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Flashcards in Brain and Cranial Nerves Deck (18):

What does the term "rostral" mean in regards to the brain?

Toward the forehead


What does the term "caudal" mean in regards to the brain?

Toward the spinal cord


What does the term "rostral" mean in regards to the spinal cord/brainstem?



What does the term "caudal" mean in regards to the spinal cord/brainstem?



What are the three major portions of the brain?

Cerebrum, cerebellum, and brainstem


What percent of the brain's volume is the cerebrum, and what does it include?

83%, consists of pair of half globes called cerebral hemispheres marked by thick folds called gyri separated by shallow grooves called sulci


What is the name of the groove separating the two hemispheres of the brain?

longitudinal fissure


What is the think bundle of nerve fibers at the bottom of the longitudinal fissure that connects the hemispheres?

corpus callosum


Where is the cerebellum located and what separates it from the cerebrum? What % of volume does it make up?

posterior cranial fossa, inferior to cerebrum, separated by the transverse cerebral fissure, makes up 10% of brain's volume


Which portion of the brain contains the majority of the neurons? What percent are in this portion?

Cerebellum, contains 50% of neurons


What does the brainstem consist of?

All of the brain except the cerebellum and cerebrum


List the major components of the brainstem, from rostral to caudal

diencephalon, midbrain, pons, and medulla oblongata


Where does the brainstem end?

foramen magnum of the skull


What is the seat of the neurosomas, dendrites, and synapses; and forms a surface layer called the cortex over the cerebrum and cerebellum; and deeper masses called nuclei surrounded by white matter?

grey matter


where is white matter in relation to grey matter in the brain?

deep to the cortical grey matter in most of the brain


what is white matter composed of?

tracts, or bundles of axons, which connect one part of the brain to another and to the spinal cord


What tissue layer of an embryo does the nervous system develop from?



Describe how brain develops during embryonic development

first 3 weeks: neural plate forms along dorsal midline of embryo, forms neural groove with raised neural folds on each side. folds roll toward each other and fuse. creates neural tube by day 26. tube separates from ectoderm, sinks, and grows lateral processes that form motor nerve fibers. lumen of tube becomes central canal
neural crest forms and gives rise to two inner meninges (arachnoid mater and pia mater); most of PNS, and other structures
by week 4: neural tube exhibits three anterior dilations, forebrain (primary vesicles, prosencephalon), midbrain (mesencephalon), and hindbrain (rhombencephalon)
5th week: brain subdivides into 5 secondary vesicles- forebrain into telencephalon and diencephalon; midbrain undivided; hindbrain into metencephalon and myelencephalon
telencephalon becomes the cerebral hemispheres, diencephalon become retinas of eyes