Motility corresponds in the broadest sense to the active ability to move. In medicine, the term refers primarily to the involuntary movements of peristalsis or is used to refer to the contractility of muscles, which in turn is associated with the integrity of the nervous system. In neurology, a failure of motility is referred to as akinesia.
What is motility?
In its extended meaning, motility is the ability to perform active movement processes. For example, in ophthalmology, motility refers to the ability of the eyes to move. In the extended meaning, motility is understood as the ability to perform active movement processes. This is to be distinguished from the property of mobility, which is considered to be the passive mobility of a person. Biology and medicine define the term motility more narrowly. In these disciplines, motility corresponds to the involuntary movement processes that take place in the body of every human being. These include, for example, the movements of the intestines, also known as peristalsis. When involuntary movement activity is decreased, we speak of hypomotility. When involuntary movement activity is excessive, the medical profession refers to it as hypermotility. What exactly the term motility refers to depends on the particular field of medicine. In ophthalmology, for example, motility refers to the ability of the eyes to move. The term can also be used when referring to motor function. In this context, the term usually refers to the ability of skeletal muscles to move.
Function and task
The term peristalsis is closely related to motility in its narrow definition. The movements of the intestine are among the involuntary movements and are controlled by an autonomic nervous system. Peristalsis corresponds to the muscular activity of the esophagus, intestines, and stomach. The urinary tract also has peristalsis. Propulsive peristalsis corresponds to annular constrictive smooth muscle contractions that occur involuntarily in a specific direction and serve to transport specific hollow organ contents. A large proportion of this type of peristalsis is characterized by the intrinsic rhythm of the smooth muscles, particularly in the stomach and ureter. The remaining part corresponds to locally occurring reflexes, which play an essential role especially in the intestine. The parasympathetic nervous system promotes peristalsis. The involuntary movements are inhibited by the sympathetic nervous system. Non-propulsive peristalsis, which also belongs to motility in the narrowest sense, must be distinguished from propulsive peristalsis. Non-propulsive peristalsis occurs exclusively in the intestine and serves to mix the ingested and digested food. Retrograde peristalsis is a transport movement in the opposite direction of propulsive peristalsis. It is also part of motility. Furthermore, motility includes reflex movements. In addition to self-reflexes, these can also be external reflexes. Reflective movements are always triggered by a specific stimulus, which causes the contraction of certain muscles or muscle groups via a reflex arc. A well-known reflex is, for example, the eyelid closure reflex, which corresponds to a protective reflex. The movement of the heart is also part of motility. The same applies to respiratory movements and contractions of vascular muscles, which are directly related to blood pressure and circulation. When we speak of motility in the extended meaning of the term, the expression refers predominantly to muscular activity and thus corresponds to the ability to actively contract muscles. This ability depends on intact innervation. Muscle contraction functions only when motor-conducting nerves connect the muscles to the central nervous system and all brain or spinal cord regions involved in movement are in an intact state.
Diseases and disorders
In the broadest sense, diseases or lesions of the central nervous system disrupt a person’s motility. In connection with disturbed motility by the nervous system, the physician distinguishes increased motility from decreased motility and complete absence of motility. The first phenomenon is called hyperkinesis. Decreased motility is called hypokinesia and lack of motility by the nervous system is known as akinesia. Hyperkinesis occurs whenever the inhibitory mechanisms in the central nervous system are disturbed.These mechanisms are part of movement control. Damage or failure of the inhibitory regions no longer allows sufficient control of movement impulses. Involuntary movements such as tics develop. These movements occur in athetotic or choreatic variants. In most cases, the symptoms are accompanied by a reduction or at least fluctuation of muscle tone. Especially lesions in the extrapyramidal motor system can disturb movement control. These lesions may be preceded by an accident. However, they may also be associated with infections, inflammatory diseases of the central nervous system, degeneration, or compression due to tumor disease. Affective psychoses can also promote hyperkinesis. The same applies to medications such as psychotropic drugs. In contrast, a lack of movement in the sense of hypokinesia is a leading symptom of Parkinson’s disease and also results from disturbances in the extrapyramidal system. Akinesia is the complete inability to move, which is also due to the extrapyramidal system. Unlike hypo- and hyperkinesis, mental illnesses such as schizophrenia or psychosis are unlikely to be the cause of akinesia. In cardiology, the term akinesia is sometimes used in echocardiography when a portion of the heart wall is scarred after damage to the heart. The term hypokinesia may also be used in cardiology. In this case, the term refers to a pathological reduction in cardiac wall motility as seen on ultrasound. In the phenomenon, on the one hand, movements of the heart walls occur less frequently and, on the other hand, at a slower rate. This phenomenon is also considered a late consequence of cardiac injury caused by myocardial infarction or coronary artery disease.
