NERVOUS SYSTEM.presentatation pptx......

Nervous system

1. NERVOUS SYSTEM DR HAFIZA SHEHREEN DPT(KING EDWARD MEDICAL UNIVERSITY)

2. Sympathetic nervous system Sympathetic nervous system also known as thoracolumbar pathway Pre ganglionic fibers arise in lateral horn cell of T1-L2 Segments of spinal cord These fibers pass through ventral root ,then spinal nerve and then enter the sympathetic ganglions through white rami communicants (WRC) Thus white rami communicants are present T1-L2 spinal nerves

3. These fibers can ascend in higher ganglions These fibers can also descend to lower ganglions The post ganglionic fibers are given to all the spinal nerves through grey rami communicants (GRC) Thus grey rami communicants are present in all the spinal nerves The pre ganglionic fibers are small and post ganglionic fibers are large in SNS Some fibers don’t relay in sympathetic ganglion .The emerge as; Greater splanchnic nerve T5-T9 ganglions Lesser splanchnic nerves T10-T11 ganglions Least splanchnic nerves T12 ganglions

4. They pierce the crus of diaphragm and relays in the celiac ganglion to form celiac plexus Post ganglionic fibers supply the GIT Some fibers don’t relay in the celiac ganglion but they directly innervate tissues and organs such as adrenal medulla

5. Parasympathetic nervous system The connector cells of this part of the system are located in the brain and the sacral segments of the spinal . Those in the brain form parts of the nuclei of origin of cranial nerves III, VII, IX, and X, and the axons emerge from the brain contained in the corresponding cranial nerves . All the efferent fibers described so far are preganglionic, and they synapse with excitor cells in peripheral ganglia, which are usually situated close to the viscera they innervate . The cranial preganglionic fibers relay in the ciliary, pterygopalatine, submandibular, and otic ganglia Characteristically, the postganglionic fibers are nonmyelinated and are relatively short compared with sympathetic postganglionic fibers.

6. The sacral connector cells are found in the gray matter of the 2nd, 3rd and 4th sacral segments of the cord. These cells are not suff i ciently numerous to form a lateral gray horn, as do the sympathetic connector cells in the thora-columbar region. The myelinated axons leave the spinal cord in the anterior nerve roots of the corresponding spi-nal nerves. They then leave the sacral nerves and form the pelvic splanchnic nerves.