What it means for a patient
- The outer brow usually drops before the inner brow.
- The outer brow has less deep support and sits outside the area the forehead muscle holds up.
- Gravity, the frown muscle and the muscle that closes the eye all act to lower the outer brow.
- The author applied these findings to how the forehead lift is performed.
- This is a cadaver anatomy study. It does not report surgical results.
Why this paper matters
It described the structures and forces that make the lateral brow droop first and tied them to forehead lift technique.
Overview
Brow drooping with age is commonly blamed on general loosening of the scalp and forehead tissues. That would lower the whole brow evenly, yet the outer (lateral) brow usually drops earlier than the inner (medial) brow. The author dissected fresh cadaver heads and examined tissue under the microscope to explain this, then applied the findings to the forehead lift.
Findings
- 20 fresh cadaver specimens (40 half-heads) dissected; histology added to the gross anatomy.
- The mechanism of brow ptosis acts more strongly on the lateral brow.
- The lateral brow has less support from deeper structures than the medial brow.
- Structures that may promote movement and descent of the brow: the galea fat pad, the preseptal fat pad and the subgaleal fat pad glide plane space.
- Force 1: resting tone of the frontalis muscle holds up the part of the brow inside the temporal fusion line of the skull.
- Force 2: gravity makes the soft tissue outside the temporal line slide over the temporalis fascia and push the lateral brow down.
- Force 3: overactivity of the corrugator supercilii, together with the lateral orbicularis oculi, can oppose the frontalis and pull the lateral brow down.
- The pivot point for these forces is the temporal fusion line near the upper orbital rim.
- The abstract gives no measurements beyond the specimen count.
Terms
- Eyebrow ptosis: drooping of the eyebrow.
- Lateral and medial brow: the outer and inner parts of the eyebrow.
- Frontalis: the forehead muscle that raises the eyebrows.
- Corrugator supercilii: the muscle between the brows that pulls them down and together when frowning.
- Orbicularis oculi: the ring-shaped muscle around the eye that closes the eyelids.
- Galea: the tough fibrous layer of the scalp.
- Temporal fusion line: a ridge on the side of the skull where the temple muscle's covering attaches.
- Temporalis fascia: the fibrous covering of the temple muscle.
- Histology: study of tissue under a microscope.
- Forehead lift: surgery that raises the brows and smooths the forehead.