Comprehensive Guide to Joints: Types, Movements, and Structures in Anatomy

Articulation

Site where two or more bones meet

Functions of joints

Give skeleton mobility and hold skeleton together

Functional classification of joints

Based on the amount of movement joint allows

Synarthroses

Immovable joints that can be fibrous or cartilaginous

Amphiarthroses

Slightly movable joints that can be fibrous or cartilaginous

Diarthroses

Freely movable joints that are all synovial joints

Structural classification of joints

Based on material binding bones together and presence/absence of joint cavity

Fibrous joints

Bones held together by dense connective tissue with no joint cavity

Cartilaginous joints

Bones joined by cartilage and lack joint cavity

Synovial joints

Bones joined by ligaments with fluid-filled joint cavity separating bone surface

Fibrous Joints: Sutures

Rigid, interlocking joints that are immovable for protection of the brain

Fibrous Joints: Syndesmoses

Bound by interosseous membrane, allowing little to no movement

Fibrous Joints: Gomphoses

Peg-in-socket joints of teeth in alveolar sockets

Cartilaginous Joints: Synchondroses

Bar/plate of hyaline cartilage unites bones and are all synarthrotic

Cartilaginous Joints: Symphyses

Pads of fibrocartilage between articulating bones that allow slight mobility

Synovial Joints: Six Distinguishing Features

Include articular cartilage, joint cavity, articular capsule, synovial fluid, ligaments, nerves, and blood vessels

Articular cartilage

Hyaline cartilage on bone surface at joint that prevents crushing of bone ends

Joint (synovial) cavity

Small, fluid-filled potential space lined by synovial membrane

Articular (joint) capsule

Outer fibrous layer that strengthens joints to prevent bones being pulled apart

Synovial fluid

Viscous, oily substance that lubricates articular cartilage on articulating surfaces, nourishes and removes wastes from articular cartilage's chondrocytes, contains phagocytic cells to remove microbes and debris, and acts as a shock absorber.

Capsular ligaments

Thickened part of fibrous layer that reinforces synovial joints.

Extracapsular ligaments

Ligaments located outside the capsule of a synovial joint.

Intracapsular ligaments

Ligaments that are deep to the capsule and covered by synovial membrane.

Nerve fibers in synovial joints

Detect pain, monitor joint position, and stretch.

Capillary beds in synovial joints

Supply filtrate for synovial fluid.

Fatty pads

Cushioning material located between the fibrous layer and synovial membrane or bone, acting as protective packing material in joint periphery.

Articular discs (menisci)

Fibrocartilage structures that separate articular surfaces to improve the fit of bone ends, stabilize the joint, and reduce wear and tear.

Bursae

Sacs lined with synovial membrane that contain synovial fluid, reducing friction where ligaments, muscles, skin, tendons, or bones rub together.

Tendon sheaths

Elongated bursae wrapped completely around tendons subjected to friction.

Stabilizing factors at synovial joints

Shapes of articular surfaces, ligament number and location, and muscle tendons that cross the joint.

Muscle tone

Keeps tendons taut and is extremely important in reinforcing shoulder and knee joints and arches of the foot.

Origin

Attachment point of a muscle to an immovable bone.

Insertion

Attachment point of a muscle to a movable bone.

Synovial joint movements

Movements occur along transverse, frontal, or sagittal planes.

Nonaxial movement

Slipping movements only, without rotation around an axis.

Uniaxial movement

Movement in one plane or axis.

Biaxial movement

Movement in two planes or axes.

Multiaxial movement

Movement in multiple planes or axes.

Plane joint

Articular surfaces are flat, allowing for limited side-to-side gliding movement in a single plane.

Hinge joint

Joint where a convex surface fits within a concave depression, allowing uniaxial movement like the hinge of a door.

Pivot joint

Joint where a bone with a rounded surface fits into a ligament ring, allowing uniaxial rotation on a longitudinal axis.

Condylar joint

Joint with an oval, convex surface articulating with a concave surface, allowing biaxial movement.

Saddle joint

Joint with convex and concave surfaces resembling a saddle shape, allowing biaxial movement.

Ball-and-socket joint

Joint where a spherical head of one bone fits into a cuplike socket, permitting multiaxial movement and is the most freely mobile type of joint.

Gliding movements

Two opposing surfaces sliding back-and-forth or side-to-side, allowing only limited movement in any direction.

Angular movements

Movements that increase or decrease the angle between two bones, including flexion, extension, hyperextension, lateral flexion, abduction, adduction, and circumduction.

Medial rotation

Turns anterior surface of bone medially

Lateral rotation

Turns anterior surface of bone laterally

Pronation

Medial rotation of forearm so palm of hand posterior

Supination

Lateral rotation of forearm so palm of hand anterior

Dorsiflexion

Talocrural (ankle) joint bent so the dorsum (superior surface) of foot moves toward the leg

Plantar flexion

Talocrural joint bent so dorsum pointed inferiorly

Eversion

Sole turns laterally at intertarsal joints of foot

Inversion

Sole turns medially at intertarsal joints of the foot

Protraction

Anterior movement from anatomic position

Retraction

Posterior movement from anatomic position

Depression

Inferior movement of a body part

Elevation

Superior movement of a body part

Opposition

Movement of thumb toward tips of fingers at carpometacarpal joint

Reposition

Opposite movement of opposition

Gliding joint

Joint allowing side-to-side (lateral excursion) grinding of teeth

Articular disc

Partitions joint into two parts forming two synovial cavities

Fibrocartilaginous glenoid labrum

Encircles socket of shoulder joint

Ulnar collateral ligament

Stabilizes medial side of the elbow joint

Radial collateral ligament

Stabilizes joint at lateral surface of elbow

Anular ligament

Surrounds the neck of the radius, binding head of the radius to the ulna

Iliofemoral ligament

Ligament providing support for anterior articular capsule of hip joint

Ischiofemoral ligament

Intracapsular ligament posteriorly located in hip joint

Pubofemoral ligament

Triangular thickening of capsule's inferior region in hip joint

Anterior cruciate ligament (ACL)

Prevents hyperextension and anterior displacement of tibia

Posterior cruciate ligament (PCL)

Prevents hyperflexion and posterior displacement of tibia

Femoropatellar joint

Plane joint

Allows gliding motion during knee flexion

Lateral and medial tibiofemoral joints

Femoral condyles with lateral and medial menisci of tibia

Allow flexion, extension, and some rotation when knee partly flexed

Quadriceps femoris muscle tendon

Passes over knee's anterior surface, surrounds patella

Patellar ligament

Extends from patella to tibial tuberosity

Fibular collateral ligament

Reinforces lateral surface of joint

Extends from femur to fibula

Prevents hyperadduction

Tibial collateral ligament

Reinforces medial surface of joint

Extends from femur to tibia

Prevents hyperabduction

Medial Meniscus and Lateral Meniscus

Deep to articular capsule within knee joint

C-shaped fibrocartilage pads on top of tibial condyles Cushioning between articular surfaces

Change shape to conform to articulating surfaces Partially stabilize joint medially and laterally