What it means for a patient
- Numbness or tingling of the scalp after a forehead lift comes mostly from injury to the deep branch of this nerve.
- The deep branch ran along the same path in every specimen and supplied the same area in every volunteer.
- The findings apply to both open and endoscopic forehead and brow procedures.
- Limits: an anatomy study of 12 cadavers and 30 volunteers. The abstract reports no surgical outcomes.
Why this paper matters
It mapped the two divisions of the supraorbital nerve and identified the deep division as the source of most scalp numbness after forehead lift.
Overview
Most anatomy textbooks do not describe in detail how the supraorbital nerve runs across the forehead and under the scalp, and drawings of its course beyond the eye socket rim are often wrong. The nerve is at risk in many plastic surgery techniques. The author dissected cadavers and used selective nerve blocks in living volunteers to map its course and the skin it supplies. The PubMed abstract is cut off at 250 words.
Findings
- 12 fresh cadaver specimens (24 half-heads) dissected.
- Sensory distribution mapped in 30 living subjects with selective nerve blocks.
- Beyond the orbital rim, the nerve has 2 consistently present divisions.
- Superficial (medial) division: passes over the frontalis muscle and supplies the forehead skin; in 90 percent of subjects it reached only the front margin of the scalp.
- Deep (lateral) division: runs up across the outer forehead between the galea aponeurotica and the pericranium, and is the sensory nerve to the frontoparietal scalp.
- Injury to the deep division during a forehead lift causes most of the distressing scalp numbness and tingling afterward.
- The deep division's course was consistent in all cadaver specimens, and its sensory area was consistent in all volunteers.
- The superficial division did not show this consistency.
- The findings apply to any procedure with scalp or forehead incisions, such as the forehead lift and endoscopic facial techniques.
Terms
- Supraorbital nerve: a sensory nerve that leaves the skull above the eye and supplies the forehead and scalp.
- Galea aponeurotica: the tough fibrous layer of the scalp.
- Pericranium: the thin layer covering the skull bone.
- Frontalis: the forehead muscle that raises the eyebrows.
- Frontoparietal scalp: the scalp over the top and front of the head.
- Paresthesia: tingling, prickling or altered feeling in the skin.
- Selective nerve block: numbing one nerve to see which area of skin it supplies.
- Forehead lift: surgery that raises the brows and smooths the forehead.
- Half-head: one side of a cadaver head, dissected as a separate specimen.