What muscles originates at the annulus of Zinn?
What muscles originates at the annulus of Zinn?
Introduction. The Annulus of Zinn is described as the common tendinous origin of the four extraocular (EO) rectus muscles, located in the orbital apex.
What goes through Zinn annulus?
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.
What is Zinn annulus?
A mnemonic to remember the contents of the tendinous ring (also known as the annulus of Zinn) from superior to inferior is: One Canal, Several Orbital Nerves In One Annulus.
Which muscle is the only one that does not originate at the annulus of Zinn?
Unlike most of the other extraocular muscles (recti and superior oblique), the inferior oblique muscle does not originate from the common tendinous ring (annulus of Zinn).
What muscles attach to the tendinous ring?
The tendinous ring, also known as the annulus of Zinn, is the common origin of the four rectus muscles (extraocular muscles). The tendinous ring straddles the lower, medial part of the superior orbital fissure.
What are the 4 rectus muscles?
These muscles are the four rectus muscles—the inferior, medial, lateral, and superior recti—and the superior and inferior oblique muscles.
What is circle of Zinn Haller?
The circle of Zinn–Haller (CZH) is known to be an intrascleral arteriolar anastomosis derived from medial and lateral paraoptic short posterior ciliary arteries (SPCAs). The significance of this arterial circle in supplying the anterior optic nerve and peripapillary region has been the subject of controversy.
What is the tendinous ring of Zinn?
Which structure does not pass through the annulus of Zinn?
Correct Answer: Ophthalmic artery.
Where does the inferior oblique muscle originate?
 Unlike all other extraocular muscles, the inferior oblique does not originate from the annulus of Zinn or common tendinous ring. Instead, the inferior oblique originates from the orbital floor just lateral to the nasolacrimal groove.
What is tendinous ring of Zinn?
What passes through tendinous ring?
Through it (from superior to inferior) pass: superior division of the oculomotor nerve (CN III) nasociliary nerve (a branch of the ophthalmic nerve) inferior division of the oculomotor nerve (CN III)
Does the superior oblique attach to the annulus of Zinn?
The superior oblique originates just posterior to the annulus of Zinn and passes through the trochlea before turning posterolaterally to insert on the globe under and posterior to the insertion of the superior rectus.
What are the 7 extraocular muscles?
- Superior rectus.
- Inferior rectus.
- Lateral rectus.
- Medial rectus.
- Superior oblique.
- Inferior oblique.
- Levator palpebrae superioris.
What is lamina Cribrosa?
The lamina cribrosa (LC) is a mesh-like structure at the optic nerve head that surrounds and supports the retinal ganglion cell axons as they form the optic nerve. 1–3. Deformation and displacement of the LC have been increasingly implicated as the primary pathophysiologic mechanism of glaucomatous optic neuropathy.
What is a Cilioretinal artery?
Cilioretinal arteries belong to the posterior ciliary artery system. They arise either directly from the choroid or from one of the posterior ciliary arteries, providing additional or alternative blood supply to the retina. Usual location is the edge of the optic nerve head, most commonly on the temporal side.
Which nerve controls the inferior oblique muscle?
the oculomotor nerve
The inferior oblique is innervated by the inferior division of the oculomotor nerve, which enters the muscle on its upper surface.
What is the function of the common tendinous ring?
a fibrous ring that surrounds the optic canal and the medial part of the superior orbital fissure; it gives origin to the four rectus muscles of the eye and is partially fused with the sheath of the optic nerve.
What muscles are yoked for Dextroversion?
Yoke muscles (contralateral synergists):- It refers to the pair of muscles (one from each eye) which contract simultaneously during version movements. For example, right lateral rectus and left medial rectus act as yoke muscles for dextroversion movements.
What is Neuroretinal rim?
Introduction. The neuroretinal rim is the intrapapillary equivalent of the optic nerve fibers. It is one of the most important morphologic parameters to detect glaucomatous optic neuropathy and to grade the amount of glaucomatous optic nerve damage .
What is focal notching?
Notching of the rim. Notching of the neuroretinal rim is a sign that a focal area of loss occurred within the rim tissue. Notching most commonly occurs at the inferior temporal or superior temporal aspect of the disc and often is associated with corresponding nerve fiber layer defects.
Where is Cilioretinal artery?
What does inferior oblique muscle do?
 The inferior oblique is responsible for extorsion, elevation, and abduction. Because of their course, the superior and inferior oblique muscles are the only muscles that can depress or elevate the eye, respectively when the eye moves in adduction.
What muscles arise from the annulus of Zinn?
The annulus of Zinn serves as the origin of six of the seven extraocular muscles (Fig. 50-2 ). Superiorly, the superior rectus arises from the annulus, which at this point is fused with the dura of the optic nerve. The levator palpebrae arises medial and superior to the superior rectus muscle but remains intimately associated with it.
What is the anulus of Zinn?
The anulus of Zinn is a fibrous band giving rise to the origins of six of the seven extraocular muscles. This fibrous tissue is in continuity with the dural sheath of the optic nerve. The two heads of the lateral rectus loop around that portion of the superior orbital fissure known as the oculomotor foramen.
Where does the tendinous annulus attach to the bone?
The tendinous annulus attaches to the greater and lesser wings of the sphenoid bone as well as to the periosteum, the dense connective tissue lining the orbit. The annulus crosses over the inferior portion of the superior orbital fissure and runs superior and medial to the optic foramen ( Figure 2 ).