Articulations
(Joints)
Articulations
• Body movement occurs at joints
(articulations) where 2 bones connect
Joint Structure
• Determines direction and distance of
movement (range of motion)
• Joint strength decreases as mobility
increases
Naming of Joints
• Usually derived from the names of the
articulating bones.
9-3
Joints
 Articulations
• Point at which two bones join together
– Allow movement
– Transmit forces
• Anatomy
– Capsule or ligaments
– Synovial membrane
– Articular cartilage
– Joint space filled with
synovial fluid
Structural Classifications
•
•
•
•
Bony
Fibrous
Cartilaginous
Synovial
Functional Classifications
• Synarthrosis:
– no movement
• Amphiarthrosis:
– little movement
• Diarthrosis:
– more movement
Classifications
• Structural Categories:
– Fibrous
– Cartilaginous
– Synovial
• Functional Categories:
– Synarthroses—immoveable
– Amphiarthroses—slightly
moveable
– Diarthroses—freely
moveable
Synarthroses
• Immoveable joints
• Lack synovial cavity
• Held together by
fibrous connective
tissue
• Structural types:
– Sutures
– Syndesmoses
– Gomphoses
Synarthroses
• Sutures
– Thin layer of dense fibrous connective tissue
– Unites bones of skull
• Syndesmosis
– Joints where bones connected by ligaments
– i.e. fibula/tibia and radius/ulna
• Gomphosis
– Conical process fits into socket and is held in place by
ligaments
– i.e. tooth in alveolus (socket), held in place by peridontal
ligament
Amphiarthroses
• Slightly moveable
• Connected by hyaline cartilage or fibrocartilage
• i.e. ribs to sternum or vertebrae
Diarthroses
 Synovial joints
• Freely moveable
• Ends of opposing bones
are covered with articular
cartilage
• Separated by joint cavity
• Components of joints
enclosed in dense fibrous
joint capsule
Synovial joint
Synovial Joint Anatomy
• Articular capsule
– Joint capsule
– Consists of bundles of collagen and functions to
maintain a relative joint position
Synovial Joint Anatomy
• Synovial Membrane and Synovial Fluid
– Lines the synovial joint(articular) capsule
– Made of connective tissue with flattened cells
– Synovial fluid acts as a lubricant.
– Able to vary its viscosity (thicker with slower
movements and it thins with faster movements)
Synovial Fluid
•
Contains slippery proteoglycans secreted by
fibroblasts
• Functions of Synovial Fluid
1. Lubrication
2. Nutrient distribution
3. Shock absorption
Synovial Joint Anatomy
-Articular Cartilage
• Hyaline cartilage: Found on the articular ends of our
long bones
• Pad articulating surfaces within articular capsules:
– prevent bones from touching
• Smooth surfaces lubricated by synovial fluid:
– reduce friction
– Fibrocartilage: cushioning type of cartilage
• Found in the menisci in our knees, intervertebral disks, pubic
symphysis
-Elastic cartilage:
• Found in the external ear
Synovial Joint Anatomy
• Bursa
– Fluid-filled sac of synovial tissue found in our
synovial joints.
– Found in between anatomical structures to reduce
friction
– Can become chronically inflammed
Synovial Joint Stabilization
• Muscle tension is important in limiting
unwanted joint movement
• If joint capsule is overstretched, reflex
contraction of muscles in the area prevent
overstretching (Hilton’s Law)
Synovial Joint Stabilization
• Joints that are shallow and fit poorly must
depend on capsular structures or muscles for
support
Synovial Joint Stabilization
• Capsular and ligamentous tissue help to
maintain anatomical integrity and structural
alignment of synovial joints
Synovial Joints
•
6 Types Synovial
Joints:
–
–
–
–
–
–
Pivot joint
Gliding joint
Hinge joint
Condyloid joint
Ball-and-Socket joint
Saddle joint
Types of Synovial Joints
• Classified by the shapes of their articulating surfaces
• Types of movement they allow
– uniaxial if the bone moves in just one plane
– biaxial if the bone moves in two planes
– multiaxial (or triaxial) if the bone moves in multiple planes
9-22
Uniaxial Joints
permits movement around one axis and one plane
• projection of one bone articulating with a
ring/notch of another bone
– examples - between vertebrate
• allows only flexion and extension
– examples – elbow, knee
• knee joint
– largest joint, most complex, most
frequently injured
Biaxial Joints
permits movement around two perpendicular axes and planes
• Example
– thumb
• only saddle
joint in the
body
• condyle fits into an
elliptical socket
• Example
– between radius
and carpals
ellipsoidal
Multiaxial Joints
permits movement around three or more axes and planes
• most moveable joints
• ball shaped head fits into concave depression
• example - shoulder, hip
– humeroscapular joint
• most mobile joint
– sacroiliac joint
• hip joint
• relatively flat articulating surface that allows
gliding movement
• example
– between carpals
– between tarsals
– between vertebrate
Types of Joints
(ellipsoidal)
Pivot Joints
• Rotation only (monaxial)
Figure 9–6 (3 of 6)
Pivot Joint
• Freely moveable joint in
which bone moves
around central axis,
creating rotational
movement
• Radius, ulna
Gliding Joints
• Flattened or slightly curved faces
• Limited motion (nonaxial)
Figure 9–6 (1 of 6)
Gliding Joint
• Allows bones to make
sliding motion
• Carpals and tarsals
• Between vertebrae
and spine
Hinge Joints
• Angular motion in a single plane (monaxial)
Figure 9–6 (2 of 6)
Hinge Joint
• Allows only flexion and extension
• Convex surface of one bone fits concave surface of other
• Knee, elbow, phalanges
Condyloid/Ellipsoidal Joints
• Oval articular face within a depression
• Motion in 2 planes (biaxial)
Figure 9–6 (4 of 6)
Condyloid Joint
•  ellipsoidal joint
• Bones can move
about one another in
many directions, but
cannot rotate
• Named for condylecontaining bone
• Metacarpals,
phalanges
Ball-and-Socket Joints
• Round articular face in a depression (triaxial)
Figure 9–6 (6 of 6)
Ball & Socket Joint
• One bone has
rounded end that
fits into concave
cavity on another
bone
• Widest range of
movement
possible
• Hips, shoulders
Saddle Joints
• 2 concave faces, straddled (biaxial)
Figure 9–6 (5 of 6)
Saddle Joint
• Two bones have both
concave and convex
regions, shape of two
bones complementing
one another
• Wide range of
movement
• Thumb = only saddle
joint in body
Movements of Diarthroses
•
•
•
•
•
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•
•
•
Flexion
Extension
Hyperextension
Abduction
Adduction
Rotation
Circumduction
Elevation
Depression
•
•
•
•
•
•
•
•
•
Supination
Pronation
Plantar flexion
Dorsiflexion
Inversion
Eversion
Protraction
Retraction
Opposition
Flexion/Extension
Abduction/Adduction
• Abduction—moving a body part away from
midline
• Adduction—moving a body part toward the
midline
Internal/External Rotation
• Internal rotation—
rotation towards the
center of the body
 medial rotation
• External rotation—
rotation away the center
of the body
 lateral rotation
Internal/External Rotation
Hip Internal Rotation
Plantar Flexion/Dorsiflexion
Supination/Pronation
Elevation/Depression
Inversion/Eversion
What are the structures
and functions of the shoulder,
elbow, hip, and knee
joints…
And what is the relationship
between joint strength and
mobility?
The Shoulder Joint
• Also called the glenohumeral joint:
– allows more motion than any other joint
– is the least stable
– supported by skeletal muscles, tendons, ligaments
Structure of the Shoulder Joint
• Ball-and-socket diarthrosis
• Between head of humerus and glenoid cavity
of scapula
Shoulder
Socket of the Shoulder Joint
• Glenoid labrum:
– deepens socket of glenoid cavity
– fibrocartilage lining
– extends past the bone
Processes of the Shoulder Joint
• Acromion (clavicle) and coracoid process
(scapula):
– project laterally, superior to the humerus
– help stabilize the joint
Shoulder Ligaments
•
•
•
•
•
Glenohumeral
Coracohumeral
Coracoacromial
Coracoclavicular
Acromioclavicular
Shoulder
• Glenohumeral
• Sternoclavicular
• Acromioclavicular
Glenohumeral
joint
Shoulder Muscles
• Also called rotator cuff:
– supraspinatus
– infraspinatus
– subscapularis
– teres minor
The Elbow Joint
Figure 9–10
The Elbow Joint
• A stable hinge joint
• With articulations between humerus, radius,
and ulna
Articulations of the Elbow
• Humeroulnar joint:
– largest articulation
– trochlea of humerus and trochlear notch of ulna
– limited movement
• Humeroradial joint:
– smaller articulation
– capitulum of humerus and head of radius
Elbow
• Radiohumeral
• Humeroulnar
• Radioulnar
Elbow Muscle
• Biceps brachii muscle:
– attached to radial tuberosity
– controls elbow motion
Elbow Ligaments
• Radial collateral
• Annular
• Ulnar collateral
Hand and wrist
The hand and wrist comprise a number
of different joint types: saddle, gliding
and condyloid. Together, these joints
give the hands & fingers a great deal of
mobility
Wrist
• Radiocarpal
• Intercarpal
• Carpalmetacarpal
Hand
– Intermetacarpal
– Metacarpalphalangeal
– Interphalangeal
Hip joint: Coxal bone - femur
The Hip Joint
• Also called coxal joint
• Strong ball-and-socket diarthrosis
• Wide range of motion
Structures of the Hip Joint
• Head of femur fits into it
• Socket of acetabulum
• Which is extended by fibrocartilage acetabular
labrum
Ligaments of the Hip Joint
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•
•
•
•
Iliofemoral
Pubofemoral
Ischiofemoral
Transverse acetabular
Ligamentum teres
Sacroiliac joint
The Knee Joint
Figure 9–12a, b
Articulations of the Knee Joint
• 2 femur–tibia articulations:
– at medial and lateral condyles
– 1 between patella and patellar surface of femur
Menisci of the Knee
• Medial and lateral menisci:
– fibrocartilage pads
– at femur–tibia articulations
– cushion and stabilize joint
– give lateral support
Locking Knees
• Standing with legs straight:
– “locks” knees by jamming lateral meniscus
between tibia and femur
7 Ligaments of the Knee Joint
• Patellar ligament (anterior)
• 2 popliteal ligaments (posterior)
• Anterior and posterior cruciate ligaments
(inside joint capsule)
• Tibial collateral ligament (medial)
• Fibular collateral ligament (lateral)
TIBIOFEMORAL JOINT
TIBIOFIBULAR JOINT