anatomy chapter 13

the ectoderm differentiates into nervous tissue

neural plate, fold, tube

the neural tube is

a rudimentary (simple beginning of the) spinal cord

The neural tube enlarges on one end

called "cephalization" cephalic means head

primary enlargement

at about 4 weeks into development, two constrictions in the neural tube occur, leading to three "enlargements"

Three primary "enlargement"

Prosencephalon

Mesencephalon

Rhombencephalon

Procencephalon

forebrain

Mesencephalon

midbrain

Rhombencephalon

hindbrain

secondary "enlargements"

at about 5 weeks two more constrictions (of the forebrain and hindbrain) lead to the development of 5 rudimentary brain regions

secondary development from forebrain

telencephalon and diencephalon

secondary development from midbrain

still just the mesencephalon

secondary development from the hindbrain

metencephalon and myelencephalon

These same five regions (encephalons) develop into

the parts of the adult brain (with remaining neural tube becoming the spinal cord)

the telencephalon grows into

the largest part of the human brain, called the cerebrum

the cerebral cortex

the wrinkled portion off the most superior brain region

wrinkling increases the

surface area, which increases the number of cells, which increases intelligence

some individuals with adverse cortex development will

have mental impairment

ex. fetal alcohol syndrome

longitudinal fissure

separates the cerebrum into left and right hemispheres

corpus callosum

connection between the two hemispheres

basal nuclei

collection of nerve cell bodies that does cognitive processing

limbic system

around corpus callous and basal nucleus, but some may someday be disregarded as a true brain "region"

involved in emotions, memory, and behavior

cerebral cortex has 4 lobes

frontal, parietal, occipital, temporal - some include a fifth lobe called the insult, being the temporal lobe

Fruity

Pebbles \n On \n Toast \n Ick

Frontal \n Parietal \n Occipital \n Temporal \n Insula

gyrus

a ridge/hill of the wrinkles fold

sulcus

a groove between the gyro

ex. the central sulcus separates the frontal lobe from the parietal lobe

Brodmann's areas (map)

identifies functional areas of the cerebral cortex (still used today)

occipital lobe

visual perception area

temporal lobe

auditory sensation area

parietal lobe

somatonsensation (sensations from the body)

frontal lobe

controls motor functions (voluntary muscles)

the cortex (gray matter) is made up of

neurons that are called "integrators" that receive info from the body (via sensory neurons)

the neurons in the cortex are gray because

they are myelinated

integrators process what the response to the stimuli should be and

the motor neurons carry that response out of the cerebrum

sensory and motor neurons are not grey but because they are myelinated (to speed up the information transfer/conduction)

there are pockets of gray matter (nonmyelinated neuron cell bodies) within the white matter (called nuclei)

hippocampus and Amygdala

involved in memory and emotions

basal nuclei

(caudate, putamen, globus pallidus) - help control movement

similar to the telencephalon, the diencephalon is

derived form the forebrain (prosencephalon)

three main parts of the diencephalon

thalamus, hypothalamus, epithalamus

thalamus

relay center for all sensory info, except smell

functions for hypothalamus

ex. temperature control, thirst, hunger, sex drive

a major function is regulation of the endocrine (hormone) system

brainstem is made up of

midbrain, pons, medulla oblongata (a few anatomists will include the diencephalon, but not most)

The pons & medulla are involved in

control of vital functions

ex. heart rate, respiratory rate, blood pressure

the medulla connects to the

spinal cord (exits skull through the foramen magnum)

the midbrain (mesencephalon) is between

thalamus (diencephalon) and pons

the midbrain (mesencephalon) includes the tectum (on the posterior side) made up of four "bumps" called

the inferior (2) & superior (2) colliculus

the inferior and superior colliculus

is involved in reflex head movement and the tegmentum (receive and sends information from cranial nerves)

the pons is derived from the

hindbrain/rehombencephalon (along with the medulla)

pons is part of the

metencephalon (along with the cerebellum)

pons is

anterior surface/bulge of brain stem

pons is the main connection

to the cerebellum (NOT cerebrum) on the posterior side

the medulla (oblongata) has a significant amount of

decussation (crossing over from right to left and white and grey matter)

grey matter is on the outside (cortex) of the cerebrum but is on the

inside (medulla) of the spinal cord (transition is mainly in the medulla)

reticular formation

area that extends through the pons & midbrain as well, and controls consciousness (sleep and wakefulness)

medulla is a generic term which means

"middle"

if referring the the brain region between the pons and spinal cord

then use medulla referenced is the medulla oblongata

the cerebellum looks familiar to cerebrum

but smaller and fold are parallel

the cerebellum compares information from the cerebrum

with sensory feedback from the periphery (to help determine output corresponding to input)

ex. someone whispers you whisper back; someone shouts you shout back

the anterior median tissue and posterior median sulcus

divide the spinal cord into two hemispheres

white matter (myelinated neurons)

on the outside of the spinal cord

The white matter on the spinal cord is divided into

three columns (for each hemisphere) dorsal, lateral, ventral

the three columns can be further divided into

tracts (ascending vs. decending)

ascending tracts

sensory

depending tracts

motor

the dorsal column is predominantly

ascending tracts

the ventral column is predominantly

depending tracts

the lateral column is

a mixture of both ascending and defending tracts

gray matter is divided into 3 "horns"

posterior

anterior

lateral (only found in thoracic area)

posterior horn

sensory processing

anterior horn

motor signals

lateral horn

sympathetic division of ANS (autonomic nervous system)

dorsal nerve root

axons enter here/sensory

anterior nerve root

axons leave here/motor

meninges

protect CNS (& PNS)

cover outer surface of CNS (brain AND spinal cord)

series of membranes (dura, arachnoid, & pia matter)

dura mater (meninges)

"tough mother"

thick fibrous layer

convert entire brain & spinal cord

arachnoid mater (meninges)

arachnoid means spider

middle layer

subarachnoid space

filled with a watery fluid

middle layer of arachnoid mater

blood vessels make it look "spider web like"

subarachnoid space in arachnoid mater

space between the dura & arachnoid mater

watery fluid in arachnoid mater

used for protection, called cerebrospinal fluid (CSF)

pia mater

"tender mother"

touches brain & spinal cord

ventricles

four total

2 later ventricle (right and left, 1st & 2nd)

third ventricle

fourth ventricle

ventricles produce and circulate

cerebral spinal fluid (CSF)

ventricles connect to each other and

the subarachnoid space - CSF moves from the inside pockets (ventricles) to the outside

since CSF is constantly produced, it needs to constantly be

absorbed (through the arachnoid granulation of villi)

choroid plexus

made of ependymal cells (type of glial cell) - line ventricle, produce and secretes CSF from components in blood

CSF produced daily

about 500 mL

used for physical protection (cushion) and chemical (toxins) protection

Peripheral Nervous System (PNS) consists of

everything outside of the CNS (including nerves coming off of the brainstem, called cranial nerves)

Ganglia

clusters of cell bodies in the PNS

dorsal root ganglion

coming off the spinal cord in the back (dorsal root) is a ganglion bulge

made up of neurons

cranial nerve ganglion

trigemina ganglion

sympathetic chain ganglia

the dorsal root and ventral root merge to form

spinal nerves (31 pairs - right & left)

the spinal nerves diverge to

innervate the entire body

the spinal nerves and their branches are all part of

the PNS

what we call a nerve is really

a bundle of axons

the axons are held together by

connective tissues, similar to how muscle cells are bundled

Epineurium

outer surface of a nerve

Perineurinium

surrounds fascicles of a nerve

Endoneurium

inner surface, surrounds individual axons on a nerve

cranial nerves

there are twelve pair (right and left)

some cranial nerves are

only sensory, some are only motor, and some are mixed (both sensory and motor)

cranial nerves are numbered

using roman numerals