Lab 2 Answers PDF

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Neuroanatomy 300754: LAB 2Brain Topography & gross/macroscopic characteristicsPre-reading from Nolte: Chapters 3, 6 & 22 and Lecture 1& 3 notesStudents should be able to:  describe the major components of the cerebral hemispheres on the lateral, inferior, medial & mi...

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300754 neuroanatomy Spring 2017

Neuroanatomy 300754: LAB 2 Brain Topography & gross/macroscopic characteristics Pre-reading from Nolte: Chapters 3, 6 & 22 and Lecture 1& 3 notes Students should be able to:  describe the major components of the cerebral hemispheres on the lateral, inferior, medial & midsagittal surfaces of the brain  define the anatomical boundaries of the cortical lobes  identify and locate major surface anatomical landmarks of the cerebral cortices  identify and locate major anatomical landmarks in midsagittal sections of the cerebrum and diencephalon  identify and locate nuclei and major white matter tracts of the cerebrum in midsagittal sections

Task 1: Identification of cerebral surface features The surface of the cerebral hemispheres comprises multiple gyri and sulci whose patterns differ slightly in individual specimens; even the right and left hemispheres are not mirror images of each other. However, a generalised pattern is observable (rule of 3’s) and you should learn the names and location of major gyri and sulci. Due to the variability in sulcal patterns, gyral boundaries are not always absolutely clear. Sulci are not always continuous – some are interrupted, others may have branches, or even arise as a branch of another sulcus. Because of these variations, it is important to examine all the specimens available. Be advised that simply learning gyral patterns from text images without consolidating this with the examination of real specimens will not be helpful when you are asked to identify these features on specimens under examination conditions. Back in lab 1 you were asked to identify some major gyri, fissures and sulci. Use the drawings from Martin to re-familiarize yourself with some of these landmarks and to further identify the other labelled gyri and sulci listed below on each of the specimens provided. Try identifying the gyri and sulci from each of the viewpoints shown in the line drawings on real brains and the models. General land marks  Frontal pole  Lateral fissure (of Sylvius)  Longitudinal fissure (separates the hemispheres)

  

Occipital pole Temporal pole Transverse fissure

Mark these on the diagram below

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300754 neuroanatomy Spring 2017

Lateral hemisphere features 1. angular gyrus 2. central sulcus 3. inferior frontal gyrus (opercular, triangular & orbital parts) 4. inferior frontal sulcus 5. inferior parietal lobule (= angular gyrus & supramarginal gyrus) 6. inferior temporal gyrus 7. inferior temporal sulcus 8. intraparietal sulcus 9. middle frontal gyrus 10. middle temporal gyrus

11. post-central gyrus 12. post-central sulcus 13. precentral gyrus 14. precentral sulcus 15. pre-occipital notch 16. superior frontal gyrus 17. superior frontal sulcus 18. superior parietal lobule 19. superior temporal gyrus 20. superior temporal sulcus 21. supramarginal gyrus

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300754 neuroanatomy Spring 2017

Medial hemisphere features 1. calcarine sulcus 2. callosal sulcus 3. cingulate gyrus 4. cingulate sulcus 5. cuneus 6. gyrus rectus 7. isthmus of cingulate gyrus 8. lingual gyrus

9. occipitotemporal (fusiform) gyrus 10. occipitotemporal sulcus 11. paracentral lobule 12. parahippocampal gyrus 13. parieto-occipital sulcus 14. precuneus 15. superior frontal gyrus 16. uncus

Inferior surface features (hindbrain removed) 1. collateral sulcus 11. occipitotemporal sulcus 2. corpus callosum 12. olfactory bulb 13. olfactory sulcus 3. frontal pole 14. olfactory tract 4. gyrus rectus 15. optic chiasm 5. hypothalamus 16. optic nerve 6. inferior temporal gyrus 17. optic tract 7. inferior temporal sulcus 18. orbital gyri 8. infundibular stalk 19. parahippocampal gyrus 9. lingual gyrus 20. uncus 10. occipitotemporal (fusiform) gyrus

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300754 neuroanatomy Spring 2017

Other External & Midsagittal Brain Features Tracts: 1. anterior commissure 2. corpus callosum - rostrum 3. corpus callosum - genu 4. corpus callosum - body 5. corpus callosum - splenium 6. fornix – body Nuclei 12. Habenula (part of epithalamus) 13. hypothalamus 14. insula (long and short gyri) 15. mammillary bodies (part of hypothalamus)

7. infundibular stalk 8. inter-thalamic adhesion 9. optic chiasm 10. posterior commisure 11. septum pellucidum (fibrous sheet) 16. pineal gland (part of epithalamus) 17. thalamus

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300754 neuroanatomy Spring 2017

Anatomical terms are often derived from Latin. Here are just a few Latin terms you should become familiar.  uncus (hook)  tegmentum (body)  cingulate (cingulum)  sulcus (groove)  operculum (operire)  rostrum (front)  pons (bridge)  genu (knee)  tectum (roof)  leptos (thin, fine) 

hippocampus (curiously, this Latin term was adapted from two Greek words – hippo = horse and campus = sea monster so it looks like a seahorse!)

Be aware that there is some inconsistency in the naming of some structures between various text books. One of the more notable inconsistencies is the naming of the temporal sulci. Some authors identify a middle temporal sulcus, consequently displacing the location of the inferior temporal sulcus to the position of the sulcus otherwise identified as the occipitotemporal sulcus. While it is acceptable to use either convention, it is easier to name the temporal sulci without the inclusion of a 5

300754 neuroanatomy Spring 2017 middle temporal sulcus – this is then consistent with the sulci of the frontal lobe & therefore makes it easier to remember.

Brain vasculature Blood reaches the brain via two sets of arteries. Most comes through the internal carotid arteries and their major branches the middle and anterior cerebral arteries (and the anterior communicating arteries, which connect the latter) constitute the anterior circulation. The vertebral arteries convey the remaining arterial supply to the brain and they, the basilar, the posterior cerebral arteries and the branches to which they give rise, comprise the posterior circulation. The posterior communicating arteries establish the circle of Willis around the optic chiasm by linking the anterior and posterior circulations. Use your printout of “Blood supply line drawings” (from vUWS). On these diagrams, identify the following major arteries: 1. 2. 3. 4. 5. 6. 7.

anterior cerebral anterior communicating anterior inferior cerebellar anterior spinal basilar internal carotid middle cerebral

8. pontine branches 9. posterior cerebral 10. posterior communicating 11. posterior inferior cerebellar 12. posterior spinal 13. superior cerebellar 14. vertebral

Other arteries of note are the:  labyrinthine - arises from the basilar or the anterior inferior cerebellar and supplies the inner ear (vertigo & deafness).  anterior choroidal - arises from anterior cerebral and supplies optic tract, choroid plexus of inferior horn, globus pallidus, amygdala, hippocampus, internal capsule, thalamus. The perforating arteries are branches of anterior cerebral, anterior communicating, middle cerebral, posterior cerebral, and posterior communicating that enter the cerebrum through the anterior and posterior perforated substances. They supply deep structures such as basal ganglia, thalamus, internal capsule, and hypothalamus and are terminal arteries. The lenticulostriate arteries are one important example of these perforating arteries - they arise from the middle cerebral artery and supply lenticular nucleus and striatum (putamen, globus pallidus, caudate). Identify these in the ‘Blood supply figures from Diamond’ resource. Inspect the real brains and brain models available and see if you can find any arterial vessels?

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300754 neuroanatomy Spring 2017

Look at the circle of Willis - do all the specimens available follow the “normal” pattern i.e. do all the vessels seem to be in their correct places and are they bilaterally symmetrical? Now see if you can identify the anterior and posterior perforated substances on the specimens available. The anterior is located rostral to the hypothalamus, around the region of the optic chiasm. The posterior perforated substance is located posterior to the mammillary bodies, at the level of the midbrain. Complete the table below and answer the following questions Cerebral Artery Anterior Cerebral

Middle Cerebral

Posterior Cerebral

Functional cortical areas supplied Control of movement and sensation: hips to feet, bladder & sexual organs (Primary motor and somatosensory cortex). Emotions (limbic system) Hearing (Primary auditory cortex), language (expression &comprehension (Broca’s & Wernicke’s areas). Control of movement and sensation: hips to head (Primary motor and somatosensory cortex). Taste (Primary taste cortex); motor planning (frontal lobe). Vision (Primary visual cortex), consciousness (thalamus, midbrain)

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300754 neuroanatomy Spring 2017

Describe how the internal carotid artery enters the middle cranial fossa Enters the brain cavity through the carotid canal (in the petrosal & sphenoid) to emerge in the middle cranial fossa via foramen lacerum (that is only visible in a dried skull; in life it is filled with cartilage). The arteries make a series of s-shaped turns as it passes through the cavernous sinus, before emerging, on each side, next to the optic chiasm What blood vessel passes through foramen spinosum? Middle meningeal artery

Venous drainage of the brain is by way of veins which empty into a number of dural venous sinuses. Identify the following vessels on the diagrams in the ‘Blood supply figures’ resource, and label them on the image below 1. 2. 3. 4. 5. 6. 7.

Great cerebral vein of Galen Inferior anastomotic vein Inferior cerebral veins Inferior sagittal sinus Internal jugular vein Middle cerebral vein Occipital sinus

8. Occipital vein 9. Sigmoid sinus 10. Straight sinus 11. Superior anastomotic vein 12. Superior cerebral veins 13. Superior sagittal sinus 14. Transverse sinus

What are emissary veins? What do they do, where are they located and why are they important? Emissary veins connect extracranial (scalp) veins to (intracranial) dural venous sinuses. They are important as they provide a route of transport/infection across 8

300754 neuroanatomy Spring 2017 skull; also important in thermoregulation as cooler blood comes from outside to inside of skull.

Using a skull see how many of the venous sinuses you can identify.

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