movements and joints Flashcards
Articulation
—site where two or more bones meet
functions of joints
Give skeleton mobility
Hold skeleton together
joints classified by
structure and function
Three functional classifications
Synarthroses—
Amphiarthroses
Diarthroses—
Synarthroses—
immovable
Amphiarthroses
slightly moveable
Diarthroses
freely moveable
Three structural classifications:
Fibrous
Cartilaginous
Synovial
Fibrous Joints
Bones joined by dense fibrous connective tissue
No joint cavity
Most are synarthrotic (immovable)
Three types:
three types fibrous joints
Sutures (head)
Syndesmoses /(arm)
Gomphoses (teeth sockets)
sutures
Rigid, interlocking joints containing short connective tissue fibers
Allow for growth during youth
In middle age, sutures ossify and are called synostoses
Syndesmoses
Bones connected by ligaments (bands of fibrous tissue)
Movement varies from immovable to slightly movable
Syndesmoses example
tibia, fibula, radius, ulna
Gomphoses
Peg-in-socket joints of teeth in alveolar sockets
Fibrous connection is the periodontal ligament
Cartilaginous Joints
Bones united by cartilage
No joint cavity
Two types:
Cartilaginous Joints two types
Synchondroses
symphses
Synchondroses
A bar or plate of hyaline cartilage unites the bones
All are synarthrotic
symphses
Hyaline cartilage covers the articulating surfaces and is fused to an intervening pad of fibrocartilage
Strong, flexible amphiarthroses
Synovial Joints
All are diarthrotic
Include all limb joints; most joints of the body
Synovial Joints distinguishing features
Articular cartilage: hyaline cartilage
Joint (synovial) cavity: small potential space
Articular (joint) capsule:
Synovial fluid
Three possible types of reinforcing ligaments
Rich nerve and blood vessel supply
Articular (joint) capsule
Outer fibrous capsule of dense irregular connective tissue; Inner synovial membrane of loose connective tissue
Synovial fluid
Viscous slippery filtrate of plasma + hyaluronic acid
Lubricates and nourishes articular cartilage
Weeping lubrication
Contains phagocytic cells
Synovial Joints Three possible types of reinforcing ligaments
Capsular (intrinsic)—part of the fibrous capsule
Extracapsular—outside the capsule
Intracapsular—deep to capsule; covered by synovial membrane
Synovial Joints: Friction-Reducing Structures
Bursae
Tendon sheath
Bursae
Flattened, fibrous sacs lined with synovial membranes
Contain synovial fluid
Commonly act as “ball bearings” where ligaments, muscles, skin, tendons, or bones rub together
Tendon sheath
Elongated bursa that wraps completely around a tendon
What Stabilizes Synovial Joints
Shapes of articular surfaces (minor role)
Ligament number and location (limited role)
Muscle tone, which keeps tendons that cross the joint taut (important for shoulder and knee)
Origin
attachment to the immovable bone
insertion
attachment to the movable bone
Synovial Joints: Movement
Muscle attachments across a joint
Muscle contraction causes the insertion to move toward the origin
Movements occur along transverse, frontal, or sagittal planes
Synovial Joints nonaxial
slipping movements only
carpals
Synovial Joints uniaxial
movement in one plane
elbows
Synovial Joints biaxial
movement in two planes
pointer finger
Synovial Joints multiaxial
movement in or around all three planes
shoulder or hip
Movements at Synovial Joints
gliding
angular movements
rotation
gliding
One flat bone surface glides or
slips over another similar
surface (carpals, tarsals, vertebrae)
Angular movements:
Angular movements:
Flexion, extension, hyperextension
Abduction, adduction
Circumduction
rotation
medial, lateral rotation
Movements that occur along the sagittal plane
flexion
extension
hyperextension
flexion
decreases the angle of the joint
to bend
extension
to straighten
increases the angle of the joint
Hyperextension
excessive extension beyond normal range of motion
past anatomical position
Movements that occur along the frontal plane
abduction
adduction
circumduction
abduction
movement away from the midline, lifting arm from side
adduction
movement toward the midline
bringing arm down toward side
circumduction
circle arm motion
rotation
The turning of a bone around its own long axis
ex rotating humerus
Movements of radius around ulna:
supination (palm up)
pronation (palm down)
Movements of the foot
dorsiflexion vs plantar flexion
Dorsiflexion (upward movement) Plantar flexion (downward movement)
Movements of the foot
inversion vs eversion
Inversion (turn sole medially)
Eversion (turn sole laterally)
movements in transverse plane protraction vs retraction
protraction (anterior movement) (push jaw out)
Retraction (posterior movement) (push jaw in)
elevation
lifting a body part superiorly
depression
moving a body part inferiorly
Opposition of the thumb
pinching movement
Classification of Synovial Joints based on shape of articular surfaces:
Plane Hinge Pivot Condyloid Saddle Ball and socket
Plane Joints
Nonaxial joints
Flat articular surfaces
Short gliding movements
carpals
Hinge Joints
Uniaxial joints
Motion along a single plane
Flexion and extension only
elbow
Pivot Joints
Rounded end of one bone conforms to a “sleeve,” or ring of another bone
Uniaxial movement only
radius
Condyloid (Ellipsoidal) Joints
Biaxial joints
Both articular surfaces are oval
Permit all angular movements
phalanges
Saddle Joints
Biaxial
Allow greater freedom of movement than condyloid joints
Each articular surface has both concave and convex areas
thumb
Ball-and-Socket Joints
Multiaxial joints
The most freely moving synovial joints
shoulder
