Chapter 8: Joints Flashcards
Joints (Articulations)
Articulation:
*site where 2 or more bones meet
Functions of joints:
- give skeleton mobility
- hold skeleton together
2 Classifications:
- Functional
- structural
Functional Classification of Joints
Based on
*Amount of movement joint allows
Three functional classifications:
*Synarthroses—immovable joints
Syn= together, arthro= joint
- Amphiarthroses—slightly movable joints
- Diarthroses—freely movable joints
Structural classification of joints
Based on
- Material binding bones together
- Presence/absence of joint cavity
Three structural classifications:
- Fibrous joints
- Cartilaginous joints
- Synovial joints
Fibrous Joints
- Bones joined by dense fibrous connective tissue
- No joint cavity
- Most synarthrotic (immovable)
* depends on length of connective tissue fibers
Three types:
- sutures
- syndesmoses
- gomphoses
Fibrous Joints- suture
Joint held together with very short, interconnecting fibers, and bone edges interlock. found only in the skull
Fibrous Joints- syndesmosis
joint held together by a ligament. fibrous tissue can vary in length, but is longer than in sutures. (fibula and tibia)
Fibrous Joints- gomphosis
“peg in socket” fibrous joint. periodontal ligament holds tooth in socket.
Cartilaginous joints
- Bones united by cartilage
- No joint cavity
- Not highly movable
Two types:
Synchondroses
*(synarthrosis - immovable)
*bones united by hyaline cartilage
Symphyses
- (amphiarthrosis –slightly movable)
- bones united by fibrocartilage
- symphyses are amphiarthrosis joints (slightly moveable), especially the pubic symphysis during pregnancy
Synovial joints
- Bones seperated by fluid-filled joint cavity
- all are diarthrotic
- include- all limb joints; most joints of the body
- have 6 distinguishing features
- articular cartilage
- joint (synovial) cavity
- articular (joint) capsule
- synovial fluid
- different types of reinforcing ligaments
- nerves and blood vessels
Synovial joints- Articular cartilage
- hyaline cartilage
* prevents crushing of bone ends
Synovial joints- joint (synovial) cavity
-small, fluid-filled potential space
Synovial joints- articular joint capsule
- 2 layers
- external fibrous layer- dense irregular connective tissue
*inner synovial membrane- loose connective tissue. makes synovial fluid.
Synovial joints- synovial fluid
- Viscous, slippery filtrate of plasma and hyaluronic acid
- Lubricates and nourishes articular cartilage
- Contains phagocytic cells to remove microbes and debris
Synovial joints- different types of reinforcing ligaments
Capsular:
Thickened part of fibrous layer
Extracapsular:
Outside the capsule
Intracapsular:
Deep to capsule; covered by synovial membrane
Synovial joints- nerves and blood vessels
- nerve fibers detect pain, monitor joint position (proprioception) and stretch
- capillary beds supply filtrate for synovial fluid
Other features of some synovial joints
Fatty pads:
For cushioning between fibrous layer 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
Structures associated with synovial joints
Bursae:
- Sacs lined with synovial membrane (Contain synovial fluid)
- Reduce friction where ligaments, muscles, skin, tendons, or bones rub together
Tendon Sheaths:
Elongated bursa wrapped completely around tendon subjected to friction
When someone has “slipped a disc” of the vertebral column, which type of joint is disrupted?
Symphysis
3 stabilizing factors at synovial joints
- shapes of articular surfaces (minor role)
- ligament number and location (limited role)
- Muscle tendons that cross joint (most important)**
- muscle tone keeps tendons taut (extremely important in reinforcing shoulder and knee joints and arches of the foot)
structural and functional characteristics of body joints
Slide 25 (PPW A)
Synovial joints: movements allowed
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
Synovial joints: range of motion
- Nonaxial
- Uniaxial
- Biaxial
- Multiaxial
Nonaxial
Slipping movements only
Uniaxial
movement in one plane
Biaxial
movement in 2 planes
Multiaxial
movement in or around all 3 planes
3 general types of movements at synovial joints
- Gliding
- Angular movements:
- flexion, extension, hyperextension
- abduction, adduction
- circumduction
- Rotation
- medial and lateral rotation
Gliding movements (synovial joint)
-One flat bone surface glides or slips over another similar surface
Examples:
-Intercarpal joints (wrist bones)
- Intertarsal joints (ankle bones)
- Between articular processes of vertebrae
- flat bone surfaces move side to side
- no alteration of joint angle
- limited in range due to articular capsule & ligaments
- intercarpal & intertarsal joints
Angular movements (synovial joints)
- Increase or decrease angle between two bones
- Movement along sagittal plane:
- Flexion—decreases the angle of the joint
- Extension—increases the angle of the joint
- Hyperextension—excessive extension beyond normal range of motion
- Movement along frontal plane:
- Abduction—movement away from the midline
- Adduction—movement toward the midline
Circumduction:
-Involves flexion, abduction, extension, and adduction of limb
-Limb describes cone in space, circular
Rotation (synovial joints)
Turning of bone around its own long axis:
*Toward midline or away from it
*Medial and lateral rotation
Examples:
Between C1 and C2 vertebrae
Rotation of humerus and femur
Special movements at synovial joints
- Supination and pronation of radius and ulna
- Dorsiflexion and plantar flexion of foot
- Inversion and eversion of foot
- Protraction and retraction
- Elevation and depression of mandible
- Opposition of thumb of mandible
Types of synovial joints
synovial joints are divided into 6 sub-categories based on type of movement
- Plane
- Hinge joints
- Pivot joints
- condylar (ellipsoid)
- Saddle joints
- Ball and socket joints
Synovial joints:
1. Plane (gliding)
nonaxial movement
ex: intercarpal and intertarsal joints
Synovial joints:
2. Hinge joints
Uniaxial
ex: elbow joints, interphalangeal joints
This type of synovial joint is used when you bend your fingertips to hang onto a cliff.
Synovial joints:
3. Pivot joints
uniaxial
ex: prox radioulnar joint,
atlantoaxial joint
Synovial joints:
4. Condylar (ellipsoid) joints
biaxial
ex: wrist joints,
metacarpophalangeal joint
Synovial joints:
5. Saddle joints
biaxial
ex: carpometacarpal joint of the thumb
Synovial joints:
6. Ball and socket joints:
multiaxial
ex: hip joint and shoulder joint
Structural Class:
FIBROUS
Types:
a) suture
b) syndesmosis
c) gomphosis
examples;
a) skull
b) distal tib-fib
c) tooth
Structural Class:
CARTILAGINOUS
Types:
a) synchondrosis
b) symphyses
examples:
a) epiphyseal plate
b) pubic symphysis
Structural Class:
SYNOVIAL (DIARTHROSES)
Types:
a) plane
b) hinge
c) pivot
d) condylar
e) saddle
f) ball and socket
example;
a) intercarpal and intertarsal
b) elbow, interphaalangeal
c) prox radial-ulnar, atlas axis
d) metacarpophalangeal
e) carpometacarpal of thumb
f) shoulder and hip
Knee Joint
The largest and most complex joint in the body
Modified hinge joint: primary movement is uniaxial hinge movement
Three joints within a single synovial cavity
- tibiofemoral joint (laterally) - tibiofemoral joint (medially) - patellofemoral joint
Allows flexion, extension, slight medial and lateral rotation in a flexed position
Look at slides 8 & 9 10 on PPW B
Ligaments stabilizing knee joint
Capsular and extracapsular ligaments
*Help prevent hyperextension of knee
- Fibular and tibial collateral ligaments
- Oblique popliteal ligament
- Arcuate popliteal ligament
Ligaments stabilizing knee joint
Intracapsular ligaments:
*Prevent anterior-posterior displacement
*Reside outside synovial cavity
*Anterior cruciate ligament
(Attaches to anterior tibia)
*Posterior cruciate ligament
(Attaches to posterior tibia)
Knee joint injuries
- Absorbs great vertical force
- Vulnerable to horizontal blows, especially laterally blows to extended knee*Three C’s:
Collateral ligaments
Cruciate ligaments
Cartilages
Pointing your toes downward is described as what type of movement
Plantar flexion
pointing upwards- dorsiflexion
Shoulder joint
- AKA: glenohumeral joint
- Shoulder joint is a ball and socket joint
- Allows: flexion, extension, hyperextension, abduction, adduction, medial rotation, lateral rotation, circumduction
- The most freely movable joint in the body
- Rotator cuff muscles help stabilize the joint
Shoulder joint:
Reinforcing ligaments
*Primarily on anterior aspect
*Coracohumeral ligament
-Helps support weight of
upper limb
*Three glenohumeral ligaments
-Weak and sometimes
absent
Elbow joint
- hinge joint
- primarily trochlear notch of ulna with trochlea of humerus
- allows: flexion and extension of the forearm
Hip joint
- Ball and socket joint
- Allows: flexion, extension, abduction, adduction, circumduction, medial & lateral rotation of the thigh
Reinforcing ligaments:
- Iliofemoral ligament
- Pubofemoral ligament
- Ischiofemoral ligament
