Anatomy of Joints: Types, Structures, and Disorders

Joint

A place where two or more bones meet.

Fibrous joint

Joints connected by dense regular connective tissue with no joint cavity; most are immovable.

Suture

Rigid, interlocking fibrous joints found in the skull; ossify and fuse in middle age.

Gomphoses

Peg-in-socket fibrous joints like teeth in alveolar sockets connected by periodontal ligament.

Syndesmoses

Fibrous joints where bones are connected by ligaments; movement depends on fiber length.

Inferior tibiofibular joint

A syndesmosis with short fibers allowing little to no movement.

Interosseous membrane between radius and ulna

A syndesmosis with longer fibers allowing more movement.

Cartilaginous joint

Joints where bones are united by cartilage; no joint cavity and not highly movable.

Synchondroses

Cartilaginous joints where bones are united by hyaline cartilage; e.g., epiphyseal plates, 1st rib with sternum.

Symphyses

Cartilaginous joints united by fibrocartilage; strong, slightly movable joints like pubic symphysis and intervertebral discs.

Synovial joint

A freely movable joint with bones separated by a fluid-filled joint cavity; most limb joints.

Articular cartilage

Covers the ends of bones in synovial joints; absorbs compressive forces.

Joint (synovial) cavity

A fluid-filled space that separates the articulating bones in a synovial joint.

Articular capsule

Two-layered capsule surrounding synovial joints; outer fibrous layer and inner synovial membrane.

Synovial fluid

Viscous fluid in synovial joints that lubricates and reduces friction.

Reinforcing ligaments

Ligaments that strengthen synovial joints: capsular, extracapsular, and intracapsular.

Tendon

Connects muscle to bone.

Ligament

Connects one bone to another.

Bursae

Fluid-filled sacs that reduce friction in joints.

Tendon sheath

An elongated bursa that wraps around a tendon.

Monaxial joint

A joint that moves in one plane.

Biaxial joint

A joint that moves in two planes.

Multiaxial joint

A joint that moves in three planes.

Ball-and-socket joint

Multiaxial synovial joints like the shoulder and hip; round head fits into cuplike depression.

Condylar joint

Biaxial joints allowing flexion/extension and abduction/adduction; e.g., occipital bone and atlas.

Saddle joint

Biaxial joints with saddle-shaped articular surfaces; e.g., trapeziometacarpal, sternoclavicular joints.

Plane joint

Nonaxial joints with flat surfaces allowing sliding movements; e.g., carpals, tarsals, vertebral processes.

Hinge joint

Monaxial joints like elbows, knees, and interphalangeal joints; act like a door hinge.

Pivot joint

Monaxial joints where one bone rotates within a ring; e.g., atlantoaxial and radioulnar joints.

Sprain

A condition where reinforcing ligaments are stretched or torn.

Common sprain sites

Ankle, knee, and lumbar region of the back.

Sprain healing

Difficult due to poor blood supply; treated by sewing, grafts, or immobilization.

Arthritis

Inflammatory joint disorder with pain, stiffness, and swelling; over 100 types.

Acute arthritis

Caused by bacteria; treatable with antibiotics.

Chronic arthritis

Includes osteoarthritis, rheumatoid arthritis, and gouty arthritis.