Chapter 4: The Motor System

This is perhaps the most objective component of the neurologic examination. It must be remembered that normal movement depends not only on the reflex arc of the anterior horn cell, the neuromuscular junction, and muscle, but also on intact bones, joints, and soft tissue. This is the foundation upon which supranuclear motor control initiates the “engram," the motor program of movement, its smoothness (cerebellum), its relation to gravity (vestibular system), the control of blood pressure in the upright position (autonomic reflexes) and the desire to move (anterior cingulate gyrus and parietal cortex). Automatic movements for walking (locomotor centers) and for emotion (amygdala, thalamus, and basal ganglia) are clearly important for daily living and have an examination of their own with specific defects that point to specific pathology.

Preliminary General Inspection (Figs 4.1– 4.3)

The aim is to detect specific asymmetries and deformities. This is a combination of genetic defects (dysmorphism) vs acquired lesions. Trophic factors, neuritic outgrowth factors with guidance molecules, and developmental receptors are critical. Congenital abnormalities may lead to overuse syndromes, pressure and destruction of nerve roots as they exit their spinal foramina, as well as stenosis in the cervical and lumbar areas. All the congenital defects can be diagnosed during the neurologic examination.

The patient is evaluated in the supine, sitting, and erect positions. The upper extremities are placed in repose on the lap. A comparison of the size, shape and any adventitial movements is noted.