Clinical Neuroanatomy Made Ridiculously Simple - Part 2

Clinical Neuroanatomy Made Ridiculously Simple - Part 2 -...

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CHAPTER 4. BRAIN STEM In evaluating a patient, the neuroIogist asks a sequence of questions. First, where is the lesion (spinal cord, brain stem, cerebrum, etc.)? Second, what is the lesion (tumor, infection, hemorrhage, etc.)? third, what can be done to help the patient (medication, surgery, etc.)? The neurologist tries to determine if a single lesion can account for the patient" symptoms and signs. If multiple lesions must be postulated, this generally implies either metastatic disease, multiple sclerosis, the presence of two different diseases, or the presence of malingering or hysteria. Precise anatomica1 localization of the Iesion is very important in neurolog- ical diagnosis. It therefore imponant to know the locations of the major fiber tracts and nuclei. The brain stem is very important in this regard. The folIow- ing chapter describes the anatomy of the major nucIei and fiber pathways in the brain stern. Clinical iIluskrations the usefulness of this data will given in the questions following Chapter 5. Don't panic. The brain stem is incredibly simple when studied in a Iogical sequence, as follows. 1. Memorize the 12 cranial nerves and their functions. Ribald mnemonics will help. You must know the individual cranial nerves and their functians on instant recall. CMI : CN2 r CNs 3,4 and 6: CN5: CN7: CN8: CN9: CMIO: Smells Sees Move eyes; CN3 constricts pupiIs, accommodates Chews and feels front head Moves the face, tastes, salivates, cries Hears, regulates balance Tastes, salivates, swallows, monitors carotid body and sinus Tastes, swallows lifts palate, talks, communication to and from thoraco-abdominal viscera Turns head, lifts shoulders Moves tongue 2. Next, memorize the chart in figure 19 which includes the same infor- mation as above remanged differently. Unlike the spinal nerves, which are mixed nerves containing motor and sensory components, the cranial nerves are much simpler. Three of them are purely sensory, 5 purely motor and only four are mixed. The term "sornatovisceral" will explained later.
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SPINAL CORD ' ~ornotovisearul' nuclear dllplacsmbnt famay motor mor = Sonmtic asnrwy Visceral (AutmomiF1 3- 3omatle motor AUTONOMIC :T?-,\ BRAIN II I,$ SOMATIC VISCERAL S0MP.m MOTOR MOTOR SENSORY SEN= Not In brwn atem CN4 Troehlew Fig. 19 The homology between the spinal cord and brain stem. The brain stem resembles a spinal cord stretched in the direction indicated by the midline arrows, somatic and qerd components of the grey matter remain in the same relative position in spinal cord and brain stem. Chart indicates the major nuclei of the cranial nerves. Note: a) There we 3 sensory nerves. b) There are 5 motor nerves of which one (CN3) bas a visd motor component in addition to a somatic motor component. The remainder of the motor nerves arc: purely somatic motor. c) There are 4 mixed (sensory plus motor) flerves.
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Clinical Neuroanatomy Made Ridiculously Simple - Part 2 -...

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