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Opposition is the thumb movement that brings the tip of the thumb in contact with the tip of a finger. This movement is produced at the first carpometacarpal joint, which is a saddle joint formed between the trapezium carpal bone and the first metacarpal bone. Thumb opposition is produced by a combination of flexion and abduction of the thumb at this joint. Returning the thumb to its anatomical position next to the index finger is called reposition (see [link] l ).
| Movements of the Joints | ||
|---|---|---|
| Type of Joint | Movement | Example |
| Pivot | Uniaxial joint; allows rotational movement | Atlantoaxial joint (C1–C2 vertebrae articulation); proximal radioulnar joint |
| Hinge | Uniaxial joint; allows flexion/extension movements | Knee; elbow; ankle; interphalangeal joints of fingers and toes |
| Condyloid | Biaxial joint; allows flexion/extension, abduction/adduction, and circumduction movements | Metacarpophalangeal (knuckle) joints of fingers; radiocarpal joint of wrist; metatarsophalangeal joints for toes |
| Saddle | Biaxial joint; allows flexion/extension, abduction/adduction, and circumduction movements | First carpometacarpal joint of the thumb; sternoclavicular joint |
| Plane | Multiaxial joint; allows inversion and eversion of foot, or flexion, extension, and lateral flexion of the vertebral column | Intertarsal joints of foot; superior-inferior articular process articulations between vertebrae |
| Ball-and-socket | Multiaxial joint; allows flexion/extension, abduction/adduction, circumduction, and medial/lateral rotation movements | Shoulder and hip joints |
The variety of movements provided by the different types of synovial joints allows for a large range of body motions and gives you tremendous mobility. These movements allow you to flex or extend your body or limbs, medially rotate and adduct your arms and flex your elbows to hold a heavy object against your chest, raise your arms above your head, rotate or shake your head, and bend to touch the toes (with or without bending your knees).
Each of the different structural types of synovial joints also allow for specific motions. The atlantoaxial pivot joint provides side-to-side rotation of the head, while the proximal radioulnar articulation allows for rotation of the radius during pronation and supination of the forearm. Hinge joints, such as at the knee and elbow, allow only for flexion and extension. Similarly, the hinge joint of the ankle only allows for dorsiflexion and plantar flexion of the foot.
Condyloid and saddle joints are biaxial. These allow for flexion and extension, and abduction and adduction. The sequential combination of flexion, adduction, extension, and abduction produces circumduction. Multiaxial plane joints provide for only small motions, but these can add together over several adjacent joints to produce body movement, such as inversion and eversion of the foot. Similarly, plane joints allow for flexion, extension, and lateral flexion movements of the vertebral column. The multiaxial ball and socket joints allow for flexion-extension, abduction-adduction, and circumduction. In addition, these also allow for medial (internal) and lateral (external) rotation. Ball-and-socket joints have the greatest range of motion of all synovial joints.
Watch this video to learn about anatomical motions. What motions involve increasing or decreasing the angle of the foot at the ankle?
Dorsiflexion of the foot at the ankle decreases the angle of the ankle joint, while plantar flexion increases the angle of the ankle joint.
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