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Anatomy and
Physiology I
BIOL 2401
Chapter 9
Articulations
Articulations
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A point where two skeletal elements
meet.
Skeletal elements: bone, cartilage,
teeth
Arthrology: study of joints
Kinesiology: study of movement
Classified on basis of structure or
function
Classification Based on Function
• Synarthrosis: immovable (syn= together)
• Amphiarthosis: slightly moveable (amphi= on both
sides)
• Diarthrosis: freely moveable (diarthro= double joint;
very moveable)
Classification Based on Structure
Types
• Fibrous: No joint cavity; bones held together
by fibrous connective tissue.
• Cartilaginous: No joint cavity; bones held
together by cartilaginous connective tissue.
• Synovial: Presence of joint cavity, allows free
movement
Classification Based on Structure
Fibrous Joints
No joint cavity; bones held together by fibrous connective tissue.
Synarthoses or amphiarthroses.
Suture = seam; bones joined by thin layer of dense fibrous connective tissue.
– Synarthosis – immovable joint.
– When replaced by bone in an adult- synostosis
Syndesmosis = Fibrous interosseous membrane or ligament.
– Amphiarthrosis – some movement.
Gomphosis = Cone-shaped peg (tooth) fits into a socket (alveolar process of maxilla
or mandible).
– Synarthrosis
Classification Based on Structure
Cartilaginous Joints
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No joint cavity
Bones held together by cartilage
Examples: epiphyseal plate, pubic symphysis
Types
– Synchondrosis
– Symphysis
Classification Based on Structure
Cartilaginous Joints
Synchondrosis: Bones connected by hyaline cartilage
– Synarthosis – Immovable joint.
– Epiphyseal plate of growing long bones; joints between ribs and sternum
Symphysis: growing together
– Intervertebral discs and symphysis pubis.
– Amphiarthrosis – partial movement.
Classification Based on Structure
Synovial Joints
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Cavity in the joint.
Bones held together by a capsule and ligaments.
Diarthrosis.
Examples: knee, TMJ, shoulder, hip, elbow, interphalangeal joints.
Classification Based on Structure
Synovial Joints
Diarthrosis = freely movable.
Synovial cavity with synovial membrane separates articulating bones:
• Articular capsule: encloses the synovial cavity, unites the articulating
bones. Has two parts: fibrous capsule and synovial membrane (see
next slide).
Fibrous capsule: outer, dense irregular connective tissue; attaches to
periosteum of articulating bones.
Synovial membrane: Inner, areolar connective tissue with elastic
fibers and some adipose.
Classification Based on Structure
Synovial Joints
Articular cartilages: hyaline cartilage; cover articular surface of bones to
protect the ends of the bones.
Synovial fluid: fluid secreted by synovial membrane of the articular capsule
- Fills cavity
- Lubricates joint
- Nourishes articular cartilages
- Contains phagocytes
Classification Based on Structure
Synovial Joints – Accessory Structures
Accessory ligaments
• Extracapsular ligaments lie outside the articular capsule.
• Intracapsular ligaments occur within the articular capsule.
Articular discs (menisci)
• Pads of fibrocartilage within the synovial joint. Attached at their margins
to the fibrous capsule.
• Make a better fit for the bones; add to stability.
Bursae
• Sac-like structures.
• Reduce friction between bones, skin, tendons, muscles or ligaments
– Bursitis: Inflammation of the bursae.
Types of Movements
Gliding: Surface of one bone moves back and forth and side to side over a
flat surface.
Angular: Increase or decrease in the angle between bones
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Flexion/extension
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Hyperextension
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Abduction/adduction
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Circumduction
Rotation: Bone revolves around its own longitudinal axis
Special: occurring only at particular joints
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Inversion/eversion
Dorsiflexion/plantar flexion
Protraction/retraction
Supination/pronation
Elevation/depression
Types of Movements at Synovial Joints
Gliding
• Surface of one bone moves
back and forth and side to
side over a flat surface.
• No angular or rotational
motion.
• Occurs at wrist and ankle
joints.
Types of Movements at Synovial Joints
Angular
Increase or decrease the angle
between the bones.
Flexion: decrease in the angle
between articulating bones.
Extension: increase in the
angle between two
articulating bones
Hyperextension: continuation
of extension beyond the
anatomical position.
Prevented at some joints by
the shape of the articulating
bones and the ligaments
associated with the joint.
Types of Movements at Synovial Joints
Angular
Abduction: movement of a bone away from the midline.
Adduction: movement of a bone toward the midline.
Circumduction: movement of the distal end of a part of the body in a circle.
Results as a continuous sequence of flexion, abduction, extension, and
adduction.
Types of Movements at Synovial Joints
Rotation
A bone rotates around its own long
axis.
Medial rotation: anterior surface of
a bone or a limb is turned
toward the midline.
Lateral rotation: anterior surface
of a bone or a limb is turned
away from the midline.
Types of Movements at Synovial Joints
Special Movements
Elevation/Depression: upward/downward movement of a body part.
Protraction/Retraction: movement anteriorly in transverse plane/return
to anatomical position of a body part.
The jaw and the shoulders.
Types of Movements at Synovial Joints
Special Movements
Inversion: movement of the soles medially at the intertarsal joints so that they
face each other.
Eversion: movement of the soles laterally at the intertarsal joints so that they
face away from each other.
Dorsiflexion: bending the foot superiorly at the ankle.
Plantar flexion: bending the foot at the ankle toward the plantar surface.
Types of Movements at Synovial Joints
Special Movements
Supination: movement of the forearm
at the proximal and distal radioulnar
joints so that the palm is turned
anteriorly (when the arm is straight) or
superiorly (when the arm is flexed at
the elbow).
Pronation: movement at the same
joints as in supination, but so that the
distal end of the radius crosses over
the distal end of the ulna and the palm
is turned posteriorly (when the arm is
straight) or inferiorly (when the arm is
extended at the elbow).
Opposition: movement of the thumb
so that it touches the fingers.
Types of Synovial Joints
• Planar
• Hinge
• Pivot
• Condyloid (Ellipsoid)
• Saddle
• Ball and socket
Types of Synovial Joints
Gliding (Planar) Joint
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Side-to-side and back-and-forth gliding movements.
Monaxial
Rotation prevented by ligaments
Examples
– Intercarpal/intertarsal joints
– Sternoclavicular joints
– Vertebrocostal joints
– Between patella and femur
Types of Synovial Joints
Hinge Joint
• Concave surface of one bone articulates with
and fits into the convex surface of another bone.
• Monaxial.
• Flexion or extension
• Examples:
Knee, elbow, ankle, interphalangeal joints.
Types of Synovial Joints
Pivot Joint
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Round or pointed surface of one bone fits into a
ring formed by another bone and a ligament.
Rotation
Monaxial
Proximal radioulnar joint (supination and
pronation); atlanto-axial joint (“no” movement of
head).
Types of Synovial Joints
Condyloid Joint (Ellipsoid)
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Oval-shaped condyle of a bone fits into an
elliptical cavity of another bone
Flexion, extension, adduction, abduction,
circumduction
Biaxial movement
Wrist, metacarpophalangeal joints for digits 2
through 5
Types of Synovial Joints
Saddle Joint
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Articular bones are shaped like saddle and rider
Flexion, extension, abduction, adduction,
circumduction
Biaxial
Trapezium of carpus and metacarpal of the thumb
Types of Synovial Joints
Ball and Socket Joint
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Ball-shaped surface of a bone fits into the cuplike depression of the second bone.
Flexion, extension, abduction, adduction,
rotation, circumduction.
Triaxial
Shoulder and hip joints
Arthritis
Osteoarthritis
Degenerative disease caused by aging and wear and tear.
• Degeneration of cartilage, no involvement of synovial membrane
• Can cause production of bone spurs that restrict movement
• After joint is stationary for a time, pain at first movement that
diminishes with continued movement
Gouty Arthitis
Urate crystals, a waste product of DNA and RNA metabolism,
build up in joints causing pain.
• Crystals are deposited in cartilage causing inflammation and swelling
• Bones can fuse
• Occurs in middle-aged men with an abnormal gene
Rheumatoid Arthritis
• Autoimmune disorder where white blood cells attack articular cartilages
– Inflammation, swelling , severe pain
– Deformation of extremities
– Eventual fusion of the joints
Other Disorders
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Lyme disease
Bacterial infection transmitted by deer ticks. Joint stiffness, fevers,
chills, headache, stiff neck. First associated with Lyme, Connecticut
Ankylosing spondylitis
Syndrome of unknown cause that affects joints between the vertebrae
and between the sacrum and hip bone.
Ankle sprains
Most common joint to be sprained or fractured. Treatment includes
“RICE”: rest, ice, compression, elevation.
Aging and Joints
• Decreased production of synovial fluid
• Thinning of articular cartilages
• Loss of ligament length and flexibility
Arthroscopy: joint examination using instruments the size of a pencil that
allows the use of tiny instruments and a tiny microscope. Small incision
through which repairs can be made including removal of torn cartilages
of the knee.
Arthroplasty: replacement of a joint. Hip, knee and shoulder are commonly
replaced. Articular elements are replaced by plastic/stainless steel.