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PowerPoint® Lecture Slides prepared by Leslie Hendon, University of Alabama, Birmingham 13 HUMAN ANATOMY fifth edition MARIEB | MALLATT | WILHELM PART 2 The Central Nervous System Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Performs the most complex neural functions Intelligence Consciousness Memory Sensory-motor integration Involved in innervation of the head Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Embryonic Development of the Brain Brain arises from rostral part of the neural tube Three primary brain vesicles in four-week old embryo Prosencephalon – the forebrain Mesencephalon – the midbrain Rhombencephalon – the hindbrain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Embryonic Development of the Brain Secondary brain vesicles Prosencephalon Divides into telencephalon and diencephalon Mesencephalon – remains undivided Rhombencephalon Divides into metencephalon and myelencephalon Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Embryonic Development of the Brain Structures of the adult brain Develop from secondary brain vesicles Telencephalon the cerebral hemispheres Diencephalon thalamus, hypothalamus, and epithalamus Metencephalon pons and cerebellum Myelencephalon medulla oblongata Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Embryonic Development of the Brain Brain stem includes The midbrain, pons, and medulla oblongata Ventricles Central cavity of the neural tube enlarges Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Embryonic Development of the Brain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.7a–e Embryonic Development of the Brain Brain grows rapidly, and changes occur in the relative position of its parts Cerebral hemispheres envelop the diencephalon and midbrain Wrinkling of the cerebral hemispheres More neurons fit within limited space Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Brain Development from Week 5 to Birth Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.8a–d Basic Parts and Organization of the Brain Divided into four regions Cerebral hemispheres Diencephalon Brain stem Midbrain, pons, and medulla Cerebellum Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Basic Parts and Organization of the Brain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.9 Basic Parts and Organization of the Brain Organization Centrally located gray matter Externally located white matter Additional layer of gray matter external to white matter Due to groups of neurons migrating externally Cortex – outer layer of gray matter Formed from neuronal cell bodies Located in cerebrum and cerebellum Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Basic Parts and Organization of the Brain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.10 Ventricles of the Brain Expansions of the brain’s central cavity Filled with cerebrospinal fluid Lined with ependymal cells Continuous with each other Continuous with the central canal of the spinal cord Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Ventricles of the Brain Lateral ventricles – located in cerebral hemispheres Horseshoe-shaped from bending of the cerebral hemispheres Third ventricle – lies in diencephalon Connected with lateral ventricles by interventricular foramen Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Ventricles of the Brain Cerebral aqueduct – connects 3rd and 4th ventricles Fourth ventricle – lies in hindbrain Connects to the central canal of the spinal cord Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Ventricles of the Brain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.11a, b The Brain Stem Includes the Midbrain Pons Medulla oblongata Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Stem Several general functions Produces automatic behaviors necessary for survival Passageway for all fiber tracts running between the cerebrum and spinal cord Heavily involved with the innervation of the face and head 10 of the 12 pairs of cranial nerves attach to it Which CN do NOT attach to brain stem? Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Ventral View of the Brain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.12 The Brain Stem – The Medulla Oblongata Most caudal level of the brain stem Is continuous with the spinal cord Choroid plexus lies in the roof of the fourth ventricle External landmarks of medulla Pyramids of the medulla Lie on its ventral surface Decussation of the pyramids Crossing over of motor tracts Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Stem – The Medulla Oblongata External landmarks of medulla (continued) Inferior cerebellar peduncles Fiber tracts connecting medulla and cerebellum Olive (olive of the medulla) Contains inferior olivary nucleus Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Stem – The Medulla Oblongata Cranial nerves VIII–XII attach to the medulla VIII – Vestibulocochlear IX – Glossopharyngeal nerve X – Vagus nerve XI – Accessory (Spinal Accessory – a branch of the vagus nerve) XII – Hypoglossal nerve Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Stem – Medulla Oblongata Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.13a The Brain Stem – Medulla Oblongata Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.13b The Brain Stem – The Medulla Oblongata The core of the medulla contains Much of the reticular formation Nuclei influence autonomic functions Visceral centers of the reticular formation include Cardiac center Vasomotor center The medullary respiratory center Centers for hiccupping, sneezing, swallowing, and coughing Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Stem – The Medulla Oblongata Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Table 13.1 (1 of 3) The Brain Stem – The Medulla Oblongata Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.13c The Brain Stem – The Pons A “bridge” between the midbrain and medulla oblongata Pons contains the nuclei of cranial nerves V – Trigeminal nerve VI – Abducens nerve VII – Facial nerve Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Stem – The Pons The pons contains Motor tracts coming from the cerebral cortex Pontine nuclei Connect portions of the cerebral cortex and cerebellum Send axons to cerebellum through the middle cerebellar peduncles Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Stem – The Pons Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.14b The Brain Stem – The Pons Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Table 13.1 (2 of 3) The Brain Stem – The Midbrain Lies between the diencephalon and the pons Cerebral aqueduct The central cavity of the midbrain Cerebral peduncles located on the ventral surface of the brain Contain pyramidal (corticospinal) tracts Superior cerebellar peduncles Connect midbrain to the cerebellum Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Stem and Diencephalon Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.13a The Brain Stem and Diencephalon Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.13b The Brain Stem – The Midbrain Periaqueductal gray matter surrounds the cerebral aqueduct Involved in two related functions Fright-and-flight reaction Mediates response to visceral pain Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.21 The Brain Stem – The Midbrain Corpora quadrigemina (quad-ri-gemina) The largest nuclei Divided into the superior and inferior colliculi Superior colliculi – nuclei that act in visual reflexes Inferior colliculi – nuclei that act in reflexive response to sound Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Brain Stem – Dorsal View Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.13c The Brain Stem – The Midbrain Imbedded in the white matter of the midbrain Two pigmented nuclei Substantia nigra – neuronal cell bodies contain melanin Functionally linked to the basal nuclei Red nucleus – lies deep to the substantia nigra Largest nucleus of the reticular formation Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Cerebellum Located dorsal to the pons and medulla Smoothes and coordinates body movements Helps maintain equilibrium Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Cerebellum Consists of two cerebellar hemispheres Surface folded into ridges called folia Separated by fissures Hemispheres each subdivided into Anterior lobe Posterior lobe Flocculonodular lobe (tiny) Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Cerebellum Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings Figure 13.15a The Cerebellum Composed of three regions Cortex – gray matter Arbor vitae Internal white matter Deep cerebellar nuclei – deeply situated gray matter Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Cerebellum Cerebellum receives information from the cerebral cortex On equilibrium On current movements of Limbs, neck, and trunk Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings The Cerebellum – Cerebellar Peduncles Thick tracts connecting the cerebellum to the brain stem are Superior cerebellar peduncles Middle cerebellar peduncles Inferior cerebellar peduncles Fibers to and from the cerebellum are ipsilateral Run to and from the same side of the body Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings