Class 13 - Joints Flashcards
Joint (articulation)
Any point where two bones meet, whether or not the bones are moveable at that interface
Arthrology
Science of joint structure, function, and dysfunction
Kinesiology
The study of musculoskeletal movement
Bony joint (synostosis) + example
An immobile joint formed when the gap between bones ossifies, and the bones become essentially one single bone
Example: left and right frontal and mandibular bones fuse in infants
Can occur in either fibrous or cartilaginous joint
Fibrous joints (synarthrosis) + 3 types
Adjacent bones are bound by collagen fibers that emerge from one bone and penetrate into the other.
- Sutures
- Gomphoses
- Syndesmoses
Sutures + 3 types
Immobile or slightly mobile fibrous joints in which short collagen fibers bind the bones of the skull to each other
- Serrate suture
- Lap (squamous) suture
- Plane (butt) suture
Serrate suture + 3 examples
Interlocking wavy lines
Examples: coronal, sagittal, and lambdoid sutures.
Lap (squamous) suture + 2 examples
Overlapping beveled edges.
Examples: temporal and parietal bones
Plane (butt) suture + example
Straight non-overlapping edges
Palatine processes of the maxillae.
Gomphosis
Attachment of a tooth in its socket.
Held in place by fibrous periodontal ligament.
Collagen fibers attach tooth to jawbone, allowing tooth to move slightly
Syndesmosis + 2 examples
A fibrous joint at which two bones are bound by long collagen fibers
Separation of bones and long fibers = more mobile joint
- Mobile example: Interosseus membrane of ulna and radius
- Less mobile: joint between tibia and fibula
Cartilaginous joints (amphiarthrosis) + 2 types
Two bones linked by cartilage.
- Synchondroses
- Symphyses
Synchondrosis + 2 examples
Type of cartilaginous joint. Bones joined by HYALINE cartilage.
- Temporary joint between epiphysis and diaphysis in child formed by epiphyseal plate cartilage
- First rib attached to sternum
Symphysis + 2 examples
Type of cartilaginous joint. Two bones joined by FIBROCARTILAGE
- Interpubic disc of pubic symphysis
- Bones of vertebrae joined by intervertebral discs.
Synovial joint (diarthrosis)
Joint in which two bones are separated by a joint cavity.
Most freely mobile, structurally complex, and likely to develop dysfunction.
Structure of synovial joints (5)
- Articular cartilage - layer of hyaline cartilage covering the facing bone surfaces
- Joint (articular) cavity - separates articular surfaces
- Synovial fluid - lubricant, nourishes articular cartilage/removes waste
- Joint (articular) capsule - connective tissue enclosing the cavity and retaining fluid.
- Articular disc OR meniscus
Joint capsule 3 features
- Outer fibrous capsule - continuous with periosteum of adjoining bones
- Inner synovial membrane - composed of fibroblast-like cells which secrete synovial fluid, and macrophages which remove debris
- Lamellar corpuscles - sensory receptors which enable the brain to monitor limb movements
Synovial joints: Articular disc vs meniscus + examples
- Articular disc - fibrocartilage pad crosses the entire joint capsule
Example: TMJ jaw joint, joints of clavicle, between ulna and carpal bones
- Meniscus - crescent-moon shaped pad, does not cross joint entirely. Absorbs shock and pressure, stabilizes bones in joint
Example: found in knee.
Accessory structures associated with synovial joints (4)
- Tendon - collagenous tissue attaching muscle to bone
- Ligament - collagenous tissue attaching one bone to another
- Bursa - fibrous sac filled with synovial fluid.
- Tendon (synovial) sheath - elongated cylindrical bursa wrapped around a tendon; abundant in hand and foot
Synovial joint accessory: Bursa + 3 functions
Fibrous sac filled with synovial fluid; located between muscles, where tendons pass over bone, or between bone and skin
- Cushions muscles
- Helps tendons slide more easily over joints
- Modifies direction of tendon pull
How exercise affects articular cartilage (3)
- Warms synovial fluid—>more easily absorbed by cartilage—>swell into cushion
- Protects cartilage from wear and tear
- Repetitive compression squeezes out fluid and metabolic waste, sucks in synovial fluid/oxygen/nutrients to chondrocytes.
Range of motion + 3 determining factors
Degree through which a joint can move.
- Structure of articular surfaces - (elbow: olecranon of ulna in olecranon fossa of humerous restricts movement)
- Strength and tautness of ligaments and joint capsules
- Action of muscles and tendons - nervous system maintains joint position and muscle tone (tension)
Axes of rotation + 3 main types for joints
Passes through bone in direction perpendicular to plane of movement
- Multiaxial joint
- Biaxial
- Monoaxial
6 types of synovial joints
- Ball and socket - Multiaxial
- Condylar - Biaxial
- Saddle - Biaxial
- Plane - Biaxial
- Hinge - Monoaxial
- Pivot - Monoaxial
Ball-and-socket joint + 2 examples
Multiaxial. Smooth, hemispheric head fits within cup-like socket.
Examples: shoulder, hip
Condylar joints + example
Biaxial. Allow significant movement in two planes. Oval convex surface of one bone fits into a complementary shaped depression on the other
Examples: radius and scaphoid, metacarpophalangeal joints, atlas and occipital bone
Saddle joints + example
Biaxial. Both bones have an articular surface shaped like a saddle, one concave, the other convex
Examples: trapeziometacarpal (thumb)
Plane joints + 2 examples
Biaxial. Flat, articular surfaces. Bones slide over each other.
Examples: Between carpal and tarsal bones, between articular processes of vertebrae
Hinge joints + example
Monoaxial. Allow angular movement. One bone with convex surface fits into concave depression of another bone.
Examples: Elbow, knee, between phalanges
Pivot joints + 2 examples
Monoaxial. Bone spins on its longitudinal axis.
Examples: altantoaxial joint, radioulnar (elbow) joint
Flexion, extension, hyperextension
Flexion - decreases joint angle
Extension - straightens joint/returns body part to zero position
Hyperextension - extension of a joint behind zero position
Abduction/hyperabduction, adduction/hyperadduction
Abduction - movement of body part in frontal plane away from midline
Hyperabduction - raise arm over back or front of head
Adduction - movement in frontal plane back toward midline
Hyperadduction - crossing fingers, crossing ankles
Elevation, depression
Elevation - movement raises body part vertically in frontal plane (e.g. shrugging shoulders)
Depression - lowers body part in same plane
Protraction, retraction
Protraction - anterior movement of a body part in the transverse (horizontal) plane
Retraction - posterior movement
Circumduction
One end of an appendage remains stationary while other end makes circular motion (e.g. painting a circle)
Rotation + 2 types
Rotation - bone spins on its longitudinal axis
- Medial rotation - turns bone inward
- Lateral rotation - turns bone outward.
Supination, pronation
Forearm movements.
Supination - palm turns to face anteriorly or upward (as in anatomical position)
Pronation - palm turns to face posteriorly or downward (radius + ulna cross)
Special movements of head and trunk (4)
- Flexion - Forward bending movements at the waist or neck
- Extension - Straightens trunk or neck.
- Hyperextension - Bending over backward
- Lateral flexion - Tilting head or trunk to right/left at the midline.
Special movements of the hand (4)
- Flexion - hand moves anteriorly
- Extension - hand moved posteriorly
- Radial flexion - hand tilts toward thumb
- Ulnar flexion - hand tilts toward pinky finger
Special movements of the digits (4)
- Flexion - curling the fingers
- Extension - straightening the fingers
- Abduction - spreading fingers apart
- Adduction - bringing fingers together again
Special movements of the thumb (4)
- Radial abduction - thumb moves away from hand, staying in plane of hand
- Palmar abduction - thumb moves away from the plane of hand to point anteriorly
- Opposition - thumb moves to approach tip of another finger
- Reposition - Return of thumb to zero position
Special movements of the foot (4)
- Dorsiflexion - elevating toes of foot forward (heel strike)
- Plantar flexion - extending foot so toes point downward (tip-toe)
- Inversion - soles turn in medially
- Eversion - Soles turn out laterally
NOTE: feet can also pronate and supinate but they are complex combined movements
Special movements of the mandible (4)
- Protraction - out and forward
- Retraction - pull back to neutral
- Elevation/depression - opening and closing mouth
- Lateral/medial excursion
