Projection areas are regions of the cortex where specific motor or sensory activity is localized. The pre-central gyrus (the raised area in front of the central sulcus) is the primary motor area. It is the center for voluntary control of the skeletal muscles. Each area of the body, for that matter each muscle, is controlled by a specific part of the pre-central gyrus. (See Figure 12.11) The orientation is generally reversed in position compared to the body location, i.e. the muscles of the leg and foot are generally projected to the top of the gyrus, those in the head and neck to the bottom of the gyrus. The area represented reflects the level of activity and control over the muscles, not their size. For example more area is devoted to the muscles of facial expression, speech, and hand movement as to all the rest of the muscles. The pre-central gyrus is the origin of the corticospinal tracts.
	The post-central gyrus is the comparable area for sensory perception, called the somatosensory area. It receives the conscious sensations from the musculocutaneous regions of the body: pain, temperature, touch, and pressure. These sensations are brought by the spinothalamic tract and the fasciculus gracilis and cuneatus. As before, these sensations terminate in specific positions on the gyrus which are inversely related to body position and directly related to the degree of sensation and its importance, not the size of the area.