JOINTS• Joints are where two or more bones articulate

(move).• Joints are classified according to how much

movement they allow.

1. Fibrous – these are fixed or immovable joints such as the cranium, sacrum and the coccyx.

2. Cartilaginous – these are slightly movable joints such as the vertebrae.

3. Synovial – these are freely movable joints such as the shoulder and hip.

Synovial joints• In PE these are the most important joints.• There are 6 types of synovial joint.

1. Ball & socket – hip and shoulder.

2. Hinge – knee, elbow and ankle.

3. Pivot – radio-ulna, atlas/axis.

4. Saddle – thumb.

5. Condyloid – wrist.

6. Gliding – between vertebrae in spine.

Ball & socket joints

The hip joint• The head of the femur fits into a

deep cavity called the acetabulum on the pelvic bone.

• This deep cavity gives the hip joint stability.

• The presence of strong ligaments add to the stability making it difficult to dislocate the hip.

The shoulder joint• The head of the humerus

fits into a shallow cavity on the scapula called the glenoid fossa.

• The shoulder is the most mobile joint in the body but is also fairly unstable because of the shallow cavity.

• Stability is improved by ligaments and muscles.

Hinge Joints

The knee joint• In the knee joint the

femur articulates with the tibia.

• The patella (knee cap) helps to give a better angle of pull.

• The fibula is not part of the knee joint and so the tibia is the weight bearing bone.

• The ankle joint• In the ankle the talus

articulates with the tibia and fibula.

• Ligaments provide stability to the joint.

• The elbow joint• In the elbow the

humerus articulates with the radius and the ulna.

• Movement can only occur in one plane.

The pivot joint

• The radio-ulna • In this joint the radius

and ulna articulate within the elbow joint.

• This joint allows the elbow some twisting movement (pronation & supination.

• Atlas/axis• In this joint the atlas

and axis bones articulate to allow a rotation movement as in shaking your head.

Condyloid and gliding joints

• The wrist• In this joint the

radius and ulna bones articulate with 3 of the carpal bones.

• The spine• The spine has five areas

and has to fulfil many functions such as weight bearing stability and support.

• There are three type of joint in the spine but for A level the main one to know is the gliding joints between the vertebral arches.

Features of a synovial joint• Synovial joint have a number of common

features.FEATURE STRUCTURE FUNCTION

Hyaline/articular cartilage

Smooth& spongy covers ends of bones

•Prevents friction between articulating bones

Two layered joint capsule

Outer layer – tough & fibrous

Inner – synovial membrane covers all internal surfaces

•To strengthen joint•To secrete synovial fluid

Synovial fluid Slippery fluid like egg white which fills joint capsule

•Reduce friction•Nourish cartilage•To get rid of waste from joint

FEATURE STRUCTURE FUNCTION

Ligament A band of strong fibrous connective material

•Joins bone to bone•Provides stability

Pads of fat Fatty pad found between capsule, bone or muscle

•Increases joint stability•Acts as shock absorber•Reduces friction

Meniscus A wedge of tough flexible cartilage

•Improves fit between bone ends•Increases stability•Reduces wear & tear to joint surfaces

Bursae Fluid filled sac found between tendon and bone

•Reduces friction

Movements around a joint

• All synovial joints can move freely but the amount and type of movements which occur at each joint varies.

• Many of the movements occur in pairs – they are the opposite of each other.

• Technical terms to describe the movements you need to know include:-

TERM MEANING

FLEXION A decrease in the angle that occurs in a joint

EXTENSION An increase in the angle which occurs at a joint

ABDUCTION Movement away from the midline of the body

ADDUCTION Movement towards the midline of the body

ROTATION Movement of a bone around its axis (can be inward (medial) or outward (lateral))

CIRCUMDUCTION Lower end of bone moves around in a circle

LATERAL FLEXION Bending sideways

PLANTAR FLEXION Pointing the foot downwards

DORSIFLEXION Bending the foot upwards towards tibia

PRONATION Facing the palm of the hand down

SUPINATION Facing the palm of the hand up

JOINT POSSIBLE MOVEMENTS

SHOULDER Flexion & extension, adduction & abduction, circumduction, rotation

ELBOW Flexion & extension

RADIO-ULNA Pronation & supination

WRIST Flexion & extension, adduction & abduction, circumduction

SPINE Flexion & extension, lateral extension, rotation

HIP Flexion & extension, adduction & abduction, circumduction

KNEE Flexion & extension

ANKLE Dorsiflexion & plantaflexion

MUSCLES

• The human body contains more than 650 individual muscles.

• They do everything from pumping blood throughout your body to providing movement for the body.

• You have three different types of muscles in your body: smooth muscle, cardiac muscle, and skeletal muscle.

Smooth Muscle

• Smooth muscles are involuntary muscles.• You can't control this type of muscle. Your

brain and body (nervous system and hormones) tell these muscles what to do without you even thinking about it.

• Much of our internal organs is made up of smooth muscles. They are found in the urinary bladder, gallbladder, arteries, and veins. Also the digestive tract is made up of smooth muscle as well.

Cardiac Muscle

• This is the muscle that makes up the heart.• It is also known as the myocardium.• The thick muscles of the heart contract to

pump blood out and then relax to let blood back in after it has circulated through the body.

• Cardiac muscles are also involuntary muscles.

Skeletal Muscle • Skeletal muscles are voluntary muscles.• These muscles help to make up the

musculoskeletal system.• The skeletal muscles work with your bones to

give your body power and strength. • Skeletal muscle is attached to one end of a

bone, stretches all the way across a joint, and then attaches again to another bone.

• Skeletal muscles are held to the bones with the help of tendons.

• Together, this system allows you to do many amazing things with your body in terms of movement.

• Watch the following animation on how the muscles, tendons and bones work together in moving a joint: http://kidshealth.org/misc/movie/bodybasics/bodybasics_knee.html

• Skeletal musclesoften work in pairs.A muscles that bends part of your body is called a flexor.A muscle that straightenspart of your body is anextensor.

• Skeletal muscles have two types of muscle fibers: fast-twitch and slow-twitch.

• Anaerobic exercise uses fast-twitch fibers for example: Weightlifting, sprinting, and push-ups.

• Aerobic exercise uses slow-twitch muscle fibers for example: Long distance running and cycling.

• Skeletal muscles also have muscle tone, which is what gives us the shape our bodies have!

• You need to keep your muscles in shape by exercising regularly, eating a proper diet and leading a healthy life style.

• Lack of regular movement can lead to muscle atrophy – loss of muscle tissue.

• Muscles are important inso many ways, so keepthem in shape. Ask yourPE teacher for exerciseprograms to help you stayhealthy!