The<unk>  is a branch of the frontal nerve, which itself comes from the ophthalmic division of the trigeminal (or fifth) cranial nerve. 
It is smaller than the nearby supraorbital nerve. It passes above the pulley of the Superior oblique muscle, and gives off a descending filament that joins the infratrochlear branch of the nasociliary nerve.
The<unk>  then exits the orbit between the pulley of the superior oblique and the supraorbital foramen, curves up on to the forehead close to the bone, and ascends beneath the Corrugator supercilii and Frontalis muscles. It then divides into branches which pierce these muscles and supplies the following areas:
skin of the lower part of the forehead, close to the midline
conjunctiva
skin of the upper eyelid.
Supratrochlear nerve
Auriculotemporal nerve
Abducens nerve
Vestibular nerve
Oculomotor nerve
Trigeminal nerve
Vestibulocochlear nerve
Nasopalatine nerve