Question: Where can you find the annulus of Zinn?

Context:
Should the annular tendon of the eye be named 'annulus of Zinn' or 'of Valsalva'?
The annular tendon is commonly named 'annulus of Zinn', from the German anatomist and botanist Johann Gottfried Zinn (1727-1759) who described this structure in his Descriptio anatomica oculi humani (Anatomical Description of the Human Eye, 1755).
It arose at the annulus of Zinn, passing forwards between the inferior rectus muscle and lateral rectus muscle, and insert directly on the sclera. 
Drilling was continued toward the annulus of Zinn (AZ) and optic nerve superiorly and over the intracavernous ICA posteriorly.
Measurements before and after resection of the ACP included the length of C6 segment of the ICA on its lateral aspect; C6 segment length on its medial aspect; and medial length of the optic nerve from the optic chiasm to falciform ligament (before ACP resection) then to the annulus of Zinn (after ACP resection).
The muscles, situated between the optic nerve and the lateral rectus muscle, originated from the annulus of Zinn and branched off two heads; one inserted into the medial inferior side of the superior rectus muscle and the other inserted into the central superior side of the inferior rectus muscle. 
 In 30 cadavers, the superior division of the oculomotor nerve was severed en bloc 1.5 cm anterior to the annulus of Zinn with the levator palpebrae superioris (LPS) and the superior rectus muscles. 
The optic canal was subsequently removed en bloc, beginning at the annulus of Zinn and extending to the optic chiasm.
PURPOSE: To describe a combined transcranial-orbital approach for en bloc resection of optic nerve gliomas with preservation of the annulus of Zinn that minimizes recurrence and prevents postoperative paralytic ptosis.DESIGN: A retrospective, noncomparative, interventional case series.STUDY POPULATION: All patients who underwent optic nerve glioma resections using this technique with the authors between 1994 and 2010.PROCEDURE: A transcranial-orbital approach is used to resect the intracranial segment of the optic nerve glioma from 2 mm anterior to the chiasm to the posterior extent of annulus of Zinn.
No patients had tumor recurrence or developed postoperative paralytic ptosis.CONCLUSIONS: The combined transcranial-orbital approach with preservation of the annulus of Zinn is a safe and effective way to remove optic nerve gliomas and ensure tumor clearance while avoiding paralytic ptosis.
To describe a combined transcranial-orbital approach for en bloc resection of optic nerve gliomas with preservation of the annulus of Zinn that minimizes recurrence and prevents postoperative paralytic ptosis.A retrospective, noncomparative, interventional case series.All patients who underwent optic nerve glioma resections using this technique with the authors between 1994 and 2010.A transcranial-orbital approach is used to resect the intracranial segment of the optic nerve glioma from 2 mm anterior to the chiasm to the posterior extent of annulus of Zinn
Through a superior orbitotomy exposure, the entire retrobulbar segment of the tumor is transected from the globe to the annulus of Zinn
A simulation of the procedure in a cadaver and en bloc resection of the orbital apex are performed to demonstrate the subdural plane of dissection within the annulus of Zinn.Postoperative outcome measures include: health of the ipsilateral globe, paralytic ptosis, postoperative complications, and tumor recurrence.Eleven patients underwent resection of optic nerve gliomas using this technique
No patients had tumor recurrence or developed postoperative paralytic ptosis.The combined transcranial-orbital approach with preservation of the annulus of Zinn is a safe and effective way to remove optic nerve gliomas and ensure tumor clearance while avoiding paralytic ptosis
The orbital surface of the medial rectus and inferior rectus are exposed from the annulus of Zinn to a position close to where the muscles penetrate Tenons capsule
The orbital surface of the medial rectus and inferior rectus are exposed from the annulus of Zinn to a position close to where the muscles penetrate Tenon's capsule. 
The muscles, situated between the optic nerve and the lateral rectus muscle, originated from the annulus of Zinn and branched off two heads; one inserted into the medial inferior side of the superior rectus muscle and the other inserted into the central superior side of the inferior rectus muscle.
The optic canal was subsequently removed en bloc, beginning at the annulus of Zinn and extending to the optic chiasm.
The distance from the annulus of Zinn to the trochlea was the same in both eyes.The findings for our patients, particularly in those who underwent additional high resolution MRI, did not provide evidence of a lack of CN IV as a cause of Brown syndrome.
Should the annular tendon of the eye be named 'annulus of Zinn' or 'of Valsalva'?
The distance from the annulus of Zinn to the trochlea was the same in both eyes.
The optic canal was subsequently removed en bloc, beginning at the annulus of Zinn and extending to the optic chiasm.
Through a superior orbitotomy exposure, the entire retrobulbar segment of the tumor is transected from the globe to the annulus of Zinn.

Answer: Annulus of Zinn is in the orbit.
Exact answer: orbit, EYE