20240824-biol-1191-lecture-3.pdf

The brain and cranial nerves Biology 1191 Lecture 3 Fall 2024  Brain anatomy Cerebrospinal fluid Brain stem and reticular formation Outline Cerebellum, diencephalon, and cerebrum Functional organization of the cerebral cortex...

The brain and cranial nerves Biology 1191 Lecture 3 Fall 2024  Brain anatomy Cerebrospinal fluid Brain stem and reticular formation Outline Cerebellum, diencephalon, and cerebrum Functional organization of the cerebral cortex Cranial nerves Homeostatic imbalances 9/25/2024 Sample Footer Text 2 You must be able to describe the anatomy of the brain using anatomical terms! 9/25/2024 Sample Footer Text 3 Use these helpful videos to help you learn to describe the anatomy of the brain: https://www.youtube.com/watch?v=D1zkVBHPh5c&t=233s https://www.youtube.com/watch?v=8hC6NGQReL4&t=497s 9/25/2024 Sample Footer Text 4 The adult brain consists of four main parts The brainstem Includes the medulla oblongata, the pons, and the midbrain Continuous with the spinal cord The cerebellum Forms posterior and inferior brain 9/25/2024 Sample Footer Text 5 Brain anatomy (cont’d) The diencephalon Includes thalamus, hypothalamus, and epithalamus Superior to brainstem The cerebrum Largest and most superior portion of brain Supported by diencephalon and brainstem 9/25/2024 Sample Footer Text 6 Brain anatomy (cont’d) 9/25/2024 Sample Footer Text 7 Like the spinal cord, the brain is protected The cranial meninges are continuous with the spinal meninges and share common names: 1. The superficial cranial dura mater has two layers: An outer periosteal layer An inner meningeal layer 2. Intermediate arachnoid mater 3. Deep pia mater 9/25/2024 Sample Footer Text 8 Protective coverings of the brain (cont’d) There is no epidural space surrounding the brain The pia mater loosely wraps blood vessels that penetrate brain tissue from the surface Extensions of the dura mater separate parts of the brain: The right and left hemispheres of the brain are separated by the falx cerebri 9/25/2024 Sample Footer Text 9 Protective coverings of the brain (cont’d) The hemispheres and of the cerebellum are separated by the falx cerebelli The cerebrum and the cerebellum are separated by the tentorium cerebelli 9/25/2024 Sample Footer Text 10  Blood flow to the brain is extensive and selective The main arteries that supply oxygenated, nutrient-rich blood to the brain are the anterior internal carotid and posterior vertebral arteries The dural venous sinuses drain deoxygenated, nutrient-poor blood into the internal jugular veins As the activity of neurons increases, blood flow to the brain also increases! 9/25/2024 Sample Footer Text 11  The BBB consists of continuous capillaries The blood-brain barrier (BBB) with tight junctions between endothelial maintains the selective cells permeability of brain tissues to Astrocytes (neuroglia) associate tightly with capillaries and secrete substances in blood substances to maintain tight junctions Blood-CSF Blood-Brain Barrier Barrier Outer CSF- Brain Barrier D’Agata et al., Molecules (2017) Saunder et al., Front. Pharmacol., (2012) 9/25/2024 Sample Footer Text 12 The BBB (cont’d) The BBB is permeable to: Lipid-soluble substances (e.g. steroid hormones, nonpolar molecules like O2 and CO2) Water molecules Glucose Some ions (slow transport) The BBB is impermeable to proteins and antibiotics 9/25/2024 Sample Footer Text D’Agata et al., Molecules (2017) 13  Questions: What could disrupt the structure/function of the BBB? What is the result of a compromised BBB? 9/25/2024 Sample Footer Text 14  iClicker question: Through what type of transport do water and glucose cross the BBB? A. Simple diffusion B. Facilitated diffusion C. Direct or primary active transport D. Indirect or secondary active transport E. I don’t know 9/25/2024 Sample Footer Text 15 Cerebrospinal fluid (CSF) fills the ventricles of the brain CSF consists of mainly water plus glucose, ions, proteins, lactic acid, urea, and some leukocytes Continuously circulates through cavities around the brain called ventricles and through spinal cord Septum pellucidum There are four ventricles: Septal nuclei 2 lateral ventricles around each brain hemisphere separated by the septum pellucidum 9/25/2024 Sample Footer Text 16 The ventricles of the brain (cont’d) The third ventricle is a thin, slit-like cavity between the two halves of the thalamus and superior to the hypothalamus Connected to lateral ventricles by the interventricular foramina The fourth ventricle lies between the brainstem and the cerebellum 9/25/2024 Sample Footer Text 17  What does CSF do? The functions of CSF include: 1. Mechanical protection of the brain and spinal cord Permits brain and spinal cord to float within their respective body cavities 2. Chemical protection of neuronal electrical signals Maintains the specific electrochemical environment required for accurate neuronal signalling 3. Circulation of nutrients and waste 9/25/2024 Sample Footer Text 18 Where is CSF synthesized? In the choroid plexuses: capillary networks that line the ventricles Ependymal cells filter blood plasma and secrete the filtered substance as CSF Secretion is bidirectional Joined by tight junctions to form blood-CSF barrier 9/25/2024 19  Which of the following statements about the blood-brain barrier (BBB) is INCORRECT? A. It is permeable to water-soluble iClicker substances. B. It is formed by ependymal cells joined by question: tight junctions. C. It is impermeable to proteins. D. It is sealed by the secretions of astrocytes. E. All of the above are correct. 9/25/2024 Sample Footer Text 20 How is CSF circulated? CSF from the choroid plexuses of the lateral ventricles flows through the interventricular foramina into the third ventricle More CSF is secreted by the choroid plexuses in the third ventricle CSF flows through the midbrain via the cerebral aqueduct and into the fourth ventricle More CSF is contributed by the choroid plexuses of the fourth ventricle 9/25/2024 Sample Footer Text 21 Sample Footer Text CSF circulation (cont’d) 9/25/2024 22 CSF circulation (cont’d) CSF flows into the subarachnoid space via three openings (apertures) in the roof of the fourth ventricle: A central median aperture surrounded by two lateral apertures CSF then circulates through the central canal of the spinal cord and through the subarachnoid space around the brain and spinal cord 9/25/2024 Sample Footer Text 23 CSF is reabsorbed Through arachnoid granulations (villi), which are extensions of the arachnoid mater Project into the dural venous sinuses Especially prominent in superior sagittal sinuses Rates of filtration and reabsorption are relatively constant; therefore volume of CSF is relatively constant! 9/25/2024 Sample Footer Text 24  Summary of CSF circulation 9/25/2024 Sample Footer Text 25 Hydrocephalus is the result of increased CSF pressure May be caused by tumours, inflammation, or malformations Pressure on delicate brain and spinal cord tissues > altered function Treatment: drain excess CSF to relieve pressure Usually via surgical insertion of a shunt 9/25/2024 Sample Footer Text 26 The brainstem and reticular formation The brainstem consists of the medulla oblongata, pons, and midbrain Within the brainstem, the reticular formation is a network of grey and white matter 9/25/2024 Sample Footer Text 27 The medulla oblongata (MO) is continuous with the spinal cord Forms the inferior portion of the brainstem White matter contains all sensory and motor tracts that run between brain and spinal cord Anterior bulges are called pyramids: enlarged corticospinal tracts that control voluntary movements of limbs and trunk 9/25/2024 Sample Footer Text 28 At junction of MO with spinal cord … 90% of axons on right cross to the left side of the body; 90% of axons on left cross to the right Forms the decussation of pyramids This crossing is the reason one side of the brain controls the movements of the opposite side of the body! 9/25/2024 Sample Footer Text 29 The MO controls multiple body functions at the nuclei Recall: nuclei are collections of cell bodies in the CNS Examples include the cardiovascular centre that controls heart rate and contractility and the respiratory centre Other functions include reflexes (e.g. vomiting, coughing, sneezing, hiccupping, swallowing) 9/25/2024 Sample Footer Text 30 An olive contains a nucleus Bulges just lateral to each pyramid Receives information from the cerebral cortex, midbrain, and spinal cord Neurons in the inferior olivary nucleus extend their axons into the cerebellum > regulate muscle activity 9/25/2024 Sample Footer Text 31 Other nuclei of the MO Other nuclei of the medulla: Gracile and cuneate nuclei Somatic sensations e.g. touch, pressure, vibration, conscious proprioception Gustatory (taste), cochlear (hearing), and vestibular (equilibrium) nuclei Somatic pathways Nuclei for cranial nerves VIII - XII 9/25/2024 Sample Footer Text 32 iClicker question: Trauma to the MO can lead to death. Why? A. It leads to hydrocephaly and that is always fatal. B. It is fatal to lose sensory neuron function. C. It is fatal to lose motor neuron function. D. It is fatal to lose any white matter. E. It is fatal to lose respiratory and cardiovascular regulation. 9/25/2024 Sample Footer Text 33 The pons Consists of both nuclei and tracts The pons (“bridge”) connects parts of the brain with each other via tracts, including: Right and left sides of cerebellum Nerve impulses controlling voluntary skeletal movements from the cerebral cortex to cerebellum 9/25/2024 Sample Footer Text 34 The pons (cont’d) Nuclei that help control breathing Pontine nuclei & respiratory group Vestibular nuclei Nuclei for cranial nerves V - VIII 9/25/2024 Sample Footer Text 35 The midbrain (mesencephalon) Extends from pons to diencephalon Contains cerebral aqueduct, which connects third and fourth ventricles Contains sensory tracts, motor tracts, and nuclei (visual and auditory info) 9/25/2024 Sample Footer Text 36 The midbrain (cont’d) The posterior tectum possesses four bumps: Two superior colliculi are reflex centres for visual stimuli Two inferior colliculi are reflex centres for auditory stimuli Controls the startle reflex 9/25/2024 Sample Footer Text 37 The startle reflex Sample Footer Text 9/25/2024 38 The midbrain (cont’d) The anterior cerebral peduncles Three paired bundles of axons (corticospinal, corticobulbar (brain stem nuclei), corticopontine) Ascending (sensory) axons carry sensory information to thalamus Descending (motor) tracts run between the cerebrum, pons, medulla, and spinal cord 9/25/2024 Sample Footer Text 39 Other midbrain nuclei Substantia nigra: large and darkly pigmented Neurons release dopamine: helps control subconscious muscle activity; roles in reward + addiction Red nuclei: red because of rich blood supply Axons from cortex and cerebellum synapse here to coordinate muscular movements of the limbs Nuclei for cranial nerves III and IV 9/25/2024 Sample Footer Text 40  True or false: The primary neurological function of cerebral peduncles of the midbrain is to relay information between the iClicker cerebellum and the skeletal question: muscles. A. True B. False 9/25/2024 Sample Footer Text 41 The reticular formation White (myelinated axons) and grey matter (cell bodies) form a net-like arrangement through brainstem Both ascending (sensory) and descending (motor) functions Ascending portion is called the reticular activating system (RAS) Controls visual, auditory, mental activity, pain/touch/pressure sensing and consciousness 9/25/2024 Sample Footer Text 42 The reticular formation (cont’d) The ascending portion of the RAS also controls: Arousal (waking up from sleep) Attention (ability to focus on one thing) and alertness Sensory overload (ability to filter excessive auditory/visual stimuli) 9/25/2024 Sample Footer Text 43 The reticular formation (cont’d) The descending portion of the RAS controls muscle tone via the cerebellum and spinal cord Also regulates some autonomic functions, such as HR, BP, and respiratory rate Inactivation of the RAS > sleep Damage to RAS > coma 9/25/2024 Sample Footer Text 44 What doesn’t the RAS help process? Olfactory stimuli! What sense do the receptors for these stimuli control? This means … you’ll never wake up from a strong odour! (e.g. smoke from a house fire) 9/25/2024 Sample Footer Text 45  iClicker question: Which of the following statements about the pons is CORRECT? A. It controls alertness and attention. B. It controls only ascending (sensory) functions. C. It consists of white and grey matter arranged in a net-like pattern. D. It is intermediate to the MO and the midbrain. E. All of the above. 9/25/2024 Sample Footer Text 46  Which of the following statements about the function of the reticular formation is CORRECT? A. It controls consciousness. iClicker B. It contains nuclei that control heart contractility and rate. question: C. It permits CSF to circulate from the third to the fourth ventricle. D. It controls respiratory depth. E. It permits a sense of smell. 9/25/2024 Sample Footer Text 47 The cerebellum 10% of brain mass but contains 50% of neurons Superficial portion is made of grey matter called outer grey matter cortex Extensively folded = increased surface area 9/25/2024 Sample Footer Text 48 The cerebellum (cont’d) The cerebellar peduncles attach the cerebellum to the brainstem Superior, middle, and inferior peduncles White matter tracts that coordinate muscle movements 9/25/2024 Sample Footer Text 49 The cerebellum (cont’d) Viewed superiorly or inferiorly, looks like a butterfly The central “body” of the butterfly is called the vermis Separates cerebellum into left and right cerebellar hemispheres Fissures divide the hemispheres into lobes 9/25/2024 Sample Footer Text 50 The cerebellum (cont’d) Anterior and posterior lobes control subconscious movement The flocculonodular lobe controls equilibrium and balance 9/25/2024 Sample Footer Text 51  Determines the accuracy of muscle movements and initiates adjustments What are the Smooths out movements, corrects errors, helps with learning complex movement functions of sequences the Regulates posture and balance cerebellum? Connections to cerebral cortex suggest nonmotor functions in learning, memory, etc. may also exist 9/25/2024 Sample Footer Text 52 Damage to the cerebellum results in ataxia Uncoordinated movements and gait Also results in slurred or mumbling speech May be due to trauma or drugs (e.g. alcohol) 9/25/2024 Sample Footer Text 53 The diencephalon ”Core” of brain tissue Consists of three parts: 1. Thalamus 80% of the diencephalon Right and left halves are joined in 70% of humans by the interthalamic adhesion (grey matter) Contains multiple nuclei 9/25/2024 Sample Footer Text 54 The thalamic nuclei Seven major groups that form different connections to cerebral cortex: Anterior nucleus Medial nuclei Lateral group Ventral group Intralaminar nuclei Periventricular nucleus Reticular nucleus of the prethalamus 9/25/2024 Sample Footer Text 55 What are the Relays signals from spinal cord and brainstem to primary sensory cortex of functions of cerebrum the Also transmits signals from cerebellum to primary motor cortex of cerebrum thalamus? Roles in consciousness 9/25/2024 Sample Footer Text 56 The hypothalamus 2. Hypothalamus Inferior to the thalamus in diencephalon 12 nuclei divided into four groups: Posterior hypothalamic area: olfaction; feeding reflexes (licking, swallowing) Intermediate hypothalamic area: contains infundibular stalk that connects to pituitary gland; regulates anterior pituitary gland function 9/25/2024 Sample Footer Text 57 The hypothalamus (cont’d) Anterior hypothalamic area: Axons from paraventricular and supraoptic nuclei transport antidiuretic hormone (ADH) and oxytocin to posterior pituitary Preoptic area: Anterior part of hypothalamus; helps regulate certain autonomic activities (e.g. body temperature) 9/25/2024 Sample Footer Text 58 What are the functions of the hypothalamus? Control of the autonomic nervous system (ANS) Axons from hypothalamus extend to sympathetic and parasympathetic nuclei in brainstem and spinal cord Stimulate smooth / cardiac muscle contraction, secretions from glands Hormone production Release hormones into capillary network → carried to anterior pituitary → stimulate or inhibit secretion of anterior pituitary hormones Cell bodies in paraventricular and supraoptic nuclei produce antidiuretic hormone (ADH) and oxytocin → transported through the infundibulum and released by the posterior pituitary gland 9/25/2024 Sample Footer Text 59  Functions of the hypothalamus (cont’d) Regulation of emotional and behavioural patterns With limbic system, participates in expression of rage, aggression, pain, pleasure, sexual arousal Regulation of eating and drinking Contains thirst center, feeding center, and satiety center Certain cells stimulated by increasing osmotic pressure of ECF and cause thirst sensation → drinking water restores normal osmotic pressure 9/25/2024 Sample Footer Text 60 Functions of the hypothalamus (cont’d) Control of body temperature Functions as the body’s thermostat When temperature of blood flowing through hypothalamus changes, activates ANS responses to restore homeostatic temperature Regulation of circadian rhythms and states of consciousness Suprachiasmatic nucleus receives visual input from retina (light-dark cycle) to synchronize biological rhythms to 24-hour cycle Serves as the body’s internal biological clock 9/25/2024 Sample Footer Text 61 The epithalamus 3. Epithalamus Superior and posterior to thalamus Consists of : Pineal gland: part of endocrine system; secretes melatonin to regulate circadian rhythms Habenular nuclei: regulate emotional responses to olfactory stimuli 9/25/2024 Sample Footer Text 62 The circumventricular organs Located around the third ventricle Includes parts of the hypothalamus, the pineal gland, the pituitary gland, and others Lack a blood-brain barrier Coordinate endocrine and nervous responses to maintain homeostasis E.g. BP, fluid volumes and compositions, hunger, thirst, etc. Maybe site of HIV dissemination (from place where initial infection occurs to new organs in the body) 9/25/2024 Sample Footer Text 63 iClicker question: Which of the following functions is regulated by the structures of the diencephalon? A. Circadian rhythms B. Consciousness C. Body temperature D. Sexual arousal E. All of the above 9/25/2024 Sample Footer Text 64 The cerebrum Three parts: Outer cerebral cortex Inner cerebral white matter Deep grey matter nuclei Functions to produce intelligence, learning, imagination, and memory 9/25/2024 Sample Footer Text 65 The cerebral cortex Made of grey matter Extensively folded ridges are called cerebral gyri Three types: Cerebral sulci divide individual gyri Interlobal sulci divide the cerebrum into lobes Cerebral fissures divide the brain into parts 9/25/2024 Sample Footer Text 66 The longitudinal cerebral fissure defines the cerebral hemispheres The falx cerebri (extension of the arachnoid dura mater) runs through this fissure Internally, the cerebral hemispheres are connected by white matter axons called the corpus callosum 9/25/2024 Sample Footer Text 67 The cerebral hemispheres can be further subdivided into lobes The lobes are named after the cranial bones that cover them Each processes sensory input and outputs motor function to the opposite side of the body. Why? Assignment of function is inexact; boundaries are not physically defined 9/25/2024 Sample Footer Text 68 Fissures define lobes Longitudinal fissure Separates cerebrum into right and left hemispheres Central cerebral sulcus Separates frontal lobe from parietal lobe Lateral cerebral sulcus Separates frontal lobe from temporal lobe Parieto-occipital sulcus Separates parietal lobe from occipital lobe 9/25/2024 Sample Footer Text 69 Functions of the brain lobes Brain lobe Function(s) Frontal lobe Cognitive functions, control of emotions, voluntary movement Parietal lobe(s) Processes information about temperature, taste, touch, movement, proprioception Occipital lobe Processes visual information Temporal lobe(s) Processes memories and integrates them with sensations of taste, sound, sight and touch Insula Taste 9/25/2024 Sample Footer Text 70 Cerebral white matter Consists of myelinated axons distributed across three tracts: 1. Association tracts: conduct nerve impulses between gyri in the same hemisphere 2. Commissural tracts: conduct nerve impulses between corresponding gyri in opposite hemispheres Includes: the corpus callosum, the anterior and posterior commissures 9/25/2024 Sample Footer Text 71 Cerebral white matter (cont’d) 3. Projection tracts: conduct nerve impulses from cerebrum to other parts of the brain and spinal cord Includes internal capsule: thick band of white matter containing both ascending and descending tracts 9/25/2024 Sample Footer Text 72 Cerebral white matter anatomy 9/25/2024 Sample Footer Text 73 The corpus striatum is a group of nuclei buried deep within each cerebral hemisphere The globus pallidus lies close to the thalamus Together with the nearby putamen, forms the lentiform nucleus The caudate nucleus 9/25/2024 Sample Footer Text 74 What are the functions of the corpus striatum? Corpus striatum receives input from the cerebral cortex and sends output back to motor cortex via thalamus Also communicates with midbrain (substantia nigra) Helps start and stop movements Activity in corpus striatum is detected prior to muscle movements Helps control muscle tone, subconscious movements, posture E.g. swinging arms when walking, true spontaneous laughter Also affects attention, memory, planning, and coordinate with limbic system to regulate emotional behaviours 9/25/2024 Sample Footer Text 75 The limbic system Collection of structures from the cerebrum, diencephalon, and midbrain, connected by the fornix (a white matter bundle) Forms floor of diencephalon Wraps up and around corpus callosum 9/25/2024 Sample Footer Text 76 The limbic system (cont’d) Frontal lobe Involved in establishing emotional states Thalamus Pain, pleasure, docility, affection, anger… Hippocampus Olfaction and memory In animals, when different areas of Amygdala limbic system are stimulated, different emotional behaviours are shown (e.g. Hypothalamus amygdala = rage and fear) The hippocampus is involved in memory storage and retrieval Olfactory bulb Contains cells capable of mitosis 9/25/2024 Sample Footer Text 77 Have you heard of a lobotomy? What is it and what was it used for? 9/25/2024 Sample Footer Text 78 iClicker question: What is the likely effect of a traumatic injury to the hippocampus? A. Uncontrollable rage B. Ataxia C. Coma D. Loss of memory E. Paralysis 9/25/2024 Sample Footer Text 79 Functional organization of the cerebral cortex Certain types of sensory information are processed by specific areas of cerebral cortex Assist with sensory perception, executing voluntary movements, and higher-level thinking 9/25/2024 Sample Footer Text 80 Primary sensory areas Sensory information from peripheral receptors arrives to the cerebral cortex posterior to the central cerebral sulci (primary somatosensory cortex) Receives touch, pressure, vibration, itch, tickle, temperature, pain, and proprioception information Also: primary visual, auditory, gustatory, and olfactory cortex 9/25/2024 Sample Footer Text 81 Sensory association areas Sensory association areas lie nearby the primary sensory areas Facilitate sensory information processing along with other brain centres (i.e. recognition and awareness) 9/25/2024 Sample Footer Text 82 The sensory areas link the peripheral receptors into a misshapen map of the body Called a somatosensory map or sensory homunculus Each sensory area receives stimuli from a specific part of the body What determines how much area of the somatosensory map is devoted to a body part? 9/25/2024 Sample Footer Text 83 The sensory areas Primary visual cortex Posterior tip of occipital lobe Receives impulses that convey information (e.g. shape, colour, movement) for vision Primary auditory cortex Superior part of temporal lobe, near lateral cerebral sulcus Interprets basic characteristics of sound (e.g. rhythm and pitch) 9/25/2024 Sample Footer Text 84 Sensory areas (cont’d) Primary gustatory cortex Located in the insula Receives impulses for taste Primary olfactory cortex In temporal lobe on medial aspect Receives impulses for smell 9/25/2024 Sample Footer Text 85 Motor areas The motor areas govern voluntary muscular movement Formed by anterior portions of each cerebral hemisphere, including: Primary motor cortex Premotor cortex Broca’s area Frontal eye field 9/25/2024 Sample Footer Text 86 Like the sensory areas, there is a motor homunculus in the primary motor cortex Each region controls specific skeletal muscles on the contralateral side of body. Why? Number of neurons devoted to a muscle group is dependent on whether the area is responsible for fine or skilled movements (more neurons) versus gross movements (less neurons) Electrical stimulation of a point controls muscle contraction(s) 9/25/2024 Sample Footer Text 87 In the primary somatosensory and motor areas, each side of the body is controlled by the opposite hemisphere of the brain 9/25/2024 Sample Footer Text 88 Functions of other motor areas Premotor cortex Motor association area anterior to primary motor cortex Controls complex, learned, sequential, coordinated movements (e.g. typing) Also, serves as memory bank for these movements 9/25/2024 Sample Footer Text 89 Other motor area functions (cont’d) Frontal eye field Partially in and anterior to premotor cortex Controls voluntary scanning movements of eyes (e.g. reading a line of text) 9/25/2024 Sample Footer Text 90 Other motor area functions (cont’d) Broca’s area: Helps to control articulation of speech (ability to speak) Production of speech In >95% of people, it is located in left frontal lobe Lesions to Broca’s area → can’t speak but can understand 9/25/2024 Sample Footer Text 91 Broca’s aphasia Aphasia is communication dysfunction, including inability to speak, understand, or write 9/25/2024 Sample Footer Text 92 Association areas of the cerebral cortex The association areas are concerned with complex integrative functions such as memory, emotions, reasoning, will, judgement, personality traits, and intelligence Different association areas are connected to each other by association tracts Nerve impulses are transmitted from primary areas to association areas 9/25/2024 Sample Footer Text 93 The somatosensory association area Posterior to somatosensory area Receives input from primary somatosensory cortex, thalamus Integrates and interprets sensations Determine exact shape / texture of object by feel alone Storage of past somatic sensory experiences (memories) E.g. You remember what your keys feel like so you can pull them out of your bag without looking 9/25/2024 Sample Footer Text 94 Other association areas Visual association area In occipital lobe Receives sensory input from primary visual cortex and thalamus Relates present and past visual experiences (object recognition) 9/25/2024 Sample Footer Text 95 Other association areas (cont’d) Facial recognition area Inferior temporal lobe (right hemisphere usually dominant) Receives input from visual association area Stores information about faces (recognize people by sight) 9/25/2024 Sample Footer Text 96 Other association areas (cont’d) Auditory association area Inferior and posterior to primary auditory area, in temporal cortex Recognition of sound as speech, music, or noise Orbitofrontal cortex Lateral part of frontal lobe Receives sensory impulses from primary olfactory area Identify and distinguish different odours 9/25/2024 Sample Footer Text 97 Other association areas (cont’d) Wernicke’s area Broad area in left temporal and parietal lobes Interprets meaning of speech by recognizing spoken words Areas in right hemisphere corresponding to Broca’s area and Wernicke’s area add emotional content to language Comprehension of speech, translation of words to thought 9/25/2024 Sample Footer Text 98 Wernicke’s aphasia Can speak, but cannot arrange words coherently (Lack speech comprehension) 9/25/2024 Sample Footer Text 99 Other association areas (cont’d) Common integrative area Surround somatosensory, visual, and auditory association areas Integrates sensory interpretations → formation of thoughts based on sensory input from different areas Transmits signals to parts of brain for appropriate responses 9/25/2024 Sample Footer Text 100 Other association areas (cont’d) Prefrontal cortex Extensive area of anterior frontal lobe that is well-developed in primates, especially humans Many connections with other brain regions The prefrontal cortex regulates personality, intellect, information recall, initiative, judgement, foresight, reasoning, conscience, intuition, mood, future planning, abstract ideas 9/25/2024 Sample Footer Text 101  iClicker question: Which of the following association areas of the cerebral cortex are involved in writing, recognizing, and understanding written words? A. Wernicke’s area B. The orbitofrontal cortex C. Broca’s area D. A and B E. A and C 9/25/2024 Sample Footer Text 102 Hemispheric lateralization Functional asymmetry of the brain Established early in development Includes both structural and functional differences between the hemispheres Differences vary between individuals and may be less pronounced in biological females (more commissural tracts) Less pronounced aphasia after damage to left hemisphere 9/25/2024 Sample Footer Text 103  Visual and spatial skills Language Right hemisphere functions Left hemisphere functions Receives sensory signals from and outputs motor signals to Receives sensory signals from and outputs motor signals to left side of body right side of body Musical and artistic awareness Space and pattern recognition Reasoning Recognition of faces and facial expressions (emotions) Numerical and scientific skills Generating emotional content of language Ability to use and understand sign language Producing a mental picture of spaces Spoken and written language Identifying and discriminating between odours Damage to Broca’s/Wernicke’s areas speak in a monotone > Damage to left hemisphere often results in aphasia cannot generate emotional inflection in speech 9/25/2024 Sample Footer Text 104 Brain waves The many neurons of the brain are sending millions of nerve impulses Electrical signals give rise to brain waves Electrodes placed on the forehead and scalp can produce a digital output called an electroencephalogram (EEG) 9/25/2024 Sample Footer Text 105  Frequency (Hz) Four types of brain waves in normal individuals Alpha waves: awake and resting with eyes closed, absent during sleep Beta waves: awake and mentally active Delta waves: occur only during deep sleep in adults Amplitude Theta waves: sign of emotional stress in adults 9/25/2024 Sample Footer Text 106  iClicker question: Hand preference when writing is an example of which of the following phenomena? A. Cranial nerve damage. B. Hemispheric lateralization. C. Damage to the olfactory nerve. D. Damage to Broca's area. E. Theta brain waves. 9/25/2024 Sample Footer Text 107 Lecture 3: Brain and Cranial Nerves iClicker question: (participation marks) What do you think your brain waves are right now? A. Mostly alpha (awake but resting) B. Mostly beta (awake and alert) C. Mostly theta (stressed!) D. Mostly delta (deep sleep) 9/25/2024 108 Cranial nerves: a note It is very helpful to use mnemonics to learn these nerves and their functions One example is explained here: https://www.youtube.com/watch?v=Y0p21LC4wZ8 Other examples were provided in lab Choose one that works best for you and use it!!! Note: additional details are provided in the slides to explain each nerve. You must know the location, type, and function of each nerve 9/25/2024 Sample Footer Text 109 When you study … Identify cranial nerve Know its location in the brain Describe function of cranial nerve If sensory – what stimuli is received?, from which parts of the body? If motor – what effector(s) is/are innervated? If mixed – what are the sensory and motor functions? 9/25/2024 Sample Footer Text 110  The cranial nerves are I. Olfactory Nerve named and numbered II. Optic Nerve III. Occulomotor IV. Trochlear V. Trigeminal 12 pairs (part of PNS) VI. Abducens Each cranial nerve has a number and VII. Facial a name: VIII. Vestibulocochlear Roman numeral – indicates order IX. Glossopharyngeal they arise from the brain, from anterior to posterior X. Vagus Nerve Name – indicates nerve’s function XI. Accessory XII. Hypoglossal Oh Oh Oh To Touch And Feel Very Green Vegetables AH! 9/25/2024 Sample Footer Text 111 Cranial nerves (cont’d) CN I, II, and VIII are special sensory nerves unique to the head and associated with the special senses of smelling, seeing, and hearing Cell bodies of most sensory neurons are located in ganglia outside the brain CN III, IV, VI, XI, XII are motor nerves that contain motor axons Cell bodies of motor neurons are in nuclei within the brain CN V, VII, IX, and X are mixed nerves that contain both sensory and motor neuron Some Say Marry Money, But My Brother Says Big Brains Matter More 9/25/2024 Sample Footer Text 112  Cranial nerves - overview Sensory Also in weekly Motor I. Olfactory Nerve anatomy 3 Mixed II. Optic Nerve III. Occulomotor IV. Trochlear V. Trigeminal VI. Abducens VII. Facial VIII. Vestibulocochlear IX. Glossopharyngeal X. Vagus Nerve XI. Accessory XII. Hypoglossal Cranial nerve mnemonics: 9/25/2024 https://www.youtube.com/watch?v=Y0p21LC4wZ8 Sample Footer Text 113  Cranial nerves – overview (brain structures are shown here) 9/25/2024 Sample Footer Text 114 Brain structures CNI: The olfactory nerve Olfactory Olfactory bulb tract Cribriform plate Olfactory (I) nerve Axon Sensory nerve that relays Olfactory epthelium Olfactory olfactory information Anterior sensory neuron Dendrite Extends from olfactory mucosa of nasal cavity (start) → olfactory Olfactory bulb Olfactory tract bulb (end) → synapses with neurons that form the olfactory tracts → primary olfactory area in temporal lobe 9/25/2024 Sample Footer Text 115 CNII: optic nerve Bipolar Ganglion Rod Cone cell cell Axons of ganglion cells Ganglion cells’ axons form optic nerve → merge and some axons Retina cross in optic chiasm → optic ANTERIOR tracts → thalamus → primary Optic chiasm Retina visual cortex Optic (II) nerve Eyeball Some axons go to midbrain Optic tract (instead of cortex) to synapse with motor neurons that control eye movements 9/25/2024 Sample Footer Text 116  CN II: the optic nerve Special sensory nerve Sense impulses for vision Starts in the retina: rods and cones → bipolar cells→ ganglion cells Enters the brain through the optic foramen Most optic tracts end in the lateral geniculate nucleus in the thalamus Synapse with neurons and axons of these neurons extend to the primary visual cortex Others extend to the superior colliculi (midbrain) and motor nuclei of brainstem Synapse with motor neurons that control extraocular and intrinsic eye muscles 9/25/2024 Sample Footer Text 117 CN III, IV, and VI: oculomotor, Medial Superior trochlear, abducens rectus rectus Levator palpebrae superioris Superior muscle muscle branch muscle Preganglionic parasympathetic nerve Upper eyelid Lateral rectus muscle (cut) (a) or Short ciliary nerves (carry ANTERIOR ot Synapse with muscles for lom erve postganglionic parasympathetic u Oc III) n neurons) ( Inferior Inferior branch moving the eyeballs and upper Ciliary rectus Inferior oblique muscle ganglion muscles T ro c h lear (IV ) nerv e eyelid (b) Superior oblique muscle Midbrain Note that CN III has autonomic Pons Ab du motor output to constrict pupils ce n s (c) (V I) ne ver Inferior surface of brain Lateral rectus muscle 9/25/2024 Sample Footer Text 118 CN III, IV, VI III (oculomotor) Motor nerve Superior innervates: superior rectus, levator palpebrae superioris Inferior innervates: medial rectus, inferior rectus, inferior obliques muscles, ciliary muscle, circular muscle of iris IV (trochlear) Motor nerve Innervates superior oblique muscle of eyeball VI (abducens) Motor nerve Innervates lateral rectus muscle of eyeball (lateral rotation of eyeball) 9/25/2024 Sample Footer Text 119 Damage to CN III, IV, and V lead to strabismus Disorder where the eyes do not line up in the same direction 120 Sample Footer Text 9/25/2024 CN V: trigeminal nerve Ophthalmic branch ANTERIOR Maxillary branch Mixed nerve Mandibular branch Branchial motor neurons Pons innervate muscles of mastication (control chewing movements) Sensory axons enter through Trigeminal (V) nerve Trigeminal ganglion trigeminal ganglion and Inferior surface of brain terminate in nuclei of pons 9/25/2024 Sample Footer Text 121 CN V: trigeminal nerve Three branches: Ophthalmic: Sensory axons from skin over upper eyelid, lacrimal glands, cornea etc Maxillary: Sensory axons from mucosa of nose, upper teeth, palate etc Mandibular: Sensory axons for 2/3 of tongue (not taste), lower teeth, etc 9/25/2024 Sample Footer Text 122 Pathologies of CN V Trigeminal neuralgia Shingles Muscle weakness, loss of sensation in face 9/25/2024 Sample Footer Text 123 CN VII: facial nerve ANTERIOR Mixed nerve Sensory axons Pons Sensory axons extend from the taste buds of 2/3 (anterior) of tongue Axons then extend to thalamus, then to Geniculate ganglion Tongue gustatory areas of cerebral cortex Facial (VII) nerve Inferior surface of brain Salivary glands Sensory axons that extend from the external acoustic meatus in the skin relay touch, pain, thermal sensations 9/25/2024 Sample Footer Text 124 CN VII: facial nerve ANTERIOR Motor axons (innervates muscles of facial expression and the stapedius muscle) Pons Branchial motor axons Innervates middle ear, facial, Geniculate scalp and neck muscles ganglion Tongue Facial (VII) nerve Parasympathetic motor axons Inferior surface of brain Salivary glands End in two ganglia that extends to the lacrimal glands, palatine glands, nasal glands, oral cavity glands, etc 9/25/2024 Sample Footer Text 125  Damage to CN VII is known as Bell’s palsy 9/25/2024 Sample Footer Text 126 CN VIII: vestibulocochlear nerve Vestibular ganglion ANTERIOR Semicircular canal Vestibular branch Vestibule (contains saccule and utricle) Special sensory nerve Cochlear branch Impulses for equilibrium and Vestibulocochlear (VIII) nerve hearing Pons Vestibular branch Impulses for equilibrium Extends from semicircular canals, Cochlea and vestibule (saccule, and utricle) (contains spiral organ) of inner ear Ends in vestibular nuclei in pons and cerebellum 9/25/2024 Sample Footer Text 127 CN VII: vestibulocochlear nerve Vestibular ganglion ANTERIOR Semicircular canal Vestibular branch Vestibule (contains saccule and utricle) Cochlear branch Cochlea branch Impulses for hearing Vestibulocochlear (VIII) nerve Originate in spiral organ in Pons cochlea of inner ear Extends to nuclei in medulla oblongata and ends in Cochlea (contains spiral organ) thalamus Note: motor fibers of this nerve regulate hair cells in inner ear and do not innervate muscle tissue. 9/25/2024 Sample Footer Text 128  CN IX: glossopharyngeal nerve Mixed nerve Sensory axons ANTERIOR Originate from: Tastebuds on posterior 1/3 of tongue Parotid gland Otic ganglion Proprioreceptors of some swallowing muscles Soft palate Inferior ganglion Palatine Baroreceptors Medulla tonsil oblongata Tongue Chemoreceptors Superior ganglion Carotid body External ear Glossopharyngeal Carotid sinus (IX) nerve Inferior surface of brain Cell bodies are located in superior and inferior ganglia Pass through jugular foramen and ends in medulla 9/25/2024 Sample Footer Text 129 CN IX: glossopharyngeal nerve ANTERIOR Parotid gland Motor neurons Otic ganglion Soft palate Originate from nuclei in medulla Inferior ganglion Palatine Exit skull through the jugular Medulla tonsil foramen oblongata Superior Tongue Carotid Branchial motor axons innervate ganglion body stylopharyngeus muscle which Glossopharyngeal (IX) nerve Carotid sinus helps with swallowing Inferior surface of brain Parasympathetic motor neurons stimulate parotid gland for saliva secretion 9/25/2024 Sample Footer Text 130  Carotid sinus Carotid body CN X: Vagus nerve Aortic bodies Larynx Glossopharyngeal (IX) nerve Heart ANTERIOR Lungs Mixed nerve Liver and gallbladder Inferior Sensory axons ganglion Originate from: Medulla Superior ganglion Vagus (X) Stomach Pancreas oblongata (behind The skin of external ear for touch, pain, and Inferior surface of brain nerve Pancreas stomach) thermal sensations; few taste buds in epiglottis and pharynx; proprioceptors in muscles of neck Small intestine Large intestine and throat; baroreceptors in carotid sinus; chemoreceptors in carotid and aortic bodies; visceral sensory receptors in organs in thoracic and abdominal cavities Injury to this nerve could be fatal 9/25/2024 Sample Footer Text 131  Carotid sinus CN X: vagus nerve Carotid body Aortic bodies Larynx Glossopharyngeal (IX) nerve Heart Branchial motor neurons ANTERIOR Lungs Branchial motor axons innervate muscles of pharynx, larynx, soft palate (for swallowing, vocalization, Liver and coughing) gallbladder Inferior ganglion Parasympathetic motor neurons Medulla Superior ganglion Vagus (X) Stomach Pancreas supply lungs heart, glands of oblongata nerve (behind stomach) digestive canal, smooth muscles of Inferior surface of brain Pancreas passageways and intestine (visceral Small intestine Large intestine organs) 9/25/2024 Sample Footer Text 132 CN XI: Accessory nerve ANTERIOR Motor nerve Cranial accessory is part of vagus nerve Spinal accessory Medulla oblongata Motor axons: Spinal cord Originate from anterior grey horn of C1 – C5 Accessory (XI) nerve Trapezius Sternocleidomastoid muscle Ascends to skull through foramen magnum muscle Inferior surface of brain Innervates sternocleidomastoid and trapezius muscles to coordinate head movement 9/25/2024 Sample Footer Text 133 CN XII: hypoglossal nerve ANTERIOR Motor nerve Somatic motor axons supply muscles of the tongue (during speech and swallowing) Medulla oblongata Hypoglossal (XII) nerve Inferior surface of brain 9/25/2024 Sample Footer Text 134 Review: CN I through XII 9/25/2024 Sample Footer Text 135 iClicker question: 1 Oculomotor (III) nerve Which cranial nerves innervate only 2 Trigeminal (V) nerve one eye muscle? A. 1, 2, 3 3 Abducens (VI) nerve B. 1, 2, 3, 4, 5 C. 3 and 5 only 4 Vestibulocochlear (VIII) nerve D. 2 and 5 E. 2, 3, 4 5 Trochlear (IV) nerve 9/25/2024 Sample Footer Text 136  A iClicker question: B Damage to which of the following C cranial nerves will result in Bell’s palsy? D E 9/25/2024 Sample Footer Text 137 Homeostatic imbalances Cerebrovascular accident (CVA) or Stroke o Results from death of brain cells due to lack of oxygen o 85% of strokes are ischemic (due to blood clot) o 15% of strokes are hemorrhagic (leaky or ruptured vessel) What determines the severity of a stroke? 9/25/2024 Sample Footer Text 138 9/25/2024 139 Summary Sample Footer Text Summary charts available for you to fill out on Brightspace!