{{Short description|Ring of fibrous tissue around optic nerve at its entrance to the eye}} {{Infobox anatomy | Name = Common tendinous ring | Latin = anulus tendineus communis | Image = Eyemuscles.png | Caption = ''Rectus muscles:'' <br>2 = superior, 3 = inferior, 4 = medial, 5 = lateral<br>''Oblique muscles:'' 6 = superior, 8 = inferior<br>''Other muscle:'' 9 = levator palpebrae superioris<br>''Other structures:'' 1 = Common tendinous ring, 7 = Trochlea, 10 = Superior tarsus, 11 = Sclera, 12 = Optic nerve | Image2 = Eye orbit anterior.jpg | Caption2 = ''Anterior view'' | System = }} The '''common tendinous ring''', also known as the '''annulus of Zinn''' or '''annular tendon''', is a ring of fibrous tissue surrounding the optic nerve at its entrance at the apex of the orbit. It is the common origin of the four recti muscles of the group of extraocular muscles.
It can be used to divide the regions of the superior orbital fissure.<ref name="pmid17080461">{{cite journal |vauthors=Shi X, Han H, Zhao J, Zhou C |title=Microsurgical anatomy of the superior orbital fissure |journal=Clin Anat |volume=20 |issue=4 |pages=362–6 |year=2007 |pmid=17080461 |doi=10.1002/ca.20391|s2cid=43849585 }}</ref>
The arteries surrounding the optic nerve form a vascular structure known as the circle of Zinn-Haller, or sometimes as the ''circle of Zinn''.<ref name="pmid10381675">{{cite journal |vauthors=Ko MK, Kim DS, Ahn YK |title=Morphological variations of the peripapillary circle of Zinn-Haller by flat section |journal=Br J Ophthalmol |volume=83 |issue=7 |pages=862–6 |year=1999 |pmid=10381675 |doi= 10.1136/bjo.83.7.862|url= |pmc=1723100}}</ref>
The following structures pass through the tendinous ring (superior to inferior):
* Superior division of the oculomotor nerve (CN III) * Nasociliary nerve (branch of ophthalmic nerve) * Inferior division of the oculomotor nerve (CN III) * Abducens nerve (CN VI) * 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.<ref name="Shumway2">{{cite journal |last1=Shumway |first1=Caleb L. |last2=Motlagh |first2=Mahsaw |last3=Wade |first3=Matthew |title=Anatomy, Head and Neck, Eye Inferior Rectus Muscle |url=https://www.ncbi.nlm.nih.gov/books/NBK518978/ |website=StatPearls |publisher=StatPearls Publishing |access-date=15 January 2022 |date=2022|pmid=30085520 }}</ref>
==Eponym== It is named for Johann Gottfried Zinn.<ref>{{WhoNamedIt|synd|3938}}</ref><ref>J. G. Zinn. Descriptio anatomica oculi humani. Göttingen, B. Abrami Vandenhoeck, 1755.</ref> It should not be confused with the zonule of Zinn, though it is named after the same person.
==References== {{Reflist|2}}
{{Eye}} {{Authority control}}
Category:Histology Category:Human eye anatomy