The orbital septum separates the intraorbital fat from the palpebral part of the orbicularis oculi m. An anatomic study after injection of colorant into the intraorbital fat allows definition of a fibroadipose layer anterior to the orbital septum. This consists of radial fibers and extraorbital fatty lobules. The septum is derived embryologically from the mesenchyme of the second arch, but the structure of the anterior layer remains controversial. The septum has an important mechanical function in containing the orbital fat and is involved in orbital movements. A knowledge of these different layers facilitates surgical approaches and helps to define the anatomic landmarks in palpebral surgery for conditions such as ptosis and in blepharoplasty.