ch 8 Flashcards
functional classification of human joints (ROM considered)
Synarthrosis: immovable joint
-bony edges are close together, may interlock or fuse
-extremely strong joints
-located where movement is prevented
–bony fusion/bony joint (synostosis)
–fibrous (suture)
–cartilaginous (synchondrosis: epiphyseal plate)
Amphiarthrosis: Slightly movable
-stronger than freely movable joints
–fibrous: syndesmosis, gomphosis
–cartilaginous: symphysis : intervertebral discs
Diarthrosis: fdreely movable also weakest
–also called Synovial Joints
–typically at ends of long bones
–subdivided by nature of movement : monoaxial, biaxial, triaxial, multiaxial
4 distinguishing features of synovial joints
1) articular cartilage:
-articular (hyaline) cartilage covers the ends of the bones forming the joint preventing contact between the bony surfaces
-slick and smooth
- not covered by the perichondruim with a more watery matrix
2) joint capsule (articular capsule): unique to synovial joints
-joint surfaces are enclosed by a sleeve or capsule of outer fibrous capsule or fibrous membrane: dense collagenous CT
–continuous with the periostea of articulating bones
-lined by a smoothe inner synovial membrane: synoviocytes + areolar CT and elastic fibers
3) joint cavity (synovial cavity):
-enclosed by the joint capsule
-contains a thin film of lubricating synovial fluid:
–resembles interstitial fluid, but conatin high concentration of proteoglycans
(3 primary functions of synovial fluid 1. lubrication, 2. nutrient distribution, 3. shock absorption)
4) reinforcing accessory structures: pads of cartilage or fat, ligaments, tendons and bursae
reinforcing structures
cartilages and fat pads: several joints contain fat pads
-localized adipose tissue
-covered by a layer of synovial membrane
-commonly found superficial to joint capsule
-protect articular cartilages
-act as packing material for the joint (some contain articular discs or meniscus: pad of fibrocartilage)
Tendon:
- not part of the joint
-tendons passing across or around a joint stabilizes it and provide mechanical support
reinforcing structures
cartilages and fat pads: several joints contain fat pads
-localized adipose tissue
-covered by a layer of synovial membrane
-commonly found superficial to joint capsule
-protect articular cartilages
-act as packing material for the joint (some contain articular discs or meniscus: pad of fibrocartilage)
Tendon:
- not part of the joint
-tendons passing across or around a joint stabilizes it and provide mechanical support for it
Sensory nerves and blood vessels:
-numerous in synovial joints
-nerves detect painful stimuli, monitors movement and stretch (golgi tendon organ- found in tendons)
reinforcing accessory structures cont’d
ligaments:
-support, strengthen reinforce articulating bones
-sprain: ligament is stretched to the point where some or all the collagen fibers are torn
bursa
-small flattened fluid pockets
-contain synovial fluid
-outer dense collagenous CT lined with synovial membrane
- may be connected or separate from the joint cavity
- common where ligaments, muscles, skin, tendons, and bones rub together
Tendon sheaths (synovial sheaths)
-elongated bursa that wraps completely around a tendon
-protects all sides of tendon as they slide back and forth
planes of dynamic motion
nonaxial(translational):
-gliding allows only small amounts of movement, but may occur back-and-forth, and side to side
-gliding does not permit rotation
-plane (gliding) joints (intercarpal joints of the wrists, intertarsal joints, and claviculosternal joints)
monaxial (uniaxial):
-movement along one axis (angular or rotation movement)
-hinge joints (elbow), pivot joints (proximal radio-ulnar joint)
biaxial
-movement along one axis (angular or rotation movement only)
-condylar joints (radiocarpal joint, metacarpophalangeal joints, saddle joints)
Triaxal joints (multiaxial):
-movement along three axes (angular and rotational movement)
-ball and socket joints (shoulder and hip joints )
gliding joint (plane joint)
flattened or slightly curved articulating surfaces that slide across one another back and forth, side to side
i.e.: intercarpal and intertarsal
hinge joint
angular movement in one axis (monaxial)
either angular or rotation
i.e. elbow joint, knee joint, ankle joint
pivot joint
rotational movement in one axis (monaxial)
i.e. atlanto-axial joint, proximal radio-ulnar joint
ellipsoid joint (condylar joint)
oval articular face within a depression allowing for angular movemnts around two axes (including circumduction), but not rotation. can do more than one angular movement
i.e. radiocarpal joint, metacarpophalangeal joints 2-5, metatarsophalangeal joints
saddle joint
concave-convex articulation permitting angular movement around two axes; limited circumduction, but not rotation
i.e. first carpometacarpal joint
ball and socket joint
round head of one bone within a cup shaped depression in another
all combinations of angular (including circumduction) and rotational movements
shoulder joint
- between head of humerus and glenoid cavity of scapula
- ball and socket joint
- allows more motion than any other joint
- least stable; supported by skeletal muscles, tendons, ligaments.
- glenoid labrum: socket of shoulder joint- deepens socket of glenoid cavity, fibrocartilage lining, extends past bone
- acromion and coracoid process: project laterally, superior to humerus; help stabilize joint
elbow joint
- stable hinge joint due to thick joint capsule, bony surfaces of humerus and ulna interlock closely and multiple, strong ligaments reinforce joint
- withing articulations involving humerus, radius, and ulna
hip joint (coxal joint)
- strong ball and socket joint: diarthrosis
- wide range of motion
