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Flashcards in ch 8 Deck (17):

Joints (articulation)

Functions of joints: give skeleton mobility and hold skeleton together


Classification of Joints

Structural: three types based on what material binds the joints and whether a cavity is present

Functional classifications: three types based on movement joint allows
Synarthroses: immovable joints
Amphiarthroses: slightly movable joints
Diarthroses: freely movable joints


Fibrous Joint

Bones joined by dense fibrous connective tissue
No joint cavity
Most are immovable

Sutures-Rigid, interlocking joints of skull Allow for growth during youth

Syndesmoses- Bones connected by ligaments, bands of fibrous tissue Fiber length varies, so movement varies

Gomphoses- Only examples are the teeth in alveolar sockets


Cartilagenous Joint

Bones united by cartilage

Like fibrous joints, have no joint cavity

Not highly movable

Two types:

Synchondroses-Bones united by hyaline cartilage

Symphyses- Bones united by fibrocartilage


Synovial Joint

Bones separated by fluid-filled joint cavity
All are diarthrotic (freely movable)
Include almost all limb joints

Have six general features
Have bursae and tendon sheaths associated with them
Stability is influenced by three factors
Allow several types of movements
Classified into six different types


Synovial joints have six general features

Articular cartilage: consists of hyaline 
 cartilage covering ends of bones
Prevents crushing of bone ends

Joint (synovial) cavity: small, fluid-filled 
 potential space that is unique to synovial joints

Articular (joint) capsule: two layers thick
External fibrous layer: dense irregular connective tissue
Inner synovial membrane: loose connective tissue that makes synovial fluid

Synovial fluid: viscous, slippery filtrate of 
 plasma and hyaluronic acid
Lubricates and nourishes articular cartilage
Contains phagocytic cells to remove microbes and debris

Different types of reinforcing ligaments
Capsular: thickened part of fibrous layer
Extracapsular: outside the capsule
Intracapsular: deep to capsule; covered by synovial membrane

Nerves and blood vessels
Nerves detect pain; monitor joint position and stretch
Capillary beds supply filtrate for synovial fluid


Other Synovial Joint feature

Fatty pads
For cushioning between fibrous layer of capsule and synovial membrane or bone

Articular discs (menisci)
Fibrocartilage separates articular surfaces to improve “fit” of bone ends, stabilize joint, and reduce wear and tear


Three factors determine stability of joints to prevent dislocations

Shape of articular surface (minor role)
Shallow surfaces less stable than ball-and-socket

Ligament number and location (limited role)
The more ligaments, the stronger the joint

Muscle tone keeps tendons taut as they cross joints (most important)
Extremely important in reinforcing shoulder and knee joints and arches of the foot


Movement allowed by synovial

All muscles attach to bone or connective tissue at no fewer than two points
Origin: attachment to immovable bone
Insertion: attachment to movable bone

Muscle contraction causes insertion to move toward origin
Movements occur along transverse, frontal, or sagittal planes

Range of motion allowed by synovial joints
Nonaxial: slipping movements only
Uniaxial: movement in one plane
Biaxial: movement in two planes
Multiaxial: movement in or around all three planes

Three general types of movements
Angular movements



One flat bone surface glides over another similar surface


Angular movement

Increase or decrease angle between two bones
Movement along sagittal plane (extension, Flexion, circumduction, adduction)



turning of bone around axis, (pronation, supination)


six different types of synovial joints

Non Axial movement- plane joint

Uniaxial joint- hinge joint/ Pivot joint

Biaxial movement- condylar joint/ saddle joint

multiaxial- ball and socket


Five main synovial joints



Knee Joint general

Largest, most complex joint of body

Consists of three joints surrounded by single cavity

Femoropatellar joint
Plane joint
Allows gliding motion during knee flexion

2. Lateral joint and 3. Medial joint
Lateral and medial joints together are called tibiofemoral joint
Joint between femoral condyles and lateral and medial menisci of tibia
Hinge joint that allows flexion, extension, and some rotation when knee partly flexed


Knee Joint

Anteriorly, quadriceps tendon gives rise to three broad ligaments that run from patella to tibia

Capsular, extracapsular, or intracapsular ligaments act to stabilize knee joint

Capsular and extracapsular ligaments help prevent hyperextension of knee

Intracapsular ligaments reside within capsule, but outside synovial cavity
Help to prevent anterior-posterior displacement


Shoulder joint

Glenoid labrum: fibrocartilaginous rim around glenoid cavity
Helps to add depth to shallow cavity

Cavity still only holds one-third of head of humerus

Reinforcing muscle tendons contribute most to joint stability
Tendon of long head of biceps brachii muscle is “superstabilizer”