Brain and Cranial Nerves - Chapter 14 PDF

Brain and cranial nerves BIOL 1191 – CHAPTER 14 JANAINA BRUSCO PHD Outline Brain Organization and Protection Formation and Circulation of Cerebrospinal Fluid Structures of the Brain Functional Organization of the Cerebrum Cranial Nerves  Intended Learning Outcomes After learning about the br...

Brain and cranial nerves BIOL 1191 – CHAPTER 14 JANAINA BRUSCO PHD Outline Brain Organization and Protection Formation and Circulation of Cerebrospinal Fluid Structures of the Brain Functional Organization of the Cerebrum Cranial Nerves  Intended Learning Outcomes After learning about the brain and cranial nerves, you should be able to: 1. Identify the major parts of the brain 10. Describe the components and functions of the 2. Explain how the brain is protected and describe its diencephalon three protective coverings. 11. Describe and locate the major anatomical features of 3. Describe the blood supply of the brain the cerebrum 4. Discuss the structure and function of the blood brain 12. Describe three types of cerebral white matter tracts barrier 13. Describe the structures and functions of the limbic 5. Describe the function of cerebrospinal fluid, and system explain its formation and circulation in the CNS 14. Describe the locations and functions of the sensory, 6. Compare and contrast different brain regions and their association, and motor areas of the cerebral cortex functions 15. Explain the importance of hemispheric lateralization 7. Describe the structure and functions of the brainstem 16. Explain the importance of brain waves and reticular formation 17. Identify the origins and functions (both sensory and 8. Describe the structure and functions of the cerebellum motor) for CN I through CN XII 9. Define ‘decussation’  ILO 1 Major Parts of the Brain The main parts of the brain are: 1. Brainstem ◦ Medulla oblongata, pons, and midbrain 2. Diencephalon ◦ Thalamus, hypothalamus, epithalamus 3. Cerebrum 4. Cerebellum  ILO 2 Protective Coverings of the Brain The brain is protected by: 1. Cranial bones 2. Cranial meninges - dura, arachnoid, and pia maters. ▪ Unlike the spinal dura mater, the cranial dura mater has 2 layers – periosteal layer (external) and meningeal layer (internal) ▪ Two layers are fused together except where they separate to enclose venous sinuses (drain blood and CSF) ▪ No epidural space around brain Dura mater extensions ◦ Falx cerebri – separates the cerebrum hemispheres. It attaches to the crista galli of the ethmoid bone ◦ Falx cerebelli – separates the cerebellum hemispheres ◦ Tentorium cerebelli – separates the cerebrum from cerebellum  SUPERIOR Superior sagittal sinus Skin Parietal bone Cranial meninges: Subarachnoid space Dura mater Arachnoid mater Pia mater Falx cerebri Cerebral cortex Anterior view of frontal section  ILO 3 Brain Blood Flow 20% of oxygen & glucose in blood gets used by brain Good supply of O2 and glucose is vital to brain function ◦ no glucose stores in brain ◦ low level of O2 or glucose in blood leads to confusion, dizziness, unconsciousness ◦ 1–2-minute interruption leads to impaired function ◦ > 4 minutes = permanent damage Brain Blood Flow Blood flow to brain: ◦ Internal carotid and vertebral arteries Blood flow away from brain to heart: ◦ Dural venous sinuses drain into internal jugular veins When activity of neurons and neuroglia increases in a region of the brain → flow to that area also increases Blood Brain Barrier ILO 3 Protects brain cells from harmful substances by preventing substances from blood entering brain tissue Three things form the BBB: 1. Tight junctions seal endothelial cells of brain capillaries 2. A thick basement membrane surrounds endothelial cells 3. Astrocytes press up against capillaries – secrete substances that selectively allow/inhibit substances to pass from blood to neurons Blood Brain Barrier Lipid-soluble substances cross easily (i.e. oxygen, Trauma, inflammation, and carbon dioxide, alcohol, nicotine, caffeine, and certain toxins can all cause a most anesthetic agents) breakdown of the BBB Water-soluble substances may be transported (i.e. glucose) Other substances are transported across very slowly (i.e. most ions) Big molecules (antibiotic drugs, proteins) do not enter at all Formation and Circulation of Cerebrospinal Fluid Cerebrospinal Fluid (CSF) ILO 5 Clear liquid containing glucose & O2 and other chemicals essential to neurons and neuroglia Functions ◦ mechanical protection ◦ softens contact/impact with skull, and makes brain float (reducing weight) ◦ chemical protection ◦ regulation of pH and other ions concentration ◦ circulation ◦ Clearance of waste products into the bloodstream CSF is contained in four 2 lateral ventricles different ventricles (one for each cerebral hemisphere) Interventricular foramen Third ventricle along midline, between right and left halves of thalamus Ventricular system, Cerebral Ventricular system, lateral view anterior view aqueduct Fourth ventricle between brainstem and cerebellum From Visual Anatomy & Physiology, 1e Martini/Ober/Nath p.429 Formation of CSF in Choroid plexus = network of capillaries in walls of ventricles Capillary covered by ependymal cells ventricles covered by ependymal cells Ependymal cells make the CSF by filtration of blood plasma CSF Ventricle Ependymal cells are joined by tight junctions, so substances from blood MUST go through cells before they enter the brain ventricles  Nutrients, Interstitial fluid O2 in thalamus Capillaries Waste products, CO2 Neuron Astrocyte Choroid plexus cells Ependymal cells Removal of waste Cerebrospinal Production fluid in of CSF third ventricle Choroid plexus Circulation 1. Flows from lateral of CSF ventricles to 3rd ventricle via interventricular foramina 2. Next through cerebral aqueduct to 4th ventricle (through midbrain) 3. Then into subarachnoid space through median and 2 lateral apertures in 4th ventricle 4. Into central canal of spinal cord and subarachnoid space of cord and brain (purple arrows) Hydrocephalus When CSF production exceeds reabsorption ◦ accumulation of fluid in brain (swelling) ◦ in newborn or fetus, fontanels allow expansion of skull ◦ implantation of shunt can redirect CFS to veins ◦ in adults, skull can’t expand so swelling can lead to rapid death Cerebral spinal fluid is produced in which structure(s)? a) Choroid plexuses b) Cerebral aqueduct c) Arachnoid villi d) Median aperture e) All the above Which of the following statements is true about the blood-brain barrier and blood-CSF barrier? a) Both involve astrocytes b) Both involve tight junctions c) Both involve ependymal cells d) A and B e) B and C Structures of the Brain BRAINSTEM CEREBELLUM DIENCEPHALON CEREBRUM The Brain Stem MEDULLA OBLONGATA, PONS AND MIDBRAIN ILO 7 The Brain Stem The brainstem is the part of the brain between the diencephalon and the spinal cord 3 sections: ◦ Medulla oblongata ◦ Pons ◦ Midbrain Medulla Oblongata A continuation of spinal cord containing: ◦ Ascending sensory tracts ◦ Descending motor tracts ◦ Nuclei ◦ Integrating centers ◦ Send information in and out of cerebellum Medulla oblongata White Matter of the Medulla The white matter is composed of ascending Anterior surface of sensory tracts and motor descending tracts. the medulla oblongata The anterior portion of the medulla bulges out; these are called the pyramids and are composed of motor tracts. Pons About 90% of pyramidal tracts on left cross to right, and vice versa; called decussation (means crossing). From Visual Anatomy & Physiology, 1e Martini/Ober/Nath p.432 White Matter of the Medulla The 4th ventricle is in the superior/posterior aspect of the medulla CN X Due to the decussation of pyramids, the left side of the brain controls the right side CN XII of the body, and vice-versa. pyramids CN XI Spinal cord The term “decussation” means? a) To split in half b) Control of movement c) A form of sensory input d) Crossing of axons e) Leaping of axons A common site of decussation for motor tracts is a) In the pyramids of the medulla b) In the anterior area of the medulla c) In the pons d) In the midbrain e) a and b Gray Matter of the Medulla The Medulla contains many nuclei that act as integration centers or relay centers. Medulla Oblongata Lateral to each pyramid is an oval- shaped swelling called an olive ◦ Contains inferior olivary nucleus ◦ Receives input from cerebral cortex, midbrain and spinal cord ◦ Sends input to cerebellum →Controls proprioceptive signals →Gives precision to movements Nuclei of the Medulla Control many vital body functions ◦ Cardiovascular center ◦ Controls force and rate of heartbeat, diameter of blood vessels ◦ Respiratory center ◦ Sets basic rhythm of breathing ◦ Reflex centers for coughing, sneezing, swallowing, vomiting, hiccupping Other nuclei of the medulla: Gracile and cuneate nuclei: Associated with somatic sensations (touch, pressure, vibration, conscious proprioception) Gustatory (taste), cochlear (hearing), and vestibular (equilibrium) nuclei Nuclei for cranial nerves (VIII-XII) Pons Located superior to the medulla Consists of both nuclei and tracts The pons (“bridge”) connects the parts of brain with each other via tracts ◦ Connects right and left sides of cerebellum ◦ Relays nerve impulses related to voluntary skeletal movements from the cerebral cortex to the cerebellum (both sensory and motor tracts) Nuclei in the Pons control aspects of breathing, sleep, swallowing, bladder control, hearing and equilibrium, as well as taste and facial expressions. The Pons contains nuclei for cranial nerves V-VIII Midbrain, aka mesencephalon Extends from pons to diencephalon Contains cerebral aqueduct, which connects 3rd ventricle above to 4th ventricle below Contains sensory tracts, motor tracts and nuclei (visual and auditory info)  White Matter of Midbrain The anterior midbrain contains the cerebral peduncles. These contain tracts of motor neurons leading to different parts of the CNS from the cerebrum; they also contain sensory tracts leading up from medulla to thalamus ANTERIOR ANTERIOR CN III POSTERIOR  Superior colliculus Tectum Periaqueductal gray matter Reticular (contains mesencephalic formation nucleus) View Aqueduct of the midbrain Medial (cerebral aqueduct) lemniscus Medial geniculate nucleus Oculomotor nucleus Red nucleus Substantia nigra Cerebral Corticospinal, corticopontine, Transverse peduncle and corticobulbar axons plane Oculomotor (III) nerve ANTERIOR Transverse section of midbrain Gray matter of Midbrain View Thalamus ANTERIOR CN III CN IV In the posterior midbrain, the superior colliculi (nuclei) deal with visual reflexes CN VII tracking CN VIII CN IX POSTERIOR direct movement of head, neck and eyes CN X in response to visual stimuli CN XI Spinal nerve C1 the inferior colliculi (nuclei)deal with auditory reflexes direct movement of head, neck and eyes in response to sudden/loud auditory stimuli (startle reflex) Gray matter of Midbrain ANTERIOR The substantia nigra is the site of Dopamine production helps control subconscious muscle activity involved in rewards and addiction Axons from the cortex and the cerebellum synapse in the Red nuclei to assess and coordinate POSTERIOR upper limb movements and overall muscle tone The nuclei for cranial nerves III and IV are in the midbrain Parkinson disease results from a) a decrease in the size of the midbrain b) a decrease in neurons from the substantia nigra c) a decrease in the release of serotonin d) a decrease in neurons from the pyramids e) b and c Which structure is the pons? a) A b) B c) C d) D e) None of these Excessive hiccupping could indicate dysfunction in which part of the brain? a) Midbrain b) Medulla oblongatta c) Pons d) RAS e) Mesencephalon Where are the cerebral peduncles found? a) Midbrain b) Medulla oblongatta c) Pons d) RAS e) Cerebrum A superior view of a horizontal section through the midbrain Posterior Superior colliculus Red nucleus Aqueduct of Substantia nigra the midbrain Cerebral peduncle From Visual Anatomy & Physiology, 1e Martini/Ober/Nath p.436 Anterior Diminished substantia nigra in Parkinson patient Normal substantia nigra The Reticular Formation The Reticular formation is a series of scattered nuclei located in the brain stem. They are involved in: maintaining posture and muscle tone relaying pain and analgesic information sleep, alertness and consciousness (via the Reticular activating system - RAS) differentiate between meaningless stimuli (e.g., background noise) and meaningful ones Which part of the brain has failed this student? a) Midbrain b) Medulla oblongatta c) Pons d) RAS e) Mesencephalon The Cerebellum ILO 8 The cerebellum ~10% of weight of the brain, but 50% of the neurons Evaluate how well movements initiated by motor areas in the cerebrum are being carried out Adjusts postural muscles to maintain balance Programs and fine tunes both voluntary and involuntary movements Stores memories of learned movements Cerebellum Cerebellar hemispheres (left and right) each consist of anterior and posterior lobes separated by fissures Flocculonodular lobe Cerebellar peduncles (superior, middle, inferior) the superior part of the cerebellum is involved in regulating subconscious aspects of skeletal muscle movements the cerebellar peduncles attach the cerebellum to the brain stem they contain tracts that link the cerebellum to other parts of the brain The flocculonodular lobe is involved in balance/equilibrium Cerebellar Dysfunction Damage to the cerebellum can cause ataxia = loss of ability to coordinate movements No sense of proprioception Uncoordinated speech muscles and abnormal walking (like a drunk person – alcohol affects cerebellar functions) Can also be result of side effect of certain diseases or medication Which statement about the cerebellum is true? a) The cerebellar peduncles attach it to the cerebrum b) The cerebellar lobes are also called tentorium cerebelli c) Its main function is to ‘fine tune’ motor function d) Its main function is to initiate motor function  ILO 10 The Diencephalon THALAMUS HYPOTHALAMUS EPITHALAMUS The Diencephalon - Between the top of the brain stem and the bottom of the cerebrum - Wraps around the third ventricle Thalamus the thalamus forms ~80% of the diencephalon it is mainly a mass of gray matter – nuclei with interspersed tracts two egg-shaped halves, connected by the intermediate mass, surrounding 3rd ventricle Thalamus: sensory functions The thalamus mainly acts as a relay station for sensory and motor functions: Sensory functions: ◦ sensory info from spinal cord and brain stem goes through thalamus to cerebral cortex ◦ pain, temperature, pressure, hearing… ◦ the thalamus acts as a filter, passing on to the cerebral cortex only a small portion of the sensory information it receives ◦ each region of the thalamus contains nuclei that connect to specific regions of the cerebral cortex Thalamus: motor functions Motor functions: ◦ sends information from cerebellum & basal nuclei to primary motor areas of cerebral cortex ◦ acts as relay station between parts of cerebrum Also involved in consciousness, learning, memory, emotions, cognition (thinking and knowing) Thalamic Nuclei 1. Anterior nucleus 2. Medial nuclei 3. Lateral group 4. Ventral group 5. Intralaminar group 6. Midline group Functions: emotions, alertness, memory, learning, 7. Reticular group awareness, cognition, integration of sensory info, motor planning, somatic sensations, vision, and auditory relay point (Note, all sensory impulses except smell) Hypothalamus the hypothalamus is located between the thalamus and Choroid plexus the pituitary gland intermediate mass it contains about 12 nuclei – divided into four major groups Pineal gland It plays a big role in maintaining homeostasis Pituitary gland Thalamus From Visual Anatomy & Physiology, 1e Martini/Ober/Nath p.438 Hypothalamus: Mammillary region Intermediate Key: Mammillary region mass of thalamus Tuberal region Supraoptic region Preoptic region the mammillary region is in the posterior part of the Optic (II) nerve Optic chiasm hypothalamus, anterior to the Pituitary midbrain gland it is associated with olfaction, POSTERIOR ANTERIOR and feeding reflexes (swallowing, licking)  Hypothalamus: Tuberal region Intermediate Key: Mammillary region mass of thalamus Tuberal region Supraoptic region Preoptic region the tuberal region is just anterior to the mammillary region Optic (II) nerve Optic chiasm It contains the hormonal center, Pituitary and is involved in the control of gland the anterior pituitary gland POSTERIOR ANTERIOR  Hypothalamus: Supraoptic region Intermediate Key: Mammillary region mass of thalamus Tuberal region Supraoptic region Preoptic region the supraoptic region is just anterior to the tuberal region Optic (II) nerve Axons from these nuclei Optic chiasm synthesize and transport Pituitary antidiuretic hormone (ADH) and gland oxytocin (OT) along the POSTERIOR ANTERIOR hypothalamo-hypophyseal tract to the posterior pituitary lobe Hypothalamus: Preoptic region Intermediate Key: Mammillary region mass of thalamus Tuberal region Supraoptic region Preoptic region the preoptic region is in the anterior region of the Optic (II) nerve Optic chiasm hypothalamus Pituitary Involved in regulating gland certain autonomic activities POSTERIOR ANTERIOR such as body temperature Other Functions of the Hypothalamus ▪Controls and integrates activities of the ANS which regulates smooth & cardiac muscle (heart rate, GI tract, bladder) and glands ▪Regulates emotions/behavior such as rage, aggression, pain, pleasure & sexual arousal ▪Regulates hunger and thirst ▪Helps regulate circadian rhythm (daily patterns of sleep) Which of the following is NOT a function of the hypothalamus? a) It controls the activity of the anterior pituitary gland via different hormones b) It is associated with olfaction and feeding reflexes c) Is controls hunger, thirst and feeding reflexes d) It acts as a relay station between different parts of the cerebellum Epithalamus Pineal gland Endocrine gland, size of small pea Secretes melatonin during darkness Promotes sleepiness and sets biological clock Habenular nuclei Involved in olfaction, especially emotional responses to odors Circumventricular Organs (CVOs) Structures that lie in the wall of the third ventricle and lack a blood-brain barrier ◦ Include hypothalamus, pineal gland, pituitary gland, and a few other nearby structures Can monitor chemical changes in the blood Coordinate homeostatic activities of endocrine and nervous systems ◦ Regulation of blood pressure, fluid balance, hunger, and thirst CVOs are thought to be the sites of entry into the brain of HIV The highlighted structure is the: a) Epithalamus b) Thalamus c) Hypothalamus d) Midbrain e) Pons Which of the following is true about the thalamus? a) It is the major relay center for just motor impulses b) It is a component of the diencephalon c) It precisely locates sensations of pain, temperature, pressure and sound d) A and B Are hypothalamic axons part of the nervous system or endocrine system? a) Nervous system b) Endocrine system c) Both d) Neither The Cerebrum ILO 11 The cerebrum Where the intelligence comes from (higher level thinking) The outer portion is the cerebral cortex: gray matter The internal region is white matter, with nuclei deep within Two hemispheres subdivided into 5 regions Parietal lobe Frontal lobe Occipital lobe Insula Cerebellum Temporal lobe fissure, gyrus, sulcus Longitudinal fissure ANTERIOR Precentral gyrus Frontal lobe Central sulcus gyrus Postcentral gyrus sulcus Parietal lobe Occipital lobe fissure Parieto-occipital sulcus POSTERIOR Left hemisphere (a) Superior view Right hemisphere Characteristics of the cerebral hemispheres Each hemisphere receives sensory input and generates motor outputs to the opposite side of the body ◦ Anatomically the same, with functional differences The assignment of function to a particular region is not exact, because lobe boundaries are indistinct. Cerebral White Matter ILO 12 There are 3 kinds of tracts in the Cerebral cortex cerebral white matter: Tracts 1. association tracts run between gyri in the same hemisphere Corpus callosum 2. commissural tracts run from gyri of one hemisphere to corresponding gyri of the other hemisphere Anterior 3. projection tracts form descending commissure & ascending tracts Commissural Tracts Corpus callosum Posterior commissure Anterior commissure Which of the following tracts connect different parts of the brain within the same hemisphere? a) Commissural tracts b) The Corpus Callosum c) Projection tracts d) Association tracts A projection tract is one which: a) Consists of axons that conduct nerve impulses to or from the cerebrum b) Consists of axons that conduct impulses between ipsilateral gyri c) Includes the corpus callosum as an example d) Is also known as a commissural tract e) Conducts nerve impulses to a different area of the same hemisphere Corpus Striatum, aka Basal Nuclei Frontal plane Corpus callosum The corpus striatum are 3 nuclei deep within View each hemisphere: Longitudinal fissure Lateral ventricle Caudate nucleus Insula Thalamus Putamen Hypothalamus and associated nuclei Globus pallidus Third ventricle Corpus Striatum The Corpus Striatum are involved in the execution of movements – They control muscular movements by influencing the cerebral cortex rather than via direct descending pathways They communicate with the cerebral cortex (sensory area and motor area), the thalamus and the midbrain (substantia nigra) They help regulate the initiation and termination of movements (activity in basal ganglia is detected prior to muscle movements) They help control muscle tone, subconscious movements, posture (with substantia nigra) ◦ eg swinging of arms when walking, true spontaneous laughter  The Limbic System ILO 13 Mammillary body (in hypothalamus) The limbic system is a circle of structures forming the floor of the diencephalon and wrapping up and around the corpus callosum It is involved in the establishment Hippocampus (in temporal lobe) of emotional states - pain, pleasure, docility, affection, anger… Olfactory bulb Also involved in memory storage Amygdala and retrieval Which component of the brain is referred to as the “emotional brain,” as it plays a primary role in a wide range of emotions? a) basal nuclei b) frontal lobe of the cerebrum c) corpus callosum d) limbic system e) cerebral cortex  ILO 14 Functional Organization of the Cerebrum SENSORY AREAS MOTOR AREAS ASSOCIATION AREAS  Primary motor area Central sulcus (precentral gyrus) Primary somatosensory Premotor area area (postcentral gyrus) ANTERIOR Somatosensory association area 4 Frontal eye field area 5 7 1 Parietal lobe 6 2 3 8 9 Common integrative area Frontal lobe 39 Wernicke’s 40 Broca's speech area (posterior 41 Primary gustatory language) area 42 44 10 area 22 Insula 45 Prefrontal cortex Visual association 19 area 18 11 17 Primary visual area Lateral cerebral sulcus 21 37 Occipital lobe 38 Primary auditory area 20 Temporal lobe Auditory association area 43 28 Primary olfactory area Lateral view of right cerebral hemisphere Which statement is true? a) the central sulcus separates the parietal lobe from the temporal lobe b) the postcentral gyrus contains the primary motor area c) the insula lies within the precentral gyrus d) the lateral cerebral sulcus separates the frontal lobe from the temporal lobe Primary Somatosensory Area The primary somatosensory area is in the postcentral gyrus (posterior to the central sulcus) 7 5 1 4 6 2 3 8 9 touch, pain, cold, warmth, 39 tickle, itch and proprioception 40 41 42 44 10 22 45 The main function is to POSTERIOR 18 19 11 localize the origin and 17 ANTERIOR 21 intensity of the sensation 37 38 20 Primary Somatosensory Area A lesion causes contralateral loss of sensations patient can perceive the sensation but can’t tell the degree of warmth, or where the touch comes from, or evaluate the weight of objects Somatosensory Map Primary Visual Area The primary visual area is in the posterior tip of the 4 occipital lobe 7 5 1 6 2 3 8 9 39 The primary visual area 40 41 receives visual information 22 42 44 45 10 19 and is involved in visual POSTERIOR 18 11 17 perception ANTERIOR 21 37 38 20 Primary Visual Area A lesion causes complete or partial blindness (blind spot), depending on the size of the lesion Visual map  Primary Auditory Area The primary auditory area is in the superior portion of 4 the temporal lobe, near the 7 5 1 6 lateral sulcus 2 3 8 9 39 The primary auditory area receives 40 41 information for sound and is 22 42 44 45 10 19 involved in auditory perception POSTERIOR 18 11 17 21 ANTERIOR 37 38 A lesion causes partial deafness, 20 and difficulty to locate sounds Primary Gustatory Area The primary gustatory area is in the insula The primary gustatory area 43 receives information for 28 taste and is involved in gustatory perception Primary Olfactory Area The primary olfactory area receives information for smell and is involved in olfactory perception 43 28 The primary olfactory area is located on the medial side of the temporal lobe The primary visual area is in which lobe of the brain? a) frontal b) occipital c) parietal d) flocculonodular e) posterior Motor Areas The motor areas are the regions that govern muscular movement. Two important motor areas are: Primary motor area Controls voluntary contractions of skeletal muscles on other side Broca’s speech area Production of speech Control of tongue and airway Primary Motor Area The primary motor area is in the precentral gyrus, directly anterior to the 4 central sulcus 7 5 1 6 2 3 8 9 The primary motor area is 39 40 divided into regions controlling 41 42 44 10 22 voluntary contractions of POSTERIOR 18 19 45 11 skeletal muscles 17 21 ANTERIOR 37 38 20 Primary Motor Area A lesions results in contralateral paralysis Motor Map Broca’s speech area Broca’s speech area is in the frontal lobe, close to lateral 7 5 1 4 sulcus. It is in the left hemisphere 2 3 6 8 9 in 97% of people 39 40 41 Broca’s speech area is 22 42 44 10 45 involved in the planning POSTERIOR 18 19 11 and production of speech - 17 ANTERIOR 21 - motor signals to muscles 37 38 20 in larynx, pharynx, mouth and breathing muscles Broca’s speech area Pre-motor area muscles of larynx, pharynx and mouth Broca’s area Primary motor Breathing muscles area A stroke in Broca’s speech area causes loss of speech → patient knows what he wants to say but can’t produce the words. Reading, writing, understanding are normal Association Areas The association areas are concerned with complex integrative functions such as memory, emotions, reasoning, will, judgment, personality traits, and intelligence. Different association areas are connected to each other by association tracts Nerve impulses are transmitted Facial recognition area Orbitofrontal cortex from primary areas to association areas Somatosensory Association Area The somatosensory association area is located 7 5 1 4 directly posterior to the 2 3 6 8 9 primary somatosensory area 39 40 41 42 10 It receives information from 22 44 45 19 the primary somatosensory POSTERIOR 18 11 17 area (as well as other parts 21 ANTERIOR 37 of the brain) 38 20 The main function is to put together and interpret sensory data. Storage of past sensory experiences Somatosensory Association Area - Can tell just by touch the shape, size and texture of 7 5 1 4 an object, and can recognize 2 3 6 8 9 that object (stereognosis). 39 40 - Can tell where one part of 41 42 44 10 body is relative to another 19 22 45 POSTERIOR 18 11 17 21 ANTERIOR 37 38 20 A lesion causes astereognosis: can’t recognize an object if eyes are closed  Visual Association Area The visual association area is in the occipital lobe, next to 5 1 4 7 the primary visual area 2 3 6 9 8 receives data from the primary 39 40 visual area and the thalamus 22 41 42 44 10 45 19 POSTERIOR 18 11 17 - Compares past and 21 ANTERIOR 37 present visual experiences 38 20 - Allows recognition A lesion causes an inability to recognize objects, even though you can see them Facial Recognition Area 4 5 7 1 6 allows for the 2 3 8 9 recognition of faces 39 40 41 42 44 10 22 45 19 POSTERIOR 18 11 17 ANTERIOR ANTERIOR The facial recognition area 37 21 38 is in the inferior part of the 20 temporal lobe  Auditory Association Area The auditory association area is located inferior and posterior 7 5 1 4 to the primary auditory area 2 3 6 8 9 39 Receives data from the 40 41 primary auditory area 22 42 44 45 10 19 POSTERIOR 18 11 17 Interprets sounds (talking, 37 21 ANTERIOR 38 music, noise) 20 A lesion causes an inability to interpret sounds  Orbitofrontal Cortex It receives data from the 5 1 4 primary olfactory area 7 6 2 3 8 9 39 40 It is involved in identifying 41 42 44 10 odors and discriminating 22 19 45 among different odors POSTERIOR 18 11 ANTERIOR 17 37 21 38 The orbitofrontal cortex is 20 in the lateral part of the frontal lobe  Wernicke’s Area (posterior language area) Wernicke’s area is in the temporal and 5 1 4 7 parietal lobes; like Broca’s area, it is in 2 3 6 9 8 the left hemisphere. It interprets the 39 meaning of speech. 40 41 42 44 10 POSTERIOR 22 45 19 A lesion causes incoherent speech 17 18 11 → fluent speech, but words don’t 37 21 ANTERIOR make sense (word salad). Patient is 20 38 not aware of it. Patient cannot understand what other people say, The regions in the right hemisphere that correspond to Broca’s or written words and Wernicke’s areas give emotional content to speech  When there is a lesion in a primary sensory area a) one cannot detect any sensation b) one can detect a sensation, but cannot make sense of the sensation c) a and b  Common Integrative area The common integrative area is 4 surrounded by somatosensory, 7 5 1 6 visual and auditory association areas 2 3 8 9 39 40 41 It gets information from the POSTERIOR 22 42 44 10 45 aforementioned areas, as well as 18 19 11 gustatory, olfactory, thalamus, 17 21 ANTERIOR and parts of brainstem 37 38 20 It puts together all sorts of information, interprets the data, and signals different parts of the brain for appropriate actions, and forms thoughts.  Premotor area The premotor area is located 7 5 1 4 anterior to the primary motor area 6 2 3 9 8 39 It communicates with the 40 41 42 10 p.m.a., different sensory a.a., 44 POSTERIOR 19 22 45 basal nuclei and thalamus 18 11 17 21 ANTERIOR 37 38 20 It deals with learned, complex, sequential actions (e.g., writing, typing, playing piano) → it sends signals to specific groups of muscles in specific order to produce a sequence of contractions  Prefrontal cortex Many connections with other areas 7 5 1 4 of the brain (cerebral cortex, 2 3 6 8 9 thalamus, hypothalamus, limbic 39 system, and cerebellum) 40 41 42 44 10 POSTERIOR 22 45 ANTERIOR 19 18 11 17 37 21 38 Personality, intellect, complex learning 20 abilities, information recall, initiative, judgement, foresight, reasoning, conscience, intuition, mood, future planning, development of abstract ideas The cerebral area indicated is: a) Primary somatosensory area b) Broca’s area c) Facial recognition area d) Primary visual area e) Primary motor area The region of the brain responsible for predicting the consequence of events or actions is the a) prefrontal cerebral cortex. b) occipital association cortex. c) reticular formation. d) temporal lobe. e) cerebral ganglia. Hemispheric Lateralization ILO 15 Visual and Language Spatial Skills Differences vary between individuals and may be less pronounced in females (due to more commissural tracts) Electroencephalogram (EEG) ILO 16 Measures electrical activity = brain waves = millions of nerve action potentials in cerebral cortex (close to surface) An EEG may be used to diagnose a variety of nervous system disorders There are 4 kinds of brain waves that can be recorded from normal individuals ◦ Alpha – awake & resting ◦ Beta – mental activity ◦ Theta – emotional stress ◦ Delta – deep sleep The presence of which type of brain waves might indicate a brain injury in an awake adult? a) Alpha waves b) Beta waves c) Theta waves d) Delta waves Cranial Nerves Cranial Nerves ILO 17 12 pairs of cranial nerves (I to XII) Part of PNS Indicated by roman number & name CN I, II and VIII are sensory nerves, because they contain Sensory axons only/mostly CN III, IV, VI, XI and XII are motor nerves, because they contain Motor axons only/mostly CN V, VII, IX and X are mixed nerves, because they contain Both sensory & motor neurons  Can you produce a better pneumonic to remember the 12 Bonus Mark on cranial nerves?? Midterm I… From your textbook: ◦Oh Oh Oh, To Touch And Feel Very Green Vegetables, AH! Next class!