Joint Mechanics Flashcards
Cartilaginous Joint
Amphiarthrosis
Two contiguous surfaces united by fibrocartilaginous disks
No cavity between the bones
Strong ligamentus support
Small amount of rocking and sliding motion
Subtypes: hyaline, fibrocartilage
Hyaline
- synchondroses
- cartilage United the bones at the unction of cartilage
- permits light bending during early life
- temporary Union in long bone growth (epiphyseal plate)
Fibrocartilage
- symphyses
- cartilage fuses into a pad of fibrocartilage that is compressible and allows some movement
- center of each pad/disc is the nucleous pulposus (cushion/shock absorber)
Synovial Joint
Diarthrosis
Most common joint
Articulating bones do not touch
Separated by a fluid-containing joint cavity
Freely mobile
Some contain fibrocartilage discs or meniscus
Articular surface covered with hyaline cartilage
Enclosed by a fibrous joint capsule creates a closed joint cavity
Synovial membrane lines the joint capsule secreting a viscous fluid nourishing and lubricating the hyaline cartilage
Types:
- plane
- hinge (ginglymus)
- saddle
- condyloid
- ball and socket (ellipsoid, condylar)
- pivot
Plane Synovial Joint
Two flat surfaces
Motion limited to minimal sliding
Ex: triquetreum-pisiform
Ginglymus Synovial Joint
Hinge
Allows for large degree of freedom of motion in one plane
Ex: elbow
Spherical Synovial Joint
Ball and socket
Round convex head that articulates with a concave surface
Allows greatest degree of motion
Modified ball and socket:
- condylar: partial flattering of both articular surfaces; limits motion; ex: metacarpal-phalangeal
- ellipsoid: head is ellipsoid; greater motion than condylar less than spheroid; ex: radiocarpal
Trochoid Synovial Joint
Composed of a ball shape that is surrounded by a circle composed of bone and ligament
Primary motion is rotation
Ex: atlas and axis
Sellar Synovial Joint
Composed of one concave and one convex bone
Allows for greater motion in all planes
Ex: thumb
Synovial Articular Discs (Meniscus)
Vascular and nerve supply at the periphery
Buffer and maintains normal joint relationship
Limit joint motion in undesirable direction
Synovial Fibrocartilaginous (Labrum)
Deepens the articular surface
Synovial Tendons
Within the capsule of the joint
Can become contiguous with fibrocartilaginous labrum
Hilton’s Law
Nerves supplying a joint also supply the muscles moving the joint and the skin covering the attachments of these muscles
Joint play, a small but precise amount of movement, which is independent of the action of voluntary muscle function is best assessed in: A. Active exam B. Passive exam C. Postmortem exam D. Practical exam
B. Passive exam
This type of joint has primarily a small amount of rocking and/or sliding motion.
A. Cartilaginous
B. Synovial
C. Fibrous
D. Colorado Gold
A. Cartilaginous
Common elements of a synovial joint include all of the following except:
A. Fibrous capsule B. Hyaline cartilage C. Ligamentous reinforcement D. Synchondrosis E. Synovial membrane
D. Synchondrosis
A synovial joint that acts as a hinge is known as this type of joint:
A. Plane B. Ginglymus C. Saddle D. Condyloid E. Ellipsoid
B. Ginglymus
The nerve endings within a joint are primarily found within this part of the joint:
A. Hyaline Cartilage B. Fibrocartilage C. Articular Capsule D. Vascular Anastomosis E. Tendons
C. Articular capsule
Wolff’s Law
Bone is increased where needed and reabsorbed where it is not
Increased density/hypertrophy related to increased stresses
Decreased - condition of disuse,aging
Can lead to altered stress/strain properties of the bone