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motion sickness discomfort felt by some people on a moving boat, train, airplane, or automobile, or even on an elevator or a swing. The discomfort is caused by irregular and abnormal motion that disturbs the organs of balance located in the inner ear. There may be mild symptoms of nausea, dizziness, or headache, as well as pallor and cold perspiration. In more acute cases, there may be vomiting and sometimes prostration. Though most people quickly adapt to travel by airplane, ship, and automobile, few are wholly immune to motion sickness. Even astronauts become ill if the inner ear organs of balance are continuously stimulated by unusual motion. Fortunately, most cases of motion sickness vanish quickly once the journey is over, leaving no ill effects.
Causes. The inner ear possesses three semicircular canals, located at right angles in three different planes. People are accustomed to movement in the horizontal plane, which stimulates certain semicircular canals, but not to vertical movements such as the motion of an elevator or a ship pitching at sea. These vertical movements stimulate the semicircular canals in an unusual way, producing the sensation of nausea, or motion sickness.

Anxiety, grief, or other emotions can also cause motion sickness. A person unaccustomed to traveling by boat or airplane may be apprehensive or nervous and therefore may develop symptoms of nausea. Some individuals with previous experience of motion sickness become ill on a boat at dock or on an airplane prior to take-off.

Airsickness usually occurs during a bumpy flight caused by stormy weather or turbulent air. However, it may also be triggered by poorly ventilated cabins, hunger, digestive upset, overindulgence in food and drink, and unpleasant odors, particularly tobacco smoke.
Treatment. Certain antihistamines have proved highly effective in treating symptoms of seasickness. Like depressants, they may be used alone or in combination with mild sedatives. Those who suffer from motion sickness should ask their health care provider for advice before they embark on a trip. Symptoms may also be reduced if the seasick person rests lying down, with the head low, in a comfortable, well aired place.
Prevention. Being rested and in good health prior to a journey helps to prevent motion sickness. During a voyage by boat, it is advisable for the passenger to remain near the center of the ship, where there will be the least motion. Ample fresh air and exercise and avoidance of stuffy rooms and disagreeable smells are also good precautions. The traveler should keep comfortably warm and avoid overeating and eating rich foods.

For those traveling by air, adequate hydration and small, easily digested meals taken during the flight help to prevent airsickness. The passenger who experiences motion sickness may benefit from reclining in the seat as far as possible and closing the eyes.

Carsickness is often relieved if the journey is interrupted for short walks in the fresh air and by keeping a window open. Children will frequently find it helpful to glance down, and to refrain from reading. Tobacco smoke can also be an aggravating factor.


1. A change of place or position. Compare: movement (1).
2. Synonym(s): defecation
3. Synonym(s): stool
[L. motio, movement, fr. moveo, pp. motus, to move]


Medtalk Movement. See Closed chain motion, Foot motion, Quality of motion, Range of motion, Triplane motion.


change in position of an object or body. linear motion motion which takes place in straight lines (rectilinear) or curves (curvilinear), but note that this does not apply to rotation. general motion motion which includes translation and rotation. See also Newton's laws of motion.


n movement
motion barrier,
n any limitation to motion.
motion of the spine, physiologic,
n principles of thoracic motion that detail movements of the vertebrae in relationship to that of the vertebral column as a whole. When the spine is in a neutral position, coupled side-bending and rotation motions for a group of vertebrae happen in different directions. When the spine is bent backward or forward, these motions happen in the same direction.
motion, accessory joint,
n See motion, secondary joint.
motion, bucket handle rib,
n the head-ward movement of the lateral sides of the ribs during respiration; occurs mainly in the lower ribs. See also axis, anteroposterior rib axis, and axis of rib motion.
motion, caliper rib,
n motion of ribs 11 and 12; characterized by moving as a single joint.
motion, iliosacral,
n motion of the ilium through the sacrum along an inferior transverse axis, influenced by the movements of the pelvis, hips, and lower extremities, as in walking.
motion, inherent,
n the spontaneous motion that characterizes all cells, tissues, etc. in the body.
motion, intersegmental,
n the relative motion between two adjacent vertebrae, with the upper vertebra in the pair described as moving upon the lower vertebra.
motion, passive,
n motion induced by the therapist or physician while the patient relaxes and exerts no effort.
motion, physiologic,
n any change in the position, within a normal range, of anatomic structures.
motion, pump handle rib,
n the head-ward movement of the anterior part of the ribs during respiration; occurs mainly in the upper ribs. See also axis of rib motion.
motion, range of,
n the movement available to a joint. Full range of motion can be restricted by shortened muscles, connective tissue injuries, scar tissue or adhesions, pain, and other conditions. Also called
motion, secondary joint,
n passive or involuntary joint motion. Also called
accessory joint motion.
motion, segmental,
n movement between two adjacent vertebrae; described through displacing a point at the upper front aspect of the superior vertebra.
motion, translatory,
n movement of a body part along an axis.


1. A change of place or position.
Compare: movement (1)
2. Synonym(s): defecation.
3. Synonym(s): stool.
[L. motio, movement, fr. moveo, pp. motus, to move]


n envelope of the three-dimensional space circumscribed by border movements and by occlusal contacts of a given point of the mandible. Also called
movement space. See also movement, border, posterior.

Patient discussion about motion

Q. How do I gain range of motion after shoulder surgery I'm 31 years old and had a shoulder replacment last year. I still don't know why my joint gave out and 4 Orthopedic Surgeons couldn't tell me either. I have limited Range of Motion and the Dr. seems to think that because of my "age" I was less likley to get full range back. I refuse to believe that, does anyone have any suggestions on how to gain ROM back?

A. i guess you go to physiotherapy no?
that is their job. to give you range of motion after injuries, surgeries ect. they'll give you exercises specially for your condition. when i had an accident i broke my leg hip and i needed 2 months of physiotherapy that helped very much.

Q. why when we drink alcohol everything seems funnier and things moves as in slow motion? how does it effect the brain and the nerve system ?

A. Donot drink an drive,Like i have said before it is your body trying to get your attention(its telling you that it cant work right with alcohol in it.drinking may seem fun now but it can turn into a nightmare,an you can loose your life,or it can become a living hell for you and the people close to you--THINK BEFORE YOU DRINK---mrfoot56

More discussions about motion
References in periodicals archive ?
In addition the elastomeric properties of the disc ensure dynamic load transfer and physiological motion between segments with the prospect consequently of reducing the risk of adjacent segment disease and facet joint degeneration.
This ball and trough configuration is designed to help provide for replication of normal physiological motion.
The revolutionary integrated nucleus-annulus-endplate design of CAdisc, and PPM process technology, combine to produce physiological motion, biomechanical function and durability characteristics which closely resemble those of the natural spinal disc.

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