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Optic Nerve: The 2nd cranial nerve. The optic nerve conveys visual information from the retina to the brain. The nerve carries the axons of the retinal ganglion cells which sort at the optic chiasm and continue via the optic tracts to the brain. The largest projection is to the lateral geniculate nuclei; other important targets include the superior colliculi and the suprachiasmatic nuclei. Though known as the second cranial nerve, it is considered part of the central nervous system.

Partial Optic Nerve Transection in Rats: A Model Established with a New Operative Approach to Assess Secondary Degeneration of Retinal Ganglion Cells

1Aier School of Ophthalmology, Central South University, Changsha, China, 2Institute of Immunology, Tsinghua University School of Medicine, Beijing, China, 3Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China, 4Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China

JoVE 56272


 Neuroscience

In vivo Imaging of Optic Nerve Fiber Integrity by Contrast-Enhanced MRI in Mice

1Hans Berger Department of Neurology, Jena University Hospital, 2Immunology, Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, 3Institute of Diagnostic and Interventional Radiology, Medical Physics Group, Jena University Hospital

JoVE 51274


 Neuroscience

Using Retinal Imaging to Study Dementia

1Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, 2Department of Medicine & Therapeutics, The Chinese University of Hong Kong, 3Therese Pei Fong Chow Research Centre for Prevention of Dementia, The Chinese University of Hong Kong, 4Gerald Choa Neuroscience Centre, The Chinese University of Hong Kong, 5Memory Aging and Cognition Centre, National University Health System, 6Department of Pharmacology, National University of Singapore, 7Singapore Eye Research Institute, Singapore National Eye Centre, 8Duke-NUS Medical School, National University of Singapore

JoVE 56137


 Medicine

Cranial Nerves Exam I (I-VI)

JoVE 10091

Source:Tracey A. Milligan, MD; Tamara B. Kaplan, MD; Neurology, Brigham and Women's/Massachusetts General Hospital, Boston, Massachusetts, USA

During each section of the neurological testing, the examiner uses the powers of observation to assess the patient. In some cases, cranial nerve dysfunction is readily apparent: a patient might mention a characteristic chief complaint (such as loss of smell or diplopia), or a visually evident physical sign of cranial nerve involvement, such as in facial nerve palsy. However, in many cases a patient's history doesn't directly suggest cranial nerve pathologies, as some of them (such as sixth nerve palsy) may have subtle manifestations and can only be uncovered by a careful neurological exam. Importantly, a variety of pathological conditions that are associated with alterations in mental status (such as some neurodegenerative disorders or brain lesions) can also cause cranial nerve dysfunction; therefore, any abnormal findings during a mental status exam should prompt a careful and complete neurological exam. The cranial nerve examination is applied neuroanatomy. The cranial nerves are symmetrical; therefore, while performing the examination, the examiner should compare each side to the other. A physician should approach the examination in a


 Physical Examinations III

Induction of Paralysis and Visual System Injury in Mice by T Cells Specific for Neuromyelitis Optica Autoantigen Aquaporin-4

1Department of Neurology, University of California, 2Program in Immunology, University of California, 3Department of Neurology and Neurological Sciences, Stanford University, 4Department of Pathology, Stanford University

JoVE 56185


 Immunology and Infection

Studying Diabetes Through the Eyes of a Fish: Microdissection, Visualization, and Analysis of the Adult tg(fli:EGFP) Zebrafish Retinal Vasculature

1Department of Vascular Biology and Tumorangiogenesis, Center for Biomedicine and Medical Technology Mannheim (CBTM), Medical Faculty Mannheim, Heidelberg University, 2V. Medical Clinic, Medical Faculty Mannheim, Heidelberg University

Video Coming Soon

JoVE 56674


 JoVE In-Press

Isolation of Primary Murine Retinal Ganglion Cells (RGCs) by Flow Cytometry

1Department of Ophthalmology, Hamilton Eye Institute, University of Tennessee Health Science Center, 2Department of Microbiology, Immunology and Biochemistry, University of Tennessee Health Science Center, 3Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, 4Department of Pharmaceutical Sciences, University of Tennessee Health Science Center

JoVE 55785


 Bioengineering

Experimental Glaucoma Induced by Ocular Injection of Magnetic Microspheres

1Ocular Biology and Therapeutics, University College London Institute of Ophthalmology, 2University College London Institue of Ophthalmology, 3Moorfields Eye Hospital, 4NIHR Biomedical Research Centre, Moorfields Eye Hospital, 5Schepens Eye Research Institute, Harvard Medical School, 6Hoffman-La Roche

JoVE 52400


 Medicine

Cranial Nerves Exam II (VII-XII)

JoVE 10005

Source:Tracey A. Milligan, MD; Tamara B. Kaplan, MD; Neurology, Brigham and Women's/Massachusetts General Hospital, Boston, Massachusetts, USA

The cranial nerve examination follows the mental status evaluation in a neurological exam. However, the examination begins with observations made upon greeting the patient. For example, weakness of the facial muscles (which are innervated by cranial nerve VII) can be readily apparent during the first encounter with the patient. Cranial nerve VII (the facial nerve) also has sensory branches, which innervate the taste buds on the anterior two-thirds of the tongue and the medial aspect of the external auditory canal. Therefore, finding ipsilateral taste dysfunction in a patient with facial weakness confirms the involvement of cranial nerve VII. In addition, knowledge of the neuroanatomy helps the clinician to localize the level of the lesion: unilateral weakness of the lower facial muscles suggests a supranuclear lesion on the opposite side, while lesions involving the nuclear or infranuclear portion of the facial nerve manifest with an ipsilateral paralysis of all the facial muscles on the involved side. Cranial nerve VIII (the acoustic nerve) has two divisions: the hearing (cochlear) division and the vestibular division, which innervates the semi


 Physical Examinations III

Ophthalmoscopic Examination

JoVE 10146

Source: Richard Glickman-Simon, MD, Assistant Professor, Department of Public Health and Community Medicine, Tufts University School of Medicine, MA

The simplest ophthalmoscopes consist of an aperture to look through, a diopter indicator, and a disc for selecting lenses. The ophthalmoscope is primarily used to examine the fundus, or the inner wall of the posterior eye, which consists of the choroid, retina, fovea, macula, optic disc, and retinal vessels (Figure 1). The spherical eyeball collects and focuses light on the neurosensory cells of the retina. Light is refracted as it passes sequentially through the cornea, the lens, and the vitreous body. The first landmark observed during the funduscopic exam is the optic disc, which is where the optic nerve and retinal vessels enter the back of the eye (Figure 2). The disc usually contains a central whitish physiologic cup where the vessels enter; it normally occupies less than half the diameter of the entire disc. Just lateral and slightly inferior is the fovea, a darkened circular area that demarcates the point of central vision. Around this is the macula. A blind spot approximately 15° temporal to the line of gaze results from a lack of photoreceptor cells at the optic disc.

Endoscopic Endonasal Trans-Sphenoidal Approach: Minimally Invasive Surgery for Pituitary Adenomas

1Department of Neurosurgery, University Hospital of Lausanne, 2Department of Otorhinolaryngology, University Hospital of Lausanne

Video Coming Soon

JoVE 55896


 JoVE In-Press

Eye Exam

JoVE 10149

Source: Richard Glickman-Simon, MD, Assistant Professor, Department of Public Health and Community Medicine, Tufts University School of Medicine, MA

Proper evaluation of the eyes in a general practice setting involves vision testing, orbit inspection, and ophthalmoscopic examination. Before beginning the exam, it is crucial to be familiar with the anatomy and physiology of the eye. The upper eyelid should be slightly over the iris, but it shouldn't cover the pupil when open; the lower lid lies below the iris. The sclera normally appears white or slightly buff in color. The appearance of conjunctiva, a transparent membrane covering the anterior sclera and the inner eyelids, is a sensitive indicator of ocular disorders, such as infections and inflammation. The tear-producing lacrimal gland lies above and lateral to the eyeball. Tears spread down and across the eye to drain medially into two lacrimal puncta before passing into the lacrimal sac and nasolacrimal duct to the nose. The iris divides the anterior from the posterior chamber. Muscles of the iris control the size of the pupil, and muscles of the ciliary body behind it control the focal length of the lens. The ciliary body also produces aqueous humor, which largely determines intraocular pressure (Figure 1). Cranial nerve


 Physical Examinations II

Lateral Canthotomy and Inferior Cantholysis

JoVE 10266

Source: James W Bonz, MD, Emergency Medicine, Yale School of Medicine, New Haven, Connecticut, USA

Lateral canthotomy is a potentially eyesight-saving procedure when performed emergently for an orbital compartment syndrome. An orbital compartment syndrome results from a buildup of pressure behind the eye; as pressure mounts, both the optic nerve and its vascular supply are compressed, rapidly leading to nerve damage and blindness if the pressure is not quickly relieved. The medial and lateral canthal tendons hold the eyelids firmly in place forming an anatomical compartment with limited space for the globe. In an orbital compartment syndrome, pressure rapidly increases as the globe is forced against the eyelids. Lateral canthotomy is the procedure by which the lateral canthal tendon is severed, thereby releasing the globe from its fixed position. Often, severing of the lateral canthal tendon alone is not enough to release the globe and the inferior portion (inferior crus) of the lateral canthal tendon also needs to be severed (inferior cantholysis). This increases precious space behind the eye by allowing the globe to become more proptotic, resulting in decompression. Most frequently, orbital compartment syndrome is the result of acute facial trauma, with the subsequent development of a retrobulbar


 Emergency Medicine and Critical Care

Finding Your Blind Spot and Perceptual Filling-in

JoVE 10195

Source: Laboratory of Jonathan Flombaum—Johns Hopkins University

In the back of everyone's eye is a small piece of neural tissue called the retina. The retina has photosensitive cells that respond to stimulation by light. The responses of these cells are sent into the brain through the optic nerve, a bundle of neural fibers. In each retina there is a place somewhere in the periphery where the outputs from retinal cells collect and the bundled optic nerve exits to the brain. At that location, there is no photosensitivity-whatever light reflects from the world and lands in that position does not produce a signal in the brain. As a result, humans have a blind spot, a place in the visual field for which they don't process incoming stimuli. However, people are not aware that they have blind spots; there is not an empty hole in the visual images in front of the eyes. So what do people see in their blind spots? The brain actually fills-in missing input based on the surroundings. This video demonstrates how to find a person's blind spot, and how to investigate the mechanisms of perceptual filling-in.


 Sensation and Perception

Implementation of a Coherent Anti-Stokes Raman Scattering (CARS) System on a Ti:Sapphire and OPO Laser Based Standard Laser Scanning Microscope

1INSERM U1051, Institut des Neurosciences de Montpellier (INM), Université de Montpellier, 2Université de Nîmes, 3CNRS, IES, UMR 5214, 4Aix-Marseille Université, CNRS, École Centrale Marseille, Institut Fresnel, UMR 7249, 5Montpellier RIO Imaging (MRI)

JoVE 54262


 Biology

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