Joints
definition : junction between two or more bones
Found all over the body except the hyoid which is just held by muscles
Function
Hold the skeleton together
Allows for bone growth
Allows for movement and flexibility
Classes of Joints
Functional/Movement
Tissue type
Cartilaginous : connected by cartilage only
Synovial : joint cavity filled with synovial fluid (most common)
Fibrous - no joint cavity, connected by fibrous connective tissue
types:
synarthrosis
connective tissue: mainly collagen
syndesmosis
Freely mobile - diathrosis Example: hip bone #
suture : between bones of skull
gomphosis :: binds teeth to bony sockets in maxillae and mandible
synostosis: when 2 bones fuse and the boundary between them disappears
Primary: Synchondroses between two articulating bones
Secondary: Symphyses between two pubic bones
united by hyaline cartilage or fibrocartilage and has no joint cavity
primarily immovable
ossify with age
plate of hyaline cartilage
articular surface covered with hyaline disc plate
connected by fibrocartilage
fibrous capsule
filled with synovial fluid
enclosed with articulating ends of bone
types
possess a joint cavity
hinge
saddle
plane
pivot
condyloid
ball and socket
outer fibrous membrane with inner synovial membrane
secreted by synovial membrane and has a high concentration of proteoglycans
provides nutrients for the area.
divided into menisci / articular discs
flat articular surface
shock absorption
lubrication
allow for gliding movement and movement in different directions
intercarpal and intertarsal joints
pulled shaped articular surface
elbow and knee joint
flexion and extension
fit into one another; one rounded, one concave
proximal radioulnar joint and atlantoaxis joint
rotation around a central axis
rounded chondyle
knee joint
two directions
reciprocally saddle shaped, concavoconvex, modified condyloid joint
between trapezium and metacarpal bone of thumb, sternoclavicular joints
wide range
ball shaped bone head, cup shape bone cavity, modified condyloid joint
hip and shoulder joint
widest range of movement. Permits movements in all planes
Other parts of joint
bursae
ligaments
reinforce joint capsule. They also support and strengthen the joint
types
extrinsic ligaments: located on either side of joint capsule
intra / extracapsular ligament:
intrinsic / capsular ligaments: localised thickenings
small, fluid filled cavity (filled with synovial fluid)
formed where a tendon or ligament rub against other tissues
reduce friction, act as shock absorbers
Movement
Flexion
Ab / Ad duction
Extension / Hyperextension
Plantar flexion
Dorsiflexion
Rotation
Supination / Pronation
Circumduction
Elevation/ Depression
Protraction / Retraction
Inversion / Eversion
Ab: away from longitudinal axis of body in the frontal plane
Ad : moving back to anatomical position
moving arm in loop
with reference to anatomical position
inversion: twisting movement of foot inwards
eversion: opposite
flexion of heel and elevation of sole
extend ankle and elevate heel
Protraction: moving body part anteriorly in horizontal plane
Retraction: reverse movement
Depression: opening mouth
Pronation: turns wrist and hand from front to facing back
Supination: opposing movement
Elevation: shrug shoulders