Articulations Flashcards
Joint classification
- Structural - based on presence of fluid filled joint space and type of connective tissue
- Functional - based on tupe of movement allowed at joint
Fibrous Synarthroses
- no joint cavity
- bones fit closely together
- little to no movement
- 3 types (syndesmoses, sutures, and gomphoses)
Syndesmoses
Joints in which ligaments connect two bones
- slightly moveable (ligament flexibility)
- radius and ulna
Sutures
Found only in skull
- thin layer of fibrous connective tissue
- adjacent bones interlock
- immovable in adults, slight movement in children
Gomphoses
- formed between root of tooth and the sockets (alveoli) of mandible or maxillae
- immovable joint when healthy
- fibrous tissue between root and bone called periodontal membrane
Cartilaginous amphiarthroses
- no joint cavity
- bones of joints are joined together by hyaline cartilage or fibrocartilage
- no motion or very little motion
- 2 types (synchondroses and symphyses)
Synchondroses
- connecting material between articulating bones is hyaline cartilage
- immovable
- 1st rib and manubrium
Symphyses
Joint with a pad or disc of fibrocartilage between two bones
- most occur in midline of body
- slight movement
- pubic symphysis
- between vertebrae
Synovial joints
Freely moveable joints
- diarthroses
- comprise of majority of joints in appendicular skeleton
7 structures of synovial joints
- Joint capsule
- Synovial membrane
- Articular cartilage
- Joint cavity
- Menisci (articular discs)
- Ligaments
- Bursae/tendon sheath
Joint capsule
- forms complete casing around synovial joint
- extension of the periosteum of each of the articulating bones
Synovial membrane
- lines the inner surface of joint capsule
- arranges to the margins of the articular cartilage
- secretes synovial fluid (lubricates and nourishes)
Articular cartilage
- thin layer of hyaline cartilage that covers the articular surfaces of bones
- reduces friction during movement and absorbs shock
Joint cavity
- small space between bones
- allows for extensive movement
Menisci (articular disks)
- pads of fibrocartilage located between articulating bones
- usually divide the joint cavity into two separate spaces allowing separate movements
- Functions:
- Shock absorption
- Better fit between articulating bones
- Larger contact surface for weight bearing
- Synovial fluid distribution across joint surfaces
Labrum
- fibrocartilaginous lip that extends form joint socket
- deepens joint socket of shoulder and hip
- increases contact area between articulating bones
Ligaments
Strong cords of dense, regular fibrous tissue that hold bones of synovial joint together more firmly
Bursae
- saclike structure surrounded by synovial membrane
- filled with synovial fluid
- between skin and bones, tendons and bones, or ligaments and bones
- cushion joint or facilitate movement of tendons
Tendon (synovial) sheaths
- tubelike bursae that wrap around tendons that receive a lot of wear and tear
- extension of joint capsule but wraps around tendon
- protects tendon as it slides back and forth with movement
Types of synovial joints
- Uniaxial: hinge and pivot
- Biaxial: saddle and condyloid
- Multiraxial: ball-and-socket and gliding
Uniaxial joints
Synovial joint that permit movement around one axis and only one plane
- Hinge: elbow
- Pivot: head of radius against ulna
Hinge joint
- uniaxial
- convex surface of one bone fits into the concave surface of another bone
Pivot joint
- uniaxial
- projection of one bone articulates with a ring or notch of another bone
Biaxial joints
Synovial diarthroses that permit movement around two perpendicalar axes in two perpendicular planes
- saddle
- condyloid
Saddle joint
Biaxial
- articulating ends of the bones resemble reciprocally shaped miniature saddles
- only in the thumb (1st cmc joint)
Condyloid (ellipsoidal) joint
Biaxial
- condyloid fits into an elliptical socket
- condyloid of the occiput in the elliptical depressions of the atlas
- the dental end of the radius fitting into the depression of the carpal bones (scaphoid, lunate, and triquitrum)
Multiraxial joint
Synovial joints that permit movements around 3+ axes in 3+ planes
- ball and socket
- gliding
Ball and socket joint
Multiaxial
- most movable joint
- ball-shaped head of one bone fits into a concave depression
- shoulder/hip
Gliding joint
Multiaxial
- relatively flat articulating surfaces that allow sliding movements along various axes
- intervertebral joints
Synovial Gliding movements
- nearly flat bones move back and forth from side to side
- limited in range secondary to support structures and joint capsule
- can be combined with rotational movements
- examples include intercapral and intertarsal joints
Synovial Angular movements
- increase or decrease in the angle between the bones
- flexion, extension, abduction, adduction, and lateral flexion
Synovial Special movements
- occur only in certain joints
- include: elevation/depression, protraction/retraction, inversion/eversión, Doris flexion/plantarflexion, supination/pronation, and opposition
