BIBB Sheep Brain Dissection Study Guide PDF

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A study guide for the sheep brain dissection practical....

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BIBB Study Guide Gyri - bumps Sulci - grooves More = smarter SA CNS = cerebrum, cerebellum, brain stem Dorsal = up Ventral = down Caudal/posterior = back Rostral/anterior = front Medial = center/middle Lateral = sides Sagittal situation - cut left and right lobes Axial/horizontal - horizontally, separates ventral and dorsal Coronal - separates anterior and posterior

Ventricles are cavities in the brain that hold cerebrospinal fluid Lined by membrane called choroid plexus which is made of ependymal cells Ependymal cells secrete the cerebrospinal fluid Ventricles are what the fluid travels in to get elsewhere Production and distribution CSF surrounds and suspends the brain in liquid, protecting them from gravity and shock Removes toxins and regulates extracellular environment of neurons

4 ventricles 2 C shaped Lateral ventricles Connected to third ventricle by interventricular foramen Third looks like a donut and hole in donut is interthalamic adhesion This is the thalamus, so it makes up the wall of the third ventricle 3rd to 4th connected by cerebral aqueduct (sylvius) 4th = between cerebellum and brainstem (tent shape) 3 openings that let CSF enter the subarachnoid space, which is the space between the skull and brain that protects it (surrounds brain) CSF leaves ventricular system through 4th ventricle CSF enters spinal through central canal, connected with 4th ventricle (it runs up and down the spine and is a cavity) If CSF is too much or ventricle blocked (like tumor), it leads to hydrocephalus, enlarged brain ventricles Spinal Cord - Ventral roots of neurons that connect to the spinal cord are efferent so send information from brain to body - Dorsal roots send information from body/sensory stuff to brain afferent - DRG (Dorsal Root Ganglia) - Contains somas of sensory afferents - Mixed Cranial Nerves - There are 12 pairs of cranial nerves seen on the ventral surface of the brain - Bring info from sense organs, control muscles, connect to glands or internal organs - Olfactory nerve (smell), Optic (vision), Oculomotor (eye movement), Trochlear (eye movement), Trigeminal (somatosensory from face), Abducens (eye movement), Facial (taste, somatosensory info from ear, muscles and facial expression), Vestibulocochlear (hearing and balance), Glossopharyngeal (taste, controls muscles in swallowing), Vagus (sensory, motor, and autonomic functions of viscera (glands, digestion, heart rate)), Spinal accessory (muscles in head movement), Hypoglossal (muscles of tongue) Meninges (in brain) - 3 membranes that surround the brain and spinal cord - Dura mater (outside) - Subdural space - Arachnoid (subarachnoid) - Trabeculae connects arachnoid membrane to pia mater - Blood vessels inside (spider)

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- Pia mater Same thing in spine pretty much

Dura mater has a periosteal layer (outer and connects dura mater to skull) and a meningeal layer (inner) Superior sagittal sinus is triangular space between the dura mater and arachnoid membrane and in between the two lobes (think of sagittal incisions) Venous blood in there After CSF is ejected into subarachnoid space, its reabsorbed by arachnoid villi and arachnoid generations into venous sinuses MRI > CT scan bc more detail and no X Rays How H atoms response to Magnetic field Diffusor Tensor Imaging (MRI) diffusion of water in brain visualiZation of large axon bundles fMRI Tracks O2 bc brain needs it (blood flow) Early Neural Development - AT 3 weeks, ectoderm thickens to form the neural plate - Folds inward and forms neural groove - Neural folds then come together and fuse at the end of three weeks - At end of 4th week, they completely have fused to form the neural tube - Eventually becomes the brain and the spinal cord - As it closes and develops, bulges and grooves form - During 4th week there are 3 of the bulges and they’re called the primary vesicles - Prosencephalon (forebrain) and will eventually form the cerebrum - Then, further, it splits into telencephalon (cerebral hemispheres, basal ganglia, hippocampus, olfactory bulb, amygdala, and basal forebrain) and diencephalon (thalamus, hypothalamus) - Mesencephalon is the midbrain and has colliculi - Rhombencephalon (hindbrain) becomes rest of brainstem and cerebellum - Then later divides into Metencephalon (pons and cerebellum) and Myelincephalon (medulla) - End of neural tube becomes the spinal cord - At 11 weeks it looks like it will at birth - Telencephalon develops fastest

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Inside lining of neural tube becomes the ventricles - Telencephalon = lateral ventricle - Diencephalon = 3rd - Mesencephalon = cerebral aqueduct - Metencephalon = fourth - Myelincephalon = fourth - Central canal from spinal cord Differentiation when structures become specialized Eyes are derived from the forebrain, not pns Forebrain - Telencephalon and Diencephalon - Corpus Callosum - Corona Radiata - Internal capsule Axons from thalamus to cortex through internal capsule Hypothalamus = endocrine and ANS Midbrain - Descending axons (from cortex to brain stem/cord) - Ascending (opposite) - Coriticospinal tract is descending from motor cortex to spinal motor neurons - Tectum - Superior colliculus (recieves info from eye) - Inferior (ear) - Tegmentum - Substantia nigra (black) part of basal ganglia (voluntary motor etc.) - Red nucleus (voluntary mvmt) (rubrospinal tract) Hindbrain - Pons - Inputs from motor neurons and relays info to cerebellum (how it coordinates mvmt) - Corticospinal fibers go to spinal cord through medullary pyramids Spinal cord = ascending and descending Types of cerebral cortex - Neocortex is only in mammals and has lobes - Archicortex has hippocampus - Paleocortex has olfactory cortex/piriform lobe - Separated from neocortex by rhinal fissure

52 brodmann areas that differ in cytoarchitecture Gray matter has 6 layers and only in neocortex

Evolution - SA changed, not structure - Developed primary sensory areas and motor - Expanded secondary areas Primary receiving areas are

Somatotopic map maps somatosensory cortex Retinotopic map maps primary visual cortex Tonotopic map maps primary auditory cortex Sheep brain - Olfactory bulbs are rostral/anterior look like two big nostrils near nose - Vermis is the median section of the cerebellum that looks like a worm (worm in latin)

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Lobes of the brain Tectum - tetris - connects cerebellum and cerebrum and function = auditory and visual reflexes - Superior (butt) and inferior colliculi - Pineal body = penis = little point above butt Peduncles are wherever the cerebellum makes contact bc carries information to and from places Tegmentum is inside (midbrain) + tectum rostral and dorsal to the pons, ventral to the tectum Optic chiasm is caudal to olfactory bulbs, which look like eyes (triangle) and it is a bulb that is rostral to the mammillary body - Mamillary body is by itself (one body) while optic chiasm is surrounded - Optic tract is lateral to the optic chiasm and right next to it Pons connected by pyramidal tracts (just fibers) split medulla Olives are posterior to the pons and anterior to the medulla and they are lateral (region on brain stem) Crus cerebri kind of looks like muscles and it is across the street from pons (anterior) in Spainish and it’s in the cerebrum - It is the cerebral peduncle! - Connects the cerebrum and cerebellum Trigeminal nerve is right next to the pons Trochlear nerve extends from pons as well, but extends more from crus cerebri Corpus Callosum is what connects the two cerebral hemispheres Sagittal cut - Corpus callosum is the white matter that appears when you cut sagittally - it is anterior to the fornix - The fornix forks off of it and looks similar - Thalamus and hypothalamus are posterior to these structure

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Also remember pineal and mammillary bodies (mamillary is on the ventral surface) Ventricles - Sagittal cut - Choroid plexus is in the third ventricle and is in the “core” of the brain - Lateral ventricle is between corpus callosum and fornix - Fourth ventricle is underneath the cerebellum - Cerebral aqueduct/midbrain aqueduct (look rostral to the pons and look for midbrain - it is there) Coronal cut first (really rostral) - Anterior commissure is the little band connecting hemispheres of the brain - Anterior → anterograde amnesia is you only remember things in the future, so it’s later on, so it’s near the bottom -

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Basal ganglia is divided by a tract called the internal capsule - Caudate nucleus - Sounds like cuddle, which is huddled in the center next to the hole - Lenticular nucleus - Putamen - Globus pallidus - In between the two Ps (pons and putamen, so putamen is higher) - We can see corpus callosum at the top Middle coronal cut - Can clearly see corpus callosum as a mustache on top - The lateral ventricle because it sounds like ,daughter and it looks like a smiling face’s eyes - Makes sense in terms of sagittal cut - Hippocampus surrounds the thalamus and it is C shaped, for campus, and encompasses the thalamus like a college campus - Thalamus looks like a butterfly Caudal coronal cut - Hippocampus is more defined (C shaped) - Lateral geniculate nucleus is LGN, which is more lateral than the medial geniculate nucleus (MGN) Hindbrain - Cerebellum has trees called folia - Foliage...