Spinal Membranes and Nerve Roots
The external, tough, fibrous dura mater continues downward as far as the second sacral vertebra, where it ends blindly. It is separated from the wall of the vertebral canal by…
Cytoarchitecture of Spinal Cord Gray Matter
Posterior Horn. Many neurons in the six laminae of the posterior horn receive direct synaptic input from spinal afferent fibers that enter the spinal cord via the posterior roots and…
Control of Eye Movements—Pathology
In addition to the pathways described above, each ocular motor nucleus also receives input for saccadic and pursuit eye movements that do not involve the vestibular nuclei. These pathways ultimately…
Cochlear Receptors
The cochlea receives dual innervation: afferent fibers, which originate from cell bodies in the adjacent spiral ganglion efferent fibers, which originate in the brainstem. Both types of fibers form synapses…
Nerves and Nuclei in Lateral Dissection
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Pathologic Causes of Vertigo
The eighth cranial nerve is vulnerable to fractures involving the petrous part of the temporal bone and by tumors affecting the brainstem or cerebellum. Vertigo may be caused by central…
Spinal Origin or Termination of Major Descending Tracts and Ascending Pathways
The descending pathways shown in parts A, B, C, and D have a variety of actions on spinal circuitry, including the modulation of somatosensory input and the production of motor…
Vestibulocochlear (VIII) Nerve
VESTIBULAR NERVE At the fundus of the internal acoustic meatus, the vestibular part of the vestibulocochlear nerve expands to form the vestibular ganglion before dividing into superior and inferior divisions….
Visual Pathways
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Facial (VII) Nerve
THE MOTOR DIVISION Fibers arise from the motor facial nucleus, located in the reticular formation of the lowest part of the pons. The nucleus is posterior to the superior olive,…
