, eventually stopping Muscle fibres do not all contract at the same time but do so in series As a result of fatigue there is a build up of lactic acid, waste products and carbon dioxide

Tendons Dense, connective tissue Connects muscles to bone Certain tendons are covered with a protective tube to allow for smooth and easy movement e.g. in the wrist Vary in length and size

Ligaments Connects bone to bone Provides support to structures Made of bundles of fibres laying parallel to each other Not very flexible Together they flex head Individually turn the head towards the shoulder