organization and primary functions of the nervous system

rootlets

come together to form roots

roots

cluster of rootlets

dorsal = carries sensory info in

ventral = sends motor info out

rami

come off spinal cord and form plexus

branch carrying mixed motor and sensory info

what do ventral rami of T2-T12 form

ventral and lateral intercostal nerves

ganglia

collection of cell bodies

somatic

implies “body”

peripheral nervous system

structures outside of brain and edge of spinal cord

are the cranial nerves part of the CNS or PNS

PNS

central nervous system

includes brain, brainstem, spinal cord

enclosed in skull and vertebral column

surrounded by meninges and CSF

gray matter

found in CNS

primarily cell bodies that serve as communication spots

white matter

found in CNS

myelin dense structures

primarily axons

what kind of info do ascending pathways carry

sensory

what kind of info do descending pathways carry

motor

phrenic nerve

C3 C4 C5 keeps you alive

innervates the diaphragm

plexus

a network of nerves with no associated cell bodies

cuneate fasciculus

carries info from the head, neck, and trunk

is the posterior funiculus made up of gray or white matter

white matter

tract

made up of cell bodies, MOSTLY AXONS, dendrites

sequenced together and functionally related

ex: sensory tracts, dorsal column medial lemniscus

pathway

a system of tracts that work together for a specific function

column

regional area of spinal cord (gray or white matter)

all cells within one may not be related and may have different functions

lumped based on PROXIMITY not function

fasciculus

smaller zone / region

fibers traveling in it are functionally related

close together AND related info or function

funiculus

large zone of white matter in spinal cord

NOT functionally related

brachium

branch of fibers connecting one structure to another

peduncle

large bundle of fibers that travel together and are functionally related

decussation

fibers crossing from one side to the other side

lemniscus

axons that travel together

functionally related

carry same type of information

commissure

point of crossing that is shorter than a decussation

afferent

information going TOWARDS a structure (dorsal columns)

most often SENSORY but not always

efferent

information going AWAY from a structure (spinal cord)

most often MOTOR but not always

homonculus

representation of the human body on the cortex surface

where is the head / face located on the homonculus? (medial, lateral)

located most laterally

where are the lower extremities and genitals located on the homonculus? (medial, lateral)

located most medially

what 4 things are needed for typical function of the CNS

genetics

hormones

electrical and chemical balance / homeostasis

neurotransmitters

what represents healthy function of the CNS

normal movement

normal sensory processing

cognitive processing

emotional control

homeostasis control

sleep and wakefulness

what are 8 parts of normal sensory processing

touch

pain

temperature

vision

audition

olfaction

taste

balance

what are 5 parts of cognitive processing

awareness and arousal

attention

memory and learning

problem solving

integration / language

what can go wrong to impair normal function of the CNS

immune system dysfunction

genetics

trauma

environment

homeostasis change

electrical abnormalities

degeneration

vascular and meningeal disruption

what do we need to do to maintain healthy function of the CNS

nutrition

physical activity

mental activity

genetics

environmental factors

sleep

healthy immune system function

avoid risky behaviors

how many neurons can a singular neuron be connected to

up to 10,000 other neurons

how many miles would nerves span if they were laid out

46 miles

how many different nerve cells are there in the brain

100 billion