JOINTS

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JOINTS
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Learning Objectives

• To know the different joint types
• To understand how to classify joint types
• To be able to discuss the importance of the
  structure and function of a synovial joint

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Joints

• The human skeleton is jointed to allow movement.

• Muscular contraction causes the bones to move
  about the joints.

A joint is where two or more bones meet
andmuscles act together to cause movement.
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Types of Joints
There are 3 main types of joint found in the body.

• Fibrous/ immovable joints
• The bones at an immoveable joint cannot
  move - they overlap or interlock, and are held
  together by a tough fibre, e.g. the skull.
• 2. Cartilaginous/slightly moveable joints
• The bones at a slightly moveable joint can only
  move
• a little - they are held together by strong
  straps
• called ligaments and are joined by protective
  pads
• known as cartilage, e.g. the ribs.
• 3. Synovial joint/freely moveable
• At a freely moveable joint the bones move freely.
• They are also known as synovial joints, and
• are the largest group of joints found in the
  body,
• e.g. the hips, shoulders and knees.

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Freely Moveable Joints

• Freely Moveable joints are also known as Synovial
  Joints.
• They are freely moving and occur where 2 or more
  bones meet.
• There are about 70 freely moveable joints in the
  human skeleton.
• These interest us the most because they allow the
  greatest range of movement and are found in the
  appendicualr skeleton

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Cartilage

• Hyaline or Articular cartilage- found on the
  surface
• of bone
• 2. Yellow Elastic cartilage- elastic and found in
  the
• external ear
• 3. White Fibrocartilage- tough, dense tissue that
• acts as a shock absorber. Found between the
  vertebrae

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• Articular/hyaline Cartilage A material which
  covers the end of each bone, and which helps
  prevent friction between the joint.
• Absorbs compression placed on the joint,
• protects the joint.

• 2. Joint Capsule The outer layer is a tough
  fibrous layer called the fibrous capsule.
• Increases stability
• The inner layer is called the synovial membrane
• Secretes synovial fluid, strengthens the joint

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• 3. Synovial Membrane Thin membrane which lines
  the inside of the joint capsule.
• It produces synovial fluid

• 4. Synovial Fluid The fluid which surrounds the
  joint and is contained in the joint cavity.
• Reduce friction between the cartilage
• Nourish the cartilage
• Get rid of any waste debris

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• 4. Ligaments A band of strong fibrous tissue,
  helps prevent dislocation.
• Connect bone to bone

• 5. Tendons Strong connective tissue that
  attached muscle to bone.
• Connect muscle to muscle
• 6. Bursa- pad of fat provide cushioning between
  the fibrous capsule and a bone or muscle.
• Cushion the joint and act as shock absorbers

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The Synovial Joint of the Knee
The knee is a hinge joint.
Femur
Articular(hyaline)Cartilage
Joint capsule
Cruciate Ligaments
Synovial Membrane
Patella
Synovial Fluid
Joint cavity
Tibia/Fibula
Tendons
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The Synovial Joint of the Hip
The Hip is a ball and socket joint.
Cartilage
Pelvis
Synovial Fluid
SynovialMembrane
Ligaments
Tendons
Femur
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• TASK
• Label the diagram of a synovial joint using a
  colour code system
• YOU MAY BE ASKED TO LABEL A SYNOVIAL JOINT IN
• EXAM OR EXPLAIN THE STRUCTURE AND FUCTION

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2. List two features that increase joint
stability and give their specific function?
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Examples of Synovial Joints
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Types of Synovial Joints
Synovial joints are classifed according to the
shape of the articulating surface.
KEY
Ball Socket Joint
Hinge Joint
Pivot Joint
Gliding Joint
Saddle Joint
Condyloid Joint
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KEY TERM ARTICULATION- The different bones that
form to make the joint EXAMPLE Joint
Joint type Articulating bones
Movement Elbow Hinge joint
Humerus, radius, ulna
Write down another example
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1. Ball and Socket Joints
The ball has a head shaped of one bone which
articulates with a cuplike socket. Allows the
greatest range of movement
Examples HIP SHOULDER
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2. Hinge Joints
They are cylindrical shaped of 1 bone articulates
with a depression of an adjacent bone Movement
is restricted to bending and straightening
EXAMPLES ELBOW KNEE
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3. Pivot Joints
These are rounded, pointed or concave of one bone
which articulates which a ring shaped
bone. Movement is restricted to 1 bone rotating
around the longitudinal axis.
EXAMPLEVERTEBRAE OFTHE NECK
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4. Gliding Joints
The articulating surfaces are flat. It allows
limited movement EXAMPLES HAND BETWEEN THE
CARPELS
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5. Saddle Joints
The articulating surfaces are shaped like a
saddle It allows very limited movement
EXAMPLE THUMB JOINT
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6. Condyloid Joints
The surfaces are flatter and oval forming a
shallow joint It allows the second greatest
range of movement.
EXAMPLE WRIST JOINT
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Structure and function Hyaline/Articular
cartilage Structure Smooth, spongy cartilage
that covers end of bone. Function prevent
friction between bones absorb
compression placed on the joint
protect bone from getting crushed Joint
capsule Structure Outer layer is a tough
fibrous layer- fibrous membrane.
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The inner layer- synovial membrane Functionstren
gthen the joint secrete synovial
fluid Synovial Fluid Structure slippery fluid,
contained in the joint cavity Function reduce
friction between cartilage nourish
the articular cartilage get rid of
waste debris in joint Ligament Structure band
of strong fibrous tissue Function connect bone
to bone
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Meniscus (cartilage) Structure white
fibrocartilage Function improves the fit between
bone ends increases joint
stability reduces wear and tear at
joint Bursa Structurefluid filled
sacs Function prevent friction where bones,
ligaments and muscles may rub together
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PLENARY
Identify the bones that articulate at the
shoulder joint? (2 marks) Identify the bones
that articulate at the elbow joint? (3 marks)
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Ball and Socket Joints
Examples HIP SHOULDER
The ball has a head shaped of one bone which
articulates with a cuplike socket. Allows the
greatest range of movement
Hinge Joints
EXAMPLES ELBOW KNEE
They are cylindrical shaped of 1 bone articulates
with a depression of an adjacent bone Movement
is restricted to bending and straightening
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Pivot Joints
VERTEBRAE OFTHE NECK
These are rounded, pointed or concave of one bone
which articulates which a ring shaped
bone. Movement is restricted to 1 bone rotating
around the longitudinal axis.
HAND BETWEEN THE CARPELS
Gliding Joints
The articulating surfaces are flat. It allows
limited movement
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Saddle Joints
EXAMPLE THUMB JOINT
The articulating surfaces are shaped like a
saddle It allows very limited movement
Condyloid Joints
The surfaces are flatter and oval forming a
shallow joint It allows the second greatest
range of movement.
EXAMPLE WRIST JOINT