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Objectives
To orient the student to the major regions of the brain. Cerebral To briefly identify the functional roles of each hemisphere lobe of the cerebrum. Diencephalon To outline the regions of cerebral motor activity & sensory activity. Cerebellum To define the association areas of the brain and Brain stem provide an example. • Midbrain To address the phenomena of lateralization. • Pons To explain the association between white matter • Medulla and basal nuclei. (d) Birth oblongata
Figure 12.3d
Regions and Organization Ventricles of the CNS I. Adult brain regions A lumen/spacelumen/space--derivedderived from the neural tube 1.1.Cerebral hemispheres Filled with spinal fluids. 2.2.Diencephalon 3.3.Brain stem (midbrain, pons, and medulla) 4.4.Cerebellum >>LateralLateral >Third ventricle II. Spinal Cord >Fourth ventricle. 1.1.Central cavity surrounded by a gray matter core. 2.2.Fiber tracts --externalexternal white matter/myelin.
Cerebrum
Septum Lateral ventricle pellucidum Anterior horn Most superior part of the brain. 83% of the brain mass
Inferior Interventricular Divided into two hemispheres. horn foramen Third ventricle ….connected by the longitudinal fissure. Lateral Cerebral aqueduct aperture Cerebral cortex ––graygray matter Fourth ventricle Contralateral control --oppositeopposite side of the Central canal body
(a) Anterior view
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Tour of the Brain --CNSCNS Anterior Longitudinal Frontal lobe Cerebrum --ResponsibleResponsible for consciousness. Divided fissure into hemispheres & association areas. Figure 12.6c Lobes and Controls: conscious mind, communication, memory Cerebral veins and understanding, voluntary movements, creativity. and arteries Parietal coveredfissures by of the cerebrallobe arachnoid Composed of primarily gray matter i.e. numerous cell mater bodies of neurons. hemispheres. Left cerebral Right cerebral --ConvolutionsConvolutions called gyri hemisphere hemisphere --GroovesGrooves are called sulci Occipital --DeepDeep grooves are called fissures .. lobe (c) Posterior
Central sulcus Lobes of the Brain Frontal lobe Parietal lobe > Frontal > Parietal Figure 12.6a LobesOccipital lobe and > Temporal Lobe Temporal lobe > Occipital fissures of the cerebral Fissure (a deep sulcus) hemispheres. Gyrus Cortex (gray matter) Sulcus White matter
(a)
Cerebral Motor Activity Central sulcus Primary motor cortex Premotor cortex Primary somatosensory cortex I. Primary (somatic) motor cortex ––consciousconscious motor Frontal eye field Somatic Somatosensory sensation association cortex control. Stroke paralyzes the body muscles controlled Broca’s area by those areas. (outlined by dashes) PrefrontalFigure cortex 12.8a Functional Working memory for spatial tasks II. II. Premotor cortex --LearnedLearned motor skills of a repetitious and structural areasPrimary ofvisual or patterned nature e.g. typing cortex Vision Solving complex, Visual multitask problems association area III. Broca’s area ––associatedassociated with language and sound the cerebral cortex.Auditory association area Hearing Primary auditory cortex IV. Frontal eye field ––voluntaryvoluntary eye movement (a) Lateral view, left cerebral hemisphere
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Posterior The motor The sensory Sensory Activity of the Cerebrum homonculus homonculus
Motor Sensory Motor map in Anterior Sensory map in Primary somatosensory cortex precentral gyrus postcentral gyrus --ReceivesReceives sensory Figure 12.9 Body maps information from the in the primary motor skin, skeletal muscles, and joints Toes cortexGenitals and --spatialspatial discrimination
somatosensoryJaw cortex of Primary visual cortex Tongue Primary motor Primary somato- cortex sensory cortex Intra- Primary auditory cortex Swallowing the(precentral gyrus)cerebrum.(postcentral gyrus) abdominal
Association Areas Cerebral Lateralization
Regions of the brain that communicate i.e. Left ––controls:controls: ““associate ” with primary regions of the brain. Speech, writing, reading and math “Analytical and sequential” AAct with other sensory association areas to analyze/interpret and act on sensory Right ––controls:controls: inputs based on past experiences .. recognition of space, patterns, music and emotion, nonnon--verbalverbal language, “tone.” Multiple inputs & multiple outputs i.e. complex “ Holistic and recognition”
End White matter
Material responsible for communication between cerebral cortex and lower CNS centers.
Composed of myelinated fibers bundled into large tracts.
Commissures : fibers connecting gray areas of the 2 hemisphere. > Corpus callosum (largest)
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Basal nuclei Dienchephalon
Associated with subthalamic nuclei (the floor of the Gray matter of the third ventricle diencephalon). (located at the core of the forebrain) Composed of distinctive cell groups: e.g. Caudate & lentiform I.I. Thalamus ––relayrelay station Play a role in motor control, may be involved with attention and cognition. II.II. Hypothalamus ––homeostasishomeostasis regulator III.III. Epithalamus ––pinealpineal gland & choroid Disorders of the basal nuclei show up as too much or too little movement such as Huntington’s or Parkinson’s plexus. diseases.
Brain Stem (intro)
Superior to Inferior ––
> Midbrain ––visualvisual & auditory reflex centers & fear > Pons ––regulationregulation of respiration > Medulla Oblongata ––respiratoryrespiratory rhythm & heart ratratee
Histology: similar to the spinal cord i.e. gray matter is deep and white matter surrounds it.
Controls –– Automatic behaviors for survival Heavily involved with the innervation of the head
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