chapter 12

name the adult neural canal regions

Adult structures derived from the neural canal

Telencephalon – lateral ventricles

Diencephalon – third ventricle

Mesencephalon – cerebral aqueduct

Metencephalon and myelencephalon – fourth ventricle

describe the right and left cerebral hemisphere

contain ridges (gyri) and shallow grooves (sulci)

are seperated by the longitudinal fissure

have three basic regions: cortex, white matter, and basal nuclei

central sulcus seperates:

the frontal and parietal lobes

deep sulci divide the hemispheres into what five lobes

frontal

parietal

temporal

occipital

insula

what is the parieto-occipital sulcus

separates the parietal and occipital lobes

what is the lateral sulcus

separates the parietal and temporal lobes

the precentral and postcentral gyri border the:

central sulcus

describe cerebral cortex

superficial gray matter, 40% of the mass of the brain

it enables sensation, communication, memory, understanding, and voluntary movements

what are the three functional areas of the cerebral cortex

motor areas- control voluntary movement

sensory areas- conscious awareness of sensation

association areas- integrate diverse info

define cerebral white matter

consists of deep myelinated fibers and their tracts

responsible for communication between the cerebral cortex and lower CNS center, and areas of the cerebrum

cerebral white matter types:

commissures- connect corresponding gray areas of the two hemispheres

association fibers- connect different parts of the same hemisphere

projection fibers- enter the hemispheres from lower brain or cord centers

describe basal nuclei

masses of gray matter( cell body clusters) found deep within the cortical white matter

the corpus striatum is composed of what three parts

caudate nucleus

lentiform nucleus- composed of the putamen and the globus pallidus

fibers of internal capsule running between and through caudate and lentiform nuclei

functions of basal nuclei

influence muscular activity

regulate attention and cognition

regulate intensity of slow or stereotyped movements

describe the diencephalon

central core of the forebrain

consists of three paired structures- thalamus, hypothalamus, and epithalamus

encloses the third ventricle

describe the thalamus

paired, egg shape masses that form the superolateral walls of the third ventricle

connected at the midline by the intermediate mass

four groups of nuclei within the thalamus:

anterior

ventral

dorsal

posterior

describe the hypothalamus

located below the thalamus, it caps the brainstem and forms the inferolateral walls of the third ventricle and extends from the optic chiasma

hypothalamic function:

regulates blood pressure, rate and force of heartbeat. digestive tract motility, rate and depth of breathing, and many other visceral activities

endocrine functions of the hypothalamus:

releasing hormones from various nuclei control secretion of hormones by the anterior pituitary

overall, regulates general body homeostasis

describe the epithalamus

most dorsal portion of the diencephalon; forms roof of the third ventricle

brain stem consists of what three regions

midbrain

pons

medulla oblongata

describe the midbrain

located between the diencephalon and the pons

midbrain structures include:

cerebral peduncles- two bulging structures that contain descending pyramidal motor tracts

cerebral aqueduct- hollow tube that connects the third and fourth ventricles

various nuclei

describe the pons

bulging brainstem region between the midbrain and the medulla oblongata

forms part of the anterior wall of the fourth ventricle

fibers of the pons:

connect higher brain centers and the spinal cord

relay impulses between the motor cortex and the cerebellum

describe the medulla oblongata

most inferior part of the brain stem

along with the pons, forms the ventral wall of the fourth ventricle

contains a choroid plexus on the ventral wall of the fourth ventricle

describe medulla nuclei

cardiovascular control center- adjusts force and rate of the heart connection

respiratory centers- control rate and depth of breathing

describe the cerebellum

located dorsal to the pons and medulla

protrudes under the occipital lobes of the cerebrum

provides precise timing and appropriate patterns of skeletal muscle contraction

all fibers in the cerebellum are:

ipsilateral

superior peduncles connect the cerebellum to the:

midbrain

middle peduncles connect the pons to the:

cerebellum

inferior peduncles connect the medulla to the:

cerebellum

cerebellum receives impulses of the intent to initiate:

voluntary muscle contraction

cerebellar cortex calculates the best way to:

perform a movement

describe “the functional brain system”

networks of neurons working together and spanning wide areas of the brain

what are the two systems of the functional brain system

limbic system

reticular formation

describe the limbic system

includes the rhinencephlon, amygdala, hypothalamus, and anterior nucleus of the thalamus

amygdala deals with-

anger, danger, and fear responses

cingulate gyrus- plays a role in:

expressing emotions via gestures, and resolves mental conflict

the limbic system interacts with the-

prefrontal lobes

hippocampal structures convert:

new information into long term memories

define RAS- reticular activating system

sends impulses to the cerebral cortex to keep it conscious and alert

filters out repetitive and weak stimuli

the brain is protected by-

bone, meninges, and cerebrospinal fluid

harmful substances are shielded from the brain by the blood brain barrier

what three connective tissue membranes lie external to the CNS- (meninges)

dura mater, arachnoid mater, and pia mater

functions of the meninges:

cover and protect the CNS

protect blood vessels and enclose venous sinuses

contain cerebrospinal fluid

form partitions within the skull

describe dura mater

leathery, strong meninx composed of two fibrous connective tissue layers

-periosteal -meningeal

what three dural septa extend inward and limit excessive movement of the brain: (dura mater)

falx cerebri- fold that drip the longitudinal fissure

falx cerebelli- runs along the vermis of the cerebellum

tentorium cerebelli- horizontal dural fold extends into the transverse fissure

describe arachnoid mater

the middle menix, which forms a loose brain covering

its seperated from the dura mater by the subdural space

describe pia mater

deep meninx composed of delicate connective tissue that clings tightly to the brain

encephalitis

describe cerebrospinal fluid (CSF)

watery solution similar in composition to blood plasma

contains less protein and different ion concentrations than plasma

forms a liquid cushion that gives buoyancy to the CNS organs

what is a choroid plexus

clusters of capillaries that form tissue fluid filters, which hang from the roof of each ventricle

have ion pumps that allow them to alter ion concentrations of the CSF

describe a blood-brain barrier

protective mechanism that helps maintain a stable environment for the brain

bloodborne substances are separated from neurons by:

continuous endothelium of capillary walls

relatively thick basal lamina

bulbous feet of astrocytes

what are blood-brain barrier functions

selective barrier that allows nutrients to pass freely

is ineffective against substances that can diffuse through plasma membranes

describe the spinal cord

CNS tissue enclosed within the vertebral column from the foramen magnum

provides two way communication to and from the brain

major reflex center

protected by bone, meninges, and CSF

what is the conus medullaris-

terminal portion of the spinal cord

what is the filum terminale-

fibrous extension of the pia mater; anchors the spinal cord to the coccyx

what are denticulate ligaments-

delicate shelves of pia mater; attach the spinal cord to the vertebrae via dura mater