Post on 15-Dec-2015
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 jointsBones 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 jointsEx. Shoulder, hip, finger, knee
Amphiarthrosis: Slightly moveable jointsEx. Symphysis pubis and intervertebral discs
Synarthroses: Immovable jointsEx. Sutures, epiphyseal plates of long bones
Diarthroses
Amphiarthrosis
Synarthroses
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