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Chemosensory Disorders and Nutrition
Published in Alan R. Hirsch, Nutrition and Sensation, 2023
Carl M. Wahlstrom, Alan R. Hirsch, Bradley W. Whitman
For olfaction to occur, all parts of the system must be operational. Cranial nerve function is a prerequisite for the cortical interpretation of smell. Similarly, a functioning cortex must integrate the transmitted information. When the cranial nerve is abnormal, odors can neither be detected (abnormal threshold) nor identified (abnormal suprathreshold). With abnormalities of the olfactory cortex, odors can be perceived since threshold levels remain normal, but the identification of these signals is not possible because of suprathreshold abnormalities. We thus infer that threshold tests measure peripheral nerve function, while suprathreshold tests measure the integrity of cortical integration.
Facial anatomy
Published in Michael Parker, Charlie James, Fundamentals for Cosmetic Practice, 2022
The trigeminal nerve is the fifth cranial nerve and has the following sensory and motor functions: Sensory innervation to the skin, mucous membranes and sinuses of the faceMotor function is derived solely from the mandibular branch of the trigeminal nerve which innervates the muscles of mastication, namely the masseter, temporalis, and medial and lateral pterygoid muscles The origin of the trigeminal nerve can be appreciated as a confluence of three sensory nuclei: the mesenteric nucleus from the midbrain, the principal sensory nucleus of the pons and the spinal nucleus of the medulla oblongata. These three nuclei combine within the pons to create the trigeminal nerve root. The smaller motor nerve root also arises from the pons and can be found directly inferior to the trigeminal nerve root.
7th Cranial Nerve (Facial) Palsy
Published in K. Gupta, P. Carmichael, A. Zumla, 100 Short Cases for the MRCP, 2020
K. Gupta, P. Carmichael, A. Zumla
The facial nerve (7th cranial nerve) supplies the muscles of facial expression, the stapedius muscle, and is responsible for the taste sensation from the anterior two-thirds of the tongue. Parasympathetic motor fibres to the salivary glands and chorda tympani are also carried with the facial nerve. Since a minor degree of facial asymmetry is not uncommon, one should not jump into making a diagnosis of facial nerve palsy without a thorough examination revealing the presence of definitive physical signs. The most common cause for an upper motor neurone lesion is a stroke that is characterized by weakness of the lower face contralateral to the lesion. The upper face is spared because of the bilateral innervation.
The therapeutic effect of nano-zinc on the optic nerve of offspring rats and their mothers treated with lipopolysaccharides
Published in Egyptian Journal of Basic and Applied Sciences, 2023
Eman Mohammed Emara, Hassan Ih El-Sayyad, Amr M Mowafy, Heba a El-Ghaweet
The optic nerve (cranial nerve II) is a central nervous system (CNS) tract that passes through the optic canal to leave the orbit. It is made up of the retinal ganglion cells (RGCs) axons. It allows vision by transmitting neural impulses from the retina to the brain. It is divided into four sections: the intraocular nerve head, the intraorbital, the intracanalicular and the intracranial [6]. The types of glial cells in the optic nerve are oligodendrocytes, astrocytes and microglia. Oligodendrocytes are responsible for producing the myelin sheaths that protect the CNS axons and contact nodes of Ranvier as well as they are the locations where action potentials are propagated and axonal integrity. Astrocytes are responsible for numerous physiological and pathological activities such as potassium homeostasis and metabolism as well as reactive astrogliosis in response to CNS trauma. Microglia are immune cells in CNS and have a significant impact on inflammation and infections [7].
Neurological manifestations of SARS-CoV-2 infections: towards quantum dots based management approaches
Published in Journal of Drug Targeting, 2023
Faezeh Almasi, Fatemeh Mohammadipanah
Part of the PNS is the set of 12 paired cranial nerves directly connected to the brain. One of the main cranial nerves controlling the sensory functions of the face is the trigeminal nerve. There are reports presenting the RNA fragments of SARS-CoV-2 in this sensory nerve indicating the probable transfer of SARS-CoV-2 to CNS via the trigeminal nerve. It is also proposed that SARS-CoV-2 spread to the medullary cardiorespiratory centres after lung infection through the mechanoreceptors of the vagus nerve, the longest nerve of cranial nerves [93]. It has been reported that other respiratory viruses, like influenza, can enter the CNS via the sensory vagus nerve [61]. Moreover, some reports demonstrate the infection of peripheral nervous gastrointestinal systems by SARS-CoV-2 [94].
Communication between the gut microbiota and peripheral nervous system in health and chronic disease
Published in Gut Microbes, 2022
Tyler M. Cook, Virginie Mansuy-Aubert
Neuronal transmission allows for nearly instantaneous processing of sensory input or generation of motor output. This rapid signaling of peripheral neurons in the gut is critical for homeostatic mechanisms such as GI motility, secretion, and even immune response modulation.39 The peripheral nervous system (PNS) consists of vagal and spinal sensory (afferent) neurons, autonomic motor (efferent) neurons, and enteric neurons (Figure 2). Afferent neurons send information from the periphery to the brain or spinal cord, while efferent neurons project out from the central nervous system (CNS) to peripheral organs. Classifying by anatomical distribution, the twelve cranial nerves project from the brain/brainstem and spinal nerves from the spinal cord. The autonomic system is divided into sympathetic, parasympathetic, and enteric nervous systems (ENS).