Presentation on theme: "Lecture # 21: The Brain and Cranial Nerves"— Presentation transcript:
1 Lecture # 21: The Brain and Cranial Nerves (Chapter 14)Objectives:1- Name the major regions of the brain and give the functions of each.2- Name the three coverings of the central nervous system and give the characteristics, location, and function of each.3- Give the functions of cerebrospinal fluid and explain its formation, circulation, and resorption.
2 Major Landmarks of the Brain I-CerebrumII- Brain StemIII- CerebellumForamen magnumSpinal cord
3 Major Landmarks of the Brain II- Brain StemBRAIN1- DiencephalonI- Cerebruma-Thalamusb- HypothalamusC- Epithalamus2- Midbraind- Cerebralpedunclesace- Corporaquadrigeminabed3- PonsIII- Cerebellum4- Medulla oblongataForamen magnumSpinal cord
4 I- The Cerebrum Frontal lobe Frontal lobe Parietal lobe Insula Right hemisphereLeft hemisphereCentral sulcusPrecentral gyrusPostcentral gyrusGyrusGyriFrontal lobeFrontal lobePrecentral gyrusParietal lobeCentral sulcusInsulaPostcentral gyrusLateral sulcusTemporal lobeOccipital lobeParietal lobeOccipital lobeLongitudinal fissureIt separates the right and left hemispheres
5 Cranial Meninges Skull Dura mater: Arachnoid mater Pia mater Arachnoid villusDura mater:Periosteal layerSuperior sagittalsinus (contains blood)Meningeal layerArachnoid materSubarachnoidSpace (contains CSF)Pia materFalx cerebri (in longitudinalfissure only)
7 Interventricular foramina (foramina of Monro) Septum pelucidumIt separates the lateral ventriclesInterventricular foramina (foramina of Monro)They communicate the lateral ventricles with the third ventricleCerebral aqueductIt communicates the third ventricles with the fourth ventricleThey connect the fourth ventricle with the sub- arachnoid spaceLateral aperturesMedial apertureCentral canal
8 The Flow of Cerebrospinal Fluid CSF is secreted by choroid plexus in each lateral ventricle.CSF flows throughInterventricular foraminainto third ventricle.Choroid plexus in thirdventricle adds more CSF.CSF flows down cerebralaqueduct to fourth ventricle.Choroid plexus in fourthventricle adds more CSF.CSF flows out two lateral aperturesand one median aperture.CSF fills subarachnoid space andbathes external surfaces of brainand spinal cord.At arachnoid villi, CSF is reabsorbedinto venous blood of duralvenous sinuses.
9 Functional regions of the Cerebral Cortex It contains the primary somatosensory cortex for touch, pain and temperature.Primary motor cortexPrimary somestheticcortexThe neurons send signals for precise, finely coordinated limb movements (contralateral)It interprets the sensory information to making cognitive sense of itMotor associationareaSomestheticassociation areaIt is where neurons plan a program for the contraction of muscles required for an action such as dancing, typing or speakingWernicke areaIt is responsible for the recognition of spoken and written languageVisual associationareaBroca areaIt generates a motor program for all the muscles of speechIt recognizes faces and other familiar objectsPrimaryvisual cortexPrefrontal cortexIt receives visual signalsIt gives us a sense of our relationship to the rest of the world, enabling us to think about it and to plan and execute appropriate behavior.Primaryauditory cortexPrimary gustatorycortexIt receives auditory signalsAuditoryassociation areaIt receives gustatory (taste) signalsIt recognizes the signals received as spoken words, a familiar piece of music, a voice, etc.
10 II- The Brain Stem 1- Diencephalon Thalamus Epithalamus Hypothalamus It contains the pineal gland that helps regulate the sleep-wake cycle1- It is the “gateway to the cerebral cortex” – nearly all sensory input to the cerebrum passes by way of synapses in the thalamic nuclei, filters information on its way to cerebral cortex2- It is involved in emotional functionsHypothalamus1- Hormone secretion. It controls anterior pituitary gland.Median section2- It is the major integrating center for the autonomic nervous system3- Thermoregulation4- Hunger center5- Thirst center that monitors osmolarity of the blood
11 II- The Brain Stem 2- Midbrain Corpora quadrigemina: Cerebral pedunclesCorpora quadrigeminaCorpora quadrigemina:Superior culliculiThey mediate visual attention and visually tracking moving objects.Inferior culliculiCerebral pedunclesThey mediates the reflexive turning of the head in response to a soundThey contain the substantia nigra, a motor center that relays inhibitory signals preventing unwanted movements.Median sectionDegeneration of the neurons of the substantia nigra leads to the muscle tremor of Parkinson’s disease.
12 II- The Brain Stem 3- Pons 4- Medulla oblongata Pons Medulla oblongata It connects the two hemispheres of the cerebellumMedulla oblongataMedian sectionIt contains:1- Cardiac center (regulates the rate and force of heartbeat)2- Vasomotor center (regulates blood pressure)3- Respiratory centers (regulates the rhythm and depth of breathing)Posterolateral view
13 III- The Cerebellum Functions: 1- It monitors muscle contractions and coordinates postural muscles2- It aids in motor coordination to produce smooth movements