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Gluteal layers

The buttock has six layers from outside in. Fat is placed only above the deep fascia; the large gluteal veins lie under the gluteus maximus, about 56 mm deep.

Techniques

Outside to inside

The layers of the buttock

1. Skin

The skin is tethered by osseocutaneous and fasciocutaneous ligaments. In 10 cadaver hemibuttocks, these ligaments could deflect a cannula deeper than intended unless they were released.[1]

2. Superficial subcutaneous fat

The outer fat layer holds the smallest vessels in the buttock. In 20 cadaver dissections the subcutaneous plane held about 25 vessels, with arteries of 0.9 mm and veins of 1.05 mm.[1]

3. Deep subcutaneous fat

A 2023 cadaver study found 7 deep subcutaneous fat compartments: 3 medial, 1 central and 3 lateral. Each keeps injected fat apart from the others above the muscle fascia, and surgeons can fill them selectively under ultrasound.[1]

4. Deep (gluteal) fascia

The fascia over the gluteus maximus is the boundary Florida law forbids fat to cross. With the fascia intact, injected fat stayed in the subcutaneous space at pressures of 125 to 150 mmHg. Through 6 mm fascia defects, fat reached the space under the muscle.[1][2]

5. Gluteus maximus

The muscle is about 27 mm thick over the center of the buttock. Fat injected into it migrated through the muscle into the deep submuscular space in every cadaver injection tested. Veins inside the muscle measured about 1.3 mm.[1][2][3]

6. Gluteal veins

The superior and inferior gluteal veins run just under the gluteus maximus, on average 56 mm deep and about 6 mm wide with the patient prone. The MRI study found no safe zone in or under the muscle. The 2018 task force reported fat in the gluteal muscle in every BBL death examined at autopsy.[1][2]