Movement of synovial joints PDF

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Structures of synovial joints, knee, shoulder, movements...

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HUBS 191 Lecture 10 - 15/03 Movement of synovial joints

- Discuss the structure of synovial joints and explain how their structure contributes to human movement. Structure of a synovial joint: - Bones involved in the joint covered with articular cartilage which helps to ease movement and dampen forces - The joint capsule surrounds the joint. It is a continuation of the periosteum (outside layer of bones) - Inner surface of joint capsule has a synovial membrane. This consists of synovial sites that produce (and absorb) synovial fluid. Synovial fluid helps to lubricate the joint and allows ease of movement - Joint cavity, is the ‘potential space’ between the two bone ends in the capsule. It is filled with the synovial fluid - Intracapsular ligaments Synovial joint - knee: - The knee joint is a good example of a synovial joint - Knee joint is exerted to huge loads - Anterior and posterior cruciate ligaments ———————> - Refine the movements of the knee a lot and are very important structural components. - The knee has a meniscus - The meniscus is made of fibrocartilage and helps to deepen the articulation of the knee joint as the distal end of the femur and proximal end of the tibia are very flat. Therefore it has a very low bony congruence, so needs the meniscus to provide soft tissue support. Synovial joint - shoulder: - Shoulder joint has a specialised structure called a bursa. - The bursa is filled with synovial fluid. - This helps to provide cushioning in the joint. - Also have a bursa at the elbow

! Synovial joint movement:

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Synovial joint is designed for free controlled movement. All these structural components are in place to facilitate this. Joints are a trade off between stability and mobility. No joint can have both ideals. When you increase the mobility, you decrease stability. e.g. hip joint is more stable than it is mobile because it has a lot of force going through it so needs to be very stable. Whereas, the shoulder joint doesn’t have much force going through it, therefore doesn’t require as much stability, thus is more of a mobile joint

Range of movement is determined by: - Bone end shape - Ligament location, thickness and length - Body surface contact

- Describe the shapes of synovial joints and explain how their structure influences their available movement. Different synovial joint shapes: Hinge joints: - Uniaxial - Flexion, Extension E.g. —> Ankle joint ! —> elbow joint! —> interphalangeal joints

Pivot joints: - Uniaxial - Pronation, Supination E.g. —> Radioulnar joints! —> C1 - C2 joint

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Saddle joints: - Biaxial⁺ (opposition and circumduction) - Flexion, Extension - Abduction, Adduction E.g. —> First metacarpal joint

Ellipsiod joints: - Biaxial - Flexion, Extension - Abduction, Adduction - Circumduction E.g. —> Radiocarpal joint (wrist)

Condylar joints: - Biaxial - Flexion, Extension - Rotation (when flexed slightly) E.g. —> Knee

Plane joints: - Multiaxial - Sliding, Gliding, Twisting - Sagittal, Coronal, Transverse plane E.g. —> Intervertebral joints

Ball & socket joints: - Multiaxial - Flexion, Extension - Abduction, Adduction - Rotation, Circumduction E.g. —> Hip joint! —> Shoulder joint

Obligatory rotation is an indirect effect of another movement and it allows us to stabilise/ lock joints. Obligatory rotation = opposition...