Common tendinous ring

It can be used to divide the regions of the superior orbital fissure.

The arteries surrounding the optic nerve form a vascular structure known as the circle of Zinn-Haller, or sometimes as the circle of Zinn.

The following structures pass through the tendinous ring (superior to inferior):

• Superior division of the oculomotor nerve (CNIII)
• Nasociliary nerve (branch of ophthalmic nerve)
• Inferior division of the oculomotor nerve (CNIII)
• Abducens nerve (CNVI)
• Optic nerve

Parts

The common tendinous ring spans the superior orbital fissure and can be described as having two parts – an inferior tendon which gives origin to the inferior rectus muscle, and to part of the lateral rectus muscle; and a superior tendon which gives origin to the superior rectus muscle, and to part of the medial and lateral recti muscles.