CH9 Flashcards
How do the joints of the skeletal system contribute to homeostasis?
- by holding bones together in ways that allow for movement and flexibility
- by acting as fulcrums that act as fixed point of stability
what is a joint?
articulation
arthrosis
- a point of contact between bones, cartilage and bones, or teeth and bones
what is kinesiology?
the study of motion of the human body
what is arthrology?
the scientific study of joints
what are the three principal types of joints?
- synovial
- cartilaginous
- fibrous
what are fibrous joints?
A joint in which the articulating bones are held together by dense irregular connective tissue (mainly collagen fibres) and allows little to no movement
what does the degree of movement in fibrous joints depend on?
on the length of the collagen fibres that join the articulating bones
the longer the collagen fibres, the more movable
the shorter the collagen fibres, the more immovable
what are the subtypes of fibrous joints?
- sutures
- syndesmoses
what are cartilaginous joints?
A joint without a synovial cavity where the articulating bones are held together by hyaline or fibrous cartilage, allowing little to no movement
what are the subtypes of cartilaginous joints?
- synchondroses
- symphyses
what is a synovial joint?
A slightly movable to fully movable joint in which a lubricated articular cavity is present between the articulating bones which are united by a two-layered articular capsule
what is the lubrication in synovial joints supplied by?
the inner layer of the articular capsule
what are the subtypes of synovial joints?
- Ball-and-socket
- Ellipsoid
- Hinge
- Pivot
- Plane
- Saddle
what is a suture?
an immovable fibrous joint composed of a thin layer of dense irregular connective tissue that joins skull bones
why are sutures strong and unlikely to fracture?
due to their irregular, interlocking edges
- can absorb shock
what is a synostosis?
a fibrous joint in which the dense irregular connective tissue that unites bones at a suture has been replaced by bone, resulting in complete fusion across the suture line
what is a syndesmosis?
a slightly movable fibrous joint in which the articulating bones are united by dense irregular connective tissue
how is a syndesmosis different from a suture?
- generally a greater distance between the articulating surfaces than in sutures
- more dense irregular connective tissue than in sutures
what are the different types of syndesmoses?
- interosseous ligament
- interosseous membrane
- gomphosis
what is an interosseous ligament?
a syndesmosis that has fibrous connective tissue arranged as a ligament that permits limited movement
what is an interosseous membrane?
a syndesmosis with a substantial sheet of dense irregular connective tissue that binds neighbouring long bones and permits slight movement
- plays important role in defining range of motion btwn the neighbouring bones
- provides increased attachment surface for muscles
what is a gomphosis?
a fibrous joint in which a cone-shaped peg fits into a socket with a small amount of dense irregular connective tissue
- permits minute shock-absorbing movements
what is the thin periodontal ligament?
The dense irregular connective tissue between a tooth and its dental alveolus
what is periodontal disease?
Inflammation and degeneration of the gums, periodontal ligament, and bone
what is a synchondrosis?
cartilaginous joint in which the connecting material is a solid piece of hyaline/fibrous cartilage that allows little or no movement
what is an epiphyseal cartilage?
a type of synchondrosis that is actually an hyaline cartilage growth center during endochondral bone formation, not a joint associated with movements
- immovable joint
ex. epiphyseal growth plate in growing long bones
what does damage to the epiphyseal cartilage lead do?
Breaks in a bone that extend into the epiphyseal plate and damage the cartilage of the synchondrosis can affect further growth of the bone, leading to abbreviated development and a bone of shortened length
what happens to epiphyseal cartilages when bone elongation ceases?
bone replaces the hyaline cartilage, and becomes a synostosis, a bony joint
what is a symphysis?
a slightly movable cartilaginous joint in which the ends of the articulating bones are covered with hyaline cartilage, but a broad, flat disc of fibrous cartilage connects the bones
what is the main characteristic that distinguish synovial joints from other joints?
presence of articular cavity btwn articulating bones
what is an articular cavity?
The space between the articulating bones of a synovial joint, filled with synovial fluid
- surrounded by an articular capsule that attaches the articulating bones
what does the presence of an articular cavity permit?
a wide range of movements from slightly movable to freely movable
what is articular cartilage?
layer of hyaline cartilage that covers the surface of articulating bones within a synovial joint
what is the function of the articular cartilage?
- covers the articulating surfaces of the bones with a smooth, slippery surface but does not bind them together
- reduces friction between bones in the joint during movement
- absorbs shock
what is autologous chondrocyte implantation?
healthy chondrocytes taken from a femoral condyle area that is not weight-bearing and cultured to generate between 5 million and 10 million cells
- cultured chondrocytes are injected under the periosteum after damaged area prepped by removing dead cartilage
- patient can put the full weight of the body on the knee in about 10 to 12 weeks
- candidates for ACI have cartilage damage due to acute or repetitive trauma, not arthritis
what is an articular capsule?
A sleevelike structure of a synovial joint that encloses the articular cavity and units the articulating bones; composed of an outer fibrous layer and an inner synovial membrane
what is the outer fibrous layer of the articular capsule?
layer consisting of dense irregular connective tissue that attaches to the periosteum of the articulating bones (thickened continuation of the periosteum btwn the bones)
what does the flexibility of the articular capsule’s fibrous layer do?
permits considerable movement at a joint
what does the tensile strength of the articular capsule’s fibrous layer do?
tensile strength (resistance to stretching) helps prevent the bones from dislocating
what is a ligament?
parallel bundles of dense regular connective tissue that attaches bone to bone and are highly adapted to resisting strains
what is the inner synovial membrane of the articular capsule?
inner layer that is composed of areolar connective tissue with collagen and elastic fibers
what are articular fat pads?
accumulations of adipose tissue in synovial membranes
do “double-jointed” people really have double joints?
NO
- they have greater flexibility in their articular capsules and ligaments
- increased range of motion
- less structurally stable
- easily dislocated
what is synovial fluid?
a viscous (gel-like), clear or pale yellow fluid secreted by the synovial membrane and forms a thin film over the surfaces within the articular capsule
what does synovial fluid consist of?
- hyaluronic acid secreted by synoviocytes in the synovial membrane
- interstitial fluid filtered from blood plasma
what are the functions of synovial fluid?
- reduces friction by lubricating the joint
- absorbs shocks
- supplies O2 and nutrients to the chondrocytes
- removes CO2 and metabolic wastes from the chondrocytes
- contains **phagocytic cells **that remove microbes and debris from normal wear and tear
What is one benefit of warming up before exercise when it comes to synovial fluid?
stimulates the production and secretion of synovial fluid; within limits, more fluid means less strain on the joints during exercise
what happens when a synovial joint is immobile for a time?
the fluid becomes quite viscous, but as joint movement increases, the fluid becomes less viscous
what is the cracking sound as certain joints move?
results as gases come out of solution to form bubbles in the articular cavity
why can you not immediately pop your knuckles again?
takes time for the gases to re-accumulate and form bubbles in the articular cavity
what are extracapsular ligaments?
accessory ligaments that lie outside articular capsule