Overview_of_Neuroanatomy_2011 - Overview of Neuroanatomy...

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Overview of Neuroanatomy The central nervous system consists of the brain and spinal cord. The peripheral nervous system consists of the cranial and spinal nerves. The brain is organized into the cerebrum and brainstem. The cerebrum consists of the Telencephalon which contains the cerebral cortex, subcortical white matter and the basal nuclei (ganglia); and the Diencephalon which contains the thalamus and hypothalamus. The brain stem contains the midbrain, pons and medulla oblongata. The cerebellum is a separate structure. The directional terminology is the same as for the remainder of the body with the addition of two terms that are commonly used: rostral and caudal. Rostral designates “toward the front or nose”. Caudal designates “lowermost or toward the tail”. The cerebrum contains 5 lobes. Four lobes underlie the corresponding cranial bones: frontal, temporal, parietal and occipital. The fifth lobe is the “insula” which is located deep to the Sylvian fissure (aka the lateral sulcus or fissure of Sylvius). The function of the insula is not well known. It is thought to be involved with the emotions of addiction, and with social emotions such as lust and disgust, pride and humiliation, guilt and atonement. It is thought to register physical sensations (heat, cold, pain, hunger, thirst, taste and visceral sensations), and interpret them as social emotions. Addiction involves not only a chemical stimulus, but other stimuli (sights, sounds, smells associated with the addictive substance or behavior). The insula is activated by these stimuli even before the person takes the substance. This especially occurs in the right frontal insula. Correlating Neuroanatomy with the Neurologic Assessment of the Patient It is important to note that the function of the brain can be described both in terms of “specifically localized areas” and “interconnected networks”. A patient may present with a loss of function that can be attributed to a specific locality, i.e. a “focal deficit” such as the loss of the right side of each visual field from a lesion to the optic tract. Thus, it is useful to localize the clinical deficit (“ locate the lesion ”) during the clinical examination. On the other hand, loss of memory, judgement and some language abilities occur from damage to the “heteromodal” association areas of the frontal and parieto- occipital association cortices or other subcortical regions of the cerebrum. Trying to localize such deficits may lead to a “false” localization of the lesion. In an attempt to localize the lesion, it is also important to note the concept of “hemispheric specialization”. Most notably, handedness and language are connected to the dominant hemisphere. Right-handedness is programmed by the left cerebral hemisphere which is usually dominant. Dominance also applies to the localization of language. 95% of right- handers have language localized to the dominant left cerebral hemisphere. 60 to70% of left-handers have language localized to the left hemisphere. Assessing language ability is part of the mental status exam.
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This note was uploaded on 02/17/2012 for the course MPAS PA 602 taught by Professor Dr.laird during the Fall '10 term at Chatham University.

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Overview_of_Neuroanatomy_2011 - Overview of Neuroanatomy...

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