Basic Terms, Circle of Willis, Corticospinal Tract

Peri

around

ex: perimeter, periaqueductal gray

Para

beside

ex: paramedic, paraventricular nucleus

Hypo

below

ex: hypodermic, hypothalamus

Epi

on top of

ex: epiglottis, epithalamus, epidural

Ipsi

same

ex: ipsilateral

Contra

opposite

ex: contralateral

Coronal

Frontal plane

Axial

Transverse plane

Sagittal plane

mid-sagittal

at the midline

para-sagittal

beside the midline

anterior, rostral

front of the brain/body

posterior, caudal

back of the brain/body

superior, dorsal

top part of the brain/body

inferior, ventral

bottom part of the brain/body

medial view

Brain is cut down the middle (from the top of the head), showing the inside left/right

lateral view

Brain viewed from side

superior view

brain viewed from top

inferior view

brain viewed from below

meninges

three layers of protective membranes that cover the brain and spinal cord

dura mater

outermost, toughest layer of the meninges

things used to remove deoxygenated blood from the brain.

dural venous sinuses

Olfactory bulbs

Process sensory information from the nose

Optic nerve

nerves that transmit signals from the retina of each eye to the brain

Optic chiasm

The X-shaped structure formed at the point below the brain where the two optic nerves cross over each other

Arachnoid

middle layer of your meninges, thin, looks like spiderweb. usually has CSF under it.

Cerebrum

largest part of brain

cerebellum

"little brain” between brainstem and cerebrum

tentorium cerebelli

a fold of the dura mater, a tough membrane lining the skull, that separates the cerebellum and brainstem from the cerebrum

sinus pathway

smaller vessels go to superior sagittal sinus. straight sinus and transverse sinus work the same way. all flow together out of the jugular vein.f

pia mater

innermost meninge

hematoma and its types

blood has leaked out and collected somewhere

subdural: below the dura (crescent)

epidural: above the dura (lens)

how to recognize CAT scan

Looks fuzzy

hemorrhage and its type

active bleeding in brain

subarachnoid means below the arachnoid layer. we can recognize it by the central pocket being lit up.

ventricle system

lateral ventricles have choroid plexues which creates CSF. Fluid drains into the 3rd ventricle, which is drained by the cerebral aqueduct, and into the 4th ventricle. CSF is released under arachnoid.

3rd ventricle looks like skinny line right on the midline when we do sagittal cut

choroid plexus (draw MRI)

network of capillaries and specialized cells located within the ventricles of the brain. Its primary function is to produce cerebrospinal fluid (CSF)

hydrocephalus, state effects and symptoms

buildup of CSF in the ventricles, compresses rest of brain and causes memory loss, etc.

spine vs. spinal cord

spinal cord is shorter than spine. in a spinal tap, the needle goes only where nerves are (sacral & lumbar region), and these move away from the needle.

telencephalon

part of embryonic brain in the prosencephalon (forebrain)

creates cerebral cortex & cerebral nuclei (amygdala, basal ganglia, basal forebrain)

associated ventricle: lateral

diencephalon

part of embryonic brain in the prosencephalon (forebrain)

creates thalamus, hypothalamus, & retina

associated ventricle: third

mesencephalon

midbrain

creates superior and inferior colliculi, red nucleus, and substantia nigra

associated ventricle: cerebral aquaduct

metencephalon

part of embryonic brain in the rhombencephalon (hindbrain)

creates cerebellum and pons

associated ventricle: fourth

myelencephalon

part of embryonic brain in the rhombencephalon (hindbrain)

creates medulla oblongata

associated ventricle: fourth

spinal cord ventricle

central canal

lobes of the brain

Brodmann’s areas

way to divide the brain (ex:BA4)

central sulcus

prominent groove on the surface of the brain that separates the frontal and parietal lobes

primary motor cortex (BA)

state alternate name

also precentral gryrus (anterior to central sulcus)

BA4

primary somatosensory cortex (BA)

aka…

postcentral gyrus

BA1, BA2, BA3

primary visual cortex (BA)

BA17

primary auditory cortex (BA)

BA41, BA42

lateral fissure/lateral sulcus

deep groove in cerebral cortex, separates frontal and temporal lobes, above BA41 & BA42

BA44, BA45

Broca’s area (BA)

Broca’s aphasia

Have trouble physically speaking/getting words out, can understand speech

Wernicke’s aphasia

Speak fluently but words don’t make sense, can’t understand speech

Wernicke’s area (BA)

BA22p, BA39, BA40

Internal Carotid Artery

Humans have one on each side of the neck. Deliver oxygen-rich blood to the brain. Split into two big artery pairs on each side: middle cerebral artery & anterior cerebral artery

Middle Cerebral Artery supplies…

Travels to lateral side of the brain, where it supplies oxygen (surface). Goes through lateral fissure.

Anterior Cerebral Artery supplies…

Travels to anterior part of the brain, where it supplies oxygen. Goes through longitudinal fissure. Supplies oxygen to medial surface of cortex.

- very unlikely to have stroke (blood clot/blockage) in this artery

Anterior Communicating Artery

Connects the anterior cerebral arteries on both sides of the brain. Aka the arterial bridge.

Vertebral Arteries

Another method of delivering oxygen-rich blood to the brain. Start as two and then fuse on the mid-line, creating the basilar artery.

Basilar Artery

Splits into posterior cerebral arteries on both sides of the brain.

Posterior Cerebral Arteries supply…

occipital lobe, and inferior and medial part of temporal lobe (amygdala & hippocampus)

Posterior Communicating Artery

Connects internal carotid to posterior cerebral artery

Circle of Willis

Aneurysm

bulging of the artery

Aneurysms typically happen

at junctions in the circle of Willis. These are weak spots

Three cerebral arteries

Middle cerebral artery: cortex (frontal, parietal, temporal)
Posterior cerebral artery: occipital lobe, inferior temporal lobe (amygdala, hippocampus)
Anterior cerebral artery: prefrontal lobe, medial surface till occipital lobe

If Middle Cerebral Artery is blocked on left hemisphere…

Affected left hemisphere =

• Broca’s area (left hemisphere)

• Wernicke’s area (left hemisphere)

• Temporal lobe

• Motor cortex (on right side of body)

• Somatosensory cortex (on right side of body)

If one Internal Carotid is blocked…

• Person will have no symptoms because blood can just flow in through the other internal carotid and to the other sides with the anterior communicating artery

• blood from basilar artery can go to side where carotid is blocked and supply that side and middle cerebral

Optic nerves vs. Internal corotid

Internal carotid is tube

Optic nerve is white tissue

Ischemic

Stroke where blood clot plugs up an artery

brighter/darker section of brain on MRI/CT

Hemorrhagic

Stroke where there is bleeding in the brain

Shows up as big bright spot on MRI/CT

Aneurism

a bulge in the wall of a blood vessel, usually an artery, caused by a weakened area in the vessel wall

if it bursts = death

corticospinal tract function and OTHER NAMES

Cell bodies are in motor cortex in prefrontal gryus
Axons/synapse are in spine

aka pyramidal tract

aka motor tract

aka descending tract

CONTROLS MOTOR MOVEMENT

spinal roots

dorsal: “top,” cell bodies are in dorsal horn in spine, axons synapse somatosensory info to spine, AP starts at axons

ventral: “bottom,” cell bodies are in ventral horn in spine, axons leave spinal cord to synapse on muscles, AP starts at axon hillock

roots are the roads (axons) and they deliver signals to the horns

Spinal cord segments each have their own..

dorsal and ventral root

Names of axons in corticospinal tract

cerebral peduncles →

pons →

pyramids (in medulla)

Pons & Medulla