Transcript Antagonistic Muscles

Antagonistic Muscles
D. Crowley, 2007
Antagonistic Muscles
To know how antagonistic muscles work, and how sports
injuries occur
Skeleton
Our skeleton is made of more than 200 bones: calcium and
other minerals make the bone strong but slightly flexible
Bone is a living tissue with a blood
supply (it can repair itself if broken, and
exercise and a balanced diet are
important for a healthy skeleton)
The skeleton has three main functions:
Supporting the body
Protecting some of the vital organs
Helping the body move
Movement
Some bones in the skeleton are joined rigidly together and
cannot move against each other - bones in the skull are joined
like this
Other bones are joined to each
other by flexible joints - muscles
are needed to move bones
attached by joints
Antagonistic Muscles
Muscles can only pull, and they work by getting shorter
(contract)
As muscles can only pull, each joint is moved by a pair of
muscles - an antagonistic pair
Muscles are attached to
bones by strong tendons when a muscle contracts, it
pulls on the bone, and the
bone can move if it is part of
a joint
Joints
If two bones just moved against each other, they would
eventually wear away - this can happen in people who have
arthritis
To stop this happening, the
ends of the bones in a joint
are covered with a tough,
smooth substance called
cartilage, kept slippery by
synovial fluid
Tough ligaments join the two
bones in the joint and stop it
falling apart
Joints
Different types of joint allow different types of movement
Hinge joints allow simple movement, the same as a door opening
and closing, e.g. knee & elbow joints
Ball and socket joints allow
movement in more
directions, e.g. hip &
shoulder joints (the bones
cannot move on their own,
needing muscles
Antagonistic Model
Try and make a model of the biceps and triceps
The elbow joint lets our forearm move up or down, controlled by
two muscles, the biceps on the front of the upper arm, and the
triceps on the back of the upper arm: when the biceps muscle contracts, the forearm moves up
when the triceps muscle contracts, the forearm moves down
Forearm up
Biceps contract
(triceps relaxed)
Forearm down
Triceps contract
(biceps relaxed)
Sports Injuries
What are some common sports injuries?
Collar bone breakage / fracture
Wrist breakage / fracture
Ankle breakage / fracture
Plaster casts can be made to support the broken bone, giving it
support whilst it heals and is reset in the correct position
However, the cast stops the muscle from moving (as a result
they are much weaker when the cast is removed)
Sports Injuries
There are also some more common sports injuries, including: Pulled muscles - muscle fibres (linking muscle cells together)
are stretched or torn (but it is more usual to pull a tendon
(tendons attach the muscle to the bone)
Sprains - ligaments in a joint are torn (ligaments are cords
which attach the bones together)
Cartilage injuries - cartilage at the end of the bone gets torn,
and breaks up
Dislocations - bones in a joint move apart or out of line, so
they no longer work