Muscular System Students Learn About: Major muscles involved in movement Muscle relationship (agonist, antagonist) Types of contraction (concentric, eccentric, isometric) Students Learn To: Identify the location of the major muscles involved in movement and related joint actions Perform and analyse, eg overarm throw by examining bones involved and the joint action and muscles involved ant the type of contraction

Muscular System There are three types of muscle tissue in the body: Skeletal muscle – is primarily attached to bones, and it moves the skeleton. It is said to be striated because of its obvious striped appearance. Contraction is under our direct control and so the movement of the muscle is said to be voluntary. Smooth muscle – is located on the walls of our internal structures, such as the stomach, blood vessels and intestines. It is nonstraited, and its movement is usually involuntary. Cardiac muscle – forms most of the heart. This muscle is striated and, because contractions occur without us knowing, its movement is said to be involuntary.

Muscular System There are three basic functions that muscle tissue serves through contracting and relaxing. Muscles can: Produce movement to walk, run, jump, breathe, digest and excrete Provide stabilisation of posture and internal organs Generate heat to maintain body temperature

Muscles of the Human Body

Muscle Origin and Insertion The muscle’s point of attachment to the more stationary bone is called its origin. In most cases, this point is nearer the trunk Insertion The insertion of a muscle is the point of attachment at the moveable end. This end tends to be away from the body’s main mass. Muscle Action The muscle action refers to movement make at the joint when the muscle contracts.

Types of Muscle Action In producing a particular movement, a muscle performs one of three roles. It can act as: An agonist An antagonist Or stabiliser (or fixator) Agonist An agonist or prime mover is the muscle causing the major action. There are agonist for all movable joints and usually more than one is involved in a particular joint movement. Antagonist An antagonist is a muscle that must relax and lengthen to allow the agonist to contract, this helping to control an action. Stabiliser Stabiliser or fixator muscles act at a joint to stabilise it, giving the muscles a fixed base.

Muscle Relationship Principle of reciprocal inhibition States that while the agonist muscle is contracting, a message is sent at the same time to the opposing muscle group to relax. This allows for smooth and efficient movement to occur. Without this process both muscles would be contracting at the same time and the weaker of the two could possibly tear.

Muscle Contraction There are three principal types of muscle contraction: Concentric Eccentric Isometric Concentric – A concentric contraction is the most common type of muscular contraction. During this contraction, the muscle shortens, causing movement at the joint. Eccentric – An eccentric contraction occurs when the muscle lengthens while under tension. The action often happens with the assistance of gravity.

Muscle Contraction Isometric – An isometric contraction occurs when the muscle fibres are activated and develop force, but the muscle length does not change, that is, movement does not occur. Examples include - hold the weight at 90 degrees at the elbow or to hold a plank position. In the elbow at 90 degree position the biceps is still producing a force against gravity, but it is not changing in length. For the plank, the abdominal and other core muscles are producing a force against gravity while not changing their length, therefore they are isometric contractions.