|
Myoclonic Triangle
The myoclonic triangle (also known by its eponym Triangle of Guillain-Mollaret or dentato-rubro-olivary pathway) is an important feedback circuit of the brainstem and deep cerebellar nuclei which is responsible for modulating spinal cord motor activity. The circuit is thus composed: # Fibers of the rubro-olivary tract project from the parvocellular red nucleus via the central tegmental tract to the ipsilateral inferior olivary nucleus. # The inferior olivary nucleus sends its afferents via climbing fibers in the inferior cerebellar peduncle to Purkinje cells of the contralateral cerebellar cortex. # The Purkinje cells send their afferents to the ipsilateral dentate nucleus. # Dentatorubral tract fibers: the dentate nucleus afferents travel via the superior cerebellar peduncle to the contralateral red nucleus, thus completing the circuit. Of note, this circuit contains a double decussation, implying that a lesion in this tract wil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Diseases Of The Nervous System (1908) (14779159452)
Nervous system diseases, also known as nervous system or neurological disorders, refers to a small class of medical conditions affecting the nervous system. This category encompasses over 600 different conditions, including genetic disorders, infections, cancer, seizure disorders (such as epilepsy), conditions with a cardiovascular origin (such as stroke), congenital and developmental disorders (such as spina bifida), and degenerative disorders (such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis). Signs and symptoms Signs and symptoms can vary depending on the condition. Given the significance of the nervous system in human physiology, symptoms can involve other organ systems and result in motor dysfunction, sensory impairment, and pain, among other things. Causes Genetic Some nervous system diseases are due to genetic mutations. For example, Huntington's disease is an inherited disease characterized by progressive neurodege ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Red Nucleus
The red nucleus or nucleus ruber is a structure in the rostral midbrain involved in motor coordination. The red nucleus is pale pink, which is believed to be due to the presence of iron in at least two different forms: hemoglobin and ferritin. The structure is located in the midbrain tegmentum next to the substantia nigra and comprises caudal magnocellular and rostral parvocellular components. The red nucleus and substantia nigra are subcortical centers of the extrapyramidal motor system. Function In a vertebrate without a significant corticospinal tract, gait is mainly controlled by the red nucleus. However, in primates, where the corticospinal tract is dominant, the rubrospinal tract may be regarded as vestigial in motor function. Therefore, the red nucleus is less important in primates than in many other mammals. Nevertheless, the crawling of babies is controlled by the red nucleus, as is arm swinging in typical walking. The red nucleus may play an additional role ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Cerebellar Connections
The cerebellum (: cerebella or cerebellums; Latin for 'little brain') is a major feature of the hindbrain of all vertebrates. Although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as it or even larger. In humans, the cerebellum plays an important role in motor control and cognitive functions such as attention and language as well as emotional control such as regulating fear and pleasure responses, but its movement-related functions are the most solidly established. The human cerebellum does not initiate movement, but contributes to coordination, precision, and accurate timing: it receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine-tune motor activity. Cerebellar damage produces disorders in fine movement, equilibrium, posture, and motor learning in humans. Anatomically, the human cerebellum has the appearance of a separate structure attached to the botto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Holmes Tremor
Holmes tremor, first identified by Gordon Holmes in 1904, can be described as a wing-beating movement localized in the upper body that is caused by cerebellar damage. Holmes tremor is a combination of rest, action, and postural tremors. Tremor frequency ranges from 2 to 5 Hertz and is aggravated with posture and movement. It may arise from various underlying structural disorders including stroke, tumors, trauma, and other cerebellar lesions. Because Holmes tremor is rare, much of the research is based on individual cases. The formation of tremors is due to two main factors: the over-excited rhythmic movement of neuronal loops and permanent structural changes from neurodegeneration. Two major neuronal networks, the corticostriatothalamocortical hap and the inferior olivary nucleus (ION) specifically target the development of the tremors. When diagnosing a patient with Holmes tremor, one must look at the neurological signs and symptoms, as well as the possibility that the tremor is c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Lateral Medullary Syndrome
Lateral medullary syndrome is a neurological disorder causing a range of symptoms due to ischemia in the lateral part of the medulla oblongata in the brainstem. The ischemia is a result of a blockage most commonly in the vertebral artery or the posterior inferior cerebellar artery. Lateral medullary syndrome is also called Wallenberg's syndrome, posterior inferior cerebellar artery (PICA) syndrome and vertebral artery syndrome. Signs and symptoms This syndrome is characterized by sensory deficits that affect the trunk and extremities contralaterally (opposite to the lesion), and sensory deficits of the face and cranial nerves ipsilaterally (same side as the lesion). Specifically a loss of pain and temperature sensation if the lateral spinothalamic tract is involved. The cross body finding is a highly suggestive symptom from which the diagnosis may be considered (however, this a symptom common to all brainstem pathology). Patients often have difficulty walking or maintaining bala ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Palatal Myoclonus
Palatal myoclonus is a rare condition in which there are rhythmic jerky movements or a rapid spasm of the palatal (roof of the mouth) muscles. Chronic clonus is often due to lesions of the central tegmental tract (which connects the red nucleus to the ipsilateral inferior olivary nucleus). When associated with eye movements, it is known as ''oculopalatal myoclonus''. Signs and symptoms Signs and symptoms of palatal myoclonus include: - A rhythmic clicking sound in the ear due to the opening and closing of the Eustachian tube. - Rhythmic, jerky movements in the face, eyeballs, tongue, jaw, vocal cords or extremities (mostly hands). Diagnosis Classifications physiologic, essential, epileptic, and symptomatic Treatment Drugs Drugs used to treat palatal myoclonus include clonazepam, carbamazepine, baclofen, anticholinergics, tetrabenazine, valproic acid, phenytoin, lamotrigine, sumatriptan, and PIR. A rare case of palatal myoclonus that associated with orofacial buccal dystonia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Reticular Formation
The reticular formation is a set of interconnected nuclei in the brainstem that spans from the lower end of the medulla oblongata to the upper end of the midbrain. The neurons of the reticular formation make up a complex set of neural networks in the core of the brainstem. The reticular formation is made up of a diffuse net-like formation of reticular nuclei which is not well-defined. It may be seen as being made up of all the interspersed cells in the brainstem between the more compact and named structures. The reticular formation is functionally divided into the ascending reticular activating system (ARAS), ascending pathways to the cerebral cortex, and the descending reticular system, descending pathways ( reticulospinal tracts) to the spinal cord. Due to its extent along the brainstem it may be divided into different areas such as the midbrain reticular formation, the central mesencephalic reticular formation, the pontine reticular formation, the paramedian pontine reticul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Reticulospinal Tract
The reticular formation is a set of interconnected nuclei in the brainstem that spans from the lower end of the medulla oblongata to the upper end of the midbrain. The neurons of the reticular formation make up a complex set of neural networks in the core of the brainstem. The reticular formation is made up of a diffuse net-like formation of reticular nuclei which is not well-defined. It may be seen as being made up of all the interspersed cells in the brainstem between the more compact and named structures. The reticular formation is functionally divided into the ascending reticular activating system (ARAS), ascending pathways to the cerebral cortex, and the descending reticular system, descending pathways ( reticulospinal tracts) to the spinal cord. Due to its extent along the brainstem it may be divided into different areas such as the midbrain reticular formation, the central mesencephalic reticular formation, the pontine reticular formation, the paramedian pontine reticular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Rubrospinal Tract
The rubrospinal tract is one of the descending tracts of the spinal cord. It is a motor control pathway that originates in the red nucleus. It is a part of the lateral indirect extrapyramidal tract. The rubrospinal tract fibers are efferent nerve fibers from the magnocellular part of the red nucleus. (Rubro-olivary fibers are efferents from the parvocelluar part of the red nucleus). It is functionally less important in humans. It is involved in motor control of distal flexors of the upper limbespecially of the hand and fingersby promoting flexor tone while inhibiting extensors. Structure The rubrospinal tract originates in the magnocellular red nucleus in the midbrain, and decussates (crosses over) at the midline in the anterior tegmental decussation. In the pons, it is situated medially within the rostral pontine tegmentum. In the medulla oblongata, it descends within the lateral tegmentum medial to the spinocerebellar tract, and posterior to the spinothalamic tract. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Decussation
Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' (), ). In Latin anatomical terms, the form is used, e.g. . Similarly, the anatomical term Chiasm (anatomy), chiasma is named after the Greek uppercase 'Χ' (Chi (letter), chi). Whereas a decussation refers to a crossing within the central nervous system, various kinds of crossings in the peripheral nervous system are called chiasma. Examples include: * In the brain, where nerve fibers obliquely cross from one lateral side of the brain to the other, that is to say they cross at a level other than their origin. See for examples decussation of pyramids and sensory decussation. In neuroanatomy, the term ''chiasma'' is reserved for crossing of- or within nerves such as in the optic chiasm. * In Botany, botanical phyllotaxis, leaf taxology, the word ''decussate'' describes an opposite leaves, opposite pattern of leaves which has successive pairs at right ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Superior Cerebellar Peduncle
In the human brain, the superior cerebellar peduncle (brachium conjunctivum) is one of the three paired cerebellar peduncles of bundled fibers that connect the cerebellum to the brainstem. The superior cerebellar peduncle connects to the midbrain. It consists mainly of efferent fibers, the cerebellothalamic tract that runs from a cerebellar hemisphere to the contralateral thalamus, and the cerebellorubral tract that runs from a cerebellar hemisphere to the red nucleus. It also contains afferent tracts, most prominent of which is the ventral spinocerebellar tract. Other afferent tracts are the ventral trigeminal tract, tectocerebellar fibers, and noradrenergic fibers from the locus coeruleus. The superior peduncle emerges from the upper and medial parts of the white matter of each cerebellar hemisphere and is placed under cover of the upper part of the cerebellum. Structure Superior cerebellar peduncles are connected together by the superior medullary velum, which can be fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
