Anatomy of Joints and Bones: Structural, Functional, and Key Features
Joint
A point where two bones meet; allows for movement and stability.
Hinge Joint
Allows flexion and extension (e.g., elbow, knee).
Condylar Joint
Allows flexion, extension, abduction, and adduction (e.g., wrist).
Plane Joint
Allows gliding (e.g., between carpals/tarsals).
Saddle Joint
Allows movement in two planes (e.g., thumb joint).
Pivot Joint
Allows rotation (e.g., atlas-axis, proximal radioulnar joint).
Iliofemoral Ligament
Anterior hip; prevents hyperextension during standing.
Pubofemoral Ligament
Anteroinferior hip; limits excessive abduction and extension.
Annular Ligament
Around head of radius; holds radius in place and allows pronation/supination.
Structural Classification of Joints
Based on material joining bones (fibrous, cartilaginous, synovial).
Functional Classification of Joints
Based on movement allowed (synarthrosis, amphiarthrosis, diarthrosis).
Patellar Ligament
Below patella; transmits quadriceps force for knee extension.
Short Plantar Ligament
Beneath long plantar; supports midfoot stability.
Medial and Lateral Menisci
Between femur and tibia; absorb shock and stabilize knee.
Syndesmoses
Between long bones (e.g., tibia and fibula); slightly movable.
Sutures
Between skull bones; immovable joints that protect the brain.
Gomphoses
Between teeth and jaw sockets; immovable.
Cartilaginous Joints
Bones joined by cartilage; limited movement.
Fibrous Joints
Bones joined by dense connective tissue; allow little or no movement.
Synovial Joints
Freely movable joints separated by a joint cavity filled with synovial fluid.
Diarthrosis
Freely movable synovial joint.
Anterior Longitudinal Ligament
Front of vertebral bodies; prevents hyperextension of the spine.
Coracoacromial Ligament
Shoulder; forms arch above humeral head and prevents superior dislocation.
Acromioclavicular Ligament
Shoulder; reinforces AC joint and prevents separation.
Conoid and Trapezoid Ligaments (Coracoclavicular)
Shoulder; stabilize clavicle and prevent AC separation.
Coracohumeral Ligament
Shoulder; supports superior capsule and prevents downward displacement of humerus.
Symphyses
Slightly movable fibrocartilaginous joints (e.g., pubic symphysis, intervertebral discs).
Amphiarthrosis
Slightly movable joint.
Long Plantar Ligament
Sole of foot; supports longitudinal arch.
Ball-and-Socket Joint
Multiaxial; allows greatest range of motion (e.g., shoulder, hip).
Ischiofemoral Ligament
Posterior hip; limits internal rotation and extension.
Ulnar Collateral Ligament
Medial elbow; prevents valgus (outward) stress.
Tibial (Medial) Collateral Ligament
Medial knee; prevents valgus (outward) stress.
Synarthrosis
Immovable joint.
Synchondroses
Immovable joints made of hyaline cartilage (e.g., epiphyseal plates).
Ligament of the Head of the Femur
Inside hip joint; supplies blood to femoral head.
Anterior Cruciate Ligament (ACL)
Inside knee; prevents anterior tibial displacement.
Posterior Cruciate Ligament (PCL)
Inside knee; prevents posterior tibial displacement.
Posterior Longitudinal Ligament
Inside vertebral canal; prevents hyperflexion and disc herniation.
Posterior Meniscofemoral Ligament
Knee; stabilizes posterior knee joint.
Posterior Talofibular Ligament (PTF)
Lateral ankle; limits dorsiflexion and inversion.
Anterior Talofibular Ligament (ATF)
Lateral ankle; limits plantarflexion and inversion; commonly injured.
Calcaneofibular Ligament
Lateral ankle; prevents inversion.
Radial Collateral Ligament
Lateral elbow; prevents varus (inward) stress.
Fibular (Lateral) Collateral Ligament
Lateral knee; prevents varus (inward) stress.
Deltoid Ligament
Medial ankle; prevents eversion and stabilizes ankle.
Spring (Plantar Calcaneonavicular) Ligament
Medial arch; supports arch and restores shape after stretch.
