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JOINTS
ARTICULATIONS
ARTICULATIONS
Classifications of Joints
• Joints can be classified by function or structure
• Functional classification is based on amount of movement
• Synarthroses—immovable; common in axial skeleton
• Amphiarthroses—slightly movable; common in axial skeleton
• Diarthroses—freely movable; common in appendicular skeleton (all
synovial joints)
Classifications of Joints
• Structural classification is based on:
• Material that binds bones together
• Presence or absence of a joint cavity
• Structural classifications include:
• Fibrous
• Cartilaginous
• Synovial
Fibrous Joints
• Bones are connected by fibrous connective tissue
• Do not have a joint cavity
• Most are immovable or slightly movable
• 3 TYPES
FIBROUS JOINT: Sutures
• Bones are tightly bound by a minimal amount of fibrous tissue
• Occur only between the bones of the skull
• Allow bone growth so the skull can expand with brain during childhood
• Fibrous tissue ossifies in middle age
• Synostoses—closed sutures
FIBROUS JOINT: Syndesmoses
• Bones are connected exclusively by ligaments
• Amount of movement depends on length of
fibers
• Tibiofibular joint—immovable synarthrosis
• Interosseous membrane between radius
and ulna
• Freely movable diarthrosis
FIBROUS JOINT:
Gomphoses
• Tooth in a socket
• Connecting ligament—the
periodontal ligament
Cartilaginous Joints
• Bones are united by cartilage
• Lack a joint cavity
• Two types
Cartilaginous Joints
Synchondroses
• Hyaline cartilage unites bones
• Epiphyseal plates
• Joint between first rib and manubrium
• Synarthrotic
Cartilaginous Joints
Symphyses
• Fibrocartilage unites bones;
resists tension and
compression
• Slightly movable joints that
provide strength with flexibility
• Intervertebral discs
• Pubic symphysis
• Hyaline cartilage—present
as articular cartilage
Synovial Joints:
each contains a fluid-filled joint cavity.
General Structure of Synovial Joints
• Articular cartilage (hyaline)
• Covers ends of opposing bones
• Absorbs compression
• Joint (articular) cavity
• Holds synovial fluid
• Articular capsule—joint cavity is
enclosed in a two-layered capsule
• Fibrous layer—dense irregular
connective tissue, which strengthens
joint
• Synovial membrane—loose
connective tissue
• Lines joint cavity
• Makes synovial fluid
#1 of 4
Ligament
Joint cavity
(contains
synovial fluid)
Articular (hyaline)
cartilage
Fibrous
layer
Synovial
membrane
Periosteum
A typical synovial joint
Articular
capsule
General Structure of Synovial Joints
• Synovial fluid
• A viscous fluid similar to raw egg white
• A filtrate of blood
• Arises from capillaries in
synovial membrane
• Contains glycoprotein molecules
secreted by fibroblasts
• Weeping lubrication—Pressure on
joints squeezes synovial fluid into and
out of articular cartilage
#2 of 4
Ligament
Joint cavity
(contains
synovial fluid)
Articular (hyaline)
cartilage
Fibrous
layer
Synovial
membrane
Periosteum
A typical synovial joint
Articular
capsule
General Structure of Synovial Joints
• Reinforcing ligaments
• Often are thickened parts of the
fibrous layer
• Sometimes are extracapsular
ligaments—located outside the
capsule
• Sometimes are intracapsular
ligaments—located internal to the
capsule
#3 of 4
Ligament
Joint cavity
(contains
synovial fluid)
Articular (hyaline)
cartilage
Fibrous
layer
Synovial
membrane
Periosteum
A typical synovial joint
Articular
capsule
General Structure of Synovial Joints
• Richly supplied with sensory nerves
• Detect pain
• Most monitor how much the capsule is
being stretched
#4 of 4
Ligament
Joint cavity
(contains
synovial fluid)
Articular (hyaline)
cartilage
Fibrous
layer
Synovial
membrane
Periosteum
A typical synovial joint
Articular
capsule
Synovial Joints with Articular Discs
• Some synovial joints contain an articular disc;
meniscus (if it only partially subdivides the cavity).
• Occur in the TMJ and at the knee joint
• Occur in joints whose articulating bones have
somewhat different shapes
• Improves the fit
Articular disc
Also, note bursa. “Bursa” is Latin for “Purse.” It is a fluid-filled
fibrous sac, which protects.
3 Types of Movements Allowed by Synovial Joints
3 Types of Movements: GLIDING
1) Gliding—one bone across the
surface of another
Gliding movements at the wrist
• Gliding occurs between:
• Carpals
• Articular processes of vertebrae
• Tarsals
3 Types of Movements - ANGULAR
2 ) Angular movement—
movements change the angle
between bones
ABDUCTION/
ADDUCTION
• Movements involve:
• Flexion and extension
• Abduction and adduction
• Circumduction
CIRCUMDUCTION
EXTENSION AND FLEXION
3 Types of Movements - ROTATION
3 ) Rotation—movement around a
bone's long axis
• Involves turning movement
of a bone around its long
axis
• The only movement
allowed between atlas and
axis vertebrae
• Occurs at the hip and
shoulder joints
Rotation of the head, neck, and lower limb
Special Movements
SOME MOVEMENTS DO NOT FIT INTO ANY
OF THE PREVIOUS CATEGORIES AND
ONLY OCCUR AT A FEW JOINTS
DURING CHEWING,
THE MANDIBLE IS
ALTERNATELY
ELEVATED AND
DEPRESSED
Elevation
of mandible
Elevation
Lifting a body part
superiorly
Depression
of mandible
Depression
Moving a body part
inferiorly
Figure 9.7b Some special body movements.
PROTRACTION
AND
RETRACTION:
NON-ANGULAR
MOVEMENTS IN
THE ANTERIOR
AND POSTERIOR
DIRECTION
Protraction
of mandible
Protraction
Moving a body part in the
anterior direction
Retraction
of mandible
Retraction
Moving a body part in the
posterior direction
Figure 9.7c Some special body movements.
Pronation
(radius rotates
over ulna)
Supination
(radius and ulna
are parallel))
P
S
Pronation (P)
Rotating the forearm so the
palm faces posteriorly
Supination (S)
Rotating the forearm so the
palm faces anteriorly
Figure 9.7d Some special body movements.
MOVEMENT OF THE
JOINT BETWEEN
METACARPAL 1 AND
THE TRAPEZIUM
Opposition
Opposition
Moving the thumb to touch the tips
of the other fingers
Figure 9.7e Some special body movements.
Inversion
Inversion
Turning the sole of the foot
medially
Eversion
Eversion
Turning the sole of the foot
laterally
Figure 9.7f Some special body movements.
Dorsiflexion
Plantar flexion
Dorsiflexion
Lifting the foot so its superior surface
approaches the shin
Plantar flexion
Depressing the foot
elevating the heel
Classification of Synovial Joints by Shape
6 Types
6 Types of Synovial Joints
Ball-and-Socket Joint
• hip
• shoulder
Condyloid Joint
• between
metacarpals and
phalanges
8-9
6 Types of Synovial Joints
PLANE JOINT
Gliding Joint
• between carpals
• between tarsals
Hinge Joint
• elbow
• between
phalanges
6 Types of Synovial Joints
Pivot Joint
between proximal
ends of radius and
ulna
Saddle Joint-between
carpal (trapezium) and
metacarpal of thumb
Selected Synovial Joints
• Temporomandibular joint
• a modified hinge joint
• The head of the mandible
articulates with the temporal bone
• Lateral excursion is a side-to-side
movement
• Two surfaces of the articular disc
allow both
• Hinge-like movement
• Gliding of superior surface
anteriorly
Shoulder Joint – the most freely movable joint
• ball-and-socket
Muscle tendons of the shoulder contribute strongly
• head of humerus
to this joint’s stability
• glenoid cavity of scapula
• loose joint capsule (lacks stability)
• bursae (cushioning)
ligaments prevent displacement:
Wrist Joint
• Composed of radiocarpal and
intercarpal joint
• Radiocarpal joint—joint
between the radius and
proximal carpals (the scaphoid
and lunate)
• Allows for flexion, extension,
adduction, abduction, and
circumduction
• Intercarpal joint—joint between
the proximal and distal rows or
carpals
• Allows for gliding movement
Radius
Ulna
Wrist joint
Lunate
Scaphoid
Triquetrum
Pisiform
Capitate
Hamate
Trapezoid
Trapezium
I
II
III
IV
Thumb
Right wrist, anterior (palmar) view
V
THE WRIST JOINT IS STABILIZED BY NUMEROUS LIGAMENTS:
Palmar
radiocarpal
ligament
Radius
Ulna
Radial
collateral
ligament of
wrist joint
Lunate
Ulnar
collateral
ligament of
wrist joint
Scaphoid
Intercarpal
ligaments
Pisiform
Hamate
Trapezium
I
II
III
IV
V
Capitate
Ligaments of the wrist, anterior (palmar) view
Carpometacarpal
ligaments
CARPAL TUNNEL SYNDROME
Hip joint
• A ball-and-socket structure
• Movements occur in all axes
• Limited by ligaments and
acetabulum
• Head of femur articulates with
acetabulum
• Stability comes chiefly from
acetabulum and capsular
ligaments
• Muscle tendons contribute
somewhat to stability
Coxal (hip) bone
Articular cartilage
Acetabular
labrum
Ligament of the
head of the femur
(ligamentum teres)
Femur
Synovial cavity
Articular capsule
Frontal section through the right hip joint
Knee joint
• The largest and most complex
joint
• a hinge joint
• Has some capacity for rotation
when leg is flexed
• Two fibrocartilage menisci occur
within the joint cavity
• Femoropatellar joint—shares
the joint cavity
• Allows patella to glide across
the distal femur
Tendon of
quadriceps
femoris
Femur
Articular
capsule
Suprapatellar
bursa
Patella
Posterior
cruciate
ligament
Subcutaneous
prepatellar bursa
Lateral
meniscus
Lateral meniscus
Anterior
cruciate
ligament
Infrapatellar
fat pad
Deep infrapatellar
bursa
Tibia
Patellar ligament
Synovial cavity
Sagittal section through the right knee joint
Superior view of the right tibia in the knee joint, showing
the menisci and cruciate ligaments
Intracapsular ligaments:
• Cruciate ligaments
• Cross each other like an
“X”
• PREVENT SLIDING
see next 2 slides.
• Each cruciate ligament runs
from the proximal tibia to the
distal femur
• Anterior cruciate ligament
• Posterior cruciate ligament
Anterior
Anterior
cruciate
ligament
Articular
cartilage
on medial
tibial condyle
Medial
meniscus
Posterior
cruciate
ligament
Articular
cartilage on
lateral tibial
condyle
Lateral
meniscus
Figure 9.16a Stabilizing function of the cruciate ligaments.
1 During movement of the knee, the anterior cruciate
prevents anterior sliding of the tibia; the posterior
cruciate prevents posterior sliding of the tibia.
Quadriceps
muscle
Anterior
cruciate
ligament
Femur
Patella
Medial
condyle
Posterior
cruciate
ligament
Lateral
meniscus
Tibia
Figure 9.16b Stabilizing function of the cruciate ligaments.
2 When the knee is fully extended, both cruciate
ligaments are taut and the knee is locked.
Anterior
cruciate
ligament
Posterior
cruciate
ligament