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Palmomental Reflex
The palmomental reflex (PMR) or Marinesco-Radovici Sign or Kinn reflex or Marinesco Reflex is a primitive reflex consisting of a twitch of the chin muscle elicited by stroking a specific part of the palm. It is present in infancy and disappears as the brain matures during childhood but may reappear due to processes that disrupt the normal cortical inhibitory pathways. Therefore, it is an example of a frontal release sign. Eliciting and observing response The thenar eminence is stroked briskly with a thin stick, from proximal (edge of wrist) to distal (base of thumb) using moderate pressure. A positive response is considered if there is a single visible twitch of the ipsilateral mentalis muscle (chin muscle on the same side as the hand tested). Clinical relevance Gheorghe Marinescu and Anghel Radovici in their seminal 1920 paper hypothesized that both the afferent (receptive) and efferent (motor) arms of the reflex are on the same side (ipsilateral) to the hand stimulated; th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primitive Reflexes
Primitive reflexes are reflex actions originating in the central nervous system that are exhibited by normal infants, but not neurologically intact adults, in response to particular stimuli. These reflexes are suppressed by the development of the frontal lobes as a child transitions normally into child development. These primitive reflexes are also called infantile, infant or newborn reflexes. Older children and adults with atypical neurology (e.g., people with cerebral palsy) may retain these reflexes and primitive reflexes may reappear in adults. Reappearance may be attributed to certain neurological conditions including dementia (especially in a rare set of diseases called frontotemporal degenerations), traumatic lesions, and strokes. An individual with cerebral palsy and typical intelligence can learn to suppress these reflexes, but the reflex might resurface under certain conditions (i.e., during extreme startle reaction). Reflexes may also be limited to those areas affected ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cerebral Cortex
The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consisting of allocortex. It is separated into two cortices, by the longitudinal fissure that divides the cerebrum into the left and right cerebral hemispheres. The two hemispheres are joined beneath the cortex by the corpus callosum. The cerebral cortex is the largest site of neural integration in the central nervous system. It plays a key role in attention, perception, awareness, thought, memory, language, and consciousness. The cerebral cortex is part of the brain responsible for cognition. In most mammals, apart from small mammals that have small brains, the cerebral cortex is folded, providing a greater surface area in the confined volume of the cranium. Apart from minimising brain and cranial volume, cortical folding is crucial for the br ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frontal Release Sign
Frontal release signs are primitive reflexes traditionally held to be a sign of disorders that affect the frontal lobes. The appearance of such signs reflects the area of brain dysfunction rather than a specific disorder which may be diffuse, such as a dementia, or localised, such as a tumor. One reflex thought to have good localizing value is the palmar grasp reflex which usually signifies damage to the frontal lobe of the opposite side. The glabellar reflex or "glabellar tap" is present in individuals with extrapyramidal disorders such as Parkinson's disease. These reflexes are believed to be "hard-wired" before birth, and are therefore able to be elicited in the newborn. As the brain matures, certain areas (usually within the frontal lobes) exert an inhibitory effect, thus causing the reflex to disappear. When disease processes disrupt these inhibitory pathways, the reflex is "released" from inhibition and can be elicited once again, hence the term "frontal release sign". Som ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thenar Eminence
The thenar eminence is the mound formed at the base of the thumb on the palm of the hand by the intrinsic group of muscles of the thumb. The skin overlying this region is the area stimulated when trying to elicit a palmomental reflex. The word thenar comes . Structure The following three muscles are considered part of the thenar eminence: * Abductor pollicis brevis abducts the thumb. This muscle is the most superficial of the thenar group. * Flexor pollicis brevis, which lies next to the abductor, will flex the thumb, curling it up in the palm. (The Flexor pollicis longus, which is inserted into the distal phalanx of the thumb, is not considered part of the thenar eminence.) * Opponens pollicis lies deep to abductor pollicis brevis. As its name suggests it opposes the thumb, bringing it against the fingers. This is a very important movement, as most of human hand dexterity comes from this action. Another muscle that controls movement of the thumb is adductor pollicis. It ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mentalis Muscle
The mentalis muscle is a paired central muscle of the lower lip, situated at the tip of the chin. It originates from the mentum of the mandible, and inserts into the soft tissue of the chin. It is sometimes referred to as the "pouting muscle" due to it raising the lower lip and causing chin wrinkles. Structure The mentalis muscle originates from the mental protuberance of the mandible near the midline. It inserts into the soft tissue and skin of the chin. Function The mentalis muscle causes a weak upward-inward movement of the soft tissue complex of the chin. This raises the central portion of the lower lip. In the setting of lip incompetence (the upper and lower lips do not touch each other at rest), the mentalis muscle contraction can bring temporary but strained oral competence. In conjunction with the orbicularis oris muscle (for the upper lip), the mentalis muscle allows the lips to "pout". Externally, the mentalis muscle contraction causes wrinkling and dimpling of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gheorghe Marinescu
Gheorghe Marinescu (; 28 February 1863 – 15 May 1938) was a Romanian neurologist, founder of the Romanian School of Neurology. History After attending the Faculty of Medicine of the University of Bucharest, Marinescu received most of his medical education as preparator at the laboratory of histology at the Brâncoveanu Hospital and as assistant at the Bacteriological Institute under Victor Babeș, who had already published several works on myelitis transversa, hysterical muteness, and dilatation of the pupil in pneumonia. Career After qualification, and on the recommendation of Babeş, the government awarded Marinescu a grant to undertake postgraduate training in neurology under Jean-Martin Charcot at the Salpêtrière Hospital in Paris, where he met Pierre Marie, Joseph Babinski, and Fulgence Raymond. Later, he worked with Carl Weigert in Frankfurt and then with Emil du Bois-Reymond in Berlin. On the assignment of Pierre Marie, he lectured on the pathological anatomy of ac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Afferent Nerve Fiber
Afferent nerve fibers are the axons (nerve fibers) carried by a sensory nerve that relay sensory information from sensory receptors to regions of the brain. Afferent projections ''arrive'' at a particular brain region. Efferent nerve fibers are carried by efferent nerves and ''exit'' a region to act on muscles and glands. In the peripheral nervous system afferent and efferent nerve fibers are part of the somatic nervous system and arise from outside of the spinal cord. Sensory nerves carry the afferent fibers to enter into the spinal cord, and motor nerves carry the efferent fibers out of the spinal cord to act on skeletal muscles. In the central nervous system non-motor efferents are carried in efferent nerves to act on glands. Structure Afferent neurons are pseudounipolar neurons that have a single process leaving the cell body dividing into two branches: the long one towards the sensory organ, and the short one toward the central nervous system (e.g. spinal co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Efferent Nerve Fiber
Efferent nerve fibers refer to axonal projections that ''exit'' a particular region; as opposed to afferent projections that ''arrive'' at the region. These terms have a slightly different meaning in the context of the peripheral nervous system (PNS) and central nervous system (CNS). The efferent fiber is a long process projecting far from the neuron's body that carries nerve impulses away from the central nervous system toward the peripheral effector organs (mainly muscles and glands). A bundle of these fibers is called an efferent nerve (if it connects to muscles, then it is a motor nerve). The opposite direction of neural activity is afferent conduction, which carries impulses by way of the afferent nerve fibers of sensory neurons. In the nervous system there is a "closed loop" system of sensation, decision, and reactions. This process is carried out through the activity of sensory neurons, interneurons, and motor neurons. In the CNS, afferent and efferent projections ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reflex
In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs via neural pathways in the nervous system called reflex arcs. A stimulus initiates a neural signal, which is carried to a synapse. The signal is then transferred across the synapse to a motor neuron which evokes a target response. These neural signals do not always travel to the brain, so many reflexes are an automatic response to a stimulus that does not receive or need conscious thought. Many reflexes are fine-tuned to increase organism survival and self-defense. This is observed in reflexes such as the startle reflex, which provides an automatic response to an unexpected stimuli, and the feline righting reflex, which reorients a cat's body when falling to ensure safe landing. The simplest type of reflex, a short-latency reflex, has a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neurological
Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the brain, the spinal cord and the peripheral nerves. Neurological practice relies heavily on the field of neuroscience, the scientific study of the nervous system. A neurologist is a physician specializing in neurology and trained to investigate, diagnose and treat neurological disorders. Neurologists treat a myriad of neurologic conditions, including stroke, seizures, movement disorders such as Parkinson's disease, autoimmune neurologic disorders such as multiple sclerosis, headache disorders like migraine and dementias such as Alzheimer's disease. Neurologists may also be involved in clinical research, clinical trials, and basic or translational research. While neurology is a nonsurgical specialty, its corresponding surgical specialty is neurosurgery. Histor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Congenital
A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can range from mild to severe. Birth defects are divided into two main types: structural disorders in which problems are seen with the shape of a body part and functional disorders in which problems exist with how a body part works. Functional disorders include metabolic and degenerative disorders. Some birth defects include both structural and functional disorders. Birth defects may result from genetic or chromosomal disorders, exposure to certain medications or chemicals, or certain infections during pregnancy. Risk factors include folate deficiency, drinking alcohol or smoking during pregnancy, poorly controlled diabetes, and a mother over the age of 35 years old. Many are believed to involve multiple factors. Birth defects may be v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Down Syndrome
Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual disability, and characteristic facial features. The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an eight- or nine-year-old child, but this can vary widely. The parents of the affected individual are usually genetically normal. The probability increases from less than 0.1% in 20-year-old mothers to 3% in those of age 45. The extra chromosome is believed to occur by chance, with no known behavioral activity or environmental factor that changes the probability. Down syndrome can be identified during pregnancy by prenatal screening followed by diagnostic testing or after birth by direct observation and genetic testing. Since the introduction of screening, Down syndrome pregnancies are often a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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