Joints Ch. 9 Flashcards
Joints
- Rigid elements of the skeleton meet at joints or articulations
- Greek root “arthro”means joint
- Structure of joints enables resistance to crushing, tearing, and other forces
FunctionalClassification of Jointsbased on amount of movement
- Synarthroses—immovable; common in axial skeleton
- Amphiarthroses—slightly movable; common in axial skeleton
- Diarthroses—freely movable; common in appendicular skeleton; all synovial joints are diarthoses
StructuralClassification of Joints
- Based on material that binds bones together
* Presence or absence of a joint cavity
Structural Classifiction of Joints
- Fibrous
- Cartilaginous
- Synovial
Fibrous Joints
- Bones are connected by fibrous dense regular connective tissue rich in collagen fibers
- Do not have a joint cavity
- Most are immovable (synarthroses)
Types of Fibrous Joints
- Sutures (short fibers)
- Syndesmoses (longer fibers)
- Gomphoses (periodontal ligaments)
Fibrous Joints: Sutures
- Bones are tightly bound by a minimal amount of fibrous tissue with short fibers
- Occur between the bones of the skull
- Allow bone growth so the skull can expand with brain growth during childhood
- Fibrous tissue ossifies in middle age to produce synostoses(= closed sutures)
Fibrous Joints: Syndesmosis
•Bones are connected exclusively by ligaments (dense regular connective tissue),fibrous tissue with relatively long fibers
•Amount of movement depends on length of fibers
–Distal tibiofibular joint articulation—synarthrosis with minimal or no movement
–Interosseous membrane between radius and ulna has quite long fibers which enables some movement between these bones
Fibrous Joints: Gomphoses
- Tooth in a socket
- Connecting ligament—the periodontal ligament
- Immobile
Tooth Structure
- Longitudinal section of tooth in bone alveolus
- Enamel
- Dentin
- Pulp cavity
- Root canal
- Cementum
- Apical foramen
- Periodontal ligament
StructuralClassification of Joints
- Fibrous •Cartilaginous
* Synovial
Cartilaginous Joints
- Bones are united by cartilage
- Lack a joint cavity
- Immobile to slightly mobile
Cartilaginous Joint Types
- Synchondroses: hyaline cartilage, immobile
* Symphyses: fibrocartilage, slightly mobile
SynchondrosisCartilaginous Joint
Bones United by HyalineCartilage
•Epiphyseal plates
•Joint between first rib and manubrium
Symphysis Cartilaginous Joint
- Fibrocartilageunites bones
- Fibrocartilage resists tension & compression stresses and can act as a shock absorber
- Slightly movable joints that provide strength with flexibility–intervertebral discs–pubic symphysis
- Hyaline cartilage is also present as articular cartilage on the bony surfaces to reduce friction between bones during movement
Synovial Joints
- Most movable type of joint•All are diarthroses(movable joints) and contain a fluid-filled joint cavity
- Adjoining bones are covered with articular cartilage and are separated by a joint cavity
- Joint cavity is enclosed within an articular capsule with the inner layer lined with synovial membrane
General Structure of Synovial Joints
•Articular cartilage
–Ends of opposing bones are covered with hyaline cartilage
–Absorbs compression
•Joint cavity(synovial cavity)
–Unique to synovial joints
–Cavity is a space that contains synovial fluid
What is connective tissue made of? Could be question on the best
LOOK UP
Ligaments
- Extend over the outer surface of the articular capsule and contribute to joint stability
- Anchored in periosteum of adjacent bones
- Dense regular connective tissue
Articular Capsule of Synovial Joints is enclosed in a two-layered capsule
•Fibrous capsule—dense irregular connectivetissueis continuous with periosteal layer of adjoining bones; strengthens joint
- Synovial membrane—loose connective tissue
* Lines inner layer of joint capsule and covers internal joint surfaces not covered by cartilage- Functions to make synovial fluid
Synovial membrane
•Rich blood supply to synovial membrane forms extensive capillary beds that provide blood filtrate that forms synovial fluid
Synovial Fluid
- Produced by synovial membrane
- Present in joint cavity
- Is a viscous fluid with consistency similar to raw egg white
- Contains glycoprotein molecules secreted by fibroblasts
How Synovial Joints Function
- Synovial joints—lubricating devices
- Friction could overheat and destroy joint tissue
- As synovial joints are subjected to compressive forces
- Fluid is squeezed out as opposing cartilages touch
- Cartilages ride on the slippery film
Sensory Fibers Richly Innervate Synovial Joints
- Detect pain
* Most monitor how much the capsule is being stretched
Three Basic Movements of Synovial Joints
- Gliding—one bone across the surface of another
- Angular movement—movements change the angle between bones
- Rotation—movement around a bone’s long axis
Synovial Joint Types
GREAT SUMMARY SLIDE
- Plane is nonaxial: intercarpal & intertarsal
- Hinge is uniaxial: elbow, ankle & interphalangeal
- Pivot is uniaxial: proximal radio-ulnar and between atlas (C1) and dens of axis (C2) which allows the skull to rotate on the neck’s axis
- Chondyloid is biaxial: metatarsophalangeal, metacarpophalangeal & wrist
- Saddle is > biaxial: sternoclavicular & 1stcarpometacarpal
- Ball & Socket is multiaxial: shoulder & hip
SLIDE found on 7
Synovial Joints Classified by Shape: Plane joint
•Articular surfaces are flat planes
•Short gliding movementsare allowed
-Intertarsal and intercarpal joints
-Movements are nonaxial
-Gliding does not involve rotation around any axisSynovial Joints Classified by Shape: Hinge Joints
- Cylindrical end of one bone fits into a trough on another bone
- Angular movement is allowed in one plane
- Elbow, ankle, and interphalangeal joints •Movement is uniaxial—allows movement around one axis only
Elbow joint
- The trochlea of the distal humerus articulates with the trochlear notch of the proximal ulna to form a hinge
- Allows flexion and extension
- Tendons of biceps brachii, triceps brachii, and brachialis provide stability
- Radial collateral ligament and ulnar collateral ligament provide stability
- Anular ligament helps stabilize proximal radius and ulna bones
Trochlea of distal humerus articulates with trochlear notch of olecronon process of proximal ulna
Ulnar (medial) collateral ligament
- Ligament that links the humerus with the ulna bone
- Fast ball pitchers can tear their ulnar collateral ligament in their pitching arm
- Tommy John surgery(TJS), known in medical practice as ulnar collateral ligament (UCL) reconstruction, is a surgical graft procedure in which the ulnar collateral ligament in the medial elbow is replaced with a tendon or ligament from elsewhere in the body.
Ankle joint
- A hinge joint between the united distal ends of tibia and fibula and the talus bone of the foot
- This hinge joint allows dorsiflexion and plantar flexion only
- Intertarsal joints are plane joints
Ligaments of the Ankle Joint
- Medial (deltoid) ligament attached to tibia
- Lateral ligaments: talofibular ligaments & calcaneofibular ligaments
- Distal ends of tibia and fibula are joined by anterior and posterior tibiofibular ligaments
Synovial Joints by ShapePivot Joints
•Classified as uniaxial–rotating bone only turns around its long axis
•Examples
-Proximal radioulnar jointwhere the head of the radius rotates within a ring-like anular ligament secured by the ulna bone
-Joint between atlas (C1) and dens of axis (C2) whichallows the skull to rotate on the neck’s axis
Pivot JointJoint between atlas and axis
- Dens(odontoid process “tooth”) is a knoblike structure which projects superiorly from the body of C2(axis) and is cradled in the anterior arch of C1atlas
- Dens acts as a pivot for rotationof the atlas and skull
- Dens participates in rotating the head from side to side
- The name axis for C2is appropriate since its dens allows the skull to rotate on the neck’s axis
Synovial Joints by ShapeCondyloid Joints
•Classified as biaxial—movement occurs along two axes
•Examples:
–Metacarpophalangeal joints
–Metatarsophalangeal joints
–Wrist joint
•Allow moving bone to travel
•Side to side—abduction-adduction
•Back and forth—flexion-extensionWrist Joint
•Stabilized by numerous ligaments
•Composed of radiocarpaland intercarpal joints
–Radiocarpal joint-condyloidjoint between the radius and proximal carpals (the scaphoid and lunate)
•Allows for flexion,
extension, adduction,
abduction, and
circumduction
–Intercarpal joints—planejoints between the proximal and distal rows or carpals
•Allows for glidingmovement
Wrist Joint stabilized by numerous ligaments
- Radiocarpal ligaments
- Intercarpal ligaments
- Carpometacarpal ligaments
- Collateral ligaments
Synovial Joints by ShapeSaddle Joints
- Each articular surface has concave and convex surfaces
- Essentially a type of condyloid joint
- Often classified as biaxial joints, however have the ability to move in more than two axes
- 1st carpometacarpal joint is a good example as it allows opposition of the thumb in addition to flexion and extension
- Sternoclavicular joint is another example78
Saddle joint Sternoclavicular joint (THERE WILL BE NO DETAILED QUESTION ABOUT SADDLE JOINTS ON EXAM)
•Is a saddle joint
•Performs multiple complex movements
•Four ligaments surround the joint
-Anterior and posterior
sternoclavicular ligaments
-Interclavicular ligament
-Costoclavicular ligamentSynovial Joints by ShapeBall-and-socket joints (THERE WILL BE NO DETAILED QUESTION ABOUT SADDLE JOINTS ON EXAM)
•Spherical head of one bone fits into round socket of another
•Classified as multiaxial—allow movement in many axes
•Flexion and extension
•Abduction and adduction
•Rotation
q•Shoulder and hip joints are examples
Hip Joint
- A ball-and-socket structure
- Movements occur in all axes
- Movements limited by ligaments & acetabulum
- Head of femur articulates with acetabulum
- Acetabulum labrum: rim of fibrocartilage around acetabulum
- Ligament of head of the femur (= ligamentum teres) is a flat intracapsular band that runs from the head of the femur to the inferior region of the acetabelum
- Stability comes chiefly from acetabulum and capsular ligaments
- Muscle tendons contribute somewhat to stability
External ligamentous thickenings of the capsule reinforce the hip joint
- iliofemoral ligament
- ischiofemoral ligament
- pubofemoral ligament
Shoulder (glenohumeral) joint
- The most freely movable joint is less stable than other joints •Articular capsule is thin and loose
- Synovial cavity of glenoid cavity
- Glenoid labrum: rim of fibrocartilage around glenoid cavity
Bursae and Tendon Sheaths
- Bursaeand tendon sheathsare not within synovial joints, but rather are closed bags of lubricant which reduce friction between body structures e.g., between a bone and a ligament or a tendon
- Bursa: a flattened fibrous sac lined with a synovial membrane and containing synovial fluid
- Tendon sheath: an elongated bursa that wraps around a tendon
Bursae and Tendon Sheaths
- Bursae and tendon sheaths are not within synovial joints, but rather are closed bags of lubricant which reduce friction between body structures e.g., between a bone and a ligament or a tendon
- Bursa: a flattened fibrous sac lined with a synovial membrane and containing synovial fluid
- Tendon sheath: an elongated bursa that wraps around a tendon
Rotator Cuff muscles
- Group of muscles and their tendons that act to stabilize the shoulder (glenohumeral) joint
- Muscles rise from the scapula and connect to the tuberosities of the head of the humerus, forming a cuff at the shoulder joint that helps hold the humerus head into the glenoid fossa of the scapula
Glenohumeral (Shoulder) Joint
•The rotator cuffis made up of four muscles and their associated tendons –subscapularis –supraspinatus –infraspinatus –teres minor
- All four of these tendons contribute to the stability of the shoulder joint
- Rotator cuff injuries are common shoulder injuries
Knee Joint
- The largest and most complex joint
- Primarily acts as a hinge joint
- Has some capacity for rotation when leg is flexed
- Structurally considered compoundand bicondyloid (both femur and tibia have two chondylar surfaces)
- Chondyles of the femur roll along the almost flat chondyles of the tibia
- Many supporting ligaments made of dense regular connective tissue
- At least 12 bursae including suprapatellar bursa, prepatellar bursa, and deep infrapatellar bursa
- Two fibrocartilagemenisci (articular discs) occur within the joint cavity—the medial & lateral menisci
- Articular cartilage (hyaline cartilage) over femoral and tibial condyles
Femoropatellar joint
- Shares the joint cavity
* Allows patella to glide across the distal femur
Synovial Joints with Articular Disc (= meniscus)
- Some synovial joints contain an articular disc (meniscus) made of fibrocartilage
- Articular disc is present in knee joint, temporomandibular joint, and sternoclavicular joint
Articular Disc (= meniscus)
- Consists of fibrocartilage
- Cushion compressive forces and help articulate bone ends of different shapes
- Permits a more even distribution of forces between the articulating surfaces of bones
- Aids in directing the flow of synovial fluid to areas of the articular cartilage that experience the most friction
- Increases the stability of the joint
Important Factors Influencing Stability of Synovial Joints including the Knee Joint
- Ligaments
- Retinacula
- Muscle tone
- Muscle tendons
Factors Influencing Stability of Synovial Joints:Ligaments
- Capsules and ligaments prevent excessive movements
- On the medial or inferior side of a joint: prevent excessive abduction
- On the lateral or superior side: resist adduction
Factors Influencing Stability of Synovial Joints:Retinacula
- Any of several fibrous bands of fascia made of dense regular connective tissue that pass over or under tendons to help keep the tendons in place
- Groups of tendons from separate muscles may pass under a retinaculum (band of dense regular connective tissue)
- Lateral & medial retinacula around the knee are anteriorand attach to tibia
Factors Influencing Stability of Synovial Joints:Muscle Tone & Muscle Tendons
- Muscle tone helps stabilize joints by keeping tension on tendons
- Is important in reinforcing knee joint as well also shoulder joint and joints in foot arches
Knee Joint ligaments
- Extracapsular ligaments: located outside the capsule
- Capsular ligaments: attached to the capsule
- Intracapsular ligaments: located internal to the capsule
Knee Joint ligaments relationship to joint capsules
NICE SUMMARY SLIDE
EXTRACAPSULAR LIGAMENTS:
•Patellar ligament is anteriorand attaches to tibia
•Fibular (lateral) collateral ligament
•Tibular (medial) collateral ligament
CAPSULAR LIGAMENTS:
•Oblique popliteal ligament crosses posterior aspect of capsule
•Arcuate popliteal ligament from posteriorcapsule to fibula
INTRACAPSULAR LIGAMENTS:
•Anterior cruciate ligament internal to capsule
•Posterior cruciate ligament internal to capsule
Intracapsular knee joints
- Anterior cruciate ligament: attaches to anterior part of tibiaand passes posteriorly to attach to the femur at the medial side of the lateral condyle
- Posterior cruciate ligament:attaches to posterior part of tibiaand passes anteriorly to attach to the femur at the lateral side of the medial condyle 122
Intracapsular knee cruciate ligaments
- Cross each other like an “X”
- Stabilize knee joint and prevent undesirable movements of the knee joint
- Anterior cruciate ligament helps prevent anterior sliding of the tibia
- Posterior cruciate ligament helps prevent posterior sliding of the tibia and forward sliding of the femur
- When the knee is fully extended, both cruciate ligaments are taut and the knee is ‘locked’
Women are more likely to have ACL injury than men
- Narrower inter-condylar notch and smaller ACL make females more prone to injury.
- Women typically have a wider pelvis, which makes the thigh bones angle downward more sharply than in men.
- This angle results in more pressure applied to the inside (medial aspect) of the knee, which can cause the ACL to tear.
Anteriolateral ligament (ALL):newly described knee extracapsular ligament
•Extends from lateral epicondyle of the femur to the anterolateral aspect of the proximal tibia
Joint Injuries
- Torn cartilage: common injury to meniscus of knee joint; meniscus (= articular disc) is a disc of fibrocartilage which extends internally from the joint capsule
- Sprain: ligaments of a reinforcing joint are stretched or torn. Ligaments connect bone to bone
- Strain: an stretch or tear to either a tendon or a muscle
- Dislocation: occurs when the bones of a joint are forced out of alignment
Joint Injuries
- Torn cartilage: common injury to meniscus of knee joint; meniscus (= articular disc) is a disc of fibrocartilage which extends internally from the joint capsule
- Sprain: ligamentsof a reinforcing joint are stretched or torn. Ligaments connect bone to bone
- Strain: an stretch or tear to either a tendon or a muscle
- Dislocation: occurs when the bones of a joint are forced out of alignment
Inflammatory Conditions:Bursitis & tendonitis
- Bursitis—inflammation of a bursa due to injury or friction
* Tendonitis—inflammation of a tendon sheath
Inflammatory and degenerative arthritis conditions which damage joints
- Osteoarthritis—most common type of “wear and tear”arthritis
- Rheumatoid arthritis—a chronic autoimmune inflammatory disorder
- Gouty arthritis(gout)—uric acid build-up causes pain in joints
Cavitation produces sounds when knuckles are ‘cracked’or spinal manipulation is performed
- When a spinal manipulation is performed or when someone ‘cracks’their knuckles, the applied force separates the articular surfaces of a fully encapsulated synovial joint, which creates a reduction in pressure within the joint cavity. •In this low-pressure environment within the joint cavity, some of the gases that are dissolved in the synovial fluid leave the solution, making a bubble, or cavity, which rapidly collapses upon itself, resulting in a “clicking” sound.
- The contents of the resultant gas bubble are thought to be mainly carbon dioxide.
- This process is known as cavitation.
Know what a hinge joint is for the exam
-he says no trick question on exam, but he cant be trusted
