The H or butterfly shape Ventral horn larger Dorsal horn smaller Ventral horn

The h or butterfly shape ventral horn larger dorsal

This preview shows page 126 - 148 out of 172 pages.

The H or "butterfly" shape , Ventral horn-larger Dorsal horn-smaller
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Ventral horn: contains the large somata of autonomic motor neurons . They receive input from integrator neurons in the cord, and send commands to contract to skeletal muscle in the periphery . Dorsal horn: contains neuron somata of the connector neurons (not motor) . They receive input from sensory fibers entering the cord through the dorsal root of the spinal nerve.
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The Leptomeninges Surround the brain and the spinal cord. The cerebrospinal fluid circulates between 2 meningeal layers called the pia matter and the arachnoid (or pia-arachnoid membranes). The outer, thicker layer serves the role of a protective shield and is called the dura matter. The spinal cord is also covered, like the brain, by the pia matter and the arachnoid membranes. The cerebrospinal fluid circulates around the pia and below the outer arachnoid, and this space is also termed the subarachnoid space. The dura surrounds the pia-arachnoid of the spinal cord, as it does for the brain. in spinal cord there is space between the dura mater and the vertebral canal is the epidural (or peridural) space, filled with adipose tissue and it contains a network of blood vessels.
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CSF subarachnoid space.
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The peripheral nervous system
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Constituents of peripheral nervous system 1. Sensory neurons, 2. Ganglia (clusters of neurons) 3. Plexuses: felt works of nerve fibres 4. Nerves and nerve roots. 12 pairs of cranial nerves 31 pairs of spinal nerves Nerve Roots A nerve root is the initial segment of a nerve leaving the central nervous system. 1. A cranial nerve root, the beginning of one of the twelve pairs leaving the central nervous system from the brain stem or the highest levels of the spinal cord; 2. A spinal nerve root , the beginning of one of the thirty-one pairs leaving the central nervous system from the spinal cord.
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Each spinal nerve root consists of the union of a sensory dorsal root and a motor ventral root. The dorsal root (or posterior root) is the afferent sensory root of a spinal nerve. The ventral root (anterior root: is the efferent motor roots of a spinal cord. At its distal end , the ventral root joins with the dorsal root to form a mixed spinal nerve. Mixed (motor and sensory) peripheral nerve: Fibers that carry motor input to limbs and fibers that bring sensory information from the limbs to the spinal cord
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