Arth-class2 Flashcards
synarthrotic joints
IMMOVABLE Joints- the bony edges are quite close together and may even interlock. These joints can be fibrous or cartilaginous
sutures
A suture (sutura, a sewing together) is a SYNARTHROTIC joint located only between the bones of the skull. The edges of the bones are interlocked and bound together at the suture by dense connective tissue.
Gomphosis
A gomphosis (gomphosis, a bolting together) is
a SYNARTHROSIS that binds the teeth to bony sockets in the
maxillary bone and mandible. The fibrous connection between a
tooth and its socket is a periodontal ligament (peri, around +
odontos, tooth).
synchondrosis
A synchondrosis (syn, together + chondros,
cartilage) is a rigid, CARTILAGINOUS bridge between two articulating bones. The hyaline cartilage of an epiphyseal plate is a synchondrosis that connects the diaphysis with the epiphysis (before puberty), even though the bones involved are part of the
same skeletal element. Another example is the cartilaginous connection between rib 1 and the manubrium of the sternum
amphiarthrosis
Structurally either FIBROUS or CARTILAGINOUS: the
articulating bones are separated by a wedge or pad of
fibrocartilage
syndesmosis
(desmos, a band or ligament): bones
are CONNECTED BY A LIGAMENT. One example is the distal articulation between the tibia and fibula or the
interosseous membranes (mid radio-ulnar joint or mid
tibofibular joint).
symphysis
the articulating bones are SEPERATED BY A WEDGE OR PAD OF FIBROCARTILIGINOUS . The articulation between the bodies of adjacent vertebrae (at the intervertebral
disc) and the anterior connection between the two pubic
bones (the pubic symphysis) are examples of this type of
joint
diarthrosis
or synovial joints permit a wide range of motion. A SYNOVIAL joint is surrounded by a fibrous articular capsule, and a synovial membrane lines the synovial cavity. The synovial cavity is filled with synovial fluid. These joints are typically found at the ends of long bones, such as those of the upper and lower limbs (appendicular skeleton).
- gliding joints
carpals, tarsals
also called PLANAR joints, have flattened or slightly curved faces. The relatively flat articular surfaces slide across one another, but the amount of movement is very slight. Although rotation is theoretically possible
at such a joint, ligaments usually prevent or restrict such movement. These joints are considered to be UNI-AXIAL or MONO-AXIAL joints.
Gliding joints are found BETWEEN THE CARPAL BONES, between the TARSAL BONES, and between the
ARTICULAR FACETS of ADJACENT SPINAL VERTEBRAE.
- Hinge joints
permit angular movement in a single plane, like the opening and closing of a door. A hinge joint is usually a UNI-AXIAL or MONO-AXIAL examples include the HUMERALULNAR, tibiofemoral, and interphalangeal joints of the appendicular skeleton.
- pivot joints
RADIAL ULNAR
are also UNIAXIAL or MONO-AXIAL, as they permit only rotation. An example of a pivot joint is between the HEAD OF THE RADIUS AND THE PROXIMAL SHAFT O FTHE ULNA, which permits pronation and supination of the hand.
- elipsoid or condyloid
an oval articular facet nestled within
a depression in the opposing surface. With such an arrangement, angular motion occurs in two planes, along or across the length of the oval. It is thus
typically a BI-AXIAL joint. Any form of angular movement, including false-circumduction, is permitted, but rotation cannot occur. Ellipsoidal joints connect the RADIUS WITH THE PROXIMAL CARPAL BONES and the phalanges of the fingers and toes with the metacarpal bones and metatarsal bones,
respectively.
- saddle joints
or sellaris joints have articular facets that resemble saddles. Each face is concave on one axis and convex on the other, and the opposing facets nest together. This arrangement permits angular motion, including
circumduction, but prevents rotation. Saddle joints are usually considered to be BIAXIAL. The CARPOMETACARPAL joint at the base of the thumb is the only true example of a saddle joint, and twiddling your thumbs will demonstrate the
possible movements
- ball and socket joints
In a ball-and-socket joint the round head of one
bone rests within a cup-shaped depression in another. All combinations of angular and rotational movements, including circumduction and rotation, can be performed at ball-and-socket joints. these are MULTI-AXIAL or TRI-AXILAR joints.
Examples include the glenohumeral and acetabulofemoral joints.
synovial joint structures
Articular Cartilages- Under normal conditions, the bony surfaces at a synovial
joint cannot contact one another, because the articulating surfaces are covered
by special articular cartilages. Articular cartilages resemble hyaline cartilages
elsewhere in the body. However, articular cartilages have no perichondrium
(which is the layer of dense irregular connective tissue that surrounds the cartilage of developing bone) and the matrix contains more water.
The surfaces of the articular cartilages are slick and smooth. This feature alone
can reduce friction during movement at the joint. However, even when pressure
is applied across a joint, the smooth articular cartilages do not actually touch one
another, because they are separated by a thin film of synovial fluid in the joint
cavity. THIS FLUID ACTS AS A LUBRICANT, keeping friction at a minimum.
Proper synovial function can continue only if the articular cartilages retain their normal structure.
If an articular cartilage is damaged, the matrix may begin to break down. The exposed surface will then change from a slick, smooth, gliding
surface (think new car!) to a rough FELTWORK of bristly COLAGEN FIBRES (think old
rusty car!). This feltwork drastically increases friction at the joint.
