Transcript Arthrology Ch. 8. Arthrology: Study of joints Joints are classified according to structure and function Structural: 1.

Arthrology
Ch. 8.
Arthrology: Study of joints
Joints are classified according to structure
and function
Structural:
1. Fibrous joints: composed of fibrous
tissue with no joint cavity
2. Cartilaginous joints: articulating bones
are united by cartilage and no joint
cavity present.
3. Synovial joints: articular bones are
separated by a fluid-filled joint cavity.
Functional:
1. Synarthroses: immovable joints
2. Amphiarthroses: slightly movable joints
(vertebral bodies and pubic bones)
3. Diarthroses: freely movable joints (most
appendicular joints)
Fibrous joints:
1. Sutures: contain dense fibrous connective
tissue until adulthood when they ossify
(synostoses). skull bones (plates)
2. Syndesmoses: bones are connected by a
filamentous sheet or cord (ligament or
interosseous membrane); fibers are longer
than in sutures but are only slightly more
resilient, movement can range from slight to
considerable. tibiofibular joint and the
radioulnar joint.
3. Gomphoses: articulation of tooth with body
alveolar surface. Peg in socket. Possesses a
fibrous connection called the periodontal
ligament.
Cartilaginous joints:
1. Synchondroses- hyaline cartilage unites
bones at a synchondrosis. Cartilage is
replaced by bone and becomes
synarthrotic. Epiphyseal plate and the
costal cartilage of the first rib and the
manubrium of the sternum.
2. Symphyses- articular surface of bone
covered by hyaline cartilage fused to
an intervening pad or plate. However,
it is compressible, resilient and
functionally amphiarthrotic. Pubic
symphysis and the intervertebral discs.
Synovial:
all synovial joints are diarthrotic (opposing
bones move freely)
Five distinct features of the skeleton
1. Articular cartilage: hyaline type forms a
glassy smooth surface over the opposing
ends of bones.
2. Joint cavity: small space
3. Synovial fluid: largely derived from blood; has a
viscous, egg-white consistency; leaks out of
cartilage; weeping lubrication.
4. Articular capsule
a. Fibrous capsule (external)
b. Synovial membrane (internal)
5. Reinforcing ligaments: support and
strengthen the joint
Synovial joints have supportive structures
called bursae. These structures are
flattened sacs lined with a synovial
membrane and contain a thin film of
synovial fluid. Bursae are located where
ligaments, muscles, and tendons overlie
and rub against bone.
Some synovial joints have pads of
fibrocartilage between the ends of bones:
menisci of the knee.
Joint motion
Gliding: bones displaced in relation to one
another (intercarpal and intervertebral joints)
Angular: changing the angle between two bones
Flexion: decreasing the joint angle
Extension: increasing the joint angle
Abduction: moving away
Adduction: moving towards
Circumduction: draw around in a circle
Rotation: turning movement of a bone around
its own axis (can be medial or lateral)
Special movements
1. Supination: turning backwards (radius/ulna)
2. Pronation: turning forwards (radius/ulna)
3. Inversion: movement of the foot medially
4. Eversion: movement of the foot laterally
5. Protraction: movement of the mandible
forward
6. Retraction: movement of the protracted part
back to its starting position
7. Elevation: lifting a body part superiorly
8. Depression: moving the elevated part inferiorly
9. Opposition: touching your thumb to the tips of
other fingers.
Types of synovial joints
1. Plane joints: articular surface is flat and only
allow for short gliding movements
(intercarpal and intertarsal).
2. Hinge joints: cylindrical projection of one
bone fits into a trough-shaped surface on
another bone (elbow).
3. Pivot joints: rounded end of one bone
protrudes into a sleeve or ring composed
of bone or ligament (radius to ulna and axis
to atlas).
4. Condyloid joints: oval articular surface of one
bone fits into a complementary
depression in another
(metacarpophalanges: knuckles).
5. Saddle joints: each articular surface has
a concave and convex area
(carpometacarpal joint of the thumb).
6. Ball and socket: the spherical end of one
bone articulates with a cuplike socket
of another bone (shoulder or hip
joints).