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Biology 205-03:Human Anatomy and Physiology IFall 2017Lecture outline 12:The brain and cranial nervesReading in Martini:Chapter 13A.Some general brain functions1.Center for registering sensations:conscious awareness of environmental changes2.Assessment of new information in context of stored information3.Decision making and direction of actions4.Center for intellect, emotions, and memory (things you are interested in but not covered in this course)5.Directs our behavior toward others (more things you are interested in but not covered in this course)B.Brain organization, protection, and blood supply1.Along with the spinal cord, the brain arises from the embryonic neural tube2.General overview of brain formationa.Differential growth along rostral-caudal (“head-to-tail”) axisb.Formation of the primary brain vesicles – regional swellings at the rostral end of the neural tube1.Prosencephalon (forebrain)2.Mesencephalon (midbrain)3.Rhombencephalon (hindbrain)c.Secondary subdivision of the prosencephalon and the rhombencephalon, and developmental fatesof the brain vesicles (bold = major regions of the adult brain)1.The prosencephalon subdivides into the telencephalon and the diencephalona.The telencephalon becomes thecerebrum(the largest region of the human brain)b.The diencephalon gives rise to thethalamus, thehypothalamus, and theepithalamus2.The mesencephalon remains undivided and gives rise to themidbrain3.The rhombencephalon divides into the metencephalon and the myelencephalona.The metencephalon gives rise to theponsb.The myelencephalon gives rise to themedulla oblongatad.Collectively the midbrain, pons, and medulla oblongata constitute thebrain steme.Another large portion of the brain – thecerebellum– arises as an outgrowth of the brain stemand remains connected by “paired stalks” to the three portions of the brain stem2.Protective coverings of the braina.Cranial bonesb.Cranial meninges1.Continuous with corresponding connective tissues that surround the spinal cord2.Three layersa.Dura mater1.Tough outer layer between the brain and surrounding cranial bones2.Subdivided into two layersa.Periosteal layer:essentially the inner periosteum of the cranial bones (thebrain dura mater – unlike the spinal cord dura mater – adheres to overlyingbone)b.Inner meningeal layer1.For the most part, closely adheres to the periosteal layer2.In specific areas the two layers are separated by dural sinusesa.Large blood-filled spacesb.The dural sinuses drain blood from the brain and return the blood tothe systemic circulation3.Extensions of the dura mater separate major regions of the brain and help tostabilize the brain1
b.Arachnoid mater1.Meshwork of loosely arranged collagen and elastic fibers2.Separated from the dura mater by the subdural space, which is filled withcerebrospinal fluidc.Pia mater1.Thin layer that adheres to the surface of brain2.Includes blood vessels3.Separated from the arachnoid matter by the subarachnoid spacea.

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Term
Fall
Professor
Carlson

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