Transcript the skeleton - Biology

JOINTS
Objectives
• Identify the bones that articulate at different
joints in the body.
• Name the 6 types of synovial joint and give
examples of each.
• Describe the structure and function of parts of a
synovial joint.
• Be able to classify joints according the
movement they allow.
• Use technical language to describe common
joint movements.
• Analyse sporting techniques in terms of joint
movements.
• The human skeleton consists of 206 bones. Many of
which move or hinge at joints. In conjunction with over
600 muscles these bones enable the human body to
achieve a variety of movements.
• The functions of the skeletal system include: • To provide a lever system against which muscles can
pull.
• To provide a large surface area for the attachment of
muscles.
• To protect delicate organs such as the brain.
• To give shape to the body.
• To give support to the body.
• To manufacture red blood cells and to store fat calcium
and phosphate.
AXIAL & APPENDICULAR
SKELETON
• The bones of the body are
grouped into two major
divisions.
• The axial skeleton consists of
the bones, which lie around
the longitudinal axis of the
body. These include the
SKULL, VERTEBRAL
COLUMN, STERNUM & RIBS.
• The appendicular skeleton
consists of the bones of the
LIMBS, PECTORAL (shoulder)
GIRDLE, & PELVIC (hips)
GIRDLE.
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 elbow joint
• The ankle joint
• In the ankle the talus • In the elbow the
humerus articulates with
articulates with the
the radius and the ulna.
tibia and fibula.
• Ligaments provide • Movement can only
occur in one plane.
stability to the joint.
The pivot joint
• The radio-ulna
• Atlas/axis
• In this joint the radius • In this joint the atlas
and ulna articulate
and axis bones
within the elbow joint.
articulate to allow a
rotation movement as
• This joint allows the
in shaking your head.
elbow some twisting
movement (pronation &
supination.
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
•Prevents friction
covers ends of bones between articulating
bones
Two layered joint
capsule
Outer layer – tough & •To strengthen joint
fibrous
•To secrete synovial
Inner – synovial
fluid
membrane covers all
internal surfaces
Synovial fluid
Slippery fluid like egg •Reduce friction
white which fills joint •Nourish cartilage
capsule
•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