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General Visceral Efferent Fiber
General visceral efferent fibers (GVE), visceral efferents or autonomic efferents are the efferent nerve fibers of the autonomic nervous system (also known as the ''visceral efferent nervous system'') that provide motor innervation to smooth muscle, cardiac muscle, and glands (contrast with special visceral efferent (SVE) fibers) through postganglionic varicosities. GVE fibers may be either sympathetic or parasympathetic. Cranial and sacral spinal fibers are parasympathetic GVE fibers, while thoracic and lumbar spinal cord give rise to sympathetic GVE fibers. The cranial nerves containing GVE fibers include the oculomotor nerve (CN III), the facial nerve (CN VII), the glossopharyngeal nerve (CN IX) and the vagus nerve (CN X).Mehta, Samir et al. Step-Up: A High-Yield, Systems-Based Review for the USMLE Step 1. Baltimore, MD: LWW, 2003. Additional images File:Gray840.png, Sympathetic connections of the ciliary and superior cervical ganglia. File:Gray839.png, Autonomic nervous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Somatic Efferent Fibers
The general (spinal) somatic efferent neurons (GSE, somatomotor, or somatic motor fibers) arise from motor neuron cell bodies in the ventral horns of the gray matter within the spinal cord. They exit the spinal cord through the ventral roots, carrying motor impulses to skeletal muscle through a neuromuscular junction. Of the somatic efferent neurons, there exist subtypes. * Alpha motor neurons (α) target extrafusal muscle fibers. * Gamma motor neurons (γ) target intrafusal muscle fibres Cranial nerves also supply their own somatic efferent neurons to the extraocular muscles and some of the muscles of the tongue. See also * Nerve fiber * Efferent nerve * General visceral efferent fiber (GVE) * Special visceral efferent fiber (SVE) References Peripheral nervous system {{Portal bar, Anatomy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oculomotor Nerve
The oculomotor nerve, also known as the third cranial nerve, cranial nerve III, or simply CN III, is a cranial nerve that enters the orbit through the superior orbital fissure and innervates extraocular muscles that enable most movements of the eye and that raise the eyelid. The nerve also contains fibers that innervate the intrinsic eye muscles that enable pupillary constriction and accommodation (ability to focus on near objects as in reading). The oculomotor nerve is derived from the basal plate of the embryonic midbrain. Cranial nerves IV and VI also participate in control of eye movement. Structure The oculomotor nerve originates from the third nerve nucleus at the level of the superior colliculus in the midbrain. The third nerve nucleus is located ventral to the cerebral aqueduct, on the pre-aqueductal grey matter. The fibers from the two third nerve nuclei located laterally on either side of the cerebral aqueduct then pass through the red nucleus. From the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Special Visceral Efferent Fiber
Special visceral efferent fibers (SVE) are the efferent nerve fibers that provide motor innervation to the muscles of the pharyngeal arches in humans, and the branchial arches in fish. Some sources prefer the term "branchiomotor" or "branchial efferent". The only nerves containing SVE fibers are cranial nerves: the trigeminal nerve (V), the facial nerve (VII), the glossopharyngeal nerve (IX), the vagus nerve (X) and the accessory nerve (XI).Drake et al. (2010), Gray's Anatomy for Students, 2nd Ed., Churchill Livingstone. See also * General somatic efferent fiber (GSE) * General visceral efferent fiber General visceral efferent fibers (GVE), visceral efferents or autonomic efferents are the efferent nerve fibers of the autonomic nervous system (also known as the ''visceral efferent nervous system'') that provide motor innervation to smooth musc ... (GVE) References Neuroanatomy {{Neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Somatic Efferent Fiber
The general (spinal) somatic efferent neurons (GSE, somatomotor, or somatic motor fibers) arise from motor neuron cell bodies in the ventral horns of the gray matter within the spinal cord. They exit the spinal cord through the ventral roots, carrying motor impulses to skeletal muscle through a neuromuscular junction. Of the somatic efferent neurons, there exist subtypes. * Alpha motor neurons (α) target extrafusal muscle fibers. * Gamma motor neurons (γ) target intrafusal muscle fibres Cranial nerves also supply their own somatic efferent neurons to the extraocular muscles and some of the muscles of the tongue. See also * Nerve fiber * Efferent nerve * General visceral efferent fiber General visceral efferent fibers (GVE), visceral efferents or autonomic efferents are the efferent nerve fibers of the autonomic nervous system (also known as the ''visceral efferent nervous system'') that provide motor innervation to smooth musc ... (GVE) * Special visceral efferent fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Efferent Nerve
A motor nerve, or efferent nerve, is a nerve that contains exclusively efferent nerve fibers and transmits motor signals from the central nervous system (CNS) to the effector organs (muscles and glands), as opposed to sensory nerves, which transfer signals from sensory receptors in the periphery to the CNS. This is different from the motor neuron, which includes a cell body and branching of dendrites, while the nerve is made up of a bundle of axons. In the strict sense, a "motor nerve" can refer exclusively to the connection to muscles, excluding other organs. The vast majority of nerves contain both sensory and motor fibers and are therefore called mixed nerves. Structure and function Motor nerve fibers transduce signals from the CNS to peripheral neurons of proximal muscle tissue. Motor nerve axon terminals innervate skeletal and smooth muscle, as they are heavily involved in muscle control. Motor nerves tend to be rich in acetylcholine vesicles because the motor nerve, a bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preganglionic Fibers
In the autonomic nervous system, nerve fibers from the central nervous system to the ganglion are known as preganglionic nerve 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 * Nerve fiber * Grey column * Terminal cisterna * Rexed lamina * Postganglionic nerve fiber * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nerve Fiber
An axon (from Greek ἄξων ''áxōn'', axis) or nerve fiber (or nerve fibre: see spelling differences) is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action potentials away from the nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. In certain sensory neurons ( pseudounipolar neurons), such as those for touch and warmth, the axons are called afferent nerve fibers and the electrical impulse travels along these from the periphery to the cell body and from the cell body to the spinal cord along another branch of the same axon. Axon dysfunction can be the cause of many inherited and acquired neurological disorders that affect both the peripheral and central neurons. Nerve fibers are classed into three typesgroup A nerve fibers, group B nerve fibers, and group C nerve fibers. Groups A and B are myelinated, and group C are unmyelinated. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vagus Nerve
The vagus nerve, also known as the tenth cranial nerve (CN X), plays a crucial role in the autonomic nervous system, which is responsible for regulating involuntary functions within the human body. This nerve carries both sensory and motor fibers and serves as a major pathway that connects the brain to various organs, including the heart, lungs, and digestive tract. As a key part of the parasympathetic nervous system, the vagus nerve helps regulate essential involuntary functions like heart rate, breathing, and digestion. By controlling these processes, the vagus nerve contributes to the body's "rest and digest" response, helping to calm the body after stress, lower heart rate, improve digestion, and maintain homeostasis. The vagus nerve consists of two branches: the right and left vagus nerves. In the neck, the right vagus nerve contains approximately 105,000 fibers, while the left vagus nerve has about 87,000 fibers, according to one source. However, other sources report sl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glossopharyngeal Nerve
The glossopharyngeal nerve (), also known as the ninth cranial nerve, cranial nerve IX, or simply CN IX, is a cranial nerve that exits the brainstem from the sides of the upper Medulla oblongata, medulla, just anterior (closer to the nose) to the vagus nerve. Being a mixed nerve (sensorimotor), it carries afferent sensory and efferent motor information. The motor division of the glossopharyngeal nerve is derived from the Basal plate (neural tube), basal plate of the embryonic medulla oblongata, whereas the sensory division originates from the cranial neural crest. Structure From the anterior portion of the medulla oblongata, the glossopharyngeal nerve passes laterally across or below the Flocculus (cerebellar), flocculus, and leaves the skull through the central part of the jugular foramen. From the superior and inferior ganglia in jugular foramen, it has its own sheath of dura mater. The inferior ganglion on the inferior surface of petrous part of temporal is related with a tri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Facial Nerve
The facial nerve, also known as the seventh cranial nerve, cranial nerve VII, or simply CN VII, is a cranial nerve that emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue. The nerve typically travels from the pons through the facial canal in the temporal bone and exits the skull at the stylomastoid foramen. It arises from the brainstem from an area posterior to the cranial nerve VI (abducens nerve) and anterior to cranial nerve VIII (vestibulocochlear nerve). The facial nerve also supplies preganglionic parasympathetic fibers to several head and neck ganglia. The facial and intermediate nerves can be collectively referred to as the nervus intermediofacialis. The path of the facial nerve can be divided into six segments: # intracranial (cisternal) segment (from brainstem pons to internal auditory canal) # meatal (canalicular) segment (with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cranial Nerves
Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck, including the special senses of Visual perception, vision, taste, Olfaction, smell, and hearing. The cranial nerves emerge from the central nervous system above the level of the Atlas (anatomy), first vertebra of the vertebral column. Each cranial nerve is paired and is present on both sides. There are conventionally twelve pairs of cranial nerves, which are described with Roman numerals I–XII. Some considered there to be thirteen pairs of cranial nerves, including the non-paired cranial nerve zero. The numbering of the cranial nerves is based on the order in which they emerge from the brain and brainstem, from front to back. The terminal nerves (0), olfactory nerves (I) and optic nerves (II) emerge f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Somatic Afferent Fibers
The general somatic afferent fibers (GSA or somatic sensory fibers) are afferent fibers that arise from neurons in sensory ganglia and are found in all the spinal nerves, except occasionally the first cervical. General somatic afferents conduct impulses of Pain#Nociceptive, pain, touch and temperature from the surface of the body through the dorsal roots to the spinal cord, and impulses of muscle sense, tendon sense and joint sense from the deeper structures. See also * Afferent nerve * General visceral afferent fiber (GVA) * Special somatic afferent fiber (SSA) * Special visceral afferent fiber (SVA) References Spinal cord {{Portal bar, Anatomy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
