Bones and joints Flashcards
What is a joint?
Point of contact between neighbouring bones, cartilage and bones or between teeth and bones.
How are joints classified and what are the 3 different types?
Classified according to: i) presence/absence of synovial cavity, ii) type of tissue that binds the bones together.
- fibrous joints
- cartilaginous joints
- synovial joints
What are the characteristics of fibrous joints?
- Lack a synovial cavity.
- Articulating bones held very closely together by fibrous CT.
- Permit little or no movement.
Give examples of fibrous joints.
- sutures of skull
- inferior tibiofibular joint
- radioulnar interosseus membrane
- posterior sacroiliac joint
- joints between roots of teeth and bone of mandible or maxilla
What are the characteristics of cartilaginous joints?
- Lack a synovial cavity.
- Artilculating bones tightly connected by cartilage.
- Permit little or no movement.
What are the 2 types of cartilaginous joints? Give examples.
Primary cartilaginous joints
- connective tissue is hyaline cartilage
- e.g. epiphyseal plates
Secondary cartilaginous joints (symphyses)
- connective tissue is a fibrocartilage disc
- e.g. pubic symphysis
What are the characteristics of synovial joints?
i) synovial cavity
ii) articular cartilage
iii) articular capsule composed of 2 layers: outer fibrous capsule that may have ligaments and inner synovial membrane which secretes the lubricating synovial fluid that fills the synovial cavity
iv) rich blood and nerve supply
v) many synovial joints also contain:
- accessory ligaments, inc. extracapsular and intracapsular ligaments
- articular discs or menisci
Name 2 structures that can reduce friction at some synovial joints during movement.
- fluid-filled sacs - bursae
2. tube-like bursae - tendon sheaths
Name the 6 different types of synovial joints.
- planar joint
- hinge joint
- pivot joint
- condyloid/ellipsoidal joint
- saddle joint
- ball and socket joint
Describe and give an example of a planar joint.
- articulating surfaces usually flat or slightly curved
- non-axial joint - only gliding side-to-side or back-and-forth movements
- e.g. sternoclavicular joint
Describe and give an example of a hinge joint.
- monoaxial joint at which convex surface of 1 bone fits into concave surface of another bone
- allows flexion and extension
- e.g. knee joint, elbow joint or ankle joint
Describe and give an example of a pivot joint.
- monoaxial joint at which rounded/pointed surface of 1 bone articulates with a ring formed partly by another bone and partly by a ligament
- rotation may occur
- e.g. rotation of atlas around dens of axis when turning head
Describe and give an example of a condyloid/ellipsoidal joint.
- biaxial joint at which oval-shaped condyl of 1 joint rests against elliptical cavity or another bone
- 4 angular movements (and circumduction) may occur
- e.g. wrist joint
Describe and give an example of a saddle joint.
- biaxial joint at which articular surface of 1 bone is saddle-shaped and articular surface of the other bone resembles the legs of a rider sitting the saddle
- is technically a modified ellipsoidal joint in which movement is less restricted
- e.g. joint between trapezium and 1st metacarpal base
Describe and give an example of a ball-and-socket joint.
- multiaxial joint at which the ball-like surface of 1 bone rests against the cup-like depression of another bone
- 4 angular movements and rotation may occur
- e.g. shoulder join and hip joint (only examples)
