Functions of Joints
hold bones to one another; in some cases, permit the human skeleton to be flexible (movement)
ARTICULATIONS
contact points between bones or cartilage and bones; closer fit at contact point stronger joint.
Explain how joints are classified structurally and functionally.
Structurally focuses on the material binding the bones together; Functional is based on the amount of movement allowed to the joint):
Functional joints
Classified by how much movement is allowed
1) Synoarthrosis (immovable)
2) amphiarthrosis (slightly movable)
3) diarthrosis (freely movable)
Structural Joints
focuses on the material binding the bones together
1) Fibrous
2) Cartilagenous
3) Synovial
Fibrous Joints
no joint cavity; joined together by dense fibrous connective; tissuea joint where the material between bones consists of fibrous connective tissue that allows very little or no movement between them.
Fibrous Joints: Sutures
Fibrous joint; occur between bones of skull and use very short dense connective tissue fibers to hold the bones together
Fibrous Joints: Syndemoses
Fibrous joint connected by a ligament or membrane that allows some movement (radius and ulna or tibia and fibula)
Fibrous Joints: Gomphoses
Fibrous joint in which a cone-shaped peg fits into a socket (i.e. union of tooth root in bony socket)
Cartilaginous Joints
Have no joint cavity; allow only slight movement, bones held together by cartilage.
1. Sychondroses
2. Symphyses
Cartilaginous Joints: Sychondroses
Cartilaginous Joint; involve a bar or plate of hyaline cartilage uniting the bones, such as the epiphyseal plate (between 1st rib and sternum)
Cartilaginous Joints: Symphyses
Cartilaginous Joint; bones are joined by fibrocartilage such as the pubic symphysis; the articular surfaces are covered with articular cartilage that is then fused to an intervening pad or plate of fibrocartilage
Synovial Joints
joints in which the articulating bones are separated by a fluid-containing joint cavity; all are freely movable diarthroses; Examples - all limb joints, and most joints of the body
Synovial Joints - 6 distinguish features
1. Joint (Synovial Cavity)
2. Articular Cartilage
3. Articular Capsule
4. Accessory Ligaments
5. Articular Disc (MENISCI)
6. Bursae
Synovial Joints - distinguish features:
1. Joint (Synovial Cavity)
potential space between bones that contains a small amount of synovial fluid
Synovial Joints - distinguish features:
2. Articular Cartilage
hyaline cartilage that covers ends of bones in synovial joints
Synovial Joints - distinguish features:
3. Articular Capsule
A. Fibrous capsule- the outer layer of the articular capsule; dense irregular connective tissue that is continuous with the periosteum layer of the joining bones; some fibers arranged in parallel bundles =LIGAMENTS
B. Synovial Membrane- inner; loose connective tissue with elastic fibers & adipose tissue; secretes SYNOVIAL FLUID which lubricates the joints and nourishes the cartilage; has phagocytic cells, has hyaluronic acid + intestinal fluid made from blood plasma, greater movement the less viscous, up to .1oz
Synovial Joints - distinguish features:
4. ACCESSORY LIGAMENTS
a) EXTRACAPSULAR - outside art. capsule (eg. fibular collateral ligament of knee)
b) INTRACAPSULAR - within art. capsule but excluded from synovial cavity by reflections of synovial membrane (eg. cruciate ligament of knee)
Synovial Joints - distinguish features:
5. ARTICULAR DISC (MENISCI)
cushion of dense, specialized connective tissue that divides the articular space into upper and lower compartments, also known as meniscus; maintains stability
Synovial Joints - distinguish features:
6. BURSAE
tiny sacs of fluid that are located near joints and help reduce friction ; found where excessive rubbing (skin over bone, tendons and bone, muscles and bone)
SYNOVIAL JOINT TYPES
1. GLIDING (ARTHRODIA)
2. HINGE (GINGLYMUS)
3. PIVOT (TROCHOID)
4. ELLIPSOIDAL (CONDYLOID)
5. SADDLE (SELLARIS)
6. BALL & SOCKET (SPHEROID
SYNOVIAL JOINT TYPES:
1. GLIDING (ARTHRODIA)
anterior surface; small, flat, concave; non-axial movement. example is between carplas and tarsals
- a joint that allows one bone to slide over the othe
SYNOVIAL JOINT TYPES:
2. HINGE (GINGLYMUS)
spool like surface fits into concave surface; mono axial (flex/extend); a joint which allows movement in one plane, can flex or extend in that plane, (eg. elbow/ankle, interphalangeal)
SYNOVIAL JOINT TYPES:
3. PIVOT (TROCHOID)
rounded, pointed or concave surface fits into ring formed by part bone/ligament; mono axial (rotational movement around a single axis) (eg.atlantoaxial joint)
SYNOVIAL JOINT TYPES:
4. ELLIPSOIDAL (CONDYLOID)
Oval part of one bone fits into an elliptical cavity of another bone.; biaxial (flex/extend, adduct/abduct) (eg. radiocarpal joint)
SYNOVIAL JOINT TYPES:
5. SADDLE (SELLARIS)
articular surface concave in 1 direction, convex in other; biaxial(flex/extend, adduct/abduct) (eg. carpometacarpal joint of thumb)
SYNOVIAL JOINT TYPES:
6. BALL & SOCKET (SPHEROID
ball into cup like depression; tri axial (flex/extend, adduct/abduct/rotational) (eg.shoulders/hips)
JOINT MOVEMENT
A. GLIDING
B. ANGULAR
C. FLEXION
D. EXTENSION
E. ABDUCTION
F. ADDUCTION
G. ROTATION
H. CIRCUMDUCTION
I.. SPECIAL
JOINT MOVEMENT:
A. GLIDING
back and forth/side to side; no angular or rotary motion (eg. between tarsals and carpals); One flat bone surface glides or slips over another similar surface
JOINT MOVEMENT:
C. FLEXION
decrease angle between anterior surface of art. bones (except for toe & knee) (eg. bend head forward)
JOINT MOVEMENT:
D. EXTENSION
increase angle between anterior surface of art. bones (eg. resumes anatomical position)
JOINT MOVEMENT:
G. ROTATION
around it's own axis
MEDIAL ant. surface of bone or extremity towards midline (eg. rotate palm inward)
LATERAL ant. surface of bone or extremity away from
midline (eg. rotate palm outward)
JOINT MOVEMENT:
H. CIRCUMDUCTION
distal end of bone moves in circle while proximal end is stable (eg. rotate outstretched arm)
JOINT MOVEMENT:
I.. SPECIAL
• INVERSION movement of foot/sole medially at ankle joint
• EVERSION movement of foot/sole laterally at ankle joint
• DORSIFLEXION flex foot at ankle joint
• PLANTAR FLEXION extend foot at ankle joint
• PROTRACTION move mandible/clavicle forward parallel to ground
• RETRACTION move mandible/clavicle backward parallel to ground
• SUPINATION forearm movement where in palm is turned ant. or sup. with flexed arm
• PRONATION forearm movement where in palm is turned post. or inf. with flexed arm
• ELEVATION upward body movement (eg. close mouth)
• DEPRESSION downward body movement (eg. open mouth)