NEURO Chapter 7: The Structure of the Nervous System

Rostral

towards the nose

caudal

towards the tail

anterior

towards the front

posterior

towards the back

dorsal

towards the back

ventral

towards belly

superior

above

inferior

below

medial

towards midline

lateral

away from the midline

Orientation in the brain

• dorsal: up (superior)

• ventral: down (inferior)

because longitudinal axis of forebrain rotate 130 degrees relative to spine

frontal/coronal plane

front → back

sagittal/lateral plane

down middle

transverse/horizontal plane

horizontal

CNS

brain + spinal cord

• cerebrum/forebrain

• brainstem

• cerebellum

PNS

• autonomic nervous system: involuntary

  • sympathetic: flight or flight

  • parasympathetic: rest and digest

• somatic: voluntary

  • sensory

  • motor

communicate with visceral organs

Spinal cord

spinal cord + cauda equina: missing spinal column, just spinal nerves

• divided into dermatomes: segment of our body corresponding to segment of spine

Info in and out of spinal cord

• Afferent: entering the cord from rest of body

  • dorsal root (sensory)

• efferent: output

  • ventral (motor)

Structure of meninges

dura mater → subdural hematoma: collection of blood → arachnoid membrane → subarachnoid space: CSF cerebrospinal fluid→ pia mater: tender

Circle of willis

collection of arteries that connect the two hemispheres together (anterior/posterior communicating artery) and arteries from other organs (internal carotid artery/vertebral artery)

• redundancies in circulation → protect against lack of bloodflow

Middle cerebral artery

artery that lines a big sulcus in brain → most common artery to have a blockage (stroke)

• serves a big amount of cortex (most of the center of brain)

forebrain

largest most front part of the brain, responsible for higher order thinking

cortex

outermost folded layer of the forebrain, responsible for higher order thinking and cognition

• gray matter

sulcus/sulci

fold in the cortex

gyrus/gyri

raised part of folded cortex

fissure

very large sulcus ex) longitudinal fissure down the middle

ventricles

4 connected cavities filled with CSF

• cushioning/clearing of waste

gray matter

cerebral cortex + basal ganglia and thalamus (lining the inside of ventricles)

white matter

myelinated neurons

• signal between brain regions

• short: within a lobe

• medium: between lobes

• long: connect two hemispheres

  • ex) corpus callosum, commissures

Cerebrospinal fluid (CSF)

• made by choroid plexus

• flow: lateral → 3rd → cerebral aqueduct → 4th → spine/subarachnoid space

• baths, cushions brain

corpus callosum

long white matter that connects both hemispheres of cortex

forebrain

largest and front-most part of the vertebrate brain, responsible for higher-level thinking, sensory processing, and emotional control

• cortex (4 lobes)

• basal ganglia

• limbic system

• diencephalon

frontal lobe (cortex)

motor and executive functions

• large in humans

central sulcus

divide frontal from parietal lobe

parietal lobe

processing sensory information (tactile functions)

• somatosensory cortex

occipital lobe

visual functions

• primary visual cortex

temporal lobe

visual, auditory, gustatory functions

• primary auditory cortex

• primary olfactory cortex

lateral fissure

divide frontal and temporal lobe

insula

major integrative bridge connecting the frontal, parietal, and temporal lobes inside cortex

hidden inside a large sulcus

• primary gustatory cortex: perception of taste

association cortices

higher order processing of sensory input from primary sensory and motor areas

• takes up most of the human forebrain

primary sensory and motor areas

take up small amount of forebrain ←> cats and rats: take up most of forebrain

• motor

• somatic sensory

• auditory

• visual

• each cortex has primary cortex and association area

Brodmann’s maps

based on the concept that changes in architecture of the brain leads to different functions

• map of abrupt changes in cytoarchitectural differences

Basal Ganglia (subcortical)

higher order movement

deep center of forebrain, buried by white matter

ex) substantia nigra: initiation of movement → affected by Parkinson’s disease

Limbic system (subcortical)

Memory and emotion processing, inner border of cerebrum

• hippocampus

• amygdala

• cingulate cortex

hipppocampus

structure within limbic system (forebrain) that controls formation of memories

named after seahorse

amygdala

structure within limbic system (forebrain) that controls fear

cingulate cortex

structure within limbic system (forebrain) that controls mood, affect, attention

Diencephalon (subcortical)

between the cerebral hemispheres and the top of the brainstem

ultimate processing bridge and relay center between the body, the brainstem, and the higher-thinking cerebral cortex.

• thalamus

• hypothalamus

Thalamus

• larger than hypothalamus

• direct projections to all cortex

• 20+ nuclei

• receive all sensory info before sending to cortex (except for olfactory)

hypothalamus

22 subnuclei

interact with pituitary to initiate responses through hormones (endocrine system)

maintain homeostasis

Brainstem

lower extension of the brain that connects the cerebral hemispheres and diencephalon to the spinal cord

• midbrain

• pons

• medulla oblongata

Midbrain

connects the deep forebrain (diencephalon) directly to the lower hindbrain

• substantia nigra

• cerebral aqueduct

• Periaqueductal Gray Matter: pain suppression → influenced by opioids

hindbrain

pons, medulla oblongata, and cerebellum

• breathing

• balance

• fine movement

Cerebellum

• highly folded structure sitting at the back of the hindbrain, right under the main hemispheres. Its name means "little brain".

• takes commands from your cortex and smooths them out so you don't shake or stumble

• highly folded surface (folds of cortex) and controls automated movements like maintaining balance and posture (anti-gravity muscles) without you falling over.