Chapter 13 - Central Nervous System Overview: Key Terms and Concepts

Rostral

toward the nose/snout

Caudal

toward the tail

Cerebrum

largest part of the brain...left and right hemispheres

Diencephalon

gives rise to the thalamus, hypothalamus, and epithalamus

Cerebellum

second largest part of the brain

brain stem

rostral continuation of the spinal cord; consists of the medulla oblongata, pons, and midbrain

lateral ventricles

cerebrum

third ventricle

diencephalon

cerebral aqueduct

brain stem: midbrain

fourth ventricle

pons, cerebellum, medulla obolongata

central canal

spinal cord

Brain ventricles

cerebrospinal fluid filled cavities within the brain

Continuous with each other and central canal

Lined with ciliated ependymal cells

provide CSF to nearby brain regions

What does CSF provide?

cushion, nutrients, buoyancy

What is the function of external wrinkles on cerebrum?

increase surface area

Fissure

deep groove

Sulcus

where groove is

Gyrus

wrinkles

Longitudinal Fissure

separates left and right cerebral hemispheres

Central sulcus

separates frontal and parietal lobes

Parieto-occipital sulcus

seperates parietal and occipital

lateral sulcus

Separates temporal lobe from parietal and frontal lobes

precentral gyrus

before central sulcus; in frontal lobe

postcentral gyrus

after central sulcus; in parietal lobe

function of precentral gyrus

primary motor cortex

function of postcentral gyrus

primary somatosensory cortex

function of temporal lobe

primary auditory cortex

function of occipital lobe

primary visual cortex

What determines amount of cortex used for a body part?

amount of cortex devoted to a given body region is proportional to either the number of muscles and motor units there or the number of receptors for a particular body part

three fibers of cerebral white matter

commissural fibers, associational fibers, projection fibers

commissural fibers

connect right hemisphere to left

Largest= corpus callosum

associational fibers

Intrahemispheric

Long or short

projection fibers

connects cortex to lower CNS areas

vertical fibers

Whats in cerebral deep grey matter?

basal nuclei (ganglia)

Basal nuclei( ganglia)

initiates and terminates body movements

suppresses unwanted movements

Thalamus: shape and how many?

Egg shaped, one for each hemisphere

hypothalamus: location

below the thalamus

Epithalamus (pineal gland) function

secretes melatonin

Thalamus function

"gateway to the cerebral cortex"; major relay station for most sensory inputs; filters info on its way to cerebral cortex

Ventral posterolateral nucleus function

sensory

medial geniculate body

auditory

lateral geniculate body

visual

function of hypothalamus

Maintains Homeostasis by regulating body temp, hunger, thirst

Optic chiasm

crossover point for optic nerve

infundibulum

connects hypothalamus to pituitary

interthalamic adhesion

connects thalamus

cerebral peduncles

composed mostly of motor axons from the cortex to the cerebellum and spinal cord

looks like columns/pillars supporting the cerebrum

located ventrally

cerebral aqueduct

passes through the center of midbrain; 3rd ventricle to fourth

corpora quadrigemina

nuclei that form 4 bumps on the dorsal midbrain

Superior colliculi: visual reflexes

Inferior colliculi: auditory reflexes

Pons location

between midbrain and medulla oblongata; functions as bridge between brain stem and cerebellum

viewed ventrally as superficial, transverse fibers

Two structures on medulla oblongata?

continuous with superior aspect of the spinal cord

pyramids and olives

Pyramids

motor tracts on anterior surface of medulla

Olives

nuclei that are lateral to pyramids; sensory relay station

Cerebellum structure

two hemispheres

cortex- grey matter with many folds called folia

white matter-tracts called arbor vitae

deep grey matter

What connects two hemispheres of cerebellum?

vermis

anterior and posterior lobe of cerebellum function

motor coordination of trunk and limbs balance

flocculonodular lobe of cerebellum

equillibrium via head/eye motor coordination

What are the protective coverings of the CNS?

skull, vertebrae, meninges

Meninges

connective tissue sheaths that surround the brain and spinal cord

Three layers of meninges

Dura mater: most superfifical

Arachnoid matter: middle

Pia mater: deepest

two layers of dura mater

periosteal layer and meningeal layer; two layers continuous unless sinus

arachnoid granulations

allow CSF to drain into sinus

Is CSF only found inside the brain?

No, inside and outside

Where is CSF deposited

dural venous sinuses around the brain

Falx Cerebri

separates the two cerebral hemispheres

tentorium cerebelli

separates cerebrum from cerebellum

falx cerebelli

separates the two cerebellar hemispheres

Spinal cord: position relative to brain and function

Inferior to head

sensory and motor innervation of the whole body

two-way conduction pathway between the brain and body

major integration center for reflexes

Most caudal part of CNS?

conus medullaris

Does spinal cord extend to end of spinal column?

No

Location of spinal cord segments?

typically superior to respective vertebrae

Where does the spinal cord end?

L1 or a little beyond; 31 pairs of spinal nerves

Are spinal nerves apart of the CNS?

No

Grey matter of spinal cord

neuron cell bodies and axons with little myelin

white matter of spinal cord

abundantly myelinated axons

Cervical spinal cord segments

large amounts of white matter; anterior grey horn is large

thoracic spinal cord segment

very small amount of grey matter

lumbar spinal cord segment

large anterior/posterior grey horns; considerably less white matter compared to cervical

sacral spinal cord segments

small in diameter, but relatively large amounts of grey matter

Function of ascending tracts of spinal cord

carry sensory information from the body to the brain

Function of descending tracts in spinal cord

Deliver motor (output) instructions

Is spinal cord white matter sensory or motor?

both

How are white matter columns in spinal cord named?

according to where a tract begins(soma) and where it ends(axon terminals)

How does CSF flow?

CSF is formed by the choroid plexus in all main ventricles. From the right and left lateral ventricles, CSF flows into the third ventricle. From there, it flows through the narrow channel of the midbrain called the cerebral aqueduct and into the fourth ventricle. From there, CSF travels into the central canal of the spinal cord AND out of the one median and two lateral apertures of the 4th ventricle into the subarachnoid space surrounding both the brain and spinal cord. Inside the brain, CSF is moved into the superior sagittal sinus through arachnoid villi. These sinuses will join together to form the internal jugular veins.