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Infection-Associated Ocular Cranial Nerve Palsies
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Hardeep Singh Malhotra, Imran Rizvi, Neeraj Kumar, Kiran Preet Malhotra, Gaurav Kumar, Manoj K. Goyal, Manish Modi, Ravindra Kumar Garg, Vivek Lal
The posterior most end of the pyramid shaped orbit is called the apex of the orbit. As depicted in Figure 16.2, the four orbital walls converge here at the craniofacial junction leaving two orifices situated in the sphenoid bone (2). The optic nerve and the ophthalmic artery pass through the optic canal and the four recti muscles take their origin from the tendinous annulus of Zinn. Other structures passing through the annulus of Zinn are the superior and the inferior branches of oculomotor nerve, the abducens nerve, and the nasociliary nerve, which pass through the middle portion of the superior orbital fissure (Figure 16.4).
Cranial Neuropathies II, III, IV, and VI
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Tanyatuth Padungkiatsagul, Heather E. Moss
The intraorbital optic nerve travels within the cone formed by the extraocular muscles and exits the orbit through the optic canal, which is situated in the lesser wing of the sphenoid. The dura covering the optic nerve becomes invested in the periosteum of the optic canal at the annulus of Zinn at the orbital apex.
Orbit
Published in Swati Goyal, Neuroradiology, 2020
The extraocular muscles (EOMs) – the four recti, two obliques, and the levator palpebrae superioris − divide the retro-orbital space into intra- and extraconal spaces. The annulus of Zinn, a fibrous tendon ring, surrounds the optic nerve at the orbital apex and inserts into the globe; it is a common origin for the four recti. Associated lesions include thyroid ophthalmopathy (Graves’ disease), and inflammatory pseudotumor.
The Endoscopic Transnasal Approach to Orbital Tumors: A Review
Published in Seminars in Ophthalmology, 2021
Edith R. Reshef, Benjamin S. Bleier, Suzanne K. Freitag
Understanding the complex neurovascular anatomy of the medial intraconal orbit is critical to avoid surgical complications. The boundaries of this small space as they pertain to endoscopic endonasal surgery are the MRM medially, the inferior rectus muscle inferiorly, the optic nerve, ophthalmic artery, nasociliary nerve, and long ciliary artery and nerve laterally, and the anterior and posterior ethmoid arteries and nerves superiorly. The ophthalmic artery extends anteriorly from the annulus of Zinn, and an inferomedial trunk (IMT) supplies the MRM via vascular pedicles that lie approximately 9 mm anterior to the sphenoid face.16 Similarly, the oculomotor nerve extends anteriorly from the annulus of Zinn and branches into superior and inferior rami. Smaller branches of the inferior ramus insert onto the posterior third of the lateral portion of the MRM (Figure 2).
Isolated Ocular Motor Nerve Palsies
Published in Journal of Binocular Vision and Ocular Motility, 2018
Stacy L. Pineles, Federico G. Velez
All three ocular motor nerves travel through the subarachnoid space at the skull base and into the cavernous sinus. Within the cavernous sinus, they are adjacent to the first and second division of the trigeminal nerve, the internal carotid artery, and the third-order oculosympathetic fibers. In the cavernous sinus, the oculomotor nerve divides into superior and inferior divisions which innervate the (1) superior rectus and LPS and (2) the inferior rectus, inferior oblique, medial rectus, and pupillary sphincter, respectively. The nerves then exit the cavernous sinus and traverse the orbit. CNIII and CNVI are positioned within the annulus of Zinn, while CNIV lies outside of the annulus of Zinn. In-depth knowledge of the pathways of the ocular motor nerves as well as adjacent structures provides clinicians with the knowledge required to understand various clinical presentations of CN palsies with coexistent neurological syndromes.
Vision loss associated with orbital surgery – a major review
Published in Orbit, 2020
Prerana Kansakar, Gangadhara Sundar
Significant blunt injury to the orbital aperture and/or globe is dispersed along the orbital walls, which absorb the forces resulting in fracture hence reducing the force dispersed to the deeper orbital contents. Damage to the optic nerve is also minimized due to a dense ring of fibrous tissue (Annulus of Zinn) that shields the nerve and sturdy optic canal.101,102