Articulation
What is an articulation?
he place where a bone meets another bone, cartilage, or teeth and categorized based on mobility and stability
Articulations Classified by structure
hat connects the joint?
• Fibrous: Bones held together by dense
regular connective tissue (ex: coronal suture)
• Cartilaginous:
Bones joined by cartilage (ex: intervertebral discs)
• Synovial:
Bones separated by fluid-filled cavity (ex: ball and socket; shoulder joint)
Articulations Classified by function
How (much) does the joint move?
• Synarthrosis: Immobile joint
(ex: coronal suture)
• Amphiarthrosis: Slightly mobile joint (ex:
pubic symphysis)
• Diarthrosis: Freely moveable joint (ex: hinge;
elbow joint)
Articulations Classified by ligaments
Connective tissue structures (dense regular and dense
irregular)
that bind bones to each other and thus play an
important role in various joints
Structural Classification: Fibrous Joints
Neighboring bones are joined together with a solid mass of dense irregular connective tissue
Structural Classification: Cartilaginous Joints
Bones are connected by cartilage; little to no movement
Structural Classification: Synovial Joints
Joins adjacent bones by a joint capsule that is continuous
with
the periosteum of the connecting bones; allows for wide
ranges of movement
(diarthroses)
Articular/Synovial capsule, two layers:
1. Outer fibrous layer made of dense regular connective
tissue;
strengthens joint
2. Inner synovial membrane;
secretes synovial fluid
Articular cartilage:
• Articular surfaces in synovial joints are covered by hyaline
cartilage
• Reduces friction and acts as shock absorber
Types of Synovial Joints
1. Plane joints:
2. Hinge joints:
3. Pivot joints:
4. Condylar joints:
5. Saddle joints:
6.
Ball-and-socket joints:
1. Plane joints:
uniaxial; side to side movemen
2. Hinge joints:
uniaxial; like hinge of a door
3. Pivot joints:
uniaxial; one bone rotates on its longitudinal
axis
4. Condylar joints:
biaxial; oval, concave surface of one
bone; convex of the othe
5. Saddle joints:
biaxial; joint surfaces resemble saddle
shape
6. Ball-and-socket joints:
multiaxial; spherical head into
cuplike socke
gliding motion
• Simple movement with a limited range
• Flat bones move from
side to side and back and forth with one another
• Ex:
Intercarpal or Intertarsal joints
angular motion
Increases or decreases the angle between bones
• Flexion
•
Extension
• Hyperextension
• Lateral flexion
•
Abduction
• Adduction
• Circumduction
rotation motion
In rotation, a bone turns on its
longitudinal axis
• Lateral rotation
• Medial rotation
• Pronation
• Supination
special movement
Movements that only occur at specific
joints
• Depression
vs. elevation
• Dorsiflexion vs. plantar flexion
• Inversion
vs. eversion
• Protraction vs. retraction
• Opposition
Double-Jointed(ness)
What we think of as being double-jointed is
actually
hyper-mobility, the ability to move a joint
beyond
the ‘normal’ range of movement
potential cause of Double Jointed(ness)
◦ Abnormal shapes at the ends of bones
◦ Flexibility of
ligaments and tendons (hormone/protein-based)
• (differences in
sex/race based on collagen)
◦ Muscle tone (or lack of)
◦
Impaired proprioception
osteoarthritis
• Chronic and degenerative, can affect any joint
• Damage to
articular (hyaline) cartilage covering bony
surfaces at
articulations
• Injury, overuse, genetics
• Most common
chronic joint problem
rheumatoid arthritis
• Systemic, autoimmune disease
• Immune system attacks joints
leading to inflammation of the
synovium
• Starts in small
joints and moves to larger joint
The Temporomandibular Joint (TMJ)
The TMJ is a diarthrotic, synovial (primarily) hinge joint between
the condylar process of the mandible and the mandibular fossa of the
temporal bone
• The only freely movable joint between skull
bones
• Functions:
◦ Depress/Elevate
◦
Protract/Retract
◦ Lateral displacement
◦ Rotation
Atlanto-axial Joint
• Between the first (atlas) and second (axis) cervical
vertebrae
• The atlas rotates around the peg-like dens of the
axis
• Pivot joint
The Shoulder Joint (Glenohumeral joint)
Ball and socket joint
• Glenoid cavity of the scapula and head
of the humerus
• Rotator cuff muscles anchor the humerus to the
scapula and provide the
most strength to this joint
• Labrum
– ring-shaped hyaline cartilage
that deepens the
socket
Movements
• More freedom than ANY other joint
•
Flexion/Extension/Hyperextension
• Abduction/adduction
•
Medial/Lateral rotation
• Circumduction
What is a Shoulder Dislocation?
Dislocation of the Glenohumeral Joint
• Anterior shoulder
dislocation accounts for
approximately 95% of dislocations of the
shoulder
• Posterior dislocations are often missed as the pt will
keep the
arm internally rotated and ADDucted
• 95% of
dislocations are from trauma
• Up to 40% of persons will also
have injury to the
axillary nerve
Shoulder Separation
• Dislocation of the Acromioclavicular (AC) Joint (synovial)
•
If the strong coracoclavicular ligament is also torn, the upper limb
droops
because it is suspended from the clavicle by this ligament.
elbow Radial collateral ligamen
from lateral epicondyle of humerus – blends with
elbow Annular ligament of the radius
encircles and holds the head of the radius in the radial notch
elbow Ulnar collateral ligament:
extends from medial epicondyle to the coronoid process and olecranon of ulna and consists of three bands
the hip
• Intrinsic to the fibrous capsule of the
hip joint
•
Iliofemoral (Y ligament of Bigalow)
• Pubofemoral
• Ischiofemoral
The Knee Joint
• Modified hinge joint
• Largest and most complex joint in the
body
• Associated ligaments/structures
• Meniscus:
fibrocartilage disc (2) between tibia and
femur
• Medial
(tibial) and lateral (fibular) collateral
ligaments
•
Patellar ligament (not shown here)
• Anterior cruciate ligament
(ACL)
• Posterior cruciate ligament (PCL)
Anterior cruciate ligament (ACL)
• Limits anterior translocation
• Anterior, intercondylar tibial
plateau → posterior part of lateral
femoral condyle
Posterior cruciate ligament (PCL)
• Limits posterior translocation
• Posterior, intercondylar
tibial plateau→ anterior part of medial
femoral condyl
Meniscus
fibrocartilage disc (2) between tibia and
femur
• Medial: C
shaped
• Attached to the medial (tibial) ligament
• Lateral:
O shape
Anterior Drawer Test
• Pull tibia anteriorly with a flexed knee
• Tests the integrity
of AC
posterior Drawer Test
• Push tibia posteriorly with a flexed knee
• Test the integrity
of the PC