Joints

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Joints
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JOINT

• A joint is the junction or pivot point between
  two or more bones.
• Movement of the body as a whole results from the
  rotation of bones about individual joints.
• Joints transfer and dissipate forces produced by
  gravity and muscle activation.

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ARTHROLOGY

• Arthrology is the study of the classification,
  structure, and function of joints.
• Aging, long-term immobilization, trauma, and
  disease all affect the structure and ultimate
  function of joints.
• These factors influence the quality and quantity
  of human movement.

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Classification of Joints

• Structural Classification
• Presence or absence of a space (synovial cavity)
• Type of Connective Tissue
• Functional Classification
• Relates to the degree of movement they permit.

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CLASSIFICATION OF JOINTS BASED ON MOVEMENT
POTENTIAL

• Two major types of joints exist within the body
• Synarthroses
• Diarthroses

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JOINTS OF THE BODY
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SYNARTHROSES

• A synarthrosis is a junction between two bones
  that allows slight to essentially no movement.
• Synarthroidial joints can be classified as either
  fibrous or cartilaginous based upon the dominant
  type of connective tissue.

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TYPES OF SYNARTHROSES

• Fibrous joints
• Dense connective tissue (high concentration of
  collagen)
• Sutures of the skull
• Joints reinforced by an interosseous membrane
  (distal tibiofibular joint).
• Cartilaginous joints
• Flexible cartilage or hyaline cartilage
• Symphysis pubis
• Interbody joints of the spine
• Manubriosternal joint

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DIARTHROSES (SYNOVIAL JOINTS)

• A diarthrosis is an articulation that allows
  moderate to extensive motion.
• Possess a synovial fluid-filled cavity.
• Compose the majority of the joints within the
  musculoskeletal system.

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SEVEN ELEMENTS OF DIARTHRODIAL JOINTS

• Articular cartilage covers the ends and other
  articular surfaces of bones
• Joint capsule (articular capsule) peripheral
  curtain of connective tissue
• Synovial membrane dcxf vcdx d cxdfv cxfefdsex
• Synovial fluid
• Ligaments
• Capsular ligaments
• Extracapsular ligaments
• Blood vessels
• Sensory nerves

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ELEMENTS OF SYNOVIAL JOINTS
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INTRA-ARTICULAR DISCS (MENISCI)

• Intra-articular discs (meninsci) pads of
  fibrocartilage imposed between articular
  surfaces.
• These pads increase congruency and improve force
  dispersion.
• Examples of intra-articular discs
• Tibiofemoral (knee)
• Distal radio-ulnar
• Sternoclavicular
• Acromioclavicular
• Temporomandibular
• Apophyseal (variable)

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PERIPHERAL LABRUM

• A peripheral labrum of fibrocartilage extends
  from the body rims of the glenoid fossa to the
  shoulder and the acetabulum of the hip.
• These structures deepen the concave surface of
  the joint.
• These structures support and thicken the
  attachment of the joint capsule.

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FAT PADS

• Fat pads thicken the joint capsule, causing the
  inner surface of the capsule to fill
  nonarticulating joint spaces formed by
  incongruent bony contours.
• They are prominent in the elbow and knee joints.
• Enlarged and inflamed fat pads can adversely
  affect the biomechanics of the joint.

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BURSAE

• A bursa is an extension or outpouching of the
  synovial membrane of a diarthroidial joint.
• Bursae are filled with synovial fluid and exists
  in areas of potential stress.
• Bursae help to absorb force and protect
  periarticular connective tissues, including bone.

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SYNOVIAL PLICA

• Synovial plicae (synovial folds, synovial
  redundancies, or synovial fringes) are slack,
  overlapped pleats of tissue composed of the
  innermost layers of the joint capsule.
• They are found in joints with large capsular
  surface area such as the knee and elbow.
• They increase the synovial surface area and allow
  full joint motion without undue tension on the
  synovial lining.
• Folds that are thickened or adhered due to
  inflammation can alter the joint biomechanics.

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Structural Classification of Joints

• Fibrous Joints
• Fibrous CT
• Lack a synovial cavity
• Cartilaginous Joints
• Cartilage
• Lack a synovial cavity
• Synovial Joints
• Have a synovial cavity
• Dense irregular CT
• Often associated with accessory ligaments

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Functional Classification of Joints

• Synarthrosis (syn together)
• Immovable joint
• Amphiarthrosis (amphi on both sides)
• A slightly moveable joint
• Diarthrosis (moveable joint)
• A freely moveable joint
• Synovial joints

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Fibrous Joints

• Lacks a synovial cavity
• Little or no movement

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Fibrous Joints

• Sutures
• Immovable
• Synostosis suture that is replaced by bone in
  the adult
• Syndesmoses
• Slightly moveable (amphiarthrosis)
• Ligament
• Interosseous membrane
• Gomphoses
• Dentoalveolar joint

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Cartilaginous Joints

• Lacks a synovial cavity
• Allows little or no movement
• Synchondroses
• Epiphyseal plate
• Symphyses
• Pubic symphisis
• Intervertebral discs

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Synovial Joints

• Synovial (Joint) Cavity space btwn. Bones
• Freely moveable
• The bones are covered by hyaline cartilage
• Contains the following
• Articular capsule
• Synovial fluid
• Accsessory ligaments and articular discs

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Classification of Synovial Joints Based on
Mechanical Analogy

• Hinge joint
• Pivot joint
• Ellipsoid joint
• Ball-and-socket joint
• Plane joint
• Saddle joint
• Condyloid joint

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HINGE JOINT

• Primary Angular Motions
• Flexion and extension only
• Mechanical Analogy
• Door hinge
• Anatomic Examples
• Humero-ulnar joint
• Interphalangeal joint

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HINGE JOINT
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PIVOT JOINT

• Primary Angular Motions
• Spinning of one member around a single axis of
  rotation
• Mechanical Analogy
• Doorknob
• Anatomic Examples
• Humeroradial joint
• Atlanto-axial joint

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PIVOT JOINT
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ELLIPSOID JOINT

• Primary Angular Motions
• Biplanar motion (flexion-extension and
  abduction-adduction)
• Mechanical Analogy
• Flattened convex ellipsoid paired with a concave
  trough
• Anatomic Examples
• Radiocarpal joint

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ELLIPSOID JOINT
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BALL-AND-SOCKET JOINT

• Primary Angular Motions
• Triplanar motion (flexion-extension,
  abduction-adduction, and internal-external
  rotation)
• Mechanical Analogy
• Spheric convex surface paired with a concave cup
• Anatomic Examples
• Glenohumeral joint
• Coxofemoral (hip) joint

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BALL-AND-SOCKET JOINT
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PLANE JOINT

• Primary Angular Motions
• Slide (translation) or combined slide and
  rotation
• Mechanical Analogy
• Relatively flat surfaces apposing each other,
  like a book on a table
• Anatomic Examples
• Carpometacarpal joints (digits II to IV)
• Intercarpal joints
• Intertarsal joints

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PLANE JOINT
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SADDLE JOINT

• Primary Angular Motions
• Biplanar motion
• Spin between bones is possible, but may be
  limited by interlocking nature of joint
• Mechanical Analogy
• Each member has a reciprocally curved concave and
  convex surface oriented at right angles to the
  other, like a horse rider and a saddle
• Anatomic Examples
• Carpometarcarpal joint of the thumb
• Sternoclavicular joint

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SADDLE JOINT
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CONDYLOID JOINT

• Primary Angular Motions
• Biplanar motion
• Either flexion-extension and abduction-adduction,
  or flexion-extension and axial rotation
  (internal-external rotation)
• Mechanical Analogy
• Mostly spheric convex surface that is enlarged in
  one dimension like a knuckle paired with a
  shallow concave cup
• Anatomic Examples
• Metacarpophalangeal joint
• Tibiofemoral (knee) joint

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CONDYLOID JOINT
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SIMPLIFYING THE CLASSIFICATION OF SYNOVIAL JOINTS

• Two articular forms based upon true movement of
  the joint.
• Ovoid joint
• Saddle joint
• Essentially all synovial joints of the body with
  the notable exception of planar joints can be
  categorized under this scheme.

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OVOID JOINT

• An ovoid joint has paired mating surfaces that
  are imperfectly spheric, or egg-shaped, with
  adjacent parts possessing a changing surface
  curvature.
• The articular surface of one bone is convex and
  of the other is concave.
• Most joints of the body are of this variety.

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SADDLE JOINT

• A saddle joint consists of paired convex and
  concave surfaces oriented at approximately 90
  degrees to each other.
• Each member has a reciprocally curved concave and
  convex surface oriented at right angles to the
  other, like a horse rider and a saddle.

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BASIC SHAPES OF JOINT SURFACES
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BIOLOGICAL MATERIALS OF PERIARTICULAR CONNECTIVE
TISSUES

• Fibrous Proteins
• Collagen (type I and II)
• Ground Substance
• Glycosaminoglycans
• Water
• Solutes
• Cells
• Fibroblasts
• Chondrocytes

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TYPES OF COLLAGEN IN PERIARTICULAR CONNECTIVE
TISSUES

• Type I
• Thick, rugged fibers that elongate when stretched
• Present in ligaments, tendons, fascia, and
  fibrous joint capsules
• Type II
• Thinner fibers than type I
• Provide a framework for maintaining the general
  shape and consistency of structures, such as
  hyaline cartilage

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Types of Movements at Synovial Joints

• Gliding
• Simple back and forth movement, limited in range,
  planar joints
• Angular Movements
• Increase or decrease in the angle btwn. bones
• Rotation
• Bone revolves around a longitudinal axis
• Special Movements

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Angular Movements

• Flexion, extension, lateral flexion,
  hyperextension
• Abduction, adduction, and circumduction

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Rotation

• Medial (internal) rotation
• Lateral (external) rotation

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Special Movements

• Elevation
• Depression
• Protraction
• Retraction
• Inversion

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Special Movements

• Eversion
• Dorsiflexion
• Plantar flexion
• Supination
• Pronation
• Opposition

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Dislocation

• Luxation displacement of a bone from a joint
• Causes tearing or ligaments, tendons, and
  articular capsules
• Subluxation
• Incomplete dislocation

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Arthroscopy

• Observaion of the interior of a joint
• Utilizes a lighted, pencil-thin instrument
• Assists in surgery and assessment of the joint
  space

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Sprain Strain

• Sprain a forcible wrenching or twisting of the
  joint that stretches or tears its ligaments, but
  does not dislocate the bones.
• The ankle joint is the most often sprained.
• The lumbar spine is another prominent location of
  sprain.
• Strain a stretched or partially torn muscle.

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Bursae Tendon Sheaths

• Bursae
• Saclike structures
• Reduce friction in some synovial joints
• Tendon sheaths
• Tubelike bursae that wrap around tendons
• Occurs where tendons pass through synovial
  cavities
• Reduce friction

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Bursitis

• An acute or chronic inflammation of a bursa
• Caused by trauma or infection
• Repeated excessive exertion
• Symptoms
• Pain, swelling, inflammation limited movement
• Treatment
• Oral anti-inflammatory agents (herbal, O.T.C. And
  prescription), corticosteroid injections

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Rotator Cuff Injury

• Supraspinatous
• Infraspinatous
• Teres Minor
• Subscapularis
• Common injury among pitchers and volleyball
  players due to excessive circumduction

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Separated Shoulder

• Injury of the acromioclavicular joint
• Due to forceful trauma such as when the shoulder
  strikes the ground in a fall

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Tennis Elbow

• Lateral epicondylitis
• Little-league elbow

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GOLFERS ELBOW

• Medial Epicondylitis

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Dislocation of the Radial Head

• The most common upper limb dislocation in
  children
• Occurs with a strong pull to the forearm while it
  is extended and supinated
• Swinging a child around with outstretched arms

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Swollen Knee

• Immediate swelling is due to blood loss
• Delayed swelling is due to excessive production
  of synovial fluid water on the knee

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Dislocated Knee

• Displacement of the tibia relative to the femur
• Most commonly dislocates anteriorly

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Rheumatism

• Any painful disorder of the supporting structures
  of the body bones, ligaments, tendons, or
  muscles that is not caused by infection or
  injury.

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Arthritis

• A form of rheumatism in which the joints are
  swollen, stiff, and painful.

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Types of Arthritis

• Rheumatoid arthritis (RA)
• Autoimmune disease the body attacks its own
  tissues
• Osteoarthritis (OA)
• Degenerative joint disease
• Gouty arthritis
• A person with gout produces excessive uric acid
  or is unable to excrete it properly

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Lyme Disease

• First reported in Lyme, CT
• Bacteria transported by deer ticks
• The rash often resembles a bulls eye target,
  although some people never develop a rash
• Symptoms
• Joint stiffness, fever, chills, headache, stiff
  neck, nausea

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Terminology

• Arthralgia pain in a joint
• Bursectomy removal of a bursa
• Chondritis inflammation of cartilage
• Synovitis inflammation of a synovial membrane
  in a joint