Joint Mechanics (DSA)

Question 1

What does ginglymos mean?

Answer 1

Hinge

Question 2

What does gomphosis mean?

Answer 2

Bolting together

Question 3

What does cartilago mean?

Answer 3

Gristle

Question 4

What does fibra mean?

Answer 4

Threadlike

Question 5

What does arthron mean?

Answer 5

joint

Question 6

What does junctio mean?

Answer 6

A joining

Question 7

What does syn mean?

Answer 7

Toghether

Question 8

What does dis mean?

Answer 8

Two

Question 9

What are the 3 types of fibrous joints (synarthroses)?

Answer 9

Sutures
Syndesmosis
Gomphosis

Question 10

What are the 2 types of cartilaginous joints (amphiarthroses)?

Answer 10

Hyaline (synchondroses)

Fibrocartilage (symphyses)

Question 11

What are the 3 type of synovial joints (diarthroses)?

Answer 11

Spheroid
Hinge
Condylar

Question 12

What is movement of fibrous joints dependent on and what unites the bones of a fibrous joint?

Answer 12

• Movement is dependent on the length of the fibers uniting the bones
• Type of joint united by dense fibrous tissue

Question 13

What are suture joints held together by?

Answer 13

Several layers of strong CT -> extremely tight, provides little movement

• Ex. Skull sutures

Question 14

What are the 2 types of suture edges of suture joints?

Answer 14

Squamous type = the edges overlap

Serrate type = the edges interlock

Question 15

What are the characteristics of a syndesmosis fibrous joint?

Answer 15

• 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

Question 16

What are characteristics of gomphosis fibrous joints?

Answer 16

• Unique joint between a tooth and the bone in its alveolus (socket)
• Fibrous tissue of the periodontal ligament firmly anchors the tooth

Question 17

What are characteristics of cartilaginous joints?

Answer 17

• Strong ligamentous support

- Small rocking, sliding motion

Question 18

What are the characteristics of primary cartilaginous joints?

Answer 18

• Bones united by hyaline cartilage
• Usually a temporary union
• Permits slight bending during early life
• Permits growth, then usually fuses when growth is completed

Question 19

What are characteristics of secondary cartilaginous joints?

Answer 19

• 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

Question 20

Joints between vertebral bodies and pubic symphysis are examples of what joint type?

Answer 20

Cartilaginous

Question 21

What are characteristics of synovial joints?

Answer 21

• Most common
• Provide free movement
• Lined with synovial membranes or capsules
• Some contain fibrocartilage disc or meniscus

Question 22

What are the characteristics of the articular cartilage found in synovial joiints?

Answer 22

• 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

Question 23

What are the characteristics of the synovial membrane of synovial joints?

Answer 23

• Vascular CT membrane that lines the entire joint caivity
• Doesnt cover the articular cartilage
• Produces synovial fluid
• Regenerates if damaged

Question 24

What are the characteristics of accessory ligaments of the articular joint capsule of synovial joints?

Answer 24

• 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

Question 25

What are characteristics of articular discs found in synovial joints?

Answer 25

- Present where the articulating surfaces are incongruous - Usually fibrocartilaginous pads holding bones together - Nerves present only at attached margins

Question 26

What is the role of the fibrocartilaginous ring (labrum) of a synovial joint?

Answer 26

- Deepens the articualr surface for one of the bones | - Ex. glenoid labrum of the shoulder

Question 27

What are characteristics of planar synovial joints?

Answer 27

- 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**

Question 28

AC joint, proximal tibiofibular joint, intercarpal joints, and the SC joint are all examples of what type of joint?

Answer 28

Planar synovial

Question 29

What are characteristics of hinge joints (ginlymus)?

Answer 29

- Uniaxial joiont with the axis being at a right angle to the bones involved - strong collaterla ligaments - Occur in elbow, knee, ankle, IP joints

Question 30

What are characteristics of ball and socket (spheroidal) synovial joints?

Answer 30

- Multiaxial, highly movable - spheroidal surface of one bone moves within the socket of another bone - Flexion/extension, ab/adduction, medial/lateral, rotation, circumduction

Question 31

What are characteristics of pivot synovial joints(trochoid)?

Answer 31

- Uniaxial joints which allow rotation - One element rotates on its own axis - Rounded process rotates within a sleeve or ring

Question 32

The radioulnar joint is an example of what type of joint?

Answer 32

Pivot synovial joint (trochoid)

Question 33

What are characteristics of condyloid and ellipsoid synovial joints?

Answer 33

- Partial flattening of both articular surfaces - modified spheroid - MCP - Radiocarpal

Question 34

What are characteristics of saddle synovial joints (sellar)?

Answer 34

- Biaxial with opposing surfaces shaped like a saddle - Allows flexion/extension, ab/adduction, circumduction - Carpalmetacarpal of thumb

Question 35

T/F: Joints have a rich nerve supply

Answer 35

True - Nerve endings are found in the articular capsule

Question 36

What is hiltons law?

Answer 36

Nerves supplying a joint also supply the muscles moving the joint and the skin covering the attachments of these muscles

Question 37

Where are pain fibers numerous in joints?

Answer 37

In the fibrous capsule aand its associated ligaments - Sensory endings respond to twisting and stretching

Question 38

What types of arteries supply joints?

Answer 38

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

Question 39

What is wolff’s law?

Answer 39

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

Question 40

What are characteristics of cartilage remodeling and adaptation?

Answer 40

- 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

Question 41

What are the characteristics of remodeling and adaptation of ligaments and tendons?

Answer 41

- 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)

Question 42

What are the 3 basic forms or arthritis?

Answer 42

Osteoarthritis Inflammatory Traumatic

Question 43

What is osteoarthritis?

Answer 43

The most common form of arthritis. Occurs when the protective cartilage on the ends of bones wears down over time

Question 44

Explain the inflammatory form of arthritis

Answer 44

Many inflammatory forms of arthritis are autoimmune diseases causing the body to degenerate its own joiints

Question 45

The fibrous capsule of a synovial joint is highly sensitive, whereas the synovial membrane is relatively insensitive. What does this mean for joint pain?

Answer 45

- Its poorly localized - Can be referred to overlying skin or muscle - May be visceral disturbances associated

Question 46

What is fibrillation in terms of joint degeneration?

Answer 46

- 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

Question 47

What is eburnation in terms of joint degeneration?

Answer 47

- 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**

Question 48

What is “joint mice” osteochondromatosis?

Answer 48

- 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”)