Joint Mechanics (DSA) Flashcards
What does ginglymos mean?
Hinge
What does gomphosis mean?
Bolting together
What does cartilago mean?
Gristle
What does fibra mean?
Threadlike
What does arthron mean?
joint
What does junctio mean?
A joining
What does syn mean?
Toghether
What does dis mean?
Two
What are the 3 types of fibrous joints (synarthroses)?
Sutures
Syndesmosis
Gomphosis
What are the 2 types of cartilaginous joints (amphiarthroses)?
Hyaline (synchondroses)
Fibrocartilage (symphyses)
What are the 3 type of synovial joints (diarthroses)?
Spheroid
Hinge
Condylar
What is movement of fibrous joints dependent on and what unites the bones of a fibrous joint?
- Movement is dependent on the length of the fibers uniting the bones
- Type of joint united by dense fibrous tissue
What are suture joints held together by?
Several layers of strong CT -> extremely tight, provides little movement
- Ex. Skull sutures
What are the 2 types of suture edges of suture joints?
Squamous type = the edges overlap
Serrate type = the edges interlock
What are the characteristics of a syndesmosis fibrous joint?
- Bones are united by a sheet of fibrous tissue
- Can be a ligament or a fibrous membrane (interosseous membrane between radius and ulna, ankle syndesmosis, etc)
- Movement can be slight up to considerable depending upon distance between the bones and the degree of flexibility of the uniting fibrous tissue
What are characteristics of gomphosis fibrous joints?
- Unique joint between a tooth and the bone in its alveolus (socket)
- Fibrous tissue of the periodontal ligament firmly anchors the tooth
What are characteristics of cartilaginous joints?
- Strong ligamentous support
- Small rocking, sliding motion
What are the characteristics of primary cartilaginous joints?
- Bones united by hyaline cartilage
- Usually a temporary union
- Permits slight bending during early life
- Permits growth, then usually fuses when growth is completed
What are characteristics of secondary cartilaginous joints?
- Surfaces of the articulating bones are covered with hyaline cartilage and the bones are united by strong fibrous CT and/or fibrocartilage
- Strong, slightly movable joints
Joints between vertebral bodies and pubic symphysis are examples of what joint type?
Cartilaginous
What are characteristics of synovial joints?
- Most common
- Provide free movement
- Lined with synovial membranes or capsules
- Some contain fibrocartilage disc or meniscus
What are the characteristics of the articular cartilage found in synovial joiints?
- Usually hyaline cartilage, although the matrix contains many collaginous fibers
- No blood vessel or nerve supply
- Nourished by synovial fluid which obtain nutrients from capillaries in synovial membrane
What are the characteristics of the synovial membrane of synovial joints?
- Vascular CT membrane that lines the entire joint caivity
- Doesnt cover the articular cartilage
- Produces synovial fluid
- Regenerates if damaged
What are the characteristics of accessory ligaments of the articular joint capsule of synovial joints?
- Intrinsic or extrinsic
- Limit joint movement in undesirable directions to aid in preventing damage to the joint
- Maintain the normal relationship between the articulating bones
- Can be injured easily
What are characteristics of articular discs found in synovial joints?
- Present where the articulating surfaces are incongruous
- Usually fibrocartilaginous pads holding bones together
- Nerves present only at attached margins
What is the role of the fibrocartilaginous ring (labrum) of a synovial joint?
- Deepens the articualr surface for one of the bones
- Ex. glenoid labrum of the shoulder
What are characteristics of planar synovial joints?
- Numerous and nearly always small
- Permit gliding or sliding movements
- Opposed bone surfaces flat or almost flat
- Move in only one axis
- Movement limited by tight articular capsules
- *Injuries relatively common**
AC joint, proximal tibiofibular joint, intercarpal joints, and the SC joint are all examples of what type of joint?
Planar synovial
What are characteristics of hinge joints (ginlymus)?
- Uniaxial joiont with the axis being at a right angle to the bones involved
- strong collaterla ligaments
- Occur in elbow, knee, ankle, IP joints
What are characteristics of ball and socket (spheroidal) synovial joints?
- Multiaxial, highly movable
- spheroidal surface of one bone moves within the socket of another bone
- Flexion/extension, ab/adduction, medial/lateral, rotation, circumduction
What are characteristics of pivot synovial joints(trochoid)?
- Uniaxial joints which allow rotation
- One element rotates on its own axis
- Rounded process rotates within a sleeve or ring
The radioulnar joint is an example of what type of joint?
Pivot synovial joint (trochoid)
What are characteristics of condyloid and ellipsoid synovial joints?
- Partial flattening of both articular surfaces
- modified spheroid
- MCP
- Radiocarpal
What are characteristics of saddle synovial joints (sellar)?
- Biaxial with opposing surfaces shaped like a saddle
- Allows flexion/extension, ab/adduction, circumduction
- Carpalmetacarpal of thumb
T/F: Joints have a rich nerve supply
True
- Nerve endings are found in the articular capsule
What is hiltons law?
Nerves supplying a joint also supply the muscles moving the joint and the skin covering the attachments of these muscles
Where are pain fibers numerous in joints?
In the fibrous capsule aand its associated ligaments
- Sensory endings respond to twisting and stretching
What types of arteries supply joints?
Numerous articular arteries
- Arise from vessels around the joint
- often communicate or anastomose to form networks
- Diffusion occurs readily from these arteries into the joint cavitty
What is wolff’s law?
Bone is increased where needed and reabsorded where it is not
- Increased density/hypertrophy related to increase stresses
- Decreased density related to disuse or aging
What are characteristics of cartilage remodeling and adaptation?
- Trauma or abnormal wear leads to structural disruption of matrix
- loses elasticity therefore increases stiffness
- limited capacity to regenerate or repair
- with repeated high stresses can lead to development of degenerative joint disease
What are the characteristics of remodeling and adaptation of ligaments and tendons?
- Become stronger and stiffer with increased stress (number and quality of callagen cross-links increase)
- Become weaker and less stiff with a reduction of stress (loss of collagen due to immobilization and aging)
What are the 3 basic forms or arthritis?
Osteoarthritis
Inflammatory
Traumatic
What is osteoarthritis?
The most common form of arthritis. Occurs when the protective cartilage on the ends of bones wears down over time
Explain the inflammatory form of arthritis
Many inflammatory forms of arthritis are autoimmune diseases causing the body to degenerate its own joiints
The fibrous capsule of a synovial joint is highly sensitive, whereas the synovial membrane is relatively insensitive. What does this mean for joint pain?
- Its poorly localized
- Can be referred to overlying skin or muscle
- May be visceral disturbances associated
What is fibrillation in terms of joint degeneration?
- Early degenerative change of the articular cartilage due to the loss of proteoglycans
- Unmasks collagen fibers and increases water content in chondrocytes
- Equivalent of a superficial erosion of the cartilage
- Affected cartilage becomes dull with a yellowish discoloration taking a characteritic ground-glass appearance
What is eburnation in terms of joint degeneration?
- Complete loss (ulceration) of articular cartilage
- Accompanied by a thickening of the subchondral bone (osteosclerosis)
- Exposed bone surfaces take an ivory-like appearance (hard and polished)
Its a permanent lesion siince lost cartilage cant be repaired
What is “joint mice” osteochondromatosis?
- Fragments of cartilage and/or bone floating free in synovial fluid
- Pieces of degeneratign cartilage detach from the subchondral bone
- Commonly seen in degenerative joint diseases (particualrly in “osteochondrosis dissecans”)
