Annulus of Zinn

Annulus of Zinn
Rectus muscles: 2 = superior, 3 = inferior, 4 = medial, 5 = lateral Oblique muscles: 6 = superior, 8 = inferior Other muscle: 9 = levator palpebrae superioris Other structures: 1 = Annulus of Zinn, 7 = Trochlea, 10 = Superior tarsus, 11 = Sclera, 12 = Optic nerve
Anterior view
Details
Latin	Anulus tendineus communis
Identifiers
Dorlands /Elsevier	a_50/12143789
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
Anatomical terminology [[[d:|edit on Wikidata]]]

The annulus of Zinn, also known as the annular tendon or common tendinous ring, is a ring of fibrous tissue surrounding the optic nerve at its entrance at the apex of the orbit. It is the origin for five of the seven extraocular muscles, omitting the inferior oblique muscle.

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

The arteries surrounding the optic nerve are sometimes called the "circle of Zinn-Haller" ("CZH"). This vascular structure is also sometimes called "circle of Zinn".

Parts

Some sources distinguish between these terms more precisely, with the anulus tendineus communis being the parent structure, divided into two parts:

• a lower, the ligament or tendon of Zinn, which gives origin to the Rectus inferior, part of the Rectus internus, and the lower head of origin of the Rectus lateralis.
• an upper, which gives origin to the Rectus superior, the rest of the Rectus medialis, and the upper head of the Rectus lateralis. This upper band is sometimes termed the superior tendon of Lockwood.

Eponym

It is named for Johann Gottfried Zinn. It should not be confused with the Zonule of Zinn, though it is named after the same person.