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Cranial Root Of Accessory Nerves
The cranial root of accessory nerve (or part) is the smaller of the two portions of the accessory nerve. It is generally considered as a part of the vagus nerve and not part of the accessory nerve proper because the cranial component rapidly joins the vagus nerve and serves the same function as other vagal nerve fibers. Recently, the concept of a cranial root of the accessory nerve has been challenged by new neuroanatomical studies which found that an unambiguous cranial root was not present in the majority of the cases. However, a small study in 2007 followed by a substantially larger study published in 2012Cranial roots of the accessory nerve exist in the majority of adult humans. Tubbs RS, Benninger B, Loukas M, Cohen-Gadol AA 2012 Clin Anat. doi: 10.1002/ca.22125 both confirmed that the cranial root of the accessory nerve is commonly found in humans, matching traditional descriptions. Path The cranial root fibers arise from the cells of the nucleus ambiguus and emerge as four or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accessory Nerve
The accessory nerve, also known as the eleventh cranial nerve, cranial nerve XI, or simply CN XI, is a cranial nerve that supplies the sternocleidomastoid and trapezius muscles. It is classified as the eleventh of twelve pairs of cranial nerves because part of it was formerly believed to originate in the brain. The sternocleidomastoid muscle tilts and rotates the head, whereas the trapezius muscle, connecting to the scapula, acts to shrug the shoulder. Traditional descriptions of the accessory nerve divide it into a spinal part and a cranial part. The cranial component rapidly joins the vagus nerve, and there is ongoing debate about whether the cranial part should be considered part of the accessory nerve proper. Consequently, the term "accessory nerve" usually refers only to nerve supplying the sternocleidomastoid and trapezius muscles, also called the spinal accessory nerve. Strength testing of these muscles can be measured during a neurological examination to assess funct ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vagus Nerve
The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right vagus nerves—but they are typically referred to collectively as a single subsystem. The vagus is the longest nerve of the autonomic nervous system in the human body and comprises both sensory and motor fibers. The sensory fibers originate from neurons of the nodose ganglion, whereas the motor fibers come from neurons of the dorsal motor nucleus of the vagus and the nucleus ambiguus. The vagus was also historically called the pneumogastric nerve. Structure Upon leaving the medulla oblongata between the olive and the inferior cerebellar peduncle, the vagus nerve extends through the jugular foramen, then passes into the carotid sheath between the internal carotid artery and the internal jugular vein down to the neck, chest, and abdom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleus Ambiguus
The nucleus ambiguus ("ambiguous nucleus" in English) is a group of large motor neurons, situated deep in the medullary reticular formation named by Jacob Clarke. The nucleus ambiguus contains the cell bodies of neurons that innervate the muscles of the soft palate, pharynx, and larynx which are associated with speech and swallowing. As well as motor neurons, the nucleus ambiguus contains preganglionic parasympathetic neurons which innervate postganglionic parasympathetic neurons in the heart.Machado, BH and Brody, MJ"Role MJ of the nucleus ambiguus in the regulation of heart rate and arterial pressure."/ref> It is a region of histologically disparate cells located just dorsal ( posterior) to the inferior olivary nucleus in the lateral portion of the upper ( rostral) medulla. It receives upper motor neuron innervation directly via the corticobulbar tract. This nucleus gives rise to the branchial efferent motor fibers of the vagus nerve ( CN X) terminating in the laryngeal, pha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Medulla Oblongata
The medulla oblongata or simply medulla is a long stem-like structure which makes up the lower part of the brainstem. It is anterior and partially inferior to the cerebellum. It is a cone-shaped neuronal mass responsible for autonomic (involuntary) functions, ranging from vomiting to sneezing. The medulla contains the cardiac, respiratory, vomiting and vasomotor centers, and therefore deals with the autonomic functions of breathing, heart rate and blood pressure as well as the sleep–wake cycle. During embryonic development, the medulla oblongata develops from the myelencephalon. The myelencephalon is a secondary vesicle which forms during the maturation of the rhombencephalon, also referred to as the hindbrain. The bulb is an archaic term for the medulla oblongata. In modern clinical usage, the word bulbar (as in bulbar palsy) is retained for terms that relate to the medulla oblongata, particularly in reference to medical conditions. The word bulbar can refer to the nerves ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vagus
The vagus nerve, also known as the tenth cranial nerve, cranial nerve X, or simply CN X, is a cranial nerve that interfaces with the parasympathetic control of the heart, lungs, and digestive tract. It comprises two nerves—the left and right vagus nerves—but they are typically referred to collectively as a single subsystem. The vagus is the longest nerve of the autonomic nervous system in the human body and comprises both sensory and motor fibers. The sensory fibers originate from neurons of the nodose ganglion, whereas the motor fibers come from neurons of the dorsal motor nucleus of the vagus and the nucleus ambiguus. The vagus was also historically called the pneumogastric nerve. Structure Upon leaving the medulla oblongata between the olive and the inferior cerebellar peduncle, the vagus nerve extends through the jugular foramen, then passes into the carotid sheath between the internal carotid artery and the internal jugular vein down to the neck, chest, and abdomen, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jugular Foramen
A jugular foramen is one of the two (left and right) large foramina (openings) in the base of the skull, located behind the carotid canal. It is formed by the temporal bone and the occipital bone. It allows many structures to pass, including the inferior petrosal sinus, three cranial nerves, the sigmoid sinus, and meningeal arteries. Structure The jugular foramen is formed in front by the petrous portion of the temporal bone, and behind by the occipital bone. It is generally slightly larger on the right side than on the left side. Contents The jugular foramen may be subdivided into three compartments, each with their own contents. * The ''anterior'' compartment transmits the inferior petrosal sinus. * The ''intermediate'' compartment transmits the glossopharyngeal nerve, the vagus nerve, and the accessory nerve. * The ''posterior'' compartment transmits the sigmoid sinus (becoming the internal jugular vein), and some meningeal branches from the occipital artery and ascending ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spinal Portion
The spinal root of accessory nerve (or part) is firm in texture, and its fibers arise from the motor cells in the lateral part of the anterior column of the gray substance of the medulla spinalis as low as the fifth cervical nerve. Passing through the lateral funiculus of the medulla spinalis, they emerge on its surface and unite to form a single trunk, which ascends between the ligamentum denticulatum and the posterior roots of the spinal nerves; enters the skull through the foramen magnum, and is then directed to the jugular foramen, through which it passes, lying in the same sheath of dura mater as the vagus, but separated from it by a fold of the arachnoid. In the jugular foramen, it receives one or two filaments from the cranial part of the nerve, or else joins it for a short distance and then separates from it again. As it exits from the jugular foramen, it runs backward in front of the internal jugular vein in 66.6% of cases, and behind it in 33% of cases. The nerve then ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jugular Ganglion
The superior ganglion of the vagus nerve, (jugular ganglion) is a sensory ganglion of the peripheral nervous system. It is located within the jugular foramen, where the vagus nerve exits the skull. It is smaller than and proximal to the inferior ganglion of the vagus nerve. Structure The neurons in the superior ganglion of the vagus nerve are pseudounipolar and provide sensory innervation (general somatic afferent) through either the auricular or meningeal branch. The axons of these neurons synapse in the spinal trigeminal nucleus of the brainstem. Peripherally, the neurons found in the superior ganglion form two branches, the auricular and meningeal branch. Function Auricular branch of the vagus nerve The superior ganglion contains neurons which innervate the concha of the auricle, the posteroinferior surface of the external auditory canal and posteroinferior surface of the tympanic membrane all via the auricular branch of the vagus nerve. Meningeal branch of the v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jugular
The jugular veins are veins that take deoxygenated blood from the head back to the heart via the superior vena cava. The internal jugular vein descends next to the internal carotid artery and continues posteriorly to the sternocleidomastoid muscle. Structure and Function There are two sets of jugular veins: external and internal. The left and right external jugular veins drain into the subclavian veins. The internal jugular veins join with the subclavian veins more medially to form the brachiocephalic veins. Finally, the left and right brachiocephalic veins join to form the superior vena cava, which delivers deoxygenated blood to the right atrium of the heart. The Jugular veins help carry blood from the heart to and from the brain. An average human brain weighs about 3 pounds, and gets about 15%-20% of the blood that the heart pumps out. It is important for the brain to get enough blood for many reasons. The jugular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Musculus Uvulæ
The palatine uvula, usually referred to as simply the uvula, is a conic projection from the back edge of the middle of the soft palate, composed of connective tissue containing a number of racemose glands, and some muscular fibers. It also contains many serous glands, which produce thin saliva. It is only found in human beings. Structure Muscle The muscular part of the uvula () shortens and broadens the uvula. This changes the contour of the posterior part of the soft palate. This change in contour allows the soft palate to adapt closely to the posterior pharyngeal wall to help close the nasopharynx during swallowing. Its muscles are controlled by the pharyngeal branch of the vagus nerve. Variation A bifid or bifurcated uvula is a split or cleft uvula. Newborns with cleft palate often also have a split uvula. The bifid uvula results from incomplete fusion of the palatine shelves but it is considered only a slight form of clefting. Bifid uvulas have less muscle in them ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Levator Veli Palatini
The levator veli palatini () is the elevator muscle of the soft palate in the human body. It is supplied via the pharyngeal plexus. During swallowing, it contracts, elevating the soft palate to help prevent food from entering the nasopharynx. Structure The levator veli palatini muscle is found in the soft palate of the mouth. It arises from the under surface of the apex of the petrous part of the temporal bone, and from the surface inferolateral to the medial lamina of the cartilage of the Eustachian tube. It does not connect with the medial lamina. It passes above the upper concave margin of the superior pharyngeal constrictor muscle. It spreads out in the palatine velum, its fibers extending obliquely downward and medially to the middle line, where they blend with those of the opposite side. It lies lateral to the choana. Nerve supply The levator veli palatini muscle is supplied by the pharyngeal plexus, which is supplied by the vagus nerve (CN X). Function The levat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
