Ch. 9

What are the two ways joints are classified?

Structural and functional classification.

What is structural classification based on?

The type of connection between bones at an articulation.

What is functional classification based on?

The amount of mobility at an articulation.

What are the three structural classifications of joints?

Fibrous, cartilaginous, and synovial.

What are the three functional classifications of joints?

Synarthrosis, amphiarthrosis, and diarthrosis.

What is a synarthrosis?

An immobile or nearly immobile joint.

What is an amphiarthrosis?

A joint that allows limited movement.

What is a diarthrosis?

A freely movable joint.

What are examples of synarthroses?

Sutures, gomphoses, and synchondroses.

What are examples of amphiarthroses?

Symphyses and syndesmoses.

What type of functional joint are all synovial joints?

Diarthroses.

What is a uniaxial joint?

A joint that moves in a single plane.

What are examples of uniaxial joints?

Elbow and knee.

What is a biaxial joint?

A joint that moves in two planes.

What is an example of a biaxial joint?

Knuckle joint.

What is a multiaxial joint?

A joint that moves in three planes.

What are examples of multiaxial joints?

Shoulder and hip.

What connects bones in fibrous joints?

Fibrous connective tissue.

Do fibrous joints have a joint cavity?

No.

What are the three types of fibrous joints?

Sutures, syndesmoses, and gomphoses.

What is a suture?

A fibrous joint connecting bones of the skull.

What is a syndesmosis?

A fibrous joint connecting bones through ligaments or an interosseous membrane.

What is an example of a syndesmosis?

The interosseous membrane between the radius and ulna.

What is a gomphosis?

A fibrous joint anchoring a tooth in its socket.

What are fontanelles?

Broad areas of fibrous connective tissue between skull bones in newborns.

What connects bones in cartilaginous joints?

Hyaline cartilage or fibrocartilage.

What are the two types of cartilaginous joints?

Synchondroses and symphyses.

What is a synchondrosis?

A cartilaginous joint connected by hyaline cartilage.

What is an example of a synchondrosis?

The epiphyseal growth plate.

What is a symphysis?

A cartilaginous joint connected by fibrocartilage.

What are examples of symphyses?

The pubic symphysis and intervertebral discs.

What type of cartilage forms the epiphyseal plate?

Hyaline cartilage.

What type of cartilage forms an intervertebral disc?

Fibrocartilage.

What is the function of an intervertebral disc?

To connect adjacent vertebrae while allowing limited movement.

What structural feature distinguishes synovial joints?

A joint cavity containing synovial fluid.

What is the articular capsule?

The covering that surrounds and defines a synovial joint cavity.

What are the two layers of the articular capsule?

Outer fibrous layer and inner synovial membrane.

What tissue forms the outer fibrous layer?

Dense connective tissue.

What is the function of the synovial membrane?

To secrete synovial fluid.

What is synovial fluid?

A viscous, oily liquid found in synovial joint cavities.

What are the three functions of synovial fluid?

Lubrication, cartilage nourishment, and shock absorption.

What is the synovial cavity?

The fluid-filled space between bones in a synovial joint.

What is articular cartilage?

A thin layer of hyaline cartilage covering articulating bone surfaces.

What is the function of articular cartilage?

To reduce friction during joint movement.

What is a ligament?

Dense regular connective tissue connecting bone to bone.

What is the function of ligaments?

To stabilize joints and resist excessive movement.

What are intrinsic ligaments?

Ligaments fused to or part of the articular capsule.

What are extrinsic ligaments?

Ligaments located outside or superficial to the joint capsule.

What is a tendon?

Dense regular connective tissue attaching muscle to bone.

What is a bursa?

A fluid-filled sac that reduces friction around a joint.

What is the function of bursae?

To reduce friction between tendons, ligaments, muscles, skin, and bone.

What are menisci?

Discs of fibrocartilage that cushion joints.

Where are menisci found?

In the knee joint.

What is the function of menisci?

Cushioning and shock absorption.

What are the six types of synovial joints?

Pivot, hinge, saddle, plane, condyloid, and ball-and-socket.

What movement does a pivot joint allow?

Rotation around a single axis.

What is an example of a pivot joint?

The atlantoaxial joint between C1 and C2.

What movement does a hinge joint allow?

Flexion and extension.

What are examples of hinge joints?

Elbow, knee, ankle, and interphalangeal joints.

What movement does a saddle joint allow?

Flexion, extension, abduction, adduction, and circumduction.

What is an example of a saddle joint?

The first carpometacarpal joint of the thumb.

What movement does a plane joint allow?

Gliding and limited movements between bones.

What is an example of a plane joint?

The joints between tarsal bones.

What movement does a condyloid joint allow?

Flexion, extension, abduction, adduction, and circumduction.

What are examples of condyloid joints?

The radiocarpal wrist joint and knuckle joints.

What movement does a ball-and-socket joint allow?

Flexion, extension, abduction, adduction, circumduction, and rotation.

What are the two ball-and-socket joints in the body?

Shoulder and hip.

Which synovial joints are uniaxial?

Pivot and hinge.

Which synovial joints are biaxial?

Saddle and condyloid.

Which synovial joints are multiaxial?

Plane and ball-and-socket.

What is a sprain?

Stretching or tearing of ligaments caused by forcible twisting of a joint.

What is a dislocation?

When bones are forced out of their normal position within a joint.

What is bursitis?

Inflammation of a bursa.

What can cause bursitis?

Infection, trauma, or irritation.

What is arthritis?

Inflammation of a joint.

What is rheumatoid arthritis?

An autoimmune joint disease that can cause pain, inflammation, and joint immobilization.

What is osteoarthritis?

A degenerative joint disorder caused by aging or prolonged wear and tear.

What happens to cartilage in osteoarthritis?

Articular cartilage wears away, leaving rough and uneven joint surfaces.

What is flexion?

A movement that decreases the angle between bones.

What is extension?

A movement that increases the angle between bones.

What is hyperextension?

Extension beyond the normal anatomical position.

What is abduction?

Movement away from the body's midline.

What is adduction?

Movement toward the body's midline.

What is circumduction?

Circular movement combining flexion, adduction, extension, and abduction.

What is internal rotation?

Rotation of a limb toward the body's midline.

What is external rotation?

Rotation of a limb away from the body's midline.

What is supination?

Rotation of the forearm so the palm faces forward in anatomical position.

What is pronation?

Rotation of the forearm so the palm faces backward in anatomical position.

What happens to the radius and ulna during supination?

They are parallel.

What happens to the radius and ulna during pronation?

The radius crosses over the ulna.

What is dorsiflexion?

Movement that brings the top of the foot toward the leg.

What is plantar flexion?

Movement that points the toes downward or lifts the heel.

What is inversion?

Movement turning the sole of the foot toward the body's midline.

What is eversion?

Movement turning the sole of the foot away from the body's midline.

What is protraction?

Forward movement of a body part, such as the mandible.

What is retraction?

Backward movement of a body part, such as the mandible.

What is elevation?

Upward movement of a body part.

What is depression?

Downward movement of a body part.

What is opposition?

Movement bringing the thumb into contact with the fingertips of the same hand.

What is reposition?

Movement returning the thumb from opposition to its anatomical position.