The face contains an abundance of small muscles that work together to help us show our emotions. You can thank these muscles for everything your face does, from smiling and frowning to making funny faces in group pictures!
Naturally, for these muscles to work, there are many tiny nerves, arteries, and veins that supply them. Let’s start off with the sensory innervation of the face.
Almost all of its sensory innervation is provided by the fifth cranial nerve, also known as the trigeminal nerve, which has three divisions.
Its superior division is known as the ophthalmic nerve, and it provides sensory innervation for the part of the scalp anterior to the vertex of the head, the forehead, the upper eyelids, the dorsum of the nose and the roof of the nasal cavity.
The ophthalmic nerve arises from the trigeminal ganglion, leaves the skull through the superior orbital fissure, and enters the orbit, where it gives rise to three branches; the frontal nerve, the nasociliary nerve and the lacrimal nerve.
So let’s look at them one by one! The frontal nerve runs across the roof of the orbit, and it gives rise to the supraorbital and the supratrochlear nerves.
The supraorbital nerve exits the orbit through the supraorbital notch and supplies the skin of the anterior part of the scalp, the anterolateral forehead, and the middle of the upper eyelids.
The supratrochlear nerve exits the orbit lateral to the trochlea and supplies the skin of the anteromedial forehead.
Next is the nasociliary nerve, which divides into the anterior ethmoidal, the posterior ethmoidal, and the infratrochlear nerves.