Skeletal System Joints Flashcards
What are joints, or articulations?
The point where two or more bones meet
What are the two primary functions of joints?
- Permit mobility
- Offer stability
Why are joints considered the weakest part of the skeleton?
They represent a ‘break’ in the continuum of the bones and are prone to wearing out
What are the two classification systems for joints?
- Structural classification
- Functional classification
What is structural classification of joints based on?
The physical structure of the joint
What type of joint is characterized by two bones joined by fibrous connective tissue with no joint cavity?
Fibrous joint
Give an example of a fibrous joint.
Sutures between the cranial bones
What type of joint is formed when two bones are joined by cartilage and lack a joint cavity?
Cartilaginous joint
Provide an example of a cartilaginous joint.
- Intervertebral discs
- Pubic symphysis
What is a synovial joint?
A joint that has a joint cavity, a joint capsule, and is filled with synovial fluid
What is the functional classification of a joint that is immovable?
Synarthrotic joint
What does an amphiarthrotic joint allow?
Slight movement
What is an example of a diarthrotic joint?
- Knee joint
- Shoulder joint
- Hip joint
What characterizes fibrous joints?
Bones are joined by connective tissue and lack a joint cavity
What is a gomphosis?
A peg-in-socket fibrous joint that ‘nails’ the tooth in the bony alveolar socket
What type of cartilage connects bones in synchondroses?
Hyaline cartilage
What are symphyses joints characterized by?
Fibrocartilage that is compressible and acts as a shock absorber
What type of joint allows for freely movable articulation?
Synovial joint
What is the role of articular cartilage in synovial joints?
Acts as a cushion to withstand compression of bone ends
What is synovial fluid derived from?
Filtration from blood flowing through capillaries in the synovial membrane
What type of movements occur at synovial joints?
- Gliding
- Angular
- Rotational
- Special movements
What is flexion?
A movement that decreases the angle between two bones
What is the opposite of flexion?
Extension
What does abduction refer to?
Movement away from the midline of the body
What is circumduction?
Movement where the distal part of a limb moves in circles while the proximal part remains stationary
What is rotation in the context of joint movements?
Turning movement of a bone around its long axis
What is opposition of the thumb?
Movement that allows the thumb tip to touch each of the other fingers
Define dorsiflexion.
Pulling the toes and the top of the foot upwards
What is plantarflexion?
Pointing the toes downwards
What does inversion refer to?
Turning the sole of the foot medially
What is the shape of the knee joint?
Complex with a single joint cavity involving three articulations
What type of joint is the Tibiofemoral joint?
Hinge joint
What is the function of bursae in joints?
Reduce friction between adjacent structures during joint activity
What are menisci?
C-shaped fibrocartilages that help deepen the joint cavity and stabilize the knee
What are the capsular ligaments of the knee?
- Patellar ligament
- Medial patellar retinaculum
- Lateral patella retinaculum
What are extracapsular ligaments?
Ligaments located outside the joint capsule
Name two extracapsular ligaments of the knee.
- Tibial collateral ligament (MCL)
- Fibula collateral ligament (LCL)
What are intracapsular ligaments?
Ligaments located inside the joint capsule
What are the names of the cruciate ligaments?
- Anterior cruciate ligament (ACL)
- Posterior cruciate ligament (PCL)
What does the ACL prevent?
Forward sliding of the tibia on the femur and resists hyperextension of the knee
What does the PCL prevent?
The tibia from moving posteriorly relative to the femur
What are the two main ligaments located inside the knee joint cavity?
Anterior cruciate ligament (ACL) and Posterior cruciate ligament (PCL)
These ligaments are named based on their attachment points on the tibia.
What does the anterior cruciate ligament (ACL) prevent?
Forward sliding of the tibia on the femur and resists hyperextension of the knee
The ACL attaches to the anterior tibial plateau.
What is the role of the posterior cruciate ligament (PCL)?
Prevents the tibia from moving posteriorly relative to the femur
The PCL attaches to the posterior tibial plateau.
Name two extracapsular ligaments of the knee.
Tibial collateral ligament (MCL) and Fibular collateral ligament (LCL)
These ligaments are located outside the articular capsule.
What reinforces the knee joint capsule besides ligaments?
Muscles and their tendons
Tendons are dense connective tissues containing collagen that attach muscle to bone.
What happens to the femur when the knee moves from flexion into extension?
The femoral condyles roll across the tibial condyles and the femur rotates medially on the tibia
This rotation happens until the ligaments are twisted and taut.
What muscle unlocks the knee joint?
Popliteus muscle
This muscle allows the femur to rotate laterally on the tibia.
What is known as ‘the unhappy triad’ in knee injuries?
Injury to the ACL, MCL, and medial meniscus
These injuries often occur together due to their anatomical connections.
True or False: The knee joint capsule is only protected by ligaments.
False
The knee joint capsule is also reinforced by muscles and their tendons.
What type of joint are synovial joints classified as?
Freely movable joints (diarthrotic)
They are the most structurally complex joints and often the most commonly dysfunctional.
Fill in the blank: Fibrous joints are generally _______.
immovable
They can be classified as synarthrotic or amphiarthrotic depending on the length of fibers.
What are the three types of joint classifications mentioned?
Fibrous, Cartilaginous, and Synovial
Each type has different characteristics and degrees of movement.
What is the main function of the ligaments in the knee?
Attach bone to bone and provide stability
They play a crucial role in maintaining joint integrity.
What can cause an ACL injury without a direct blow to the knee?
Quick changes in direction or twisting a hyperextended knee
This is common in sports like soccer or netball.
What happens when a lateral force is applied to an extended knee?
It can tear the MCL and medial meniscus, as well as the ACL
This is often seen in sports-related injuries.
