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Pseudounipolar
A pseudounipolar neuron is a type of neuron which has one extension from its cell body. This type of neuron contains an axon that has split into two branches. A single process arises from the cell body and then divides into an axon and a dendrite. They develop embryologically as bipolar in shape, and are thus termed pseudounipolar instead of unipolar. Structure A pseudounipolar neuron has one axon that projects from the cell body for relatively a very short distance, before splitting into two branches. Pseudounipolar neurons are sensory neurons that have no dendrites, the branched axon serving both functions. The peripheral branch extends from the cell body to organs in the periphery including skin, joints and muscles, and the central branch extends from the cell body to the spinal cord. In the dorsal root ganglia The cell body of a pseudounipolar neuron is located within a dorsal root ganglion. The axon leaves the cell body (and out of the dorsal root ganglion) into the dorsal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neuron
A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. Non-animals like plants and fungi do not have nerve cells. Neurons are typically classified into three types based on their function. Sensory neurons respond to stimuli such as touch, sound, or light that affect the cells of the sensory organs, and they send signals to the spinal cord or brain. Motor neurons receive signals from the brain and spinal cord to control everything from muscle contractions to glandular output. Interneurons connect neurons to other neurons within the same region of the brain or spinal cord. When multiple neurons are connected together, they form what is called a neural circuit. A typical neuron consists of a cell body (soma), dendrites, and a single axon. The soma is a compact structure, and the axon and dend ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipolar Neuron
A bipolar neuron, or bipolar cell, is a type of neuron that has two extensions (one axon and one dendrite). Many bipolar cells are specialized sensory neurons for the transmission of sense. As such, they are part of the sensory pathways for smell, sight, taste, hearing, touch, balance and proprioception. The other shape classifications of neurons include unipolar, pseudounipolar and multipolar. During embryonic development, pseudounipolar neurons begin as bipolar in shape but become pseudounipolar as they mature. Common examples are the retina bipolar cell, the ganglia of the vestibulocochlear nerve, the extensive use of bipolar cells to transmit efferent (motor) signals to control muscles, olfactory receptor neurons in the olfactory epithelium for smell (axons form the olfactory nerve), and neurons in the spiral ganglion for hearing (CN VIII). In the retina Often found in the retina, bipolar cells are crucial as they serve as both direct and indirect cell pathways. The spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensory Neuron
Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded potentials. This process is called sensory transduction. The cell bodies of the sensory neurons are located in the dorsal ganglia of the spinal cord. The sensory information travels on the afferent nerve fibers in a sensory nerve, to the brain via the spinal cord. The stimulus can come from ''exteroreceptors'' outside the body, for example those that detect light and sound, or from ''interoreceptors'' inside the body, for example those that are responsive to blood pressure or the sense of body position. Types and function Different types of sensory neurons have different sensory receptors that respond to different kinds of stimuli. There are at least six external and two internal sensory receptors: External receptors External receptors that respond to stimuli from outside the body are called ex ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inferior Ganglion Of Vagus Nerve
The inferior ganglion of the vagus nerve, (nodose 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 larger than and below the superior ganglion of the vagus nerve. Structure The neurons in the inferior ganglion of the vagus nerve are pseudounipolar and provide sensory innervation (general somatic afferent and general visceral afferent). The axons of the neurons which innervate the taste buds of the epiglottis synapse in the rostral portion of the solitary nucleus (gustatory nucleus). The axons of the neurons which provide general sensory information synapse in the spinal trigeminal nucleus. The axons of the neurons which innervate the aortic bodies, aortic arch, respiratory and gastrointestinal tract, synapse in the caudal part of the solitary nucleus. Function The neurons in the inferior ganglion of the vagus nerve innervate the taste buds on the epiglottis, the chemorecepto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Ganglion Of Vagus Nerve
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] |
Inferior Ganglion Of Glossopharyngeal Nerve
The inferior ganglion of the glossopharyngeal nerve (petrosal ganglion) is a sensory ganglion. It is larger than and inferior to the superior ganglion of the glossopharyngeal nerve. It is located within the jugular foramen. The pseudounipolar neurons of the inferior ganglion of the glossopharyngeal nerve provide sensory innervation to areas around the tongue and pharynx. More specifically: # innervation of taste buds on the posterior 1/3 of tongue # general sensory innervation of posterior 1/3 of tongue, soft palate, palatine tonsils, upper pharynx and Eustachian tubes # innervation of baroreceptor cells in the carotid sinus # innervation of glomus type I chemoreceptor cells in the carotid body The central processes of the neurons which provide taste sensation synapse in the rostral portion of the solitary nucleus (also called the gustatory nucleus). The central processes of the neurons which provide general sensory information synapse in the spinal trigeminal nucleus. Final ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superior Ganglion Of Glossopharyngeal Nerve
The superior ganglion of the glossopharyngeal nerve is a sensory ganglion of the peripheral nervous system. It is located within the jugular foramen where the glossopharyngeal nerve exits the skull. It is smaller than and superior to the inferior ganglion of the glossopharyngeal nerve. The neurons in the superior ganglion of the glossopharyngeal nerve provide sensory innervation to the middle ear and the internal surface of the tympanic membrane. The axons of these neurons branch from the glossopharyngeal nerve at the level of the inferior ganglion and form the tympanic nerve along with the preganglionic parasympathetic axons from the inferior salivatory nucleus. The tympanic nerve then travels through the inferior tympanic canaliculus to the tympanic cavity forming the tympanic plexus. From here the sensory axons provide innervation of the middle ear and internal surface of the tympanic membrane. The parasympathetic axons branch from the tympanic plexus as the lesser petrosal ner ... [...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] |
Central Nervous System
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all parts of the bodies of bilaterally symmetric and triploblastic animals—that is, all multicellular animals except sponges and diploblasts. It is a structure composed of nervous tissue positioned along the rostral (nose end) to caudal (tail end) axis of the body and may have an enlarged section at the rostral end which is a brain. Only arthropods, cephalopods and vertebrates have a true brain (precursor structures exist in onychophorans, gastropods and lancelets). The rest of this article exclusively discusses the vertebrate central nervous system, which is radically distinct from all other animals. Overview In vertebrates, the brain and spinal cord are both enclosed in the meninges. The meninges provide a barrier to chemicals dissolv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brainstem
The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is continuous with the thalamus of the diencephalon through the tentorial notch, and sometimes the diencephalon is included in the brainstem. The brainstem is very small, making up around only 2.6 percent of the brain's total weight. It has the critical roles of regulating cardiac, and respiratory function, helping to control heart rate and breathing rate. It also provides the main motor and sensory nerve supply to the face and neck via the cranial nerves. Ten pairs of cranial nerves come from the brainstem. Other roles include the regulation of the central nervous system and the body's sleep cycle. It is also of prime importance in the conveyance of motor and sensory pathways from the rest of the brain to the body, and from the body back to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vestibular Ganglion
The vestibular ganglion (also called Scarpa's ganglion) is the ganglion of the vestibular nerve. It is located inside the internal auditory meatus. The ganglion contains the cell bodies of bipolar neurons whose peripheral processes form synaptic contact with hair cells of the vestibular sensory end organs. These include hair cells of the cristae ampullares of the semicircular duct and macula in the utricle and saccule. It is named for Antonio Scarpa Antonio Scarpa (9 May 1752 – 31 October 1832) was an Italian anatomist and professor. Biography Scarpa was born to an impoverished family in the frazione of Lorenzaga, Motta di Livenza, Veneto. An uncle, who was a member of the priesthood, gav ....A. Scarpa. Anatomicarum annotationum. 2 volumes, Modena and Pavia, 1779, 1785. 2nd edition, Milano, 1792. At birth, it is already close to its final size. References External links Diagram (in French) Vestibulocochlear nerve Vestibular system {{Neuroanatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spiral Ganglion
The spiral (cochlear) ganglion is a group of neuron cell bodies in the modiolus, the conical central axis of the cochlea. These bipolar neurons innervate the hair cells of the organ of Corti. They project their axons to the ventral and dorsal cochlear nuclei as the cochlear nerve, a branch of the vestibulocochlear nerve (CN VIII). Structure Neurons whose cell bodies lie in the spiral ganglion are strung along the bony core of the cochlea, and send fibers (axons) into the central nervous system (CNS). These bipolar neurons are the first neurons in the auditory system to fire an action potential, and supply all of the brain's auditory input. Their dendrites make synaptic contact with the base of hair cells, and their axons are bundled together to form the auditory portion of eighth cranial nerve. The number of neurons in the spiral ganglion is estimated to be about 35,000–50,000. Two apparent subtypes of spiral ganglion cells exist. Type I spiral ganglion cells comprise the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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