Transcranial Approach to the Orbit: A Microanatomical Study

Objective To study the microanatomy of transcranial approach to the orbit and provide parameters for clinic. Methods Three kinds of intraorbital approaches were studied by dissecting and measuring 10 adult cadaveric heads under operation microscope. Results The medial approach passes through the space between the superior oblique and the levator palpebrae superior muscles, which is suitable for lesions located in the medial part of the orbital apex. The central approch passes through the space between the levator palpebrae superior and the superior rectus muscles. There are two variants for the central approach, the choice of which depends on whether the frontal nerve is retracted medially or laterally. The approach is available for lesions in the midportion of the intraorbital segment of the optic nerve. The lateral approach passes through the space between the superior and the lateral rectus muscles, with two variants for the lateral approach, the choice of which was determined by whether the superior ophthalmic vein is retracted medially or laterally. This approach is suitable for lesions in the superior, inferior or lateral parts of the orbital apex as well as the superior orbital fissure. Conclusion Three kinds of approaches provide a microanatomical foundation for avoiding the damages of nerves and vessels in orbit operation.