Joints Chapter 5

Joints Articulation : sites where two or more bones meet ( also called “ arthrosis ”) Functions Hold bones together securely Give skeleton mobility Classification Functionally : amount of movement joint allows Synarthroses Amphiarthroses Diarthroses Structurally : type of binding connective tissue ; presence / absence of synovial cavity Fibrous Cartilaginous Synovial Page 168, fig 5.30

Functional Classification Synarthrosis Immoveable joint Can become synostosis ( bony joint ) Ex : sutures of skull

Functional Classification Amphiarthrosis Slightly moveable joint Ex : tibiofibular joint ; slight flexibility to protect the bones of the joint but injured if moved too far

Functional Classification Diarthrosis Freely moveable joint All synovial joints ( functional and structural categories align !) link

Structural Classification

Fibrous Joints United by fibrous connective tissue No synovial cavity Most are functionally classified as synarthroses ( immoveable ) Ex : sutures of skull

Types of Fibrous Joints Sutures Between bones of skull ( only ) Amphiarthroses as fontanels Become synarthroses ( no movement ) Can become synostoses ( bony joint ) Unique to the individual like fingerprints

Types of Fibrous Joints Syndesmosis More distance Fibrous connective tissue in sheet ( interosseou s membrane ) or bundle ( ligament ) Functionall y classified as amphiarthro ses Ex : tibiofibula r joint

Types of Fibrous Joints Gomphosis ( dentoalveolar ) Cone - shaped peg in socket Functionally classified as synarthrosis Only joint between teeth and bone

Structural Classification Cartilaginous Joints Bone ends connected by cartilage Can be functionally classified as amphiathrosis ( slightly moveable ) or synarthrosis ( immoveable ) No synovial cavity Ex : pubic symphysis, intervertebral joints, epiphyseal plates

Types of Cartilaginous Joints Synchondro sis Hyaline cartilag e Synarthr osis Ex : growth plates - epiphyse al plates & joint between first rib and sternum Become synosto ses when grown

Types of Cartilaginous Joints Symphysis Fibrocartilage Found in axial skeleton ( midline of body ) Amphiarthroses Ex : pubic symphysis and intervertebral joints

Structural Classification Synovial Joints Connected by dense irregular connective tissue Articulating bone ends are separated by a joint cavity containing synovial fluid All joints of the limbs All diarthroses

Features of Synovial Joints Articular cartilage ( hyaline ) Articular capsule (2 layers ) Unites two bones Fibrous capsule : Dense Regular CT attach to periosteum or ligament Synovial membrane : loose areolar CT produces synovial fluid Synovial fluid : shock absorption, nutrients, removes microbes and debris, reduces friction Joint cavity ( contains synovial fluid ) Reinforcing ( Accessory ) ligaments Large joints : ACL, MCL, PCL More support / stabilizatio n for joints that are under a lot of stress / pressure

Synovial Joints Also can contain : Bursae : alleviate friction Tendon sheaths : wrap around tendons to reduce friction ( wrist, ankle, shoulder, fingers, toes ) Articular discs ( menisci ): cartilage that helps maintain stability, helps different shapes fit together in joint ( ex : knee, TMJ ) link Classification

Damage to connective tissue of joint Damage to muscle tissue

Inflamm ation of bursae

Movements of Synovial Joints Chapter 6, page 197 Movement caused by relationship between parts Four categories of movements 1) Gliding Flat bone surfaces against each other ; no angle Ex : intercarpal & intertarsal joints

Movements of Synovial Joints Four categories of movements 2) Angular Angle change Includes : Flexion Extension Lateral flexion Lateral extension Hyperextens ion Abduction Adduction Circumducti on

Movements of Synovial Joints Four categories of movements 3) Rotational Ex : head shaking no, foot moving laterally & medially

Movements of Synovial Joints Four categories of movements 4) Special Movements Elevation / De pression Protraction / retraction Inversion / ev ersion Dorsiflexio n / plantar flexion Supination / p ronation Opposition Movement link

Six Types of Synovial Joints Planar joint Gliding movements Flat surfaces Ex : intercarpal and intertarsal Hinge joint Convex fits into concave Like door hinge Biaxial ( no hyperextensi on ) Ex : elbow Pivot joint Rounded surface articulates with ring rotational Ex : atlas around axis

Six Types of Synovial Joints Condylar joint ( ellipsoid ) Concave into convex Movement in multiple directions ( oval shape ) biaxial Ex : wrists Saddle joint “ saddle ” shaped biaxial Ex : wrist and thumb Ball - and - socket joint multiaxial Ex : hip, shoulder

Synovial Joints Pg. 171, fig 5.32

Synovial Joints

Range of motion : amount of movement Factors affecting ROM at synovial joints : Structure or shape of articulating bones ( how they fit ) Strength and tension of ligaments ( depends on position ; disease, atrophy, etc.) Arrangement and tension of muscles ( tension restricts movement ) Contact of soft parts ( adipose tissue can affect ROM ) Hormones ( ex : relaxin with the pubic symphysis ) Disuse ( decrease synovial fluid, flexibility of ligaments and tendons, muscular atrophy )

Homeostatic Imbalance Arthritis Inflammatory joint disorder Changes in joint structure occur Osteoarthritis, rheumatoid arthritis, gouty arthritis

Temporomandibular joint disease Often caused by trauma to jaw joints, genetics, or dental procedures Symptoms include facial pain, headaches, grinding of teeth, popping of jaw, and swallowing difficulties Not well defined in medical community

link