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Anatomy Chapter 8: Joints

Terms

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Structural Classifications of Joints
Fibrous, Cartilaginous, Synovial
Functional Classification of Joints
Synarthroses, amphiarthroses, diarthroses
Synarthroses
Immovable Joints
Amphiarthroses
Slightly movable joints
Diarthroses
Freely movable joints
Fibrous Joints
Bones joined by fibrous tissue. No joint cavity present.

Amount of movement allowed depends on length of connective tissue fibres.

Mostly synarthroses. Some amphiarthroses.

Includes sutures, syndesmoses, and gomphoses.
Sutures
Fibrous joints occurring only in the skull.

Wavy articulating bone edges interlock and the junction is completely filled by a minimal amount of very short connective tissue fibres.
Synostoses
Sutures which are ossified, fused.
Syndesmoses
Fibrous joint in which bones are connected by a ligament.

Synarthroses and amphiarthroses.
Gomphoses
Articulations of the teeth with bony alveolar sockets.

Fibrous joints joined by the periodontal ligaments.

Synarthroses.
Cartilaginous Joints
Articulating bones are united by cartilage. Lack joint cavity.

Synarthroses and amphiarthroses.

Includes synchondroses and symphyses.
Synchondroses
Cartilaginous joints joined by a bar or plate of hyaline cartilage.

Almost all synarthrotic.
Symphyses
Cartilaginous joints in which the articular surfaces of the bones are covered with articular cartilage, which in turn is fused to an intervening plate of fibrocartilage.

Amphiarthrotic.
Synovial Joints
Joints in which the articulating bones are separated by a fluid-containing joint cavity.

All are diarthroses.
Distinguishing Features of Synovial Joints (5)
Articular cartilage, joint cavity, articular capsule, synovial fluid, reinforcing ligaments.
Articular Cartilage
Glassy-smooth hyaline cartilage which covers the opposing bone surfaces in a synovial joint.
Joint Cavity
Potential space of synovial joint that contains a small amount of synovial fluid.
Articular Capsule
Two-layered capsule enclosing the synovial joint cavity.

Consists of the fibrous capsule and the synovial membrane.
Fibrous Capsule
External layer of the articular capsule of a synovial joint, composed of dense irregular connective tissue. Strengthens the joint.
Synovial Membrane
Inner layer of the synovial joint capsule which is composed of loose connective tissue. Covers all internal joint surfaces that are not hyaline cartilage and secretes synovial fluid.
Synovial Fluid
Lubricating fluid derived by filtration from blood flowing through the capillaries in the synovial membrane of a synovial joint.

Provides a weight-bearing film that reduces friction between cartilages.

Also contains phagocytic cells that rid the joint cavity of microbes and debris.
Reinforcing Ligaments
Bandlike structures which reinforce and strengthen synovial joints.
Bursae
Flattened sacs lined with synovial membrane and containing a thin film of synovial fluid.

Common where parts of synovial joints rub together.
Factors Effecting the Stability of a Synovial Joint
Shapes of the articular surfaces, number/positioning of ligaments, muscle tone
Skull Joints
Articulate cranial and facial bones.

Fibrous--suture

Synarthotic.
Temporomandibular Joint
Articulates temporal bone of skull and mandible.

Synovial--modified hinge

Diarthotic.
Atlanto-occipital Joint
Articulates occipital bone and atlas.

Synovial--condyloid.

Diarthotic.
Atlantoaxial Joint
Articulates atlas and axis.

Synovial--pivot

Diarthotic
Intervertebral Joints (Between Bodies)
Articulates adjacent vertebral bodies.

Cartilaginous--symphysis

Amphiarthrotic
Intervertebral Joints (Between Articular Processes)
Articulation between articular processes of vertebrae.

Synovial--plane

Diarthotic
Vertebrocostal Joints
Articulate vertebrae and ribs.

Synovial--plane

Diarthotic.
Sternoclavicular
Articulates sternum and clavicle

Synovial--shallow saddle

Diarthrotic
Sternocostal (rib 1 only)
Articulation between sternum and rib 1

Cartilaginous--synchondrosis

Synarthrotic
Sternocostal (ribs 2-7)
Articulates sternum with ribs 2-7

Synovial--double plane

Diarthrotic
Acromioclavicular
Articulates acromion of scapula and clavicle

Synovial--plane

Diarthrotic
Glenohumeral Joint
Articulates scapula and humerus.

Synovial--ball and socket

Diarthrotic.
Elbow Joint
Articulates ulna (and radius) with humerus.

Synovial--hinge

Diarthrotic
Proximal and Distal Radioulnar Joints
Articulate radius and ulna.

Synovial--pivot

Diarthrotic
Radiocarpal Joint
Articulates radius and proximal carpals.

Synovial--condyloid

Diarthrotic
Intercarpal Joint
Articulates adjacent carpals

Synovial--plane

Diarthrotic
Carpometacarpal (Digit 1)
Articulates trapezium and metacarpal 1

Synovial--saddle

Diarthrotic
Carpometacarpal (Digit 2-5)
Articulates carpals and metacarpals.

Synovial--plane

Diarthrotic
Metacarpophalangeal Joint
"Knuckle." Articulates metacarpals with proximal phalanges.

Synovial--condyloid

Diarthrotic.
Interphalangeal Joint
Articulates adjacent phalanges

Synovial--hinge

Diarthrotic
Sacroiliac Joint
Articulates sacrum and coxal bone

Synovial--plane

Diarthrotic
Pubic Symphysis
Articulates pubic bones

Cartilaginous--symphysis

Amphiarthrotic
Coxal Joint
"Hip joint" Articulates hip bone and femur

Synovial--ball and socket

Diarthrotic
Tibiofemoral Joint
"Knee Joint" Articulates femur and tibia.

Synovial--modified hinge

diarthrotic
Femoropatellar Joint
"Knee Joint" Articulates femur and patella

Synovial--plane

Diarthrotic
Proximal Tibiofibular Joint
Articulates tibia and fibula, proximally

Synovial--plane

Diarthrotic
Distal Tibiofibular Joint
Articulates the tibia and fibula distally

Fibrous--syndesmosis

Synarthrotic
Ankle
Articulates tibia and fibula with talus

Synovial--hinge

diarhtrotic
Intertarsal Joint
Articulates adjacent tarsals

Synovial--plane

Diarthrotic
Tarsometatarsal Joint
Articulates tarsals and metatarsals

Synovial--plane

Diarthrotic
Metatarsophalangeal Joint
Articulates metatarsal and proximal phalanx

Synovial--condyloid

Diarthrotic
Nonaxial Movements
Slipping movements which have no axis around which movement can occur.
Uniaxial Movements
Movement in one plane
Biaxial Movement
Movement in two planes
Multiaxial Movement
Movement in or around all three planes of space and axes.
Gliding Movements
Translations. One flat bone glides or slips over another.
Angular Movements
Movements which increase or decrease the angle between two bones.

Flexion/extension/hyperextension, dorsiflexion/plantarflexion, abduction/adduction, circumduction
Flexion
A bending movement that decreases the angle of the joint and brings the articulating bones closer together.
Extension
Movement along the sagittal plane that increases the angle between articulating bones.
Hyperextension
Movement along the sagittal plane that increases the angle between articulating bones past 180 degrees.
Dorsiflexion
Lifting the foot so that its superior surface approaches the shin (toes up).
Plantarflexion
Depressing the foot so that the toes point down.
Abduction
Movement of a limb away from the midline or median plane of the body, along the frontal plane. Spreading the digits apart.
Adduction
Movement of a limb toward the body midline or bringing the digits into parallel, touching position.
Circumduction
Moving a limb so that it describes a cone in space. The distal end of the limb moves in a circle while the proximal end is more or less stationary.
Rotation
Turning of a bone around its own long axis.

Medial--moves toward median plane of the body

Lateral--moves away from median plane of the body
Supination
Turning the palm to face anteriorly or superiorly.

Anatomical position for the hands.
Pronation
Turning the palm to face posteriorly or inferiorly.
Inversion
Turning the sole of the foot medially.
Eversion
Turning the sole of the foot out laterally.
Protraction
Jutting out the jaw.
Retraction
Pulling in the jaw.
Elevation
Lifting a body part superiorly

(Closing mouth or shrugging shoulders)
Depression
Moving a body part inferiorly.

(Opening mouth, rounding shoulders down)
Opposition
Movement taken to touch the thumb to the fingers of the same hand.
Plane Joints
Synovial joints in which the articular surfaces are essentially flat and allow only short gliding or translational movements.
Hinge Joints
Synovial joints in which a cylindrical projection of one bone fits into a trough-shaped surface on another.

Motion is along a single plane and resembles that of a mechanical hinge.

Flexion/extension only.
Pivot Joints
Synovial joint in which the rounded end of one bone protrudes into a sleeve or ring composed of bone of another.

Allows only uniaxial, rotational movement.
Condyloid Joints
"Ellipsoidal Joints"

Synovial joints in which the oval articular surface of one bone fits into a complementary depression in another.

Biaxial--permit all angular motions (flexion/extension, abduction/adduction, circumduction)
Saddle Joints
Synovial joints that resemble condyloid joints but allow greater freedom of movement due to each articular surface having both concave and convex areas.
Ball-and-Socket Joints
Synovial joints in which the spherical or hemispherical head of one bone articulates with the cuplike socket of another.

These joints are multiaxial and the most freely moving synovial joints.

Universal movement is allowed.
Types of Synovial Joints
(Purple Helicopters Save Big Cheerful People)

Plane, hinge, saddle, ball-and-socket, condyloid, pivot

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