Plantar fascia is a thick ligament (band of tissue) on the bottom of the foot that connects the heel bone to the toes. The plantar fascia supports the arch of the foot and helps absorb stresses on the feet during movement. Inflammation of this tissue produces the condition known as plantar fasciitis.
Jameson, J. Larry, et al. Harrison's Principles of Internal Medicine, 20th Ed. New York: McGraw-Hill Education, 2018.