joints (articulations) definition: site at which two or more bones come together some joints have no...
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Joints (Articulations)Definition: Site at which two or more bones come together
Some joints have no movement
some only slight movement
some are freely moveable
Fibrous (Fixed) Joints
In these joints, the bones
are in very close contact
and are separated only
by a thin layer of fibrous
connective tissue
• An example of this type of joint is the sutures in the skull between skull bones
Cartilaginous (slightly moveable) joints
These joints are
characterized by
bones that are
connected by
hyaline cartilage
(fibro cartilage)
Example: The joints between the vertebral bodies
Synovial (freely moveable) joints
(Diarthrosis joint)
Most joints are freely
movable
Considerable
movement
is permitted at all
synovial joints
Types of movement
Movements which can occur are:
Flexion - Extension
Abduction - Adduction
Rotation - Circumduction
Pronation - Supination
Inversion - Eversion
Flexion and Extension
Flexion at the elbow joint
Extension at the elbow joint
Abduction and Adduction
Abduction at the hip joint Adduction at
the hip joint
Rotation and Cicumduction
Rotation at the atlas – axis joint
Circumduction at the shoulder joint
Types of Synovial joint
Synovial joints are subdivided according to the movements possible
They are subdivided into:
Ball and Socket
Condyloid
Saddle
Pivot
Hinge
Gliding
Ball and Socket joints
The ball-shaped end of one bone fits into a cup-shaped socket on the other bone allowing the widest range of motion including rotation.
Examples include the shoulder and hip
Condyloid joints
Oval shaped condyle fits into elliptical cavity of another allowing angular motion but not rotation.
This occurs between the metacarpals (bones in the palm of the hand) and phalanges (fingers) and between the metatarsals (foot bones excluding heel) and phalanges (toes).
Saddle joints
This type of joint occurs when the touching surfaces of two bones have both concave and convex regions, the shapes of the two bones complement one another and allow a wide range of movementThe only saddle joint in the body is in the thumb
Pivot joints
Rounded or conical
surfaces of bone fit
into a ring of bone or
tendon allowing
rotation
An example is the
joint between the
axis and atlas in the neck
Hinge jointsA convex projection A convex projection on one bone fits into on one bone fits into a concave depression a concave depression in another permitting in another permitting only only flexion and flexion and extensionextension
Examples of hinge joints Examples of hinge joints = = elbow and knee jointselbow and knee joints
Gliding joints
Flat or slightly flat
surfaces move against
each other allowing
sliding or twisting
without any circular
movement
This happens in the carpals in the wrist and the tarsals in the ankle.
Characteristics of a synovial joint
Articular or Hyaline CartilageStrong enough to support the weight of the body
Provides smooth surface for articulation
Capsular LigamentSleeve of fibrous tissue which joins the bones together,
therefore provides joint stability
Sufficiently loose to allow movement
Synovial membrane
This is composed of secretory epithelial cells that secrete a thick, sticky fluid which:
a) acts as a lubricant
b) provides nutrients
c) helps maintain joint stability
(prevents the ends of bone separating)
(Little sacs of synovial fluid – bursae -
are found in some joints, act as cushions)
Extra capsular structures
Ligaments
help stabilise the joint
Muscles
enable movement
Nerves
enable movement
Case Study 1• Callum is four years old. He has just fallen from
the slide in the park and has banged his head. He is developing a bit of a lump on his forehead (there is no skin injury) and he has started crying. His mother is also really upset and wants to take him to A & E.
• What advice would you give his mother?
• What sort of bone is the skull?
• What is the function of the skull bone?
Case Study 2• Stephen is 21 years old and has been trying to
get fit and improve his health. He has started playing rugby and has injured his ankle in a match. He finished the game but now is limping and his ankle is looking very bruised and swollen.
• What advice would you give Stephen?
• What is the collective name for the bones in the ankle?
• What sort of bones are these?
• What injuries are common in the ankle?
Case Study 3Melanie has been diagnosed with schizophrenia
and has been taking antipsychotic medication for a few years. Unfortunately, she has put on five stone in weight during this time. The CPN calculates her BMI as 31.6 (5ft 6ins and 14stone).
How might this excess weight affect Melanie’s joints?
Which joints are more likely to be affected?What advice would you give her?
Case Study 5Mrs Evans (who is 65 years of age) has Non
Insulin Dependent Diabetes Mellitus (NIDDM). She is quite concerned about her risk of osteoporosis (her mother had the condition and fractured her hip, twice).
Is she at risk?
What nutrients and hormones are required for bone health?
What advice would you give to Mrs Evans?