The Rossolimo reflex is a plantar muscle reflex of the foot, which is triggered under pathologic conditions. It represents an uncertain pyramidal tract sign and indicates lesions in the pyramidal tract.
What is the rosolimo reflex?
The Rossolimo reflex is a plantar muscle reflex of the foot, which is triggered under pathologic conditions. The Rossolimo reflex is triggered by a blow to the plantar muscles of the foot and is characterized by flexion of the foot or toes toward the sole of the foot. It is a plantar muscle reflex that occurs under pathological conditions. In this case, it represents an uncertain pyramidal pathway sign. When this reflex occurs, there may be damage to the pyramidal tract. However, since the pyramidal tract is closely connected to the extrapyramidal system, there may also be disturbances at this site. The Rossolimo reflex was discovered by the Russian neurologist Grigorij Rossolimo (1860 to 1928). Together with the Piotrowski reflex and the dorsalis pedis reflex, it belongs to the plantar muscle reflexes. The plantar muscle reflexes in turn belong to the so-called pyramidal tract signs. Pyramidal tract signs are intrinsic reflexes and are considered neurological symptoms that occur due to damage to the pyramidal tract. Thus, there are specific pyramidal tract signs for the upper and lower extremities. The Rossolimo reflex is a lower extremity reflex. However, among the multitude of pyramidal tract signs of the lower extremities, the Babinski reflex possesses the greatest significance. The significance of the other reflexes, including the Rossolimo reflex, is controversial and rather low.
Function and task
The Rossolimo reflex, as mentioned earlier, is triggered under pathologic conditions and indicates lesions in the pyramidal system. The pyramidal system controls movement coordination in mammals. However, it is most important in higher primates and in humans. It is a collection of central motor neurons whose neural processes converge in the pyramidal tract. The pyramidal tract begins bilaterally at the inferior medulla oblongata with one cord each. Both strands cross 70 to 90 percent of the way between the afterbrain and the spinal cord. The remaining nerve fibers run in the anterior cord of the spinal cord and cross the anterior horn in sections. Some tracts do not cross. Through the crossing, nerve cords from the right side of the brain supply the left side of the body and vice versa. The pyramidal system is responsible for voluntary movements and mainly regulates fine motor skills. However, it works closely with the extrapyramidal system, which is most important in most mammals. Nerves of the pyramidal system never directly innervate specific muscles and muscle groups, but always convey their signals through the extrapyramidal system. Most pyramidal cells are small and also found outside the pyramidal system. Skeletal muscles are supplied by motor neurons (motoneurons). These are efferent neurons (neurons conducting from the brain to the muscles) responsible for voluntary and involuntary movements. The motor neurons are in turn divided into lower and upper motor neurons. Here, the abbreviation for the lower motor neurons is LMN and that for the upper motor neurons is UMN. Thus, the LMN represent the actual signal transducers for the muscles. The LMN can be considered the executive leg for all reflexes and movements. It belongs to the extrapyramidal system. The UMN is responsible for the conscious control of motor activity and belongs to the pyramidal system. Here, despite being outnumbered, Betz’s giant cells play the largest role. However, UMN never directly innervates the muscles or muscle groups. It relays the signals to the LMN, which gives the impulses for movement to the appropriate muscles. With lesions in the pyramidal tract, the extrapyramidal system can take over many functions, so the deficits do not appear large. The minor importance of the pyramidal system for most mammals means that damage here can be fully compensated. In humans, voluntary motor function is somewhat reduced in these cases, possibly manifested by limitations in fine motor function.
Diseases and complaints
The Rossolimo reflex gives an indication of possible motor limitations due to lesions in the pyramidal tract. However, it is an uncertain pyramidal tract sign.Its significance on its own is not very high. In connection with other pyramidal tract signs, it may have confirmatory character. The pyramidal system can be damaged, among other things, by a stroke. As a result of the pyramidal crossing, paralysis of the physical opposite side often occurs. However, the paralysis is usually not complete, because the extrapyramidal system takes over many tasks of the pyramidal tract. Nevertheless, so-called pyramidal tract signs occur, which are manifested by limitations in fine motor skills, co-movements of various muscle groups or general clumsiness. However, the cause of these symptoms can never be found solely in isolated damage to the pyramidal system. When such deficits occur, the extrapyramidal system is always affected as well. If the pyramidal pathway were affected exclusively, hardly any symptoms would occur, since most of the functions are taken over by the other parts of the nervous system. To what extent such minor disturbances of fine motor function can be detected by reflex examinations is questionable. In addition, the reflex arc of these reflexes is not known. Only in conjunction with examination of the natural intrinsic and extrinsic reflexes can a complete picture of the disorder be drawn with the aid of the pyramidal tract signs.
