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The movement of body structures is accomplished by the contraction of muscles. Muscles may move parts of the skeleton relatively to each other, or may move parts of internal organs relatively to each other. All such movements are classified by the directions in which the affected structures are moved. In human anatomy, all descriptions of position and movement are based on the assumption that the body is in anatomical position.
The prefix hyper- is sometimes added to emphasize movement beyond the normal position, such as in hyperflexion or hyperextension. Such movements can put significant stress on the joints involved. See: Medical terminology
All motions are considered to be a mixture of or a single contribution by the following types of movement.
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General motion
Adjusting angle between two parts
Flexion - Bending movement that decreases the angle between two parts. Bending the elbow, or clenching a hand into a fist, are examples of flexion. When sitting down, the knees are flexed. Flexion of the hip or shoulder moves the limb forward (towards the anterior side of the body).
Extension - The opposite of flexion; a straightening movement that increases the angle between body parts. In a conventional handshake, the fingers are fully extended. When standing up, the knees are extended. Extension of the hip or shoulder moves the limb backward (towards the posterior side of the body).
Hyperextension - Movement of a body part beyond the normal range of motion, such as the position of the head when looking upwards into the sky.
Adjusting relation to midline of body
Abduction - A motion that pulls a structure or part away from the midline of the body (or, in the case of fingers and toes, spreading the digits apart, away from the centerline of the hand or foot). Abduction of the wrist is called radial deviation. Raising the arms laterally, to the sides, is an example of abduction.
Adduction - A motion that pulls a structure or part towards the midline of the body, or towards the midline of a limb. Dropping the arms to the sides, or bringing the knees together, are examples of adduction. In the case of the fingers or toes, adduction is closing the digits together. Adduction of the wrist is called ulnar deviation.
Elevation - Movement in a superior direction. This term is often applied to the shoulders (e.g. shrugging shoulders is elevation, and dropping them to a normal condition would be depression).
Depression - Movement in an inferior direction, the opposite of elevation.
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Special motions of the hands and feet
sides of the hands and feet
The palm (adj palmar) of the hand corresponds to the sole (adj plantar) of the foot. The term volar, used mainly in orthopaedics, is synonymous with palmar and plantar.
The dorsum (back) of the hand corresponds to the dorsum (top) of the foot.
Pronation - A rotation of the forearm that moves the palm from an anterior-facing position to a posterior-facing position, or palm facing down. This is not medial rotation as this must be performed when the arm is half flexed. (See also Pronator quadratus and Pronator teres muscle.)
Supination - The opposite of pronation, the rotation of the forearm so that the palm faces anteriorly, or palm facing up. The hand is supine (facing anteriorly) in the anatomical position. (See also Supinator muscle.)
flexion of the entire foot
Dorsiflexion - flexion of the entire foot superiorly, or upwards as when decelerating in an automobile.
Plantarflexion - Flexion of the entire foot inferiorly, or downwards as when accelerating in an automobile.
movement of the sole of the foot
Eversion - the movement of the sole of the foot away from the median plane.
Inversion - the movement of the sole towards the median plane (same as when an ankle is twisted).
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Other special motions
anterior/posterior movement
Protrusion - The anterior movement of an object. This term is often applied to the jaw.
Retrusion - The opposite of protrusion, moving a part posteriorly.
Protraction - Anterior movement of the arms at the shoulders.
Retraction - Posterior movement of the arms at the shoulders.
Rotation - A motion that occurs when a part turns on its axis. The head rotates on the neck, as in shaking the head no.
Circumduction - The circular (or, more precisely, conical) movement of a body part, such as a ball-and-socket joint or the eye. It consists of a combination of flexion, extension, adduction, and abduction. "Windmilling" the arms or rotating the hand from the wrist are examples of circumductive movement.
anterograde motion is in the normal direction of flow. (For example, passage of food from the mouth to the stomach.)
Opposition - A motion involving a grasping motion of the thumb and fingers.
Reposition - To release an object by spreading the fingers and thumb.
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See also
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