Anatomy of the Nervous System Structure and Function January 17, 2002 Gross Anatomy
Jan 02, 2016
Anatomy of the Nervous SystemStructure and Function
January 17, 2002
Gross Anatomy
Five major divisions of the brain encephalon = “inside the head” Forebrain
• Telencephalon• Diencephalon
Midbrain• Mesencephalon
Hindbrain• Metencephalon• Myelencephalon (“medulla”)
Brains stem
Diencephalon Mesencephalon Metencephalon Myelencephalon
Diencephalon
Thalamus• top of the brain stem• receives sensory signals and sends them on to
sensory cortex
Hypothalamus• located just below anterior thalamus• regulation of motivated behaviors
Mesencephalon
Tectum (“roof”)• dorsal surface of the brain stem• auditory and visual functions
Tegmentum• in front of tectum• processing pain and sensorimotor functions
Metencephalon
Pons (buldge) of the brainstem Attachment of some cranial nerves
Myelencephalon
Also called medulla Most posterior portion of the brain Large tracts running from brain to body Reticular formation (“little net”)
• sleep, attention, movement, muscle tone• reflexes - cardiac, circulatory, respiratory
Telencephalon
Greatest growth in higher vertebrates Hemispheres - right and left Four lobes in cerebrum
• frontal• temporal• parietal• occipital
Function of Telencephalon
Mediates complex functions• initiates voluntary movement• interprets sensory input• cognitive processes
• learning
• speech & language
• problem solving
Cerebral Cortex
Layer of tissue covering cerebrum Convolutions
• fissures = furrows• central and lateral fissures divide lobes
• gyri = ridges Longitudinal fissure-separates hemispheres Cerebral commissures-connect hemispheres
• largest = corpus callosum
Major Gyri
Precentral gyrus - primary motor area Postcentral gyrus - body sensations Superior temporal gyrus - auditory cortex Cingulate gyrus – emotional, somatic and
autonomic fxs
Hippocampus (“sea horse”)
Shared by cerebral cortex and limbic system
Located in the medial temporal lobe Role in learning and memory
Function of the Limbic System
Circuit of structures around the thalamus Regulate motivated behaviors
• “the four Fs”• fleeing
• feeding
• fighting
• sexual behavior
Structures of the Limbic System
Amygdala (“almond”) Hippocampus (“sea horse”) Fornix (“arc”) Cingulate cortex (“encircling”) Septum Mammillary bodies
Function of the Basal Ganglia
Voluntary motor response Example of dysfunction = Parkinson’s
• rigidity• tremors• poor movement initiation
Structures of the Basal Ganglia
Amygdala Striatum (“striped structure”)
• Caudate (“tail-like”)• Putamen
Globus pallidus (“pale globe”)
Brain Areas Relevant to Language Lichtheim-Geschwind Model
• Broca’s area• Wernicke’s area• Arcuate fasciculus• Angular gyrus
Broca’s area
Posterior portion of lower left frontal lobe Speech and language production
Wernicke’s area
Posterior portion of left temporal area Auditory comprehension
Arcuate fasciculus
Pathway that relays nerve impulses between Broca’s and Wernicke’s areas
Connections between sound patterns and production area
Angular gyrus
Parietal lobe Sensory properties of objects are associated
with words