The temporal line is a curved ridge that's found on both sides of the human skull. It's actually made up of two lines, with one sitting above the other, almost parallel. The higher of the two lines is called the superior temporal line, and the lower one is called the inferior temporal line. Both lines mark a place of attachment for the temporal muscle and the temporal fascia.
Beginning as a single ridge, the temporal line originates along the zygomatic arch, which is a convergence of the lower part of the temporal bone and the zygomatic bone, or cheekbone. The line then moves upward along the outer ridge of the eye, which is where the zygomatic and frontal bones meet. It arches backward, away from the frontal bone and toward the parietal bone, and diverges into two ridges above the temporal fossa, which is a depression in the temporal bone.
The parietal bones are located on the top and side of the skull, one on either side. Both parietal bones have a temporal line — or, more precisely, they each have a superior and an inferior temporal line. These lines are external only, because their purpose is as attachment points for the temporal muscle and the temporal fascia. The underside of the parietal bone has what are called meningeal grooves, or indentations caused by the meningeal vessels, which are arteries that feed the meningeal tissues that cover the brain.
The temporalis muscle, or temporal muscle, attaches to the inferior temporal line. It comes up from the temporal fossa and attaches to the coronoid process of the mandible, which is also called the jawbone. This muscle aids in chewing and is one of the four muscles of mastication. It can be felt in the temple region when the jaw is clenched and unclenched.
Sitting above the temporalis is the temporal fascia, also called the temporal aponeurosis. Aponeurotic tissue is a type of wide and flat connective tissue that covers and forms attachment and termination points of muscles. The temporal fascia is a single layer of tissue where it attaches to the entire expanse of the superior temporal line. It extends downward and becomes two layers of tissue where it attaches in two places to the zygomatic arch. The deep tissue of the temporal fascia merges with the surface tissue of the temporalis muscle, which allows the temporalis to form its attachment points.