Classes of Joints
Fibrous joints - Sutures - syndesmoses - gomphosis Cartilaginous joints - Synchondroses - Symphyses Synovial joints
Fibrous Joints
Sutures - Seams between skull bones Syndesmoses - Fibrous joint joined by ligament Gomphoses - Pegs that fit into sockets
Suture
Opposing bones interdigitate.
Sutural ligament:
- two periostea plus dense, fibrous, connective tissue between.
Fontanels:
- membranous areas in the suture between bones. Allow change in shape of head during birth and rapid growth of the brain after birth.
Syndesmoses
Gomphoses
Specialized joints
Pegs that fit into sockets
Held in place by regular collagenous tissue
Only found in teeth and mandible/maxilla
Peridontal bundle
- Connective tissue between teeth & sockets
Cartilaginous Joints
United 2 bones by either hyaline or fibrocartilage Synchondroses - Joints containing hyaline cartilage Symphyses - Joints containing fibrocartilage
Synchondroses
2 bones joined by hyaline cartilage Little or no movement Examples - Epiphyseal plates of growing bones - 1st rib and the sternum
Symphyes
Fibro-cartilage uniting 2 bones Movable Examples - Manubrium and body of sternum - Symphysis pubis - -Inter-vertebral disks
Synovial Joints
Contain synovial fluid Allow considerable movement Articular cartilage covers articulation sites Articular disk - Lies between articular cartilages Meniscus - Articular disk in knee or wrist
General Structural Features
Joint cavity - Encloses articular surfaces of 2 bones Joint Capsule - Encases joint cavity - Contains synovial membrane Synovial membrane - Produces synovial fluid rich in hyaluronic acid
Bursa
Synovial membrane extends to form a sac Contains synovial fluid Provides cushioning to prevent rubbing Bursitis - Inflammation of bursa & restricts movement
Types of Synovial Joints
Classified by shape of articular surfaces: Plane (Gliding) Saddle Hinge Pivot Ball-and-socket Ellipsoid
Movement of Synovial Joints
Uniaxial - One axis Biaxial - Two axes Multiaxial - Several axes
Plane Joint
2 flat bones of equal size that can glide
Movement is uniaxial
Example:
- Intervertebral
- intercarpal
- Carpometacarpal
- costovertebral, intertarsal, sacroiliac, tarsometatarsal
Saddle Joint
2 saddle shaped articulating surfaces oriented at right angles Biaxial joints Example - Carpometacarpal joint of the thumb
Hinge Joint
Uniaxial movement Convex portion of one bone articulates with concave portion of another bone Examples - Elbow - Knee - Ankle
Knee Joint
Meniscus: fibrocartilage articular disks that build up the margins of the tibia and deepen articular surface
Cruciate ligaments: extend between tibia and femur
- Anterior cruciate ligament (ACL). Prevents anterior displacement of tibia
- Posterior cruciate ligament (PCL). Prevents posterior displacement of tibia
Ankle (talocural) Joint
Highly modified hinge joint Lateral and medial thickening of articular capsule to prevent side-to-side movement Ligaments of arch - Hold bones in proper relationship - Transfer weight
Pivot Joint
Uniaxial movement Restricted movement around a single axis Cylindrical bony process that rotated within a ring of bone & ligaments Examples - Radius and ulna - Dens and atlas
Ball and Socket
A ball (head) one one bone fits into socket of another Multiaxial movement Examples - Shoulder - Hip
Hip (coxal) Joint
Ellipsoid Joint
Temporomandibular Joint (TMJ)
- Fibrocartilage disk divides joint into superior and inferior cavities
Types of Movement
Gliding: in plane joints; slight movement Angular - Flexion and Extension * Hyperextension * Plantar and Dorsiflexion - Abduction and Adduction Circular - Rotation - Pronation and Supination - Circumduction