L2: Divisions of Brain

what part is the supratentorial?

-conscious

-above the tentorium cerebelli

what part is the infratentorial?

-unconscious

-under the tentorium cerebelli

definition:

tentorium cerebelli

-separates the cerebellum from the rest of the brain

Definition:

Transverse fissure

-separates the cerebrum from the cerebellum

Definition:

Longitudnal fissure

-separates the cerebral hemispheres

– Separate the cerebrum into left and right hemispheres

summary:

rostral commissure

-connects L/R hemispheres (primarily temporal lobes)

-forebrain

-ventral to corpus callosum

summary:

frontal lobe

projection: primary motor

association: pre-motor: alterness, intellect, temperament, personality

summary:

parietal lobe

projection: primary sensory

association: cognitive - recognition & interpretation of sensory stimuli

summary:

occipital lobe

projection: visual

association: cognitive

summary:

temporal lobe

projection: auditory

association: interpretive - long term memory and thinking

major differences between projection and association fibers

-association fibers connect different parts of the same hemisphere

-projection fibers connect the cerebral cortex with other parts of the brain and spinal cord (brain → body → brain)

summary:

commissural fibers

-connect the two hemispheres (like a bridge)

what is the largest commissural fiber bundle?

-corpus callosum

summary:

epithysis

-b/t both hemispheres

-pineal gland (endocrine): bio clock

-attached to roof of 3rd ventricle (towards center)

definition:

thalamic nuclei

-groups of neuron cell bodies (called nuclei) located inside the thalamus — a major brain structure that acts as a relay station for sensory, motor, and cognitive information

what connects the two hemispheres of the thalamus?

-interthalamic adhesion

location:

thalamus

-center of brain

-dorsal to brain stem

-ventral to cerebral cortex

definition:

hypothalamus

-control center for your body’s internal balance (homeostasis)

-below thalamus

-above pituatary gland

definition:

optic chiasma

-where CN II (optic) crosses over to other side of brain

definition:

tuber cinereum

-gray matter region on the ventral to hypothalamus

-b/t the optic chiasma and the mammillary bodies

• It forms part of the floor of the third ventricle

• Gives rise to the infundibulum, which connects to the pituitary

definition:

infundium

-connects the hypothalamus to the pituitary gland

definition:

mammilary bodies

-two small, round structures located on underside of hypothalamus, just behind the tuber cinereum

-Part of the limbic system

-memory processing (especially spatial and episodic memory)

-connected to the hippocampus via the fornix

general location:

mesencephalon (midbrain)

-b/t interthalamic adhesion & pons

summary:

colliculus (rostral & caudal)

-paired structures on the dorsal midbrain, part of the brainstem

-part of tectum (root of midbrain)

-sight and sound reflexes

definition:

caudal commissure

-relay info b/t L/R sides of brain

-impt in pupillary light reflex

-rostral (in front of) the superior colliculi

-Near the junction of the diencephalon and midbrain

summary:

pons

PAIRED

-middle of the brainstem → above the medulla oblongata and below midbrain (between them, under cerebellum)

-relays information between the cerebral cortex and the cerebellum

-info from spinal cord to brain and vice versa

-breathing

-homeostasis

-hearing, taste, balance

-some CNs

summary:

cerebellum

“little brain” PAIRED

-movt coordination: fluid and accurate

-balance and posture

-fine motor control

-motor learning

-sensorimotor integration: combines sensory input → motor output

basic summary:

medulla oblongata

NOT PAIRED

-connects brainstem (pons) with spinal cord

-role in regulating essential, involuntary functions like breathing, heart rate, and blood pressure

-pathway for nerve signals traveling between brain and body

summary:

ventricular layer (germinal)

-innermost layer of neural tube

-adj to fluid filled areas

-mitotically active cells → give rise to all neurons and glia of the CNS

-produces: neuroblasts, glioblasts, ependymal cells

summary:

mantle layer (intermediate)

-neuroblasts become grey matter of CNS

-cell bodies of neurons settle and begin forming spinal cord horns (start organizing into networks and fx)

summary:

marginal layer

-outermost layer of neural tube

-nerve fibers (axons) growing from neurons in mantle layer

-white matter of the spinal cord and brain (myelinated axons)

-where neurons start to connect to other parts of the nervous system

summary:

somatic response

-voluntary or conscious responses

-skeletal mm

summary:

visceral response

-involuntary responses involving internal organs

-autonomic nervous system (homeostasis)

summary:

rostral colliculi

-reflexive visual processing

-help orient to sound

-direct saccades (eye movts towards)

-signals to brainstem and spinal cord → head and neck movts

general summary:

limbic system

-controls emotions, behavior, motivation, memory, and the sense of smell

-“emotional brain” — form strong memories, especially those tied to fear, pleasure, or survival

general:

neocortex

-outermost part of cerebral cortex

-covers most of forebrain

summary:

extrapyramidal system

-involuntary reflexes, movement, and coordination

-tectospinal, lateral vestibulospinal, pontine reticulospinal, and rubrospinal tracts

-primitive reflexes

summary:

epithalamus

-caudal part of diencephalon

-control of stress response

-control of sleep cycle

summary:

metathalamus

-part of the thalamus

-processing auditory and visual info

summary:

subthalamus

-inferior to the thalamus

-involved in the basal ganglia indirect pathway

summary:

ascending reticular system

medulla → cerebral cortex

-fx: alertness, consciousness, attention

(“on” switch)

summary:

descending reticular system

brainstem (medulla) → spinal cord

fx: motor tone, posture, autonomic functions, and pain inhibition

-projects to spinal cord via reticulospinal tracts

tegmentum & CNs

-tegmentum contains nuclei of cranial nerves III–V

-extrapyramidal motor fx

what general structures are in the intertentorial region?

-midbrain

-pons

-medulla oblongata

-cerebellum

signs (5):

spinal lesions

-loss of proprioception (horse

-loss of voluntary motor function

-altered cutaneous sensation

-altered spinal reflexes

-altered muscle tone

how to determine where a lesion is? (if intracranial signs)

(above foramen magnum - brain)

→ Is it supratentorial (seizures, etc)

→ is it infratentorial?

• which side? bilateral?

how to determine where a lesion is? (if no intracranial signs)

(below foramen magnum - spinal)

→ UMN? → C1 - C5? or T3 - L3?

→ LMN? → C6 - T2? or L4 - S3?

• motorneural or peripheral?