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Thoracic Ganglia
The thoracic ganglia are paravertebral ganglia. The thoracic portion of the sympathetic trunk typically has 12 thoracic ganglia. Emerging from the ganglia are thoracic splanchnic nerves (the cardiopulmonary, the greater, lesser, and least splanchnic nerves) that help provide sympathetic innervation to thoracic and abdominal structures. The thoracic part of sympathetic trunk lies posterior to the costovertebral pleura and is hence not a content of the posterior mediastinum Also, the ganglia of the thoracic sympathetic trunk have both white and gray rami communicantes. The white rami communicantes carry sympathetic fibers arising in the spinal cord into the sympathetic trunk, while the gray rami communicantes carry postganglionic nerve fibers of the sympathetic nervous system back to the spinal nerves A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thoracic Splanchnic Nerves
Thoracic splanchnic nerves are splanchnic nerves that arise from the sympathetic trunk in the thorax and travel inferiorly to provide sympathetic supply to the abdomen. The nerves contain preganglionic sympathetic fibers and general visceral afferent fibers. Nerves There are three main thoracic splanchnic nerves. Additional images File:Greater splanchnic nerve.png, Greater splanchnic nerve, seen in thoracic cavity The thoracic cavity (or chest cavity) is the chamber of the body of vertebrates that is protected by the thoracic wall (rib cage and associated skin, muscle, and fascia). The central compartment of the thoracic cavity is the mediastinum. There ... seen from left side. File:Gray848.png, The celiac ganglia with the sympathetic plexuses of the abdominal viscera radiating from the ganglia. File:Gray1120.png, The relations of the viscera and large vessels of the abdomen. Seen from behind, the last thoracic vertebra being well raised. File:Slide2zzzz.JPG, Thoracic s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellate Ganglion
The stellate ganglion (or cervicothoracic ganglion) is a sympathetic ganglion formed by the fusion of the inferior cervical ganglion and the first thoracic (superior thoracic sympathetic) ganglion, which exists in 80% of people. Sometimes, the second and the third thoracic ganglia are included in this fusion. The stellate ganglion is relatively big (10–12 x 8–20 mm) compared to much smaller thoracic, lumbar and sacral ganglia, and is polygonal in shape (). Stellate ganglion is located at the level of C7, anterior to the transverse process of C7 and the neck of the first rib, superior to the cervical pleura and just below the subclavian artery. It is superiorly covered by the prevertebral lamina of the cervical fascia and anteriorly in relation with common carotid artery, subclavian artery and the beginning of vertebral artery which sometimes leaves a groove at the apex of this ganglion (this groove can sometimes even separate the stellate ganglion into so called vertebral gangli ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paravertebral Ganglia
The sympathetic ganglia, or paravertebral ganglia are autonomic ganglia, of the sympathetic nervous system. Ganglia are 20,000 to 30,000 afferent and efferent nerve cell bodies that run along on either side of the spinal cord. Afferent nerve cell bodies bring information from the body to the brain and spinal cord, while efferent nerve cell bodies bring information from the brain and spinal cord to the rest of the body. The cell bodies create long sympathetic chains that are on either side of the spinal cord. They also form para- or pre-vertebral ganglia of gross anatomy. The efferent nerve cell bodies bring information from the brain to the body regarding perceptions of danger. This perception of danger can instigate the fight-or-flight response associated with the sympathetic nervous system. The fight-or-flight response is adaptive when there is a real and present danger which can be avoided or diminished through increased sympathetic activity. Sympathetic activity could be incr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sympathetic Trunk
The sympathetic trunks (sympathetic chain, gangliated cord) are a paired bundle of nerve fibers that run from the base of the skull to the coccyx. They are a major component of the sympathetic nervous system. Structure The sympathetic trunk lies just lateral to the vertebral bodies for the entire length of the vertebral column. It interacts with the anterior rami of spinal nerves by way of rami communicantes. The sympathetic trunk permits preganglionic fibers of the sympathetic nervous system to ascend to spinal levels superior to T1 and descend to spinal levels inferior to L2/3.Greenstein B., Greenstein A. (2002): Color atlas of neuroscience – Neuroanatomy and neurophysiology. Thieme, Stuttgart – New York, . The superior end of it is continued upward through the carotid canal into the skull, and forms a plexus on the internal carotid artery; the inferior part travels in front of the coccyx, where it converges with the other trunk at a structure known as the ganglion impar. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rami Communicantes
Ramus communicans (plural rami communicantes) is the Latin term used for a nerve which connects two other nerves, and can be translated as "communicating branch". Structure When used without further definition, it almost always refers to a communicating branch between a spinal nerve and the sympathetic trunk. More specifically, it usually refers to one of the following : * Gray ramus communicans * White ramus communicans The grey and white rami communicantes are responsible for conveying autonomic signals, specifically for the sympathetic nervous system. Their difference in coloration is caused by differences in myelination of the nerve fibres contained within, i.e. there are more myelinated than unmyelinated fibres in the white rami communicantes while the converse is true for the grey rami communicantes. Gray ramus communicans The grey rami communicantes exist at every level of the spinal cord and are responsible for carrying postganglionic nerve fibres from the paravertebr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White Ramus Communicans
The white ramus communicans (plural: rami communicantes) from Latin ramus (branch) and communicans (communicating) is the preganglionic sympathetic outflow nerve tract from the spinal cord. Each of the thoracic, and the first and second lumbar nerves contribute a white ramus communicans to the adjoining sympathetic ganglion, unlike the gray rami which are located at each spinal level. White rami communicantes contain both myelinated and unmyelinated preganglionic sympathetic fibers, ( GVE and GVA). The white ramus appears white because there are more myelinated than unmyelinated fibers unlike the gray rami. Structure The white rami communicantes are the preganglionic sympathetic outflow from the spinal cord. The cell bodies for the preganglionic sympathetic myelinated fibers in the white rami communicantes lie in the ipsilateral (same sided) intermediolateral cell column in the spinal cord which extends from T1-L2. These rami also contain general visceral afferent fibers (sen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinal Cord
The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spinal cord, which contains cerebrospinal fluid. The brain and spinal cord together make up the central nervous system (CNS). In humans, the spinal cord begins at the occipital bone, passing through the foramen magnum and then enters the spinal canal at the beginning of the cervical vertebrae. The spinal cord extends down to between the first and second lumbar vertebrae, where it ends. The enclosing bony vertebral column protects the relatively shorter spinal cord. It is around long in adult men and around long in adult women. The diameter of the spinal cord ranges from in the cervical and lumbar regions to in the thoracic area. The spinal cord functions primarily in the transmission of nerve signals from the motor cortex to the body, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gray Ramus Communicans
Each spinal nerve receives a branch called a gray ramus communicans (plural rami communicantes) from the adjacent paravertebral ganglion of the sympathetic trunk. The gray rami communicantes contain postganglionic nerve fibers of the sympathetic nervous system and are composed of largely unmyelinated neurons. This is in contrast to the white rami communicantes, in which heavily myelinated neurons give the rami their white appearance. Function Preganglionic sympathetic fibres from the intermediolateral nucleus in the lateral grey column of the spinal cord are carried in the white ramus communicans to the paravertebral ganglia of the sympathetic trunk. Once the preganglionic nerve has traversed a white ramus communicans, it can do one of three things. * The preganglionic neuron can synapse with a postganglionic sympathetic neuron in the sympathetic paravertebral ganglion at that level. From here, the postganglionic sympathetic neuron can travel back out the grey ramus communicans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postganglionic Nerve Fibers
In the autonomic nervous system, fibers from the ganglion to the effector organ are called postganglionic fibers. Neurotransmitters The neurotransmitters of postganglionic fibers differ: * In the parasympathetic division, neurons are ''cholinergic''. That is to say acetylcholine is the primary neurotransmitter responsible for the communication between neurons on the parasympathetic pathway. * In the sympathetic division, neurons are mostly ''adrenergic'' (that is, epinephrine and norepinephrine function as the primary neurotransmitters). Notable exceptions to this rule include the sympathetic innervation of sweat glands and arrectores pilorum muscles where the neurotransmitter at both pre and post ganglionic synapses is acetylcholine. Another notable structure is the medulla of the adrenal gland, where chromaffin cells function as modified post-ganglionic nerves. Instead of releasing epinephrine and norepinephrine into a synaptic cleft, these cells of the adrenal medulla rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinal Nerve
A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system. Structure Each spinal nerve is a mixed nerve, formed from the combination of nerve fibers from its dorsal and ventral roots. The dorsal root is the afferent sensory root and carries sensory information to the brain. The ventral root is the efferent motor root and carries motor information from the brain. The spinal nerve emerges from the spinal column through an opening (intervertebral foramen) between adjacent vertebrae. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
