Part 2: Support & Movement Joints Part 2: Support & Movement

Joints Joints or Articulations: Locations were bones join together that allow for some degree of movement. Arthrology: The scientific study of Joints! Most important joints for this test: Knee and Shoulder Classification: Either by structure or range of movement allowed.

Structural Classifications Synovial Joints: The most important type; found throughout the body and named for their synovial cavity that is lubricated by the synovial fluid. Freely movable joints Bones joined together by dense irregular connective tissue within the fibrous joint capsule Primary examples: Elbow, knee, hip, ankle

Structural Classifications Fibrous Joints: Joints where the bones are held together via collagenous fibers running from the matrix of one bone to the matrix of the other bone. NO joint cavity; little to no movement

Structural Classifications Types of Fibrous Joints: Sutures: Found only in the bones of the skull Irregular edges provide added strength against fractures. Synostosis or Bony Joint: When a suture is replaced by bone. Syndesmosis: More fibrous tissue than a suture, but permits a very small degree of movement Examples: Distal tibiofibular joint Gomphoses: A cone-shaped peg fitting into a socket. ONLY found where teeth attach.

Sutures Syndesmosis Gomphoses

Structural Classification Cartilaginous Joints: Bones are held together by hyaline or fibro cartilage. DO NOT contain a joint cavity. Allow little to no movement.

Structural Classification Types of Cartilaginous Joints: Synchondroses: Made of hyaline cartilage. Found in epiphyseal plates connecting the epiphysis and diaphysis of growing bone Found where the rib attaches to the sternum Symphyses: A flat disk of fibrocartilage connects the bones Found in the public symphysis or the intervertebral joints Slightly moveable

Synchondroses Symphyses

Functional Classification Diarthroses: Freely moveable synovial joints Ex. Shoulder, hip, finger, knee Amphiarthrosis: Slightly moveable joints Ex. Symphysis pubis and intervertebral discs Synarthroses: Immovable joints Ex. Sutures, epiphyseal plates of long bones

Diarthroses Synarthroses Amphiarthrosis

Synovial Joints Bones covered by articular cartilage, which reduces friction between bones & absorbs shock Articular Capsule: Surrounds each synovial joints, composed of… Fibrous Capsule: An outer layer Synovial Membrane: Inner layer; secretes synovial fluid Synovial Fluid: Reduces friction, supplies nutrients, contains phagocytes to help remove debris from the joint Meniscus: Cushy pad contained by some joints to further absorb shock

Synovial Joints Ligaments: Tough connective tissue bands arranged in capsule bundles. Run from bone to bone across the joint. Helps stabilize and strengthen the joint Bursae: Fluid-filled sacs beneath the muscles Help tendons glide easily over joints Bursitis: Inflammation of the bursae from overexertion of a joint Tendon Sheaths: Thin membrane enclosing the tendon. Help reduce friction at joints.

Types of Synovial Joints Ball-And-Socket Joints: Highly moveable Multiaxial Examples: Shoulder & hip joints

Types of Synovial Joints Planar Joints: “Gliding Joints” Permit some side-to-side & back-and-forth movement Nonaxial Examples: Joints between carpal & tarsal bones & between the scapula and clavicle

Types of Synovial Joints Pivot Joints: Where a projection on one bone fits into a ring shaped ligament on the other bone. Uniaxial (allows for rotationa round one axis only) Examples: Atlanto-axial joint (allows side-to-side head shakes) & where the radius articulates to the ulna.

Types of Synovial Joints Hinge Joints: Act like a hinge on a door Allow for uniaxial or monoaxial swinging motion Examples: Knee, elbow, ankle, finger, toe joints

Types of Synovial Joints Condyloid Joints: Occur where an oval convex surface fits into a similar shaped concave depress on the next bone. Biaxial Examples: Metacarpophalangeal joints of the wrist.

Types of Synovial Joints Saddle Joint: Named for its shape Biaxial Only ONE: Where the thumb metacarpal articulates with the trapezium of the wrist Allows for the opposable thumb

Joint Movement Flexion: Movement that decreases the angle of the bone in a joint Example: Bending your arm at the elbow toward you Flexing the knee to limb stairs

Joint Movement Extension: Movement that increases the angle of a joint or straightens the joint, returning it to its anatomical position. Example: Straightening your arm back out.

Joint Movement Hyperextension: Extension of a joint beyond 180 degrees Example: Tilting your head back to look up at the ceiling

Joint Movement Abduction: Movement of a body part away from the midline Example: Raising the humerus (upper extremity) laterally at the shoulder

Joint Movement Adduction: Movement of a body part toward the midline Example: Pulling your thighs together or moving the humerus back to the anatomical position

Joint Movement Circumduction: Movement in which one end (usually the proximal end) of an appendage stays relatively stationary while the other end (usually distal) makes a circular motion Example: Making a windmill motion with the arm

Joint Movement Rotation: Movement in which a bone revolves around its longitudinal axis Example: Twisting at the waist or turning your head from side to side

Joint Movement Depression: Movement that lowers a bone vertically Example: Opening the mouth Elevation: Movement that raises a bone vertically Example: Closing the mouth

Joint Movement Protraction: Movement of a bone anteriorly Example: Jutting your chin out Retraction: Movement of a bone posteriorly Example: Pulling your chin back in after jutting it out

Joint Movement Supination: Rotating the arm palm upward. Pronation: Rotating the hand palm downward

Joint Movement Inversion: When the soles of the feet turn medially to face each other. Eversion: Turns the soles of the feet laterally to face away from each other.

Joint Movement Dorsiflexion: The act of pointing the toes upward. Plantar Flexation: Pointing the toes downward.

Joint Movement Opposition: When the thumb reaches across the palm to touch the fingers Useful for grasping & manipulating objects

Joint Movement A great webside that goes through all the types of joint movement for each major joint… http://www.brianmac.co.uk/musrom.htm