Three lines. You need to locate the parietal tubercle.

• First: draw a line parallel to the motor line of 3 cm in length.
• Second: from the vertex line forward at 40° of 3 cm in length.
• Third: line caudal to the first at an angle of 40°, also 3 cm.

Treats apraxia: inability to coordinate movements to perform tasks like tying shoes, buttoning buttons, picking up an object, problems with walking.