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Title | Description | Type |
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Figure 65: Vascular Distribution and Anatomy (Including 3rd Nerve) of the Rostral Midbrain | In this axial section of the midbrain at the level of the superior colliculus, the paired 3rd nuclei are located ventral to the periaqueductal grey, and the midline central caudal nucleus (CCN) is located in between. The fascicles that exit the IIIrd nuclei carry the fibers destined to innervate the... | Image |
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Figure 65: Vascular Distribution and Anatomy (Including 3rd Nerve) of the Rostral Midbrain (Supplement) | | Image |
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Figure 65: Vascular Distribution and Anatomy (Including 3rd Nerve) of the Rostral Midbrain (Supplement) | | Image |
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Figure 68: The Course of the 4th (IV) Nerve | The 4th nucleus lies at the ventral border of the periaqueductal gray matter, at the level of the inferior colliculus. The fascicles exit the nucleus dorsally and decussate at the anterior medullary velum (anterior floor of the fourth ventricle), and then exit the brainstem dorsally. The peripheral ... | Image |
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Figure 68: The Course of the 4th (IV) Nerve (Supplement) | | Image |
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Figure 69: Vascular Distribution and Anatomy (Including 4th Nerve) of the Caudal Midbrain | In this axial section of the midbrain at the level of the inferior colliculus, the 4th nuclei are located ventral to the periaqueductal grey, dorsal to the medial longitudinal fasciculus (MLF) and medial to the oculosympathetic tract. Fascicles exit the nucleus dorsally and decussate at the anterior... | Image |
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Figure 69: Vascular Distribution and Anatomy (Including 4th Nerve) of the Caudal Midbrain (Supplement) | | Image |
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Figure 69: Vascular Distribution and Anatomy (Including 4th Nerve) of the Caudal Midbrain (Supplement) | | Image |
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Figure 80: Vascular Distribution and Anatomy Relevant to the Medial Medullary Syndrome | This axial section of the medulla highlights those structures that, when damaged, are often responsible for spontaneous upbeat nystagmus (UBN). The nucleus of Roller and nucleus intercalatus normally have an inhibitory influence over the cerebellar flocculus, and when there is a lesion of Roller/int... | Image |
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Figure 80: Vascular Distribution and Anatomy Relevant to the Medial Medullary Syndrome (Supplement) | | Image |
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Figure 80: Vascular Distribution and Anatomy Relevant to the Medial Medullary Syndrome (Supplement) | | Image |
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Periodic Alternating Nystagmus Due to Nodulus Stroke (Figure 1) | This is a 70-year-old woman who experienced the acute onset of vertigo and imbalance. MRI demonstrated a diffusion-weighted imaging hyperintensity involving the nodulus (with corresponding ADC hypointensity) consistent with an acute stroke. On examination several weeks after the stroke, periodic alt... | Image |
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Sagittal Section of the Midbrain Showing Structures Related to Normal Eyelid Function | 𝗢𝗿𝗶𝗴𝗶𝗻𝗮𝗹 𝗗𝗲𝘀𝗰𝗿𝗶𝗽𝘁𝗶𝗼𝗻: During a vertical saccade, the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF) is activated, which excites the superior rectus (SR) and inferior oblique (IO) (IIIrd nerve) subnuclei. Additionall... | Image |
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Subtle Torsional Pendular Nystagmus in Oculopalatal Tremor (OPT) (Figure 1) | This is a 50-year-old woman who presented with imbalance, and MRI demonstrated a right cerebellar cavernous malformation. She underwent surgery to resect the malformation, and post-operatively experienced right hemiparesis and ataxia. Six months after the surgery, balance worsened and vision became ... | Image |
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Using Video Head Impulse Testing to Unmask Covert Saccades in Compensated Vestibular Neuritis (Figures 1 and 2) | This is a 30-year-old woman who experienced the acute vestibular syndrome (prolonged vertigo for >24 hours, nausea, unsteadiness, spontaneous nystagmus, head motion intolerance) and was diagnosed with vestibular neuritis. This diagnosis was based on a positive head impulse test to the left (see Figu... | Image |
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A flowchart approach to nystagmus/intrusions | In tandem with the flowchart, the following added clues should be used to help with etiology: i) vector [horizontal, vertical, torsional]; ii) binocular or monocular; iii) spontaneous or provoked [e.g., BPPV]; iv) change with monocular viewing or gaze direction; v) rest of history, neurologic, and o... | Image/StillImage |
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Brainstem Ocular Motor Machinery | Seen here is a sagittal view of the brainstem. The medulla has a significant role in gaze-holding, and the nucleus prepositus hypoglossi (NPH, along with the medial vestibular nucleus ) is the horizontal neural integrator. The abducens (6th) nucleus is located in the dorsal pons, and sends off the 6... | Image/MovingImage |
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Medullary Structures Relevant to Upbeat Nystagmus | This is an axial section of the medulla, slightly more caudal as compared to (please refer to figure "medullary structures relevant to the ocular motor and vestibular consequences of the lateral medullary (Wallenberg) syndrome). Again seen are the inferior cerebellar peduncle (ICP) and caudal aspect... | Image |
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Sagittal Section of the Brainstem Showing Structures Related to Normal Eyelid Function | Seen here is a sagittal view of the brainstem, with the structures relevant to normal eyelid function highlighted. The M-group, which can be found medial to the riMLF (coordinates eye and lid movements), has (weak) projections to the facial nucleus for frontalis muscle contraction, and (strong) proj... | Image |
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Central Anatomy of the Fourth Nerve | The IVth or trochlear nucleus is located ventral to the central periaqueductal grey matter, dorsal to the medial longitudinal fasciculus (MLF) and medial to the oculosympathetic tract at the level of the inferior colliculus. The fascicles of the IVth nerve travel dorsally and caudally around the cen... | Image |
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Eyelid Anatomy | Seen here are the major muscles of eyelid opening and closure. The levator palpebrae, which is innervated by the oculomotor nerve, inserts on the tarsus via the levator aponeurosis and directly on the skin of the upper eyelid. The superior tarsal muscle (also known as Muller's muscle, which is inner... | Image |
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Relationship Between Semicircular Canals and Extraocular Muscles | Figure 1: When stimulated, each of the 6 angular acceleration detecting semicircular canals (3 on the right and 3 on the left) responds with a conjugate eye movement, with the vector(s) indicated below. PC=posterior canal; HC=horizontal (also known as lateral) canal; AC=anterior (also known as super... | Image |
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Pons: 6th and 7th Nerve Anatomy and the Central Segmental Tract | From this cross-section of the pons, the proximity of the 6th nucleus to the 7th nerve fascicles is apparent. This is the basis of the so-called facial colliculus syndrome, where an ipsilesional horizontal gaze palsy from a nuclear 6th lesion (usually related to stroke or demyelination) can be seen ... | Image |
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Coronal Section of the Brainstem Showing Ocular Motor Nuclei and Anatomy of the Vestibular Nucleus (with SCC Inputs) | (A) Seen here is a coronal view of the brainstem showing the locations of the ocular motor nuclei (IIIrd, IVth, VIth) as well as the nuclei of VII and VIII (vestibular and cochlear). The vestibular nucleus (VN) is divided into the inferior, lateral, medial, and superior subnuclei, and the medial ves... | Image |
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Saccadic Pathways in the Brainstem and Cerebellum & Mechanism for Saccadic Dysmetria in Wallenberg Syndrome - Normal Function of the Brainstem/Cerebellar Saccadic Pathways | The inferior cerebellar peduncle (ICP) carries climbing fibers to the dorsal vermis, and these fibers have an inhibitory influence over the Purkinje cells. These Purkinje cells normally inhibit the ipsilateral fastigial nucleus, and the fastigial nucleus projects to the contralateral inhibitory burs... | Image |