Carlos Ballario, Dra. Ma. Eugenia Ferri

Movement is a complex function, governed by various layers of the nervous system. Academically, motility has been divided into two large groups: kinetic and static motility. The first, by means of clonic muscular contractions, determines the displacement of one or more body segments; while static motility is the one that, once the movement is finished, maintains the body segment in that attitude. In turn, within kinetic motility we can differentiate two categories of movement: voluntary and involuntary. In voluntary movements, the will is always compromised and there is a prior mental representation of the movement that is carried out. Involuntary motility includes reflex movements,


We cannot understand motility disorders if we do not have a clear understanding of the pathways involved in the execution of the movement, in its different expressions.

The prefrontal cortex participates in the planning and initiation of voluntary movements. Its fibers project to the supplemental and premotor motor areas that participate in the programming. In the motor area, the motor neurons of the frontal cortex and its axons are connected to the spinal or spinal motor neurons through the corticospinal bundle and are called superior motor neurons. The motor neurons of the anterior horns of the spinal cord as well as the motor nuclei of the brain stem project their axons constituting the anterior spinal or spinal roots, the spinal nerves and the cranial nerves and innervate the skeletal muscles. These nerve cells and their axons make up the lower motor neurons. There are a series of brainstem nuclei projecting into the medulla such as the retinal pontine and bulbar nuclei, the vestibular nuclei, and the red nuclei. These structures participate in bipediation, and automated and repetitive movements. There are also two subcortical systems, the base ganglia and the cerebellum. The gangliobasal system is made up of the striatum, the pale globe, the substantia nigra and the sub-thalamic nucleus. Between unthem they control muscle tone, posture and coordination. the pale globe, substantia nigra and sub thalamic nucleus. Between them they control muscle tone, posture and coordination. the pale globe, substantia nigra and sub thalamic nucleus. Between them they control muscle tone, posture and coordination.

Knowing this organization we will understand the disorders derived from the involvement of each level:

  1. Apraxic disorders if the lesion is located in the association areas of the brain.
  2. Paralysis caused by compromised upper motor neurons
  3. Paralysis caused by injury to the lower motor neurons
  4. Involuntary movements and abnormal posture due to basal ganglia disease
  5. Coordination abnormalities due to involvement of the cerebellum


The complete assessment of motility includes:

  1. active motility and strength test
  2. assessment of muscle tone
  3. osteotendinous reflexes
  4. coordination
  5. presence of involuntary movements

For the first item, we can make an assessment by muscle group or globally. In the first case, we ask the patient to make a movement with the muscle group to be evaluated and we oppose our strength to it, for example: to evaluate the strength of the hand, they are asked to bring the fingers together and separate them, flex and extend them , that opposes the thumb to the other fingers etc. In this way both motility and strength are valued during the opposition. It is convenient to carry out the exploration successively from one side of the body to the other to establish a clear comparison. To detect weakness or paresis of the limbs, there are maneuvers such as Mingazzini's that can be applied to both the upper and lower limbs. The patient is instructed to extend their arms horizontally. Next, you are asked to close your eyes. If there is paresis, the limb falls or, depending on the degree of weakness, it can tend to flex. For the lower limbs, the flexion of the thighs is ordered at a right angle over the pelvis and the legs at a right angle on the thighs. It is considered positive if the member descends. The Barré maneuver consists of placing the patient in the ventral decubitus position with the legs flexed at right angles to the thighs and keeping them there. The tone is evaluated by inspection, where the limb attitude is established and if the muscle masses have a pronounced relief (hypertonia) or absent (hypotonia). Subsequently, the limb is passively mobilized and the degree of resistance or, on the contrary, the excess of amplitude will be observed in carrying out the same, as appropriate. Regarding the exploration of the reflexes, the absence or presence of the reflexes and the magnitude of the response will be assessed in order to define hypo or hyperreflexia. Coordination should be evaluated both statically and dynamically and lastly carefully inspect the patient for any involuntary movement


paralysis is defined as the total loss of strength and movement, whereas paresis is a lesser degree of weakness and can be measured on a scale of 1 to 5. (See table)

Assessment of muscle strength

Absence of contraction


Contraction that does not displace the joint


Displacement of the limb on the plane


Joint displacement against gravity


Movement against resistance


Normal strength


Depending on the paralysis or paresis due to injuries that compromise the upper or lower motor neurons, clear semiological differences can be evidenced which will allow a correct diagnostic topo. (See Table 1)

Neurological examination

Upper motor neuron

Lower motor neuron


Increased (spasticity)

Decreased (sagging)

Osteotendinous reflexes


Decreased or absent

Superficial reflections






Cortical release reflexes




Mild, due to disuse








Based on the location and distribution of the paralysis we can find:

  1. Monoplegia : when weakness affects only one limb. In this case, it will be important to distinguish the presence of upper or lower motor neuron signs in order to locate the site of the injury.
  2. Hemiplegia : affects the arm, leg and sometimes the face on the same side. In this case the level of the injury can be deduced from the accompanying data; for example: the presence of aphasia or hemianopia suggests cortical involvement while the presence of involvement of cranial nerves involving the trunk. The most common causes are Strokes, Tumors; Trauma.
  3. Paraplegia : when the decrease in strength involves both lower limbs. The lesion usually settles at the medullary level (Medullary trauma or myelitis) and less frequently in the medial frontal motor cortex (meningiomas).
  4. Quadriplegia : when the commitment of the force extends to all four members. It can be secondary to cervical spinal injury (Traumatic, Tumor) or due to diseases of the peripheral nerves (Sme. De Guillain Barré), muscle (Myopathies) and neuromuscular junction (Myasthenia Gravis).

Methodology Study

Conducted semiológica full assessment and determining the commitment of upper or lower motor neuron will be chosen methods suitable fill-mers. If we have a patient with a monoplegia with signs of a higher motor neuron, the method of choice will be Computed Axial Tomography (CAT) or Magnética Resonance (MRI) of the brain, just as if the patient has hemiplegia. If the signs on the physical examination are compatible with a peripheral injury, Electromyography and in selected cases lumbar puncture are essential for a correct diagnosis.