Joints Flashcards
What is a joint?
Meeting of two bones. Bones articulate at the joint
What are joints classified by?
Function - range of movement
structure - what links the bones
Functional classification of joints
Synarthrosis - immobile
Amphiarthrosis - Slightly mobile
Diarthrosis - Freely mobile
Structural classifications of joints
Fibrous - Dense CT
Cartilaginous - Hyaline or Fibro-cart
Synovial - Ligaments
Synostosis - Bone
Fibrous joint types
Suture and Syndesmosis
Features of suture
Bones linked by thin layer of Fibrous CT, located in skull, immovable
Features of Syndesmosis
Slightly moveable, forms interosseous membrane or ligament, more connective tissue linking bones than in sutures
What are the cartilaginous joint types
Synchondrosis and Symphysis
Synchondrosis
Hyaline cartilage links bones. Can facilitate growth of long bones
Symphysis
Fibrocartilage joint
Compressible, strong and flexible. limited movement possible
Synovial
Most common joint. Diarthroses.
Features of synovial joint
➢ Articular cartilage ➢ Articular/fibrous capsule ➢ Synovial membrane ➢ Synovial cavity & synovial fluid ➢ Accessory structures (discs or ligaments) may also be present.
How can we classify synovial joints?
Axes of movement and shape
Axes of movement
Nonaxial
Uniaxial
Biaxial
Multiaxial
Shapes of synovial joint
Plane/Gliding Hinge Pivot Condyloid Saddle Ball & Socket
What are the 5 Synovial joints
Gliding pivot/trochoidal Condyloid/ellipsoid Saddle Ball and socket/spheroidal
Gliding Synovial joint features
Articular surfaces are essentially flat.
➢ Allow short gliding movements (nonaxial).
➢ Some can be classified as amphiarthroses
Hinge Synovial joint features
A cylindrical projection (convex) of one bone fits into
a trough-shaped surface (concave) of another bone.
➢ Motion is along a single plane (uniaxial) permitting
extension& flexion.
Pivot / Trochoidal Synovial Joints
➢ The rounded end of one bone protrudes into a sleeve
composed of bone or ligaments.
➢ Allows rotation along the axis of the bone (uniaxial).
Condyloid / Ellipsoid Synovial Joints
The oval-shaped (convex) articular surface of one bone fits into complimentary depression (concave) on another bone. ➢ Permits movement in 2 planes (biaxial).
Saddle / Sellar Synovial Joint
➢ Each articular surface has both concave & convex areas.
➢ Permits significant movement in different planes (multiaxial).
Ball & Socket / Spheroidal Synovial Joints
➢ The spherical head of one bone articulates with a cupshaped socket of another bone.
➢ The most freely moveable of synovial joints (multiaxial).
Explain the shoulder joint
Known as the glenohumeral or humeroscapular joint
➢ Ball & socket articulation
Head of humerus articulates with glenoid cavity
of scapula
➢ Relatively shallow & loose joint
➢ Most freely moveable joint in body
Joint supported by
➢ Ligaments (e.g. coracohumeral)
➢ Tendons of muscles (e.g. Biceps brachii)
➢ Rotator cuff muscles
Explain the hip joint
Known as the coxal joint
➢ Ball & socket articulation (multiaxial).
Head of femur articulates with acetabulum of coxal
bone
➢ Acetabulum forms deep socket for head of femur
➢ Much more stable (but less moveable)
than shoulder joint.
Joint supported by
➢ Ligaments
➢ Tendons of thigh and hip muscles.
What are the ligaments of the hip joint?
Iliofemoral, Ischiofemoral and pubofemoral ligament
Explain the knee joint
Articulation between the femur, tibia and patella; ➢ One of the largest & most complex synovial joints in the body. Primarily a hinge joint; ➢ Joint capsule encloses posterior & medial aspects ➢ Extensions of quadriceps tendon cover anterior aspect.
Knee joint Intracapsular ligaments
Intracapsular cruciate ligaments cross each other to form
an X;
➢ Anterior cruciate ligament (ACL)
➢ Posterior cruciate ligament (PCL)
Prevent forward or backward displacement of tibia.
Knee joint Extracapsular ligaments
Fibular collateral ligament
Tibial collateral ligament
What is the knee menisci?
The (knee) joint contains two crescent-shaped pads of
fibrocartilage called lateral & medial menisci
➢ Absorb shock & prevent the femur rocking from
side to side on the tibia
3 features of the menisci
Lateral meniscus
Synovial membrane
Medial meniscus
What is the “zero position”
Original anatomical position
Flexion
Reduce angle between articulating elements
Extension
Increases angle between articulating elements
Abduction
= lateral movement; movement
away from the longitudinal axis of the
body.
Adduction
medial movement; movement
towards the longitudinal axis.
Circumduction
Conical movement; The shape of a cone is outlined by the pathway of the joint movement.
Rotation
A circular
movement along
the longitudinal
axis of a bone (s).
What are two structures associated with synovial joints?
Bursae - —flattened fibrous sacs ▪ Lined with synovial membranes ▪ Filled with synovial fluid ▪ Not actually part of the joint Reducing friction during joint motion Tendon sheath- ▪ Elongated bursa that wraps around a tendon Secrete synovial fluid to promote movement
Common injuries and disorders of the skeletal system are?
▪ Fractures Breaks in bone Different classifications Stress fractures ▪ Osteoporosis Common in the elderly ▪ Female athlete triad Involves a combination of an eating disorder, amenorrhoea and osteoporosis ▪ Sprains and dislocations
