|
Cervical Ganglion
The cervical ganglia are paravertebral ganglia of the sympathetic nervous system. Preganglionic nerves from the thoracic spinal cord enter into the cervical ganglions and synapse with its postganglionic fibers or nerves. The cervical ganglion has three paravertebral ganglia: * superior cervical ganglion (largest) - adjacent to C2 & C3; postganglionic axon projects to target: (heart, head, neck) via "hitchhiking" on the carotid arteries * middle cervical ganglion (smallest) - adjacent to C6; target: heart, neck * inferior cervical ganglion. The inferior ganglion may be fused with the first thoracic ganglion to form a single structure, the stellate ganglion. - adjacent to C7; target: heart, lower neck, arm, posterior cranial arteries Nerves emerging from cervical sympathetic ganglia contribute to the cardiac plexus The cardiac plexus is a plexus of nerves situated at the base of the heart that innervates the heart. Structure The cardiac plexus is divided into a superficial par ... [...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 Nervous System
The sympathetic nervous system (SNS) is one of the three divisions of the autonomic nervous system, the others being the parasympathetic nervous system and the enteric nervous system. The enteric nervous system is sometimes considered part of the autonomic nervous system, and sometimes considered an independent system. The autonomic nervous system functions to regulate the body's unconscious actions. The sympathetic nervous system's primary process is to stimulate the body's fight or flight response. It is, however, constantly active at a basic level to maintain homeostasis. The sympathetic nervous system is described as being antagonistic to the parasympathetic nervous system which stimulates the body to "feed and breed" and to (then) "rest-and-digest". Structure There are two kinds of neurons involved in the transmission of any signal through the sympathetic system: pre-ganglionic and post-ganglionic. The shorter preganglionic neurons originate in the thoracolumbar division o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preganglionic Nerve Fibers
In the autonomic nervous system, fibers from the CNS to the ganglion are known as preganglionic fibers. All preganglionic fibers, whether they are in the sympathetic division or in the parasympathetic division, are cholinergic (that is, these fibers use acetylcholine as their neurotransmitter) and they are myelinated. Sympathetic preganglionic fibers tend to be shorter than parasympathetic preganglionic fibers because sympathetic ganglia are often closer to the spinal cord than are the parasympathetic ganglia. Another major difference between the two ANS (autonomic nervous systems) is divergence. Whereas in the parasympathetic division there is a divergence factor of roughly 1:4, in the sympathetic division there can be a divergence of up to 1:20. This is due to the number of synapses formed by the preganglionic fibers with ganglionic neurons. See also * Postganglionic fibers In the autonomic nervous system, fibers from the ganglion to the effector organ are call ... [...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] |
Superior Cervical Ganglion
The superior cervical ganglion (SCG) is part of the autonomic nervous system (ANS); more specifically, it is part of the sympathetic nervous system, a division of the ANS most commonly associated with the fight or flight response. The ANS is composed of pathways that lead to and from ganglia, groups of nerve cells. A ganglion allows a large amount of divergence in a neuronal pathway and also enables a more localized circuitry for control of the innervated targets. The SCG is the only ganglion in the sympathetic nervous system that innervates the head and neck. It is the largest and most rostral (superior) of the three cervical ganglia. The SCG innervates many organs, glands and parts of the carotid system in the head. Structure Location The SCG is located opposite the second and third cervical vertebrae. It lies deep to the sheath of the internal carotid artery and internal jugular vein, and anterior to the Longus capitis muscle. The SCG contains neurons that supply sympathetic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Middle Cervical Ganglion
The middle cervical ganglion is the smallest of the three cervical ganglia, and is occasionally absent. It is placed opposite the sixth cervical vertebra, usually in front of, or close to, the inferior thyroid artery. It sends gray rami communicantes to the fifth and sixth cervical nerves, and gives off the middle cardiac nerve. It is probably formed by the coalescence of two ganglia corresponding to the fifth and sixth cervical nerves. Branches # Gray Rami Communicantes to the anterior rami of the fifth and sixth cervical nerves. # Thyroid Branches which pass along the inferior thyroid artery to the thyroid gland. # The middle cardiac branch, which descends in the neck and ends in the cardiac plexus in the thorax See also * Middle cardiac nerve The middle cardiac nerve (''great cardiac nerve''), the largest of the three cardiac nerves, arises from the middle cervical ganglion, or from the trunk between the middle and inferior ganglia. On the right side it descends behind the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inferior Cervical Ganglion
The inferior cervical ganglion is situated between the base of the transverse process of the last cervical vertebra and the neck of the first rib, on the medial side of the costocervical artery. Its form is irregular; it is larger in size than the middle cervical ganglion, and is frequently fused with the first thoracic ganglion, under which circumstances it is then called the "stellate ganglion." Structure It is connected to the middle cervical ganglion by two or more cords, one of which forms a loop around the subclavian artery and supplies offsets to it. This loop is named the ''ansa subclavia'' (Vieussenii). The ganglion sends gray rami communicantes to the seventh and eighth cervical nerves. Branches The inferior cervical ganglion gives off two branches: * The Inferior cardiac nerve * ''offsets to bloodvessels'' form plexuses on the subclavian artery and its branches. The plexus on the vertebral artery is continued on to the basilar, posterior cerebral, and cerebellar art ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thoracic Ganglion
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, on ... [...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] |
Cardiac Plexus
The cardiac plexus is a plexus of nerves situated at the base of the heart that innervates the heart. Structure The cardiac plexus is divided into a superficial part, which lies in the concavity of the aortic arch, and a deep part, between the aortic arch and the trachea. The two parts are, however, closely connected. The sympathetic component of the cardiac plexus comes from cardiac nerves, which originate from the sympathetic trunk. The parasympathetic component of the cardiac plexus originates from the cardiac branches of the vagus nerve. Superficial part The superficial part of the cardiac plexus lies beneath the arch of the aorta, in front of the right pulmonary artery. It is formed by the superior cervical cardiac branch of the left sympathetic trunk and the inferior cardiac branch of the left vagus nerve. A small ganglion, the ''cardiac ganglion of Wrisberg'', is occasionally found connected with these nerves at their point of junction. This ganglion, when present, is si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Autonomic Nerves
Autonomic can refer to: *Autonomic nervous system, a division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of internal organs *Autonomic computing Autonomic computing (AC) is distributed computing resources with self-managing characteristics, adapting to unpredictable changes while hiding intrinsic complexity to operators and users. Initiated by IBM in 2001, this initiative ultimately aime ..., the self-managing characteristics of distributed computing resources See also * Autonomy (other) {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
