The defeat of any part of the pyramidal path causes a violation of arbitrary movements, which can be complete or partial. Complete loss of voluntary movements is called paralysis, or plegia, partial-paresis.
Paralysis can be central or peripheral. Central paralysis develops as a result of damage to the pyramidal pathway throughout the central motor neuron in any area: in the motor cortex, in the inner capsule, in the brain stem or in the spinal cord. Central paralysis has characteristic symptoms, such as muscle hypertension, hyperreflexia, expansion of the reflexogenic zone, clonuses of the feet, kneecaps and hands, pathological reflexes, protective reflexes and pathological synkinesia. Muscle hypertension is characterized by an increase in the tone of the flexors of the arm and the extensors of the leg on one side. The Wernicke—Mann pose is formed. It consists in bringing and bending the arm, while the leg is stretched out. Pathological reflexes can be hand and foot, which are divided into flexor and extensor.
Peripheral paralysis develops as a result of damage to any part of the peripheral motor neuron: large alpha-motor neurons, cells of the motor nuclei of the brain stem, the anterior spine of the spinal cord, the nerve plexus, peripheral nerves. Peripheral paralysis is characterized by the following symptoms: areflexia, muscle atony, atrophy, degeneration reaction, fibrillar or fascicular muscle twitching.
The symptom complex of motor disorders depends on the level of damage to the pyramidal pathway. When the peripheral nerve is affected, atrophy of the muscle group that is activated by this nerve is noted, reflexes fall out. There are pains, sensitivity disorders and vegetative disorders. Damage to the anterior roots of the spinal cord causes peripheral paralysis of the muscles receiving innervation from this root, and fascicular twitching. When the anterior horns are affected, peripheral paralysis develops in the innervation zone of this segment of the spinal cord.
Fibrillar muscle twitching, atrophy and degeneration reactions are characteristic. The lesion of the lateral cord causes central paralysis of the muscles below the level of the lesion. Injuries to the horse’s tail lead to peripheral paralysis of the legs, impaired urination, sensitivity disorder in the perineum, sharp pains appear. A lesion at the level of the lumbar thickening causes flaccid paralysis and anesthesia of the lower extremities; a lesion of the thoracic region causes spastic paralysis of the legs, a violation of the sensitivity of all types of conductor type; the defeat of the cervical thickening is a central paralysis of the legs and a violation of the sensitivity of the conductor type. A lesion in the area of the intersection causes paralysis of the lower limb on the opposite side, the upper one on the same side. Damage to the brain stem leads to a central hemiplegia on the opposite side. Damage to the anterior central gyrus leads to monoparesis.