Which muscles originate from the annulus of Zinn?
Which muscles originate from the annulus of Zinn?
Extraocular Muscles The four rectus muscles (each about 3–4 cm long) originate from the annulus of Zinn at the orbital apex, which is contiguous with the dura surrounding the optic nerve and the periorbita.
What are the 4 muscles of the eye?
The four recti muscles are the lateral rectus, the medial rectus, the inferior rectus, and the superior rectus while the two oblique muscles are the inferior oblique and the superior oblique. In this post, we’ll talk about each of the six muscles and discover their function and purpose in the human eye.
What is muscle cone?
The myofascial cone is a structure within the orbit involved in the movement and support of the globe, or more simply the eye. It also serves as the physical division between the intraconal and extraconal compartments, but the cone itself is included in the contents of the intraconal space 1.
What are the 7 extraocular muscles?
There are seven extraocular muscles – the levator palpebrae superioris, superior rectus, inferior rectus, medial rectus, lateral rectus, inferior oblique and superior oblique. Functionally, they can be divided into two groups: Responsible for eye movement – Recti and oblique muscles.
What goes through the common tendinous ring?
The tendinous ring straddles the lower, medial part of the superior orbital fissure. It attaches to a tubercle on the greater wing of the sphenoid bone (at the margin of the superior orbital fissure). Through it (from superior to inferior) pass: superior division of the oculomotor nerve (CN III)
What is orbital apex syndrome?
Orbital apex syndrome is characterized by vision loss from optic neuropathy and ophthalmoplegia due to the involvement of ocular motor nerves in the anatomical region of the orbital apex.
Is your eye a muscle?
There are six muscles that attach to the eye to move it. These muscles originate in the eye socket (orbit) and work to move the eye up, down, side to side, and rotate the eye. The superior rectus is an extraocular muscle that attaches to the top of the eye. It moves the eye upward.
What does EOM mean for eyes?
EOM; Extraocular movement; Ocular motility examination. Extraocular muscle function testing examines the function of the eye muscles. A health care provider observes the movement of the eyes in eight specific directions.
What is Intorsion?
: inward rotation (as of a body part) about an axis or a fixed point especially : rotation of the eye around its anteroposterior axis so that the upper part moves toward the nose — compare extorsion.
What is Intorsion of eye?
Rotates the top of the eye towards the nose (intorsion) Moves the eye downwards (depression) Moves the eye outwards (abduction)
Does optic nerve go through common tendinous ring?
The following structures pass through the tendinous ring (superior to inferior): Superior division of the oculomotor nerve (CNIII) Nasociliary nerve (branch of ophthalmic nerve) Optic nerve.
What are the muscles of 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.
Where is the annulus of Zinn located in the eye?
At the exit of the optic canal, the optic nerve crosses the common tendinous ring ( annulus of Zinn ), to which are attached the four rectus muscles of the eye. The nerve occupies the center axis of the musculofascial cone of the bulb, in the middle of the orbital fat body.
What is the meaning of the circle of Zinn?
It is the common origin of the four rectus muscles of the group of extraocular muscles . 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”.
Where do annular muscles pass through the tendinous ring?
The following structures pass through the tendinous ring (superior to inferior): Annular muscles are found near pharynx. From pharynx annular nerve goes into separate parts of pharynx. Some sources distinguish between these terms more precisely, with the anulus tendineus communis being the parent structure, divided into two parts:
