Chapter 8: Joints & Movements

Structural classification of joints

Classification based on the type of connective tissue that joins the bones.

Fibrous joints

Joints connected by fibrous connective tissue with little or no movement.

Sutures

Fibrous joints where skull bones interlock.

Sutural ligament

Fibrous connective tissue between the periosteum of adjacent bones in a suture.

Fontanels

Membranous areas between fetal skull bones that allow the head to change shape during birth and accommodate brain growth.

Syndesmoses

Fibrous joints where bones are connected by strong ligaments or membranes.

Interosseous membrane

A strong connective tissue membrane linking adjacent bones.

Gomphoses

Peg-in-socket joints that hold teeth in their sockets.

Periodontal ligaments

Connective tissues that hold teeth in place.

Gingivitis

Inflammation of the gums that can lead to periodontal disease.

Cartilaginous joints

Joints where bones are connected by cartilage.

Synchondroses

Cartilaginous joints joined by hyaline cartilage, allowing little or no movement.

Symphyses

Cartilaginous joints joined by fibrocartilage that allow slight movement.

Hyaline cartilage

Smooth cartilage found in synchondroses and covering the surfaces of synovial joints.

Fibrocartilage

Strong cartilage found in symphyses and menisci.

Synovial joints

Freely movable joints containing synovial fluid.

Articular cartilage

Hyaline cartilage covering the ends of bones in synovial joints.

Joint cavity

The space between articulating surfaces that contains synovial fluid.

Fibrous capsule

The dense outer layer of a synovial joint capsule that helps stabilize the joint.

Synovial membrane

The membrane lining the inside of the joint capsule that produces synovial fluid.

Synovial fluid

A slippery fluid that lubricates joints and supplies nutrients to articular cartilage.

Hyaluronic acid

A substance in synovial fluid that makes it slippery.

Bursae

Fluid-filled sacs that reduce friction around joints.

Bursitis

Inflammation of a bursa.

Menisci

Fibrocartilage pads in the knee that deepen the joint surface.

Tendon sheaths

Synovial sacs that surround tendons where they pass near or over bones.

Uniaxial joints

Joints that move around one axis.

Biaxial joints

Joints that move around two axes at right angles.

Multiaxial joints

Joints that move around several axes.

Plane joints

Gliding joints where relatively flat bone surfaces slide past each other.

Saddle joints

Biaxial joints with surfaces shaped like a saddle.

Hinge joints

Uniaxial joints that mainly allow bending and straightening.

Pivot joints

Uniaxial joints that allow a bone to rotate around a single axis.

Ball-and-socket joints

Multiaxial joints that allow movement in several directions.

Ellipsoid joints

Biaxial joints with oval-shaped articular surfaces.

Gliding movement

Movement in which flat bone surfaces slide past one another.

Angular movement

Movement that changes the angle between bones at a joint.

Rotational movement

Movement in which a bone turns around its longitudinal axis.

Flexion

Movement that bends a joint and decreases the angle between body parts.

Extension

Movement that straightens a joint and increases the angle between body parts.

Hyperextension

Extension of a joint beyond the anatomical position.

Dorsiflexion

Lifting the foot toward the shin.

Plantar flexion

Pointing the foot downward, as when standing on the toes.

Abduction

Movement away from the body's median plane.

Adduction

Movement toward the body's median plane.

Medial rotation

Turning a bone toward the body's midline.

Lateral rotation

Turning a bone away from the body's midline.

Pronation

Rotation of the forearm so the palm faces posteriorly.

Supination

Rotation of the forearm so the palm faces anteriorly.

Circumduction

Circular movement combining flexion, extension, abduction and adduction.

Elevation

Moving a body structure upward.

Depression

Moving a body structure downward.

Protraction

Moving a structure forward.

Retraction

Moving a structure backward toward or beyond its anatomical position.

Excursion

Side-to-side movement of the mandible.

Opposition

Movement of the thumb toward the little finger.

Reposition

Returning the thumb to its anatomical position after opposition.

Inversion

Turning the sole of the foot inward.

Eversion

Turning the sole of the foot outward.

Temporomandibular joint (TMJ)

A joint that combines plane and ellipsoid movements to allow jaw opening, closing and side-to-side motion.

Fibrocartilage disk

A cartilage disk in the TMJ that divides the joint into upper and lower cavities.

Glenohumeral joint

The shoulder's ball-and-socket joint, which allows a wide range of movement.

Rotator cuff

A group of four muscles and their tendons that help stabilize the shoulder joint.

Humeroulnar joint

The elbow articulation between the ulna and humerus.

Humeroradial joint

The elbow articulation between the radius and humerus.

Ulnar collateral ligament

A ligament that helps stabilize the inner side of the elbow.

Radial collateral ligament

A ligament that helps stabilize the outer side of the elbow.

Radial annular ligament

A ligament that holds the head of the radius in place.

Coxal joint

The hip joint where the head of the femur fits into the acetabulum.

Acetabulum

The socket in the hip bone that receives the head of the femur.

Iliofemoral ligament

A strong hip ligament that helps support body weight while standing.

Ligament of the head of the femur

A hip ligament that may carry an artery supplying nutrients to the femoral head.

Cruciate ligaments

Knee ligaments that cross between the tibia and femur to stabilize the joint.

Anterior cruciate ligament (ACL)

A knee ligament that prevents the tibia from moving too far forward.

Posterior cruciate ligament (PCL)

A knee ligament that prevents the tibia from moving too far backward.

Collateral ligaments of the knee

Ligaments that strengthen the sides of the knee joint.

Popliteal ligaments

Ligaments that help strengthen and stabilize the knee joint.

Water on the knee

A buildup of fluid in or around the knee joint.

Holy trinity of knee injury

A combined injury involving the lateral collateral ligament, ACL and medial meniscus after a lateral blow.

Talocrural joint

The ankle joint, which mainly allows dorsiflexion and plantar flexion.

Ligaments of the foot arch

Ligaments that maintain the proper position of foot bones and help transfer weight.

Ankle sprain

An injury involving stretched or torn ankle ligaments, commonly caused by the foot turning inward.

Range of motion (ROM)

The extent to which a joint can move.

Effects of aging on joints

Aging can reduce cartilage quality, synovial fluid production, tissue repair, flexibility and range of motion.