Musculoskeletal System And Joint Classification Lecture 6 Flashcards
How many classes of joints are there
There are 3 classes of joints each made of different tissues and therefore allowing different amounts of movement.
Where are the most synovial joints found at and give an example
Mostly found in the limbs, an example can be how we wave our arms around ( the synovial joints are doing that )
What is depending on the joint structure
= How much the joints can do and the places the movement can happen in
= how the bones fit together, what the soft tissues are and where they are loacated and what movements are allowed and not allowed
Synovial joint features what they do
They are complex and have a lot of peices to them and lots of structures, they have to allow both free movement and controlled movement and we want lots of movement but only in particular ways
The shape of the bone end determines what movement we can do
What does the shape of the bone end determine
What movement we can do
What is the most essential thing for the synovial joint structure. And explain the structure
The bone ends, for bones to move against each other,
= we want hyaline cartilage on the ends of the bones, this provides a layer so when the bones move against each other it doesn’t hurt
= we want something to wrap around the whole joint and to keep everything in place/ keeping any fluids inside, this is called the JOINT CAPSULE
= inside the structure there is also going to be some free space as the bones don’t fuse with each other, this is called THE JOINT CAVITY, this provides potential space if we need it.
= there is a membrane ( SYNOVIAL MEMBRANE) this makes lots of synovial fluids to full the cavity
=and there is also ligaments
In the synovial joint structure what does the Hyaline cartilage do
The bone underneath the cartilage needs to be smooth, this smooth bone is called the SUBCHONDRAL BONE
What is the smooth bone called underneath the hyaline cartilage in the synovial joint
SUBCHONDRAL bone
What is the function of the joint capsule and what is it made out of
Because it is something that wraps around the whole joint. The joint capsule is made up of DFCT, this is to give it protection, it’s a big sheet of DFCT that wraps around the whole joint, this is to make sure that if you pull on it and tug on it, it’s not going to rip or let the bones all away from each other. However on the inner layer is something called the synovial membrane
What is the synovial membrane
This is a thin sheet of secrete cells and that lines the inner surface of joint capsules in synovial fluids, the synovial fluids acts as a lubricant and cushion within the joint, which can help reduce friction and improve movement.
What is Lubrication of Joints
we need these fluids in the joint so when the cartilage rubs over another cartilage there is water in there to help it move around more easily
Librication of joints - this decreases the friction between cartilage and allows for natural and painless joint movement
What is Synovial fluids
It is not blood but it has the same nutrients that blood has in it and it’s hanging inside the joint and so every time you bend your joint it’s going to push that fluid into the cartilage to keep the cartilage happy, they are found in the cavities of the synovial joints
Why so it important to have joint capsule
Hold the bones together and they can also be thicker or thinner depending on what we need for example if we were to have it thin and loose this would provide more movement and having it thick can provide less movement
What are the 2 types of Ligaments at the synovial joints
= capsular ligaments , these are part of the joint capsule, thy they are continuous with it, they are very particularly located thick bands that sit in the joint capsule, providing more support if we want to restrict movement, for example there are 2 capsular ligaments of the knee
1) medical collateral ligament MCL - this is on the medical side and connects the femur to the tibia, for example if your leg was to abduct that ligament would pull tight to stop that from happening / to prevent essesive sideways motion of the knee
2) Lateralu collateral ligament LCL - this connects the femur to the fibula and resists adduction, so if your body was trying your adduct it’s going to pull and stop that from happening.
= the second type is intracapsular ligaments, these are bathed in synovial fluid. For example the Cruciate ligaments of the knee , the first one is
1) anterior cruciate ligament - this starts of at the anterior of the tibia and it’s going to go backwards to the joint to the post of the femur, what this does is that it stops the femur from sliding backwards, for example if you were going to stand up and your femur was to suddenly slide backwards, you would fall over.
2) the sencond type is called posterior cruciate ligament - this starts off at the posterior is the tibia and runs forward to the middle of the joint and attaches anteriorly to the femur and this prevents the femur from sliding forwards.
What is the rule for ligaments
Restricting movement
What is a structure that is unique to the joint
Fibrocartilage pads
What are fibrocartilage pads and where is it found
fibrocartilage pads, such as the menisci provide cushioning and to act as a shock absorber. In the knee we have 2 menisci per joint and they are half moon structures that sit between the femur and tibia. The main function of it is so that we can help the fit between bones and cup around the rounder bones to make it fit better, making up for that poor bony congruence. It is very good at shock absorbing, each time you take a step you are putting 4x your body weight pressure on your knees however the shock absorber can help send the pressure off
What is the menisci
They are fibrocartilage pads and the role is to provide cushioning / acts as a shock absorber. We have 2 meniscus per joint, they are half moon shaped structures that sit between the femur and tibia. The function of the meniscus is so what it can help cup around the rounder bones and makes it fit better and makes up for the poor bony. The meniscus is very good at shock absorbing, each time you take a sep you are putting 4 times your body weight pressure in it, the shock absorption can help send the pressure off so therefore having a shock absorber is really important
Mobility and stability for synovial joints
More mobility and less stability
What are the synovial joint movements
Plane
Hinge
Pivot
Condylar
Ellipsoid
Saddle
Ball and socket
What is the plane synovial joint
They are flat and they are multiaxel joints, another name for them is called sliding and gliding joints. The plane joints are usually flat articular surfaces of bone that move against each other and they are normally really tiny joints
What is the hinge joint
These are unaxel, they only can flex and extend and they are in the Sagital plane movement. The hinge joint is made up of two or more bones with articular surfaces that are covered by hyaline cartilage and lubricated by synovial fluid.
Pivot joint
Uniaxel, there movement is rotation, for example when you shake your head you are twisting them at your C1 C2 vertebrae, you are twisting it at the transverse plane.
Condylar joint
biaxel joint so this means that they have 2 planes of movement, they are able to flex and extend and allow to some degree of abduction, adduction and circumduction and able to rotate only a little when joint is semi-fixed
Ellipsoid joints
These are Biaxial
They can flex, extend
Abduct and adduct but there is no rotation
Saddle joints
This is your thumb.
This is called biaxial plus, it can flex and extend, abduct and adduct and can also circumduct
What is the main function of the ligament
They are able to hold bones tightly together and resist tension because of the tightly packed
collagen fibres, this limits movement completely, ensuring stability and protection.
What are the capsular ligaments for the knee
This is a form of ligament at the synovial joint, what it does is that it provides more support if we want to restrict movement, for example, if we are thinking about the knee, there are 2:
- medical collateral ligament - this is on the medical side of the knee that connects the femur to the tibia and it helps to restricts abduction/ prevent essesive sideways motion of the knee
- lateral collateral ligament - this is on the lateral side of the knee that connects the femur to the fibula and helps to restrict adduction
What is intracapsular ligament
In some joints additional bands of DFCT are needed to hold bones together
- anterior cruciate ligament - anterior of tibia and posterior of femur. And restricts posterior displacement of femur
- posterior cruciate ligament - connecting posterior of tibia to anterior of femur and restricts anterior displacement of femur
