Midface injection anatomy: compartments and ligaments

The midface is where most volumising work happens, and where the difference between filling a shadow and correcting its cause is most consequential.

Layers and compartments

The midface is layered: skin, subcutaneous fat, SMAS, deep fat, deep fascia, periosteum. The fat is not a sheet but a set of discrete compartments — superficial and deep, medial and lateral — separated by septa and tethered by ligaments.

Anatomical study of the subSMAS spaces shows these are bordered by fat, muscle, fascia and ligaments, permitting independent muscle movement and offering planes that are separated from critical neurovascular structures. That is the anatomical basis for the idea of a safe plane: not an absence of vessels, but a fascial or muscular layer between the injected material and them.

Ligaments make the folds

The zygomatic ligament tethers over the malar eminence; the orbital retaining ligament runs around the rim; the tear trough ligament attaches maxilla to dermis.

Where tissue is tethered it stays; where it is not it descends. The visible folds of the midface — tear trough, nasolabial fold — sit at these boundaries. This is why filling the fold directly so often disappoints: the fold is a fixed attachment, not a volume deficit, and product placed into it fights the tether.

Restoring the deep medial cheek fat and the malar platform addresses the cause and improves the fold indirectly. Assessing volume needs before restoring support consistently overestimates them, because part of the apparent hollow is a shadow that support removes.

Naming the compartments

The deep fat of the midface is described in the literature by position, and the terms recur in technique papers: the deep medial cheek fat, the deep lateral cheek fat, and the anteromedial cheek — the region medial to the malar eminence and lateral to the nasolabial fold, which carries much of the projection a youthful cheek shows in three-quarter view.

Anteromedial cheek deflation is a common driver of both the tear trough shadow and the nasolabial fold, which is why support there frequently improves two complaints that the patient described separately.

Vessels

The angular artery ascends beside the nose toward the medial canthus, where it anastomoses with the ophthalmic circulation. The infraorbital artery emerges from its foramen roughly a centimetre below the inferior orbital rim in the mid-pupillary line, alongside the infraorbital nerve. The facial vein runs deep and lateral to the artery.

The nasolabial fold and infraorbital region both feature in the reported blindness series. The perinasal region in particular has been mapped in detail precisely because it is where vessels are superficial and consistent.

Practical implications

• Support the platform before filling the shadow.
• Respect compartment boundaries; crossing a septum distributes product where it was not intended.
• Deep supraperiosteal placement at defined points, with slow injection and small aliquots.
• Treat the infraorbital foramen as a structure to avoid rather than a landmark to inject at.