Joint Mechanics DSA

Question 1

Fibrous joints

Answer 1

Synarthroses
Sutures
Syndesmosis
Gomphosis
Type of joint united by dense fibrous tissue
Movement is dependent on the length of the fibers uniting the bones

Question 2

Cartilaginous joints

Answer 2

Amphiarthroses
Hyaline (Synchondrosis)
Fibrocartilage (symphysis)
strong ligamentous support
Small rocking, sliding motion
Intervertebral discs
Pubic symphysis

Question 3

Synovial joints

Answer 3

Diarthrosis
Spheroid 
Hinge
Condylar
Provide free movement
Contain synovial fluid, lined with a synovial membrane, some contain fibrocartilage discs or meniscus

Question 4

Sutures

Answer 4

Fibrous joint
Held together by several layers of strong CT
Extremely tight, little movement
Skull sutures
Squamous type: edges overlap
Serrate type: edges interlock

Question 5

Syndesmosis

Answer 5

Bones are united by a sheet of fibrous tissue
Can be ligament or a fibrous membrane
Interosseous membrane between ulna and radius
Movement can be slight up to considerable, depends on distance between the bones and the degree of flexibility of the uniting fibrous tissue

Question 6

Gomphosis

Answer 6

Fibrous joint

Unique between tooth and the bone In its alveolus (socket)

Question 7

Primary cartilaginous joints

Answer 7

Hyaline cartilage
Temporary union
Permits slight bending during early life, growth, and then usually fuses when growth is completed

Question 8

Secondary cartilaginous joints

Answer 8

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 9

Distinguishing features of synovial joints

Answer 9

Synovial membrane
Joint cavity
Articular cartilage-hyaline
Articular (joint) capsule

Question 10

Articular cartilage

Answer 10

Hyaline
No blood vessel or nerve supply
Nourished by synovial fluid

Question 11

Articular (joint) capsule

Answer 11

Fibrous capsule
Envelops the articulation or joint
Synovial membrane: vascular CT membrane that lines the entire joint cavity (except the articular cartilage)
Produces synovial fluid
Regeneration

Question 12

Plane joints

Answer 12

Synovial joint
Permit gliding or sliding movements
AC joint, proximal tibiofibular, intercarpal, SC
Uniaxial joint
Movement limited by tight articular capsules

Question 13

Hinge joints

Answer 13

Ginglymus
Synovial joint
Uniaxial joint
Strong collateral Ls.
Elbow, knee, ankle

Question 14

Ball and Socket joint

Answer 14

Spheroidal
Multiaxial, highly moveable joints
Spheroidal surface of one bone moves within the socket of another bone
Flexion, extension, abduction, adduction, rotation, circumduction

Question 15

Pivot joint

Answer 15

Trochoid
Uniaxial joints which allow rotation
Radioulnar

Question 16

Condyloid and Ellipsoid joints

Answer 16

Partial flattening of both articular surfaces
Modified spheroidal
MCP joint
Radiocarpal

Question 17

Saddle joints

Answer 17

Sellar synovial
Biaxial with opposing surfaces shaped like a saddle
Flexion/extension, abduction, adduction, circumduction
Carpalmetacarpal joint of thumb

Question 18

Hilton’s law

Answer 18

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

Question 19

Wolff’s law

Answer 19

Bone is increased where needed and reabsorbed were it is not

Question 20

Fibrillation

Answer 20

Early degenerative change of the articular cartilage due to the loss of proteoglycans
Unmasks collagen fibers and increases water content in chondrocytes
Superficial erosion of the cartilage
Ground-glass appearance of affected cartilage

Question 21

Eburnation

Answer 21

Complete loss (ulceration) of articular cartilage
Thickening of the subchondral bone-osteosclerosis
Exposed bone surfaces take an ivory-like appearance
Permanent lesion

Question 22

Joint mice

Answer 22

Osteochondromatosis
Fragments of cartilage and/or bone floating free in synovial fluid
Pieces of degenerating cartilage detach from the subchondral bone