What is a Joint (Articulations)?

Sites where two or more bones meet.

What are the Two functions of joints?

1. Secure bones together and 2. Allow rigid skeleton to move.

What is the only bone tha has no joints?

Hyoid

Structural classification of joints are based on?

• Based on the material binding the bones together
• Presence or absence of a joint cavity

Functional classification of joints are based on?

Amount of movement allowed

synarthroses are?

immovable joints

amphiarthroses are?

slightly movable joints

diarthroses are?

freely movable joints

What are the 3 types of fibrous joints?

sutures, syndesmoses, gomphoses

What is a fibrous joints?

Bones joined by fibrous tissue with no joint cavity present

What is a Suture

Articulating bone edges either overlap or interlock. Junctions completely filled by very short connective tissue fibers. Rigid. Examples are found between bones of the cranium.

What is a Syndesmoses?

Bones are connected by a cord or sheet of fibrous tissue (ligament or interosseous membrane). Amount of movement increases with the length of the connecting fibers (note: compare the radius-ulna interosseous membrane with that of the tibia-fibula).

What is a Gomphoses?

Refers to the way teeth are embedded in their sockets. Connection is by a short periodontal ligament

Describe the types of cartilaginous joints

• Articulating bones are united by cartilage.
• Lack a joint cavity.

What are Synchondroses?

Bones are united by a bar or plate of hyaline cartilage. During youth, provides sites and means for bone growth, while contributing to skeletal flexibility. After bone growth ends, ossification occurs and they become immovable. Most common example - epiphyseal plates of long bones, joint between 1st rib and manubrium

What are Symphyses?

Articular surfaces of the bones are covered with articular hyaline cartilage which is fused to a pad or plate of fibrocartilage. Fibrocartilage acts as a shock absorber and permits limited movement. Designed for strength with flexibility. Examples: intervertebral discs, pubic symphysis.

What are Synovial joints?

Articulating bones are separated by a fluid-filled joint cavity. Permit freedom of movement - diarthrotic joints. Examples: all joints of the limbs, most joints of the body.

What are the 6 distinguishing features of synovial joints?

Articular cartilage, joint cavity, articular capsule, synovial fluid, reinforcing ligaments, nerves and blood vessals

Describe what these features of synovial joints are:

Articular cartilage

covers opposing bone surfaces

Describe what these features of synovial joints are:

Joint cavity

cavity filled with synovial fluid

Describe what these features of synovial joints are:

Articular Capsule

cavity enclosed by a double-layered articular capsule. Outer layer (fibrous capsule) made of dense irregular connective tissue. Inner layer is the synovial membrane - lines the capsule internally and covers all internal joint surfaces that are not hyaline cartilage.

Describe what these features of synovial joints are:

Synovial fluid

provides a slippery weight-bearing film that reduces friction. Also provides nourishment to the cartilage. Derived from filtration of blood flowing through capillaries in the synovial membrane.

Describe what these features of synovial joints are:

Reinforcing ligaments

Joints reinforced and strengthed by a number of ligaments

Describe what these features of synovial joints are:

Nerves and blood vessels

Nerves detect pain as well as joint position and stretch. Blood vessel filtrate is the basis of synovial fluid.

What are Bursae?

Bursae are flattened fibrous sacs lined with synovial membrane and containing a thin film of synovial fluid. Bursae are common in sites where ligaments, muscles, skin, or muscle tendons overlie and rub against bone.

What are Tendon Sheaths

Tendon sheaths are elongated bursae that wrap completely around a tendon subjected to friction.

What are the 3 factors that contribute to the stability of synovial joints?

1. nature of articular surface
2. number and positioning of ligaments
3. muscle tone

Describe these factors of synovial joint stability:

Nature of articular surface

shapes of articular surfaces determine what movements are possible.

Describe these factors of synovial joint stability:

Number and positioning of ligaments

Ligaments unite the bones, help direct bone movement, and prevent excessive or undesirable motion.

Describe these factors of synovial joint stability:

Muscle Tone

Muscle tendons that cross the joint are the most important stabilizing factor. The tendons are kept taut at all times by the tone of their muscles. Muscle tone is defined as low levels of contractile activity in relaxed muscles that keep the muscles healthy and ready to react to stimulation. Muscle tone is extremely important in reinforcing the shoulder and knee joints.

What are the 3 ranges of motion allowed by synovial joints?

Nonaxial, Uniaxial, multiaxial

Describe the movement allowed by these 3 types of synovial ranges:

nonaxial, uniaxial, multiaxial

1. nonaxial- slipping motion only
2. uniaxial - movement in one plane
3. multiaxial - movement in or around all three planes of space or axes

Where would we see gliding movements?

intercarpal/tarsal, intervertebral, sternoclavicular joints.

What are angular movements?

list the 5 types

change the angle between two bones. flexion, extension, abduction, adduction circumduction

What is flexion?

what is extension?

flexion reduce angle, usually bending

extension increase angle, usually straightening

What is circumduction?

movement of the distal portion of a limb in a circular pattern so that the movement of the entire limb describes a cone

What is Abduction?

What is Adduction?

abduction move laterally

adduction move medially

What are these special movements?

pronation, supination, opposition

pronation rotating forearm so that the palm faces down

supination rotating forearm so that the palm faces up

opposition touching the thumb to the tips of other fingers on the same hand, allows grasping

What are these special movements?

dorsiflexion, plantarflexion

Inversion, eversion

dorsiflexion lifting the foot so that its superior surface approaches the shin, as in kicking

plantarflexion depressing the foot, pointing toes as in a ballet stance

inversion pointing the sole of the foot medially

eversion pointing the sole of the foot laterally

What are these special movements?

protraction, retraction

elevation, depression

protraction jutting out the jaw

retraction bringing jaw back to normal

elevation lifting a body part superiorly

depression moving a body part inferiorly

What are the 6 types of synovial joint structures?

Plane joints, Hinge joints, pivot joints, condyloid joints, saddle joints, ball and socket joints

Describe the following joints:

plane, hinge, pivot

1. Plane joints – articular surfaces are flat and only allow gliding movements (intercarpal joints).
2. Hinge joints – cylindrical end of one bone fits into a trough on another bone (elbow).
3. Pivot joints – rounded end of a bone fits into a ring of another bone allowing uniaxial rotation (atlas and the dens of the axis)

Describe the following joints:

condyloid, saddle, ball-and-socket

1. Condyloid joints – oval surface of one bone fits into a complementary depression in another, permitting all angular motions (radius/carpal joints, knuckle joints).
2. Saddle joints – similar to condyloid, but the joining surfaces are saddle shaped (carpometacarpal joints of the thumbs).
3. Ball-and-socket joints – spherical head of one bones articulates with cup-like socket of another, allowing universal movement (hip joint).

Describe selected articulations of the body with respect to the bones that enter into their formation, structural classification, and anatomical components:

Knee

• multiple joints in one – patella/femur; tibiofemoral joint
• menisci (cartilage disks) - prevent side to side rocking of the femur on tibia and absorb shock.
• Primarily a hinge joint allowing flexion and extension
• Ligaments prevent unwanted movements – collateral ligaments (prevent rotation when knee is extended); cruciate ligaments (centrally located, prevent displacement of articular surfaces)

Describe selected articulations of the body with respect to the bones that enter into their formation, structural classification, and anatomical components:

Shoulder

• Head of humerus articulates with glenoid cavity of scapula
• Lesser stability but more freedom of movement
• Important stabilizer is the tendon of biceps brachii muscle
• Other tendons and muscles make up rotator cuff for further stabilization
• Frequently dislocated

Describe selected articulations of the body with respect to the bones that enter into their formation, structural classification, and anatomical components:

elbow

• Distal humerus articulates with the radius and ulna (ulna most important)  Annular ligament holds radius against ulna
• Hinge joint, permits flexion and extension.

Describe selected articulations of the body with respect to the bones that enter into their formation, structural classification, and anatomical components:

hip

• Head of femur articulates with acetabulum of coxal bone
• Ball-and-socket joint – good range of motion
• Ligamentum teres – inside joint capsule, attaches femur (fovea capitis) to acetabulum
• Stability mostly from complementary bone surfaces and muscle tendons.

What is a sprain?

ligaments reinforcing a joint are stretched or torn. Most common sites are the lumbar region of the spine, ankle, and the knee. Partially torn ligaments will repair themselves. Heal slowly and tend to be painful and immobilizing. Completely ruptured ligaments must be repaired surgically and quickly, because the inflammatory response in the joint will turn the injured ligament to mush.

What are cartilage injuries?

involve tearing of the knee menisci due to high pressure and twisting motions occurring simultaneously. Being avascular tissue, cartilage rarely can repair itself. Fragments can interfere with joint function by causing locking or binding of the joint. Must be removed surgically (usually arthroscopically). Removal of some or all of a meniscus does not severely impair knee joint mobility, but the joint is definitely less stable.

What is a dislocation?

occurs when bones are forced out of their normal positions at a joint. Usually accompanied by sprains, inflammation, and joint immobilization. Common contact sports injury. Joints of the shoulders, fingers, and thumbs are commonly dislocated. Must be reduced (returned to their proper position). Subluxation is the partial dislocation of a joint.

What are bursitis and tendonitis

inflammation of a bursa caused by excessive stress or friction. Caused by: falling on one's knee (housemaid's knee or water on the knee), prolonged leaning on one's elbows (student's elbow or olecranon bursitis), bacterial infection. Symptoms include pain made worse by movement, redness, swelling. Tendonitis is inflammation of tendon sheaths. Its causes, symptoms, and treatment are the similar to that for bursitis.

What is arthritis?

over 100 different types of inflammatory or degenerative diseases that damage joints. Osteoarthritis (“wear and tear”) – normal use over time leads to more articular cartilage damage than can be fixed, bone ends thicken and restrict joint movement. Rheumatoid arthritis – autoimmune disease where the body’s own immune system attacks the joints. Inflamed synovial membrane thickens into a pannus that erodes cartilage; scar tissue later ossifies and bone ends fuse together (ankylosis), immobilizing the joint.