Musculoskeletal system Joint Classifications Flashcards
What are the three types of joints in the musculoskeletal system?
✔ Fibrous joints – least movement, high stability (e.g., skull sutures).
✔ Cartilaginous joints – some movement, shock absorption (e.g., intervertebral discs).
✔ Synovial joints – most movement, complex structure (e.g., knee, shoulder).
Why do we need different types of joints?
✔ Different joints serve different functions:
Fibrous joints provide stability (e.g., skull sutures).
Cartilaginous joints provide shock absorption (e.g., intervertebral discs).
Synovial joints allow movement (e.g., shoulder, hip).
✔ If highly mobile joints (e.g., shoulder) were fibrous, movement would be impossible.
✔ If stability-dependent joints (e.g., skull sutures) were synovial, they would be unstable.
What are the key structures of a synovial joint?
✔ Bone ends – determine the range of motion.
✔ Articular cartilage – covers bone ends, provides frictionless movement.
✔ Joint capsule – encloses the joint.
✔ Joint cavity – potential space inside the capsule.
✔ Synovial membrane – produces synovial fluid for lubrication.
✔ Ligaments – provide structural support.
What is the function of hyaline (articular) cartilage in synovial joints?
✔ Covers bone ends where they articulate.
✔ Provides smooth, frictionless movement.
✔ High water content allows it to resist compression.
✔ Lacks blood vessels – nutrients diffuse from synovial fluid.
✔ Degrades with age, leading to osteoarthritis.
What are intracapsular ligaments, and what is their function?
✔ Found inside the joint capsule, stabilizing bones internally.
✔ Example: Cruciate ligaments of the knee:
Anterior cruciate ligament (ACL) – prevents posterior displacement of the femur.
Posterior cruciate ligament (PCL) – prevents anterior displacement of the femur.
What is the function of the joint capsule?
✔ Outer layer – made of dense fibrous connective tissue (DFCT), holds bones together.
✔ Inner layer (synovial membrane) – secretes synovial fluid for lubrication & nutrition.
✔ Capsule is tight in areas needing support and loose in areas allowing movement.
What are capsular ligaments, and what is their function?
✔ Thickenings of the joint capsule that provide extra support.
✔ Example: Collateral ligaments of the knee:
Medial collateral ligament (MCL) – connects femur to tibia, restricts abduction.
Lateral collateral ligament (LCL) – connects femur to fibula, restricts adduction.
What determines the stability and mobility of a joint?
✔ Bony congruence – how well bone surfaces fit together (e.g., hip joint has high congruence, more stability).
✔ Ligaments – provide support, limit excessive movement.
✔ Joint capsule & surrounding muscles – add stability while allowing mobility.
🔹 Trade-off:
More stability = less mobility (e.g., skull sutures).
More mobility = less stability (e.g., shoulder joint).
What is the function of fibrocartilaginous pads in synovial joints?
✔ Found in some joints to fill space and absorb shock.
✔ Example: Menisci (singular: meniscus) in the knee:
Half-moon-shaped fibrocartilage structures between femur & tibia.
Help with shock absorption & joint stability.
What determines the range of motion (ROM) in a synovial joint?
✔ Bone end shape – determines how bones fit together.
✔ Ligament location & length – restricts excessive movement.
✔ Body surface contact – prevents overextension.
✔ Muscle tension – affects joint positioning.
What are the different planes of movement?
✔ Sagittal plane – forward & backward movements (e.g., flexion/extension).
✔ Coronal plane – side-to-side movements (e.g., abduction/adduction).
✔ Transverse plane – rotational movements (e.g., pronation/supination).
Which structures hold bones together in a synovial joint?
✔ Joint capsule – encloses the joint.
✔ Ligaments – provide additional support.
What are the 7 types of synovial joints?
✔ Plane joint – flat surfaces, sliding/gliding motion (e.g., intercarpal joints).
✔ Hinge joint – uniaxial, flexion/extension (e.g., elbow, knee).
✔ Pivot joint – uniaxial, rotation (e.g., radioulnar joint, C1-C2 vertebrae).
✔ Condylar joint – biaxial, flexion/extension & rotation when flexed (e.g., knee, TMJ).
✔ Ellipsoid joint – biaxial, flexion/extension & abduction/adduction, NO rotation (e.g., wrist).
✔ Saddle joint – biaxial, flexion/extension & abduction/adduction, allows opposition (e.g., thumb).
✔ Ball & socket joint – multiaxial, most mobile (e.g., shoulder, hip).
What influences the possible movements at a synovial joint?
✔ Bone end shape.
✔ Ligament location & length.
✔ Body surface contact.
✔ Muscle tension.
What type of movement occurs at a hinge joint?
Flexion & extension (e.g., elbow, knee).
What type of movement occurs at a pivot joint?
Rotation (e.g., radioulnar joint, C1-C2 vertebrae).
What type of movement occurs at a ball & socket joint?
Flexion/extension, abduction/adduction, rotation, and circumduction (e.g., shoulder, hip).
