Articulations Lesson 10 11 Articulation Articulations Body movement occurs at joints where two bones connect Joint structure o Determines direction distance of movement Range of motion ROM o Joint strength decreases as mobility increases o The more stable the joint the less moveable it is Two methods of classification o Functional Classification Based on range of motion of the joint Synarthrosis Immovable joint Amphiarthrosis Slightly moveable joint Diarthrosis Freely moveable joint o Structural Classification Relies on the anatomical organization of the joint Bony Synotoses synarthroses Fibrous Sutures and gomphoses synarthroses syndesmoses Cartilaginous Synchondroses synarthroses and symphyses amphiarthroses amphiarthroses Synovial Only diarthroses 1 Synarthroses Immovable joints o Very strong o Edges of bones may touch or interlock o Four types of synarthrotic joints Suture Bones interlocked Bound by dense fibrous connective tissue Found only in skull Gomphosis Synchondrosis Fibrous connection periodontal ligament Binds teeth to sockets A rigid cartilaginous bridge between two bones o Epiphyseal cartilage of long bones o Between vertebrosternal ribs sternum Synostosis Fused bones immovable Metopic suture of skull fuses two sides of frontal bone Epiphyseal lines of long bones Amphiarthroses o More moveable than synarthrosis o Stronger than freely moveable joint o Two types Syndesmosis Bones connected by ligaments Ex Tibia fibula Symphysis Bones separated by Fibrocartilage 2 Synovial Joints Diarthroses Ex Pubic symphysis o Also called moveable joints o At ends of long bones o Within articular capsules o Lined with synovial membrane o Articular Cartilages Pad articulating surfaces within articular capsules Prevent bones from touching Smooth surfaces lubricated by synovial fluid o Synovial Fluid Consistency of heavy molasses Reduce friction Contains slippery proteoglycans glycoproteins secreted by fibroblasts Functions of synovial fluid Lubrication articular cartilage act as sponge filled with fluid o Compression of it pushes some synovial fluid out Nutrient distribution fluid circulates as joint moves provides nutrients to chondrocytes Shock absorption o Accessory structures Cartilages Cushion the joint Fibrocartilage pad called a meniscus or aricular disc Fat Pads Adipose tissue superficial to joint capsule Protect articular cartilages Ligaments Support strengthen joints Sprain Ligaments with torn collagen fibers Tendons Help support joint Attach to muscles around joint Bursae Pockets of synovial fluid Cushion areas where tendons or ligaments rub Bursitis Inflamed bursae causing pain can result from repetitive motion irritation trauma infection o Four 4 factors that prevent injury by limiting range of motion 1 Collagen fibers joint capsule ligaments 2 Shape of the articulating surfaces menisci 3 Presence of other bones muscles or fat pads 4 Tension in the tendons of articulating bones o Pain receptors are not found on the inside of synovial joints Pain felt due to joint damage results from nerves that monitor the capsule ligaments and tendons o Injuries of the synovial joints Dislocation Luxation Articulating surfaces forced out of position Damages articular cartilage ligaments joint capsule Caused by extreme stress Shoulder joint most prone to this injury 3 Subluxation A partial dislocation Double jointed people have weakly stabilized joints that are prone to dislocation or partial dislocation o Three 3 types of dynamic motion Linear Movement Gliding Movement Two surfaces slide past each Ex Between carpal or tarsal bones and motion between the other clavicle and sternum Angular Movement Flexion Angular motion in the anterior posterior plane o Reduces angle between elements Extension Angular motion in the anterior posterior plane o Increases angle between elements Hyperextension Angular motion of extension past the anatomical position o Ex Hyperextension of neck to look at ceiling Abduction Angular motion in the frontal plane o Moves away from the longitudinal axis Adduction Angular motion in the frontal plane o Moves toward the longitudinal axis Circumduction Angular motion in a circular motion without Rotation Movement described with reference to the figure in the rotation anatomical position Relative to longitudinal axis of the body Left or right rotation Medial Rotation inward internal rotation o Rotates toward axis o Ex Bend arm at elbow move hand to chest extend arm palm anterior rotate so arm and palm is medial Lateral Rotation outward external rotation o Rotates away from axis o Ex With arm bent at elbow move hand away from chest Pronation Rotates forearm radius over ulna Supination Forearm in anatomical position o Pronation supination are not the same as medial rotation and lateral rotation 4 Special Movements specific articulations or unusual types of movements Inversion Twists sole of foot medially 5 Eversion Twists sole of foot laterally Dorsiflexion Flexion at ankle lifting toes Plantar Flexion Extension at ankle pointing toes Opposition Thumb movement toward fingers or palm grasping Reposition Opposite of opposition Protraction Moves anteriorly in the horizontal plane pushing Retraction Opposite of protraction moving posteriorly pulling forward back Elevation Moves in superior direction up Depression Moves in inferior direction down Lateral Flexion Bends vertebral column from side to side o Planes axes of dynamic motion Monaxial 1 axis forward backward 6 Biaxial 2 axes forward backward and side to side Triaxial 3 axes forward backward side to side angular o Classification of synovial joints by shape Gliding Flattened or slightly curved faces Limited motion nonaxial Hinge Angular motion in a single plane monaxial Pivot Rotation only monaxial Condylar Oval articular face within a depression Motion in tow planes biaxial Saddle Two concave straddled biaxial Ball and socket Round articular face in a depression triaxial Joints A joint cannot be both mobile and strong The greater the mobility the weaker the joint 7 Mobile joints are supported by muscles ligaments not bone to bone connections Intervertebral Articulations C2 to L5 vertebrae articulate o At inferior and superior articular processes gliding joints o Between adjacent vertebral bodies symphyseal joints Little gliding occurring at vertebral bodies Adjacent vertebral bodies separated by fibrocartilage intervertebral discs Intervertebral Discs Pads of fibrocartilage that separate vertebral bodies o Consist of
View Full Document
Unlocking...