ArthrologyArthrology

Ch. 8.Ch. 8.

Arthrology: Study of jointsArthrology: Study of joints

Joints are classified according to Joints are classified according to structure and functionstructure and function

Structural:Structural:1.  Fibrous joints: composed of fibrous 1.  Fibrous joints: composed of fibrous

tissue with no joint cavitytissue with no joint cavity2.  Cartilaginous joints: articulating 2.  Cartilaginous joints: articulating

bones bones are united by cartilage and no are united by cartilage and no joint joint cavity present.cavity present.

3.  Synovial joints: articular bones are 3.  Synovial joints: articular bones are separated by a fluid-filled joint separated by a fluid-filled joint

cavity.cavity.

Functional:Functional:

1.  Synarthroses: immovable joints 1.  Synarthroses: immovable joints

2.  Amphiarthroses: slightly movable 2.  Amphiarthroses: slightly movable joints joints (vertebral bodies and pubic (vertebral bodies and pubic bones)bones)

3.  Diarthroses: freely movable joints 3.  Diarthroses: freely movable joints (most (most appendicular joints)appendicular joints)

Fibrous joints:Fibrous joints:1.  1.  SuturesSutures: contain dense fibrous connective : contain dense fibrous connective

tissue until adulthood when they ossify tissue until adulthood when they ossify (synostoses). skull bones (plates)(synostoses). skull bones (plates)

2. 2. SyndesmosesSyndesmoses: bones are connected by a : bones are connected by a filamentous sheet or cord (ligament or filamentous sheet or cord (ligament or interosseous membrane); fibers are interosseous membrane); fibers are

longer longer than in sutures but are only than in sutures but are only slightly more slightly more resilient, movement can resilient, movement can range from slight to range from slight to considerable. tibiofibular joint and the considerable. tibiofibular joint and the radioulnar joint.radioulnar joint.

3. 3. GomphosesGomphoses: articulation of tooth with body : articulation of tooth with body alveolar surface. Peg in socket. alveolar surface. Peg in socket.

Possesses a Possesses a fibrous connection called fibrous connection called the periodontal the periodontal ligament.  ligament. 

Cartilaginous joints:Cartilaginous joints:1.   1.   SynchondrosesSynchondroses- hyaline cartilage - hyaline cartilage

unites unites bones at a synchondrosis. bones at a synchondrosis. Cartilage is Cartilage is replaced by bone and replaced by bone and becomes becomes synarthrotic.  Epiphyseal synarthrotic.  Epiphyseal plate and the plate and the costal cartilage of costal cartilage of the first rib and the the first rib and the manubrium of manubrium of the sternum.the sternum.

2.   2.   SymphysesSymphyses- articular surface of - articular surface of bone bone covered by hyaline cartilage covered by hyaline cartilage fused to fused to an intervening pad or plate.  an intervening pad or plate.  However, However, it is compressible, it is compressible, resilient and resilient and functionally functionally amphiarthrotic. Pubic amphiarthrotic. Pubic symphysis and symphysis and the intervertebral discs.the intervertebral discs.

Synovial:Synovial:all synovial joints are diarthrotic (opposing all synovial joints are diarthrotic (opposing bones move freely)  bones move freely)  Five distinct features of the skeletonFive distinct features of the skeleton

1.  Articular cartilage: hyaline type forms a 1.  Articular cartilage: hyaline type forms a glassy smooth surface over the glassy smooth surface over the

opposing opposing ends of bones.                 ends of bones.                 2.  Joint cavity: small space2.  Joint cavity: small space3.  Synovial fluid: largely derived from blood; 3.  Synovial fluid: largely derived from blood;

has a has a viscous, egg-white consistency; viscous, egg-white consistency; leaks out of leaks out of cartilage; weeping cartilage; weeping lubrication.lubrication.

4.  Articular capsule4.  Articular capsule              a.  Fibrous capsule (external)a.  Fibrous capsule (external)              b.  Synovial membrane (internal)b.  Synovial membrane (internal)5.  Reinforcing ligaments: support and 5.  Reinforcing ligaments: support and

strengthen the jointstrengthen the joint

Synovial joints have supportive Synovial joints have supportive structures called structures called bursaebursae.  These .  These structures are flattened sacs lined with structures are flattened sacs lined with a synovial membrane and contain a a synovial membrane and contain a thin film of synovial fluid.  Bursae are thin film of synovial fluid.  Bursae are located where ligaments, muscles, and located where ligaments, muscles, and tendons overlie and rub against bone.  tendons overlie and rub against bone. 

Some synovial joints have pads of Some synovial joints have pads of fibrocartilage between the ends of fibrocartilage between the ends of bones:bones:

menisci of the knee.menisci of the knee.

     

Joint motionJoint motion

GlidingGliding: bones displaced in relation to one : bones displaced in relation to one another (intercarpal and intervertebral another (intercarpal and intervertebral joints)joints)

      AngularAngular: changing the angle between two : changing the angle between two bonesbones

          Flexion: decreasing the joint angleFlexion: decreasing the joint angle

          Extension: increasing the joint Extension: increasing the joint angleangle

          Abduction: moving awayAbduction: moving away

          Adduction: moving towardsAdduction: moving towards

          Circumduction: draw around in a circleCircumduction: draw around in a circle

          Rotation: turning movement of a bone Rotation: turning movement of a bone around around its own axis (can be medial or its own axis (can be medial or lateral)lateral)

Special movementsSpecial movements

1.   Supination: turning backwards (radius/ulna)1.   Supination: turning backwards (radius/ulna)

2.   Pronation: turning forwards (radius/ulna)2.   Pronation: turning forwards (radius/ulna)

3.   Inversion: movement of the foot medially3.   Inversion: movement of the foot medially

4.   Eversion: movement of the foot laterally 4.   Eversion: movement of the foot laterally

5.   Protraction: movement of the mandible 5.   Protraction: movement of the mandible forwardforward

6.   Retraction: movement of the protracted 6.   Retraction: movement of the protracted part part back to its starting positionback to its starting position

7.   Elevation: lifting a body part superiorly7.   Elevation: lifting a body part superiorly

8.   Depression: moving the elevated part 8.   Depression: moving the elevated part inferiorlyinferiorly

9.   Opposition: touching your thumb to the tips 9.   Opposition: touching your thumb to the tips of of other fingers.other fingers.

Types of synovial jointsTypes of synovial joints

1.  Plane joints: articular surface is flat and 1.  Plane joints: articular surface is flat and only only allow for short gliding movements allow for short gliding movements (intercarpal and intertarsal).(intercarpal and intertarsal).

2.  Hinge joints: cylindrical projection of one 2.  Hinge joints: cylindrical projection of one bone fits into a trough-shaped bone fits into a trough-shaped

surface on surface on another bone (elbow).another bone (elbow).

3.  Pivot joints: rounded end of one bone 3.  Pivot joints: rounded end of one bone protrudes into a sleeve or ring composed protrudes into a sleeve or ring composed

of bone or ligament (radius to ulna of bone or ligament (radius to ulna and axis and axis to atlas).to atlas).

4.  Condyloid joints: oval articular surface of 4.  Condyloid joints: oval articular surface of one one bone fits into a complementary bone fits into a complementary depression in another depression in another (metacarpophalanges: knuckles).(metacarpophalanges: knuckles).

5.  Saddle joints: each articular surface 5.  Saddle joints: each articular surface has has a concave and convex area a concave and convex area (carpometacarpal joint of the (carpometacarpal joint of the thumb).thumb).

6.  Ball and socket: the spherical end 6.  Ball and socket: the spherical end of one of one bone articulates with a bone articulates with a cuplike socket cuplike socket of another bone of another bone (shoulder or hip (shoulder or hip joints).joints).