4. Strength and sensation

Skeletal musculature is affected by the peripheral motor neuron in the anterior horn of the spinal cord. This motor neuron acts within a reflex arc steered by sensory information from the peripheral parts of the body. The spinal reflex is modulated by higher parts of the central nervous system in order to damp the motor reaction. In the case of failing central regulation, reflexes become exaggerated and spasticity occurs. Sensory information can be divided into protopathic and epicritic sensibility. These two modalities are processed in different parts of the nervous system. There is a somatotopy for both sensory and motor functions in the central nervous system. As different systems follow different paths, it is possible to make a topical diagnosis by combining the patient’s signs and symptoms. History-taking and clinical examination are therefore crucial when taking decisions to carry out further investigation. By finding particular symptoms, it is possible to make a diagnosis of ‘non-organic disorder’.