Pons in the context of Facial nerve


Pons in the context of Facial nerve

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⭐ Core Definition: Pons

The pons (from Latin pons, 'bridge') is the part of the brainstem that, in humans and other mammals, lies inferior to the midbrain, superior to the medulla oblongata, and anterior to the cerebellum.

The pons is also called the pons Varolii ('bridge of Variolus'), after the Italian anatomist and surgeon Costanzo Varolio (1543–1575). The pons contains neural pathways and nerve tracts that conduct signals from the brain down to the cerebellum and medulla, as well as pathways that carry the sensory signals up into the thalamus.

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👉 Pons in the context of 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.

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Pons in the context of 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 heart 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 the brain. These pathways include the corticospinal tract (motor function), the dorsal column-medial lemniscus pathway (fine touch, vibration sensation, and proprioception), and the spinothalamic tract (pain, temperature, itch, and crude touch).

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Pons in the context of Respiratory center

The respiratory center is located in the medulla oblongata and pons, in the brainstem. The respiratory center is made up of three major respiratory groups of neurons, two in the medulla and one in the pons. In the medulla they are the dorsal respiratory group, and the ventral respiratory group. In the pons, the pontine respiratory group includes two areas known as the pneumotaxic center and the apneustic center.

The respiratory center is responsible for generating and maintaining the rhythm of respiration, and also of adjusting this in homeostatic response to physiological changes. The respiratory center receives input from chemoreceptors, mechanoreceptors, the cerebral cortex, and the hypothalamus in order to regulate the rate and depth of breathing. Input is stimulated by altered levels of oxygen, carbon dioxide, and blood pH, by hormonal changes relating to stress and anxiety from the hypothalamus, and also by signals from the cerebral cortex to give a conscious control of respiration.

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Pons in the context of Midbrain

The midbrain or mesencephalon is the uppermost portion of the brainstem connecting the diencephalon and cerebrum with the pons. It consists of the cerebral peduncles, tegmentum, and tectum.

It is functionally associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation.

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Pons in the context of Hindbrain

The hindbrain, rhombencephalon (shaped like a rhombus) is a developmental categorization of portions of the central nervous system in vertebrates. It includes the medulla, pons, and cerebellum. Together they support vital bodily processes.

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Pons in the context of Metencephalon

The metencephalon is the embryonic part of the hindbrain that differentiates into the pons and the cerebellum. It contains a portion of the fourth ventricle and the trigeminal nerve (CN V), abducens nerve (CN VI), facial nerve (CN VII), and a portion of the vestibulocochlear nerve (CN VIII).

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Pons in the context of Trigeminal nerve

In neuroanatomy, the trigeminal nerve (lit. triplet nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewing; it is the most complex of the cranial nerves. Its name (trigeminal, from Latin tri- 'three' and -geminus 'twin') derives from each of the two nerves (one on each side of the pons) having three major branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3). The ophthalmic and maxillary nerves are purely sensory, whereas the mandibular nerve supplies motor as well as sensory (or "cutaneous") functions. Adding to the complexity of this nerve is that autonomic nerve fibers as well as special sensory fibers (taste) are contained within it.

The motor division of the trigeminal nerve derives from the basal plate of the embryonic pons, and the sensory division originates in the cranial neural crest. Sensory information from the face and body is processed by parallel pathways in the central nervous system.

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Pons in the context of Pontine micturition center

In neuroanatomy, the pontine micturition center (PMC, also known as Barrington's nucleus) is a collection of neuronal cell bodies located in the rostral pons in the brainstem involved in the supraspinal regulation of micturition (urination). When activated, the PMC relaxes the urethral sphincter, allowing for micturition to occur. The PMC coordinates with other brain centers, including the medial frontal cortex, insular cortex, hypothalamus and periaqueductal gray (PAG). The PAG acts as a relay station for ascending bladder information from the spinal cord and incoming signals from higher brain areas.

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Pons in the context of Gamma motor neuron

A gamma motor neuron (γ motor neuron), also called gamma motoneuron, or fusimotor neuron, is a type of lower motor neuron that takes part in the process of muscle contraction, and represents about 30% of () fibers going to the muscle. Like alpha motor neurons, their cell bodies are located in the anterior grey column of the spinal cord. They receive input from the reticular formation of the pons in the brainstem. Their axons are smaller than those of the alpha motor neurons, with a diameter of only 5 μm. Unlike the alpha motor neurons, gamma motor neurons do not directly adjust the lengthening or shortening of muscles. However, their role is important in keeping muscle spindles taut, thereby allowing the continued firing of alpha neurons, leading to muscle contraction. These neurons also play a role in adjusting the sensitivity of muscle spindles.

The presence of myelination in gamma motor neurons allows a conduction velocity of 4 to 24 meters per second, significantly faster than with non-myelinated axons but slower than in alpha motor neurons.

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Pons in the context of Brain stem

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 heart 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 the brain. These pathways include the corticospinal tract (motor function), the dorsal column-medial lemniscus pathway (fine touch, vibration sensation, and proprioception), and the spinothalamic tract (pain, temperature, itch, and crude touch).

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Pons in the context of Fourth ventricle

The fourth ventricle is one of the four connected fluid-filled cavities within the human brain. These cavities, known collectively as the ventricular system, consist of the left and right lateral ventricles, the third ventricle, and the fourth ventricle. The fourth ventricle extends from the cerebral aqueduct (aqueduct of Sylvius) to the obex, and is filled with cerebrospinal fluid (CSF).

The fourth ventricle has a characteristic diamond shape in cross-sections of the human brain. It is located within the pons or in the upper part of the medulla oblongata. CSF entering the fourth ventricle through the cerebral aqueduct can exit to the subarachnoid space of the spinal cord through two lateral apertures and a single, midline median aperture.

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Pons in the context of Granule cell

The name granule cell has been used for a number of different types of neurons whose only common feature is that they all have very small cell bodies. Granule cells are found within the granular layer of the cerebellum, the dentate gyrus of the hippocampus, the superficial layer of the dorsal cochlear nucleus, the olfactory bulb, and the cerebral cortex.

Cerebellar granule cells account for the majority of neurons in the human brain. These granule cells receive excitatory input from mossy fibers originating from pontine nuclei. Cerebellar granule cells project up through the Purkinje layer into the molecular layer where they branch out into parallel fibers that spread through Purkinje cell dendritic arbors. These parallel fibers form thousands of excitatory granule-cell–Purkinje-cell synapses onto the intermediate and distal dendrites of Purkinje cells using glutamate as a neurotransmitter.

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Pons in the context of Clivus (anatomy)

The clivus (/ˈklvəs/, Latin for "slope") or Blumenbach clivus is a part of the occipital bone at the base of the skull, extending anteriorly from the foramen magnum. It is related to the pons and the abducens nerve (CN VI).

The term is also used for the clivus ocularis, an unrelated feature of the retina.

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Pons in the context of Lacrimal nucleus

The salivatory nuclei are two general visceral efferent nuclei located in the caudal pons, dorsal and lateral to the facial nucleus. Their neurons give rise to preganglionic parasympathetic nerve fibers in the control of salivation. The superior salivatory nucleus supplies fibers to the intermediate nerve (part of the facial nerve (CN VII). The inferior salivatory nucleus supplies fibers to the glossopharyngeal nerve (CN IX). The nuclei may also be involved in parasympathetic control of (extracranial and intracranial) head vasculature.

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Pons in the context of Paramedian pontine reticular formation

The paramedian pontine reticular formation (PPRF) is a subset of neurons of the oral and caudal pontine reticular nuclei. With the abducens nucleus it makes up the horizontal gaze centre. It is situated in the pons adjacent to the abducens nucleus. It projects to the ipsilateral abducens (cranial nerve VI) nucleus, and contralateral oculomotor (cranial nerve III) nucleus to mediate conjugate horizontal gaze and saccades.

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Pons in the context of Locus coeruleus

The locus coeruleus (/sɪˈrliəs/) (LC), also spelled locus caeruleus or locus ceruleus, is a nucleus in the pons of the brainstem involved with physiological responses to stress and panic. It is a part of the reticular activating system in the reticular formation.

The locus coeruleus, which in Latin means "blue spot", is the principal site for brain synthesis of norepinephrine (noradrenaline). The locus coeruleus and the areas of the body affected by the norepinephrine it produces are described collectively as the locus coeruleus-noradrenergic system or LC-NA system. Norepinephrine may also be released directly into the blood from the adrenal medulla.

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