Freely Moveable (true) Joints
- these joints are called synovial joints and are caracterised by having a joint cavity between cartilagenous bone ends, a synoval membrane (to secrete synovial fluid to lubiricate and nourish joint cartilage), a joint capsule and ligament which prevents the joint from being distracted.
Structures in a synovial joint
- Synovial joints are articular surfaces where bones make contact. The surfaces are lined wih articular cartilage which is overlain on dense sub-chondral bone and nourished by synovial fluid as there is no separate blood supply. The joint capsule surrounds the joint space with vascular onnective tissue and extends well away from the joint to allow for movement. The joint capsule has a double layered membrane; the outer layer is the synovial membrane which lines the joint capsule and secretes synovial fuid, hyauluronic acid and prevents leakage while the outer layer is the capsular ligament. Ligaments are bands of connective issue that keep the bones of the joint in position. There is both an intracapsular ligament which is inside the joint space and assists control of the joint moveement and extracapsular ligaments which are eternal to the capsule and are often bound to or form part of the capsule. Joints also contain a bursa which functions to facilitate movement and reduce friction between articulating bones.
Joint Types: 1 axis/translation
- Plane/Sliding joint: these are flat surfaces that slide on each other such as articular facets of the vertebrae. (translation)
-condylar joint: the priximal bone has cylindrical condyles and fits into articular depression distally.
-cochlear joint" this is a special form of condylar joint as it has oblique locating ridges on the trochlea (such as the hock joint)
- hinge joint: another special form of condylar joint that has perpendicular located guide.
- pivot joint: allows rotation and is dense of axis
Joint types: 2 axes
-sellar joint: articular surfaces make saddle shapes, seen in distalinterphalangeal joints
-ellipsoid joint: articular surface is an elliptical section (such as atlanto-occipital joint)
joint types: 3 axes
- ball and socket joint: has spherical articulation with mating socket less than half a hemisphere (animal hips)
-enarthrosis: special form of ball and socket; spherical articulation with mating socket greater than half a hemisphere (human hip only).
Learn More
WikiVet: The Skeleton
Textbook of Small Animal Orthopeadics
Crash Course Anatomy: Joints
Real 3D anatomy: Dog Skeleton
Veterinary Partner: Normal Joints
Pet Education: Normal Joint Anatomy in Dogs
Knowledge Testing:
- what fluids are secreted by the joint capsule?
- describe the structures of a synovial joint.
Concept testing:
- list at least 2 functions of ligaments.
- list the advantages and disadvantages of having joints with translation, 1 axis of movement, 2 axes of movement and 3 axes of movement.
- these joints are called synovial joints and are caracterised by having a joint cavity between cartilagenous bone ends, a synoval membrane (to secrete synovial fluid to lubiricate and nourish joint cartilage), a joint capsule and ligament which prevents the joint from being distracted.
Structures in a synovial joint
- Synovial joints are articular surfaces where bones make contact. The surfaces are lined wih articular cartilage which is overlain on dense sub-chondral bone and nourished by synovial fluid as there is no separate blood supply. The joint capsule surrounds the joint space with vascular onnective tissue and extends well away from the joint to allow for movement. The joint capsule has a double layered membrane; the outer layer is the synovial membrane which lines the joint capsule and secretes synovial fuid, hyauluronic acid and prevents leakage while the outer layer is the capsular ligament. Ligaments are bands of connective issue that keep the bones of the joint in position. There is both an intracapsular ligament which is inside the joint space and assists control of the joint moveement and extracapsular ligaments which are eternal to the capsule and are often bound to or form part of the capsule. Joints also contain a bursa which functions to facilitate movement and reduce friction between articulating bones.
Joint Types: 1 axis/translation
- Plane/Sliding joint: these are flat surfaces that slide on each other such as articular facets of the vertebrae. (translation)
-condylar joint: the priximal bone has cylindrical condyles and fits into articular depression distally.
-cochlear joint" this is a special form of condylar joint as it has oblique locating ridges on the trochlea (such as the hock joint)
- hinge joint: another special form of condylar joint that has perpendicular located guide.
- pivot joint: allows rotation and is dense of axis
Joint types: 2 axes
-sellar joint: articular surfaces make saddle shapes, seen in distalinterphalangeal joints
-ellipsoid joint: articular surface is an elliptical section (such as atlanto-occipital joint)
joint types: 3 axes
- ball and socket joint: has spherical articulation with mating socket less than half a hemisphere (animal hips)
-enarthrosis: special form of ball and socket; spherical articulation with mating socket greater than half a hemisphere (human hip only).
Learn More
WikiVet: The Skeleton
Textbook of Small Animal Orthopeadics
Crash Course Anatomy: Joints
Real 3D anatomy: Dog Skeleton
Veterinary Partner: Normal Joints
Pet Education: Normal Joint Anatomy in Dogs
Knowledge Testing:
- what fluids are secreted by the joint capsule?
- describe the structures of a synovial joint.
Concept testing:
- list at least 2 functions of ligaments.
- list the advantages and disadvantages of having joints with translation, 1 axis of movement, 2 axes of movement and 3 axes of movement.