Anatomic study of the distal supraorbital nerve.

This investigation was designed to extend our present knowledge of the supraorbital n. (SO n.) distal to the supraorbital notch. It is based on 40 dissected hemi-faces and the position of the notch and the periosteal and frontalis cutaneous branches of the SO n. were studied. The notch was 33.05 mm from the midline on the right side and 30.70 mm on the left. The periosteal branch arises from the lateral frontalis cutaneous branch. Its ascends in an oblique direction laterally and ends in two terminal branches. The frontalis cutaneous branch, after a very short trunk, divides into two branches, medial and lateral. The medial or deep branch enters the corrugator supercilii m. between its fibers. Most frequently, it passes under the inferior fasciculus and superficial to the middle and superior ones. Leaving the corrugator m., it ascends medially into the frontalis m., supplying the median cutaneous frontalis region. The lateral or superficial branch crosses superficial to the corrugator supercilii m. to penetrate the frontalis m. in an ascending and lateral direction, supplying the lateral frontalis region. The two branches enter the frontalis m., displaying a zigzag pattern in order to adapt its length during expressive movements. They cross the frontalis region together with the SO a. and two veins supplying the nerve and the frontalis m. These anatomic data may explain some of the complications after surgery for ptosis and blepharospasm.