Lesson 2 joints

Exercise and FitnessLvl 2Lesson 2 – Joints in Action

Lesson 1 Re-cap Progress Test• Complete Work sheet 3 on your own

Classification of Bones• There are 206 bones in the body, these can

be classified as:• Long• Short• Flat• Irregular• Sesamoid

Long Bone• Such as Femur, tibia, fibula, radius ulna,

humerous, • Blood Production occurs in the red bone

marrow of long bones• Long bones provide the body with leverage

e.g throwing a cricket ball.

Short bones• Short bones are found in the wrist and

ankle.• Short bones are useful for delicate

movement where precision is paramount e.g. writing or a surgical operations.

• Small bones also help dissipate large compressive forces generated during walking and running.

Flat Bones• Flat can be found in the scapulae, rib cage,

sternum and cranium• Flat bones offer protection and muscle

attachment e.g. the rib cage protects the heart and lungs

Irregular Bones• Irregular bones can be found in the

vertebral column• Irregular bones provide muscle attachment

points and allow varying movement patterns to occur e.g. The vertebral column

Sesamoid Bones• Sesamoid bones are small bones formed in

tendons e.g. patella ( knee cap).• Sesamoid bones provide protection for

delicate areas.

Joints – 3 types• Fused – Immovable e.g. skull

• Cartiliginous – Slightly movable e.g. between vertebral column

• Synovial – Freely movable e.g hip & knee

Key Joint Facts • Formed wherever two or more bones meet• The skeleton would be ‘fixed’ without them• Bones that form a joint ‘fit well’, if irregularities

exist they are evened out by extra layers of cartilage

• The above are called ‘menisci’ if they only partly divide a joint cavity

• If they fully divide the joint cavity this cartilage is called a disc

• Most joints are held together by ligaments

Ligaments

Fixed or Fibrous Joints• Has no movement• Tough fibrous tissue lies between the

ends of the bones• The ends are ‘dovetailed’ together• There is no joint cavity (space between

the bones’• E.g. sutures in the skull

Example of fixed Joint - Skull

Cartilagenous Joints• Allows some slight movement• Ends of the bones are covered in articular

cartilage• Ends are separated by pads of white fibro

cartilage• Compression of these pads permits slight

movement• These pads also act as ‘shock absorbers’• Eg: intervertebral discs of the spinal column

Synovial Joints• Distinguishing features;

– Ends are covered in articular cartilage– Inners surface of joint capsules is lined with a thin

synovial membrane that produces synovial fluid– Freely movable joints– Characterised by the presence of a joint capsule and

cavity (space between bones)• Range of movement can vary due to the shape of

the bony surfaces forming the joint• The synovial fluid acts as a lubricant for the joint,

provides nutrients • E.G. knee

Synovial Joint Structure

Key Synovial Joints• Ball & Socket

– Shoulder, Hip• Pivot

– Neck• Condyloid

– Wrist

• Saddle– Thumb

• Hinge– Elbow

• Gliding– Carpels

Ball & Socket • Movement in all directions

– Rotation– Adduction / abduction– Flexion / extension

• Articulating bones; Head of femur / pelvis, humerous & scapula

• E.g. – Hips & shoulders

• Sporting eg;– Clearing a hurdle / overhead

clear in badminton

Pivot & Gliding • Pivot

– Rotation– Articulating bones;

• C1 & C2 vertebrae • Neck (C1 vertebrae)

– Turning head to view situations

• Gliding– Movements across flat

surfaces of bones– Articulating bones;

• Clavicle / intercarpal/ intertarsal

– Bending back, landing; feet absorbing impact- flexion / extension of foot

Condyloid• Sometimes referred to

as Ellipsoid• Reduced ball & socket

configuration• Articulating bones;

Radio carpal joint (radius / ulna / carpals)

• Wrist• Flicking of the racket

in badmington

Saddle & Hinge• Saddle

– All movements but no rotation

– Articulating bones• Carpal & metacarpals

– Base of thumb– Gripping of sporting

equipment• Hinge

– Flexion / extension– Articulating bones;

• Humerus / radius & ulna– Elbow– Hitting a backhand

Location of Synovial Joints

Ligaments

Conclusion• Ligaments Connects bone to bone, are strong, inelastic, dense,

fibrous tissue that links boney segments. Prevent any unwanted movement & restricts movement in certain directions

• Joints are formed wherever two or more bones meet, the skeleton would be ‘fixed’ without them. Most joints are held together by ligaments

• Joints can be classified in 2 ways; Functional & Structural • The amount of movement available at the joint determines their

classification • Fixed or fibrous

– Immovable• Cartilagenous

– Slightly moveable• Synovial

– Freely movable

• The main synovial joints are; ball & socket, hinge, saddle, pivot, condyloid, gliding

Now complete….• Now complete worksheet 4