N4: white matter

anatomy yr 1

afferent fibres

• carries impulses TOWARDS higher centres

• sensory

efferent fibres

• carries impulses AWAY from high centres

• motor

• towards spinal column

decussate

cross in midline

ipsilateral 

input/out to or from same side

contralateral

input to/from opposite sides

nerve

a bundle of neurons that form a bigger structure that carries nerve impulses usually in the PNS (outside spinal cord)

tract

• a bunch of axons travelling together within CNS (spinal cord or brain)

• common function for either sensory or motor

3 types of white fibers

1. association 

2. commissural 

3. projection

association fibers location

• within the same hemisphere; horizontal 

function of association fibers

connect gyri and lobes on the same side of the brain

commissural fibers location

between left and right hemispheres; side to side

function of commissural fibers

share info across hemispheres

projection fibres location

lies btw basal ganglia and thalamus

projection fibers function

motor (efferent) /sensory (afferent) communication

long association fibers function

• responsible for high order processing (memory, language)

• travels from lobe to lobe

examples of long association

• cingulum

• superior longitudinal fasciculus

• inferior longitudinal fasciculus

short association fibers function

connect gyrus to one next it (adjacent)

location of long association fibers

deeper within white matter

short association fibers function

• short, curved (u-shaped)

• connect adjacent gyri

• sensory-motor

location of short association fibers

beneath cerebral cortex

location of cingulum

runs within the cingulate gyrus, arching around the corpus callosum

location and pathway of superior longitudinal fasciculus 

• connects frontal, parietal, occipital lobes within the same hemisphere

location and pathway of interior longitudinal fasciculus

runs from occipital lobe to anterior temporal lobe, beneath lateral sulcus

pathway of cingulum

association fibers under the gyri which connects to frontal, parietal and temporal lobes of the same hemisphere

difference btw cingulum and cingulate

cingulate: superior to corpus callosum

• grey matter

• cingulum: white matter

genu of corpus callosum

• anterior curved aspect

• connects frontal lobes

body of corpus callosum

• middle portion

• connects frontal and parietal lobes

splenium 

posterior aspect; connects occipital lobes

forceps minor

extends laterally from genu to reach most anterior aspect of frontal lobe

forceps major

extends laterally reach most posterior occipital lobe 

internal capsule location

• middle of brain

• boomerang shaped

• positioned btw basal ganglia and thalamus

type of matter for pyramids

white matter

location of pyramids

medulla oblogonta

• sends motor signals from cortex to spinal cord to brainstem

location of corona radiata

beneath the cerebral cortex and above the internal capsule

foot/leg location

medial aspect of cerebrum

torso location

superior cerebrum

arm/hand location

supero-lateral cerebrum

face location

lateral, just above lateral fissure