unit 1 glossary

gyrus

a “ridge” of cerebral cortex

sulcus

a “valley” of cerebral cortex

cortical sheet

the outer surface covering of cerebral cortex, composed of gray matter (neuron cell bodies)

cerebellum

latin for “little brain”; the small, highly ridged portion of brain that sits inferior to the cerebral cortex and posterior to the brainstem

developmental and neuroanatomical terms

anatomical planes/slices

central nervous system (CNS)

composed of the brain and spinal cord

peripheral nervous system (PNS)

composed of peripheral nerves that connect the CNS to the limbs, trunk, and internal organs

autonomous nervous system (ANS)

a subdivision of the PNS that controls visceral functions

includes parasympathetic and sympathetic nervous systems

cranial nerves

a set of 12 specialized nerves that act as the PNS (motor control and sensory info) to the head and neck

meninges

the three protective layers of tissue between the brain and the skull

dura mater

“hard mother”

the durable, leathery outer protective layer of the meninges

arachnoid mater

“spiderlike mother”

the spiderweb-like middle protective layer of the meninges that is filled with cerebral spinal fluid

pia mater

“tender mother”

the thin, shiny, inner protective layer of the meninges that “shrink-wraps” the brain

lobes of the brain

central sulcus

the sulcus dividing the frontal and parietal lobes, surrounded on each side by motor and sensory cortex

lateral fissure

the gap that divides the temporal from the frontal and parietal lobes
a fissure is another name for a large sulcus

parieto-occipital sulcus

the sulcus that divides the parietal and occipital lobes

pre-occipital notch

the notch that serves as the bottom point of the imaginary dividing line between the temporal and occipital lobes

the top of the parieto-occipital sulcus is the top point

brodmann’s areas

~50 cytoarchitectural areas defined by neuroanatomist Brodmann according to cell size, cell density, number and thickness of cortical layers, and density of myelinated axons; numbering system is becoming less common as neuroimaging measurements take over tissue histology

gray matter

outer “bark” of the cerebral cortex composed of neuronal cell bodies

this is where computations happen

much of cortex consists of six layers

white matter

inner region of cerebral cortex composed of the axons of the neurons with cell bodies in the gray matter

can be thought of as the “wiring” connecting different regions of gray matter

neuron

the basic cell in the brain that processes and transmits information in the form of electrical and chemical signals

dendrite

the branched portion of a neuron which receives inputs from synapses with other cells and sends small depolarizations towards the cell body

cell body

the “main” portion of a cell that contains the nucleus, mitochondria, and other organelles necessary for the cell to survive

axon hillock

the base of the axon, where it meets the cell body of the neuron

action potentials are initiated here

axon

the long cell structure that carries depolarizations (action potentials) away from the cell body of a neuron to the synapse

node of ranvier

the small gaps between myelin sheaths in myelinated axons involved in fast action potential propagation down the axon

synapse

the region/space which information flows across from one neuron to another neuron

space between neurons can be called the synaptic cleft

axon terminal

the very end of a branch of a neuron’s axon, specialized to release neurotransmitters from vesicles into the synapse in response to an action potential

glial cell

surround neurons in CNS and PNS and provide myelination as well as other support for them

most abundant cell types in CNS; types differ between CNS and PNS

CNS: oligodendrocytes, astrocytes, ependymal cells, microglia

PNS: satellite cells, Schwann cells

myelin sheath

a layer of protective tissue wrapped around axons of neurons to hasten the transmission of action potentials

neuronal communication

includes electrical conduction (action potential) along the axon and chemical transmission via neurotransmitter release at the synapse

corpus callosum

the main connection of white matter that is integral for communication between the two cerebral hemispheres

cerebral spinal fluid (CSF)

the fluid surrounding the brain and spinal cord that cushions the nervous system

fluid is similar to blood plasma

ventricle

CSF-filled cavities in the brain, four total (left, right, third, and fourth)

choroid plexus

the specialized cells lining the ventricles responsible for the creation of CSF

lumbar puncture

a method to withdraw CSF for testing from a low part of the spinal column just below the spinal cord

arachnoid granulations

the bubble-like portions of the arachnoid mater (middle layer of meninges) into the draining venous sinus system that are responsible for the removal of CSF from around the brain

CSF is “recycled” into the blood stream

hydrocephalus

“water on the brain”

disorder of CSF causing problems with CSF flow or reuptake

leads to enlargement, developmental problems, changes in eye gaze, and if left untreated, death

may be developmental or acquired

primarily treated with a shunt to siphon CSF away from the brain into the abdomen

hydrocephalus ex vacuo

large spaces develop inside cortex due to loss of cortical tissue - “cortical atrophy”

seen in dementia

NOT really hydrocephalus

non-communicating hydrocephalus

hydrocephalus caused by something obstructing the normal flow of CSF

CSF behind obstruction (between production in choroid plexus and obstruction) would increase in pressure

blockages can be from things like a tumor/mass or a clot of blood/infection

communicating hydrocephalus

hydrocephalus caused by a problem with the normal uptake of CSF through the arachnoid granulations

whole CSF system would have increased pressure

shunt

in brain disorders: a tube placed inside the skull to drain off extra fluid, as seen in hydrocephalus (ventriculoperitoneal) and strokes (intraventricular)

blood vessels

the part of the circulatory system that transports blood throughout the human body

three major types: the arteries which carry oxygenated blood away from the heart, the capillaries which enable the blood and the tissues, and the veins which carry de-oxygenated blood from the capillaries back toward the heart

the arteries carry high pressure blood pumping from the heart

this high pressure decreases as larger arteries branch into progressively smaller arteries

by the capillary bed, the system is at very low pressure. this low pressure continues into the venous system and back to the heart

note that the arteries have the largest smooth muscle layer. this layer provides the mechanical strength to withstand a persons blood pressure

circle of willis

a circle of arteries that supply blood to the brain

this arrangement of blood vessels allows for collateral blood flow to the brain

carotid artery

a blood vessel that supplies the head and neck with oxygenated blood

there are two, one on each side. they supply blood to the anterior part of the brain

divides in the neck into the internal (supplies circle of willis) and external (the artery you take a pulse from)

vertebral artery

a blood vessel that runs up the back of the neck

there are two one on each side, that join at the base of the skull to form the basilar artery

these vessels supply the posterior part of the brain

basilar artery

the artery that supplies the pons, cerebellum, posterior cerebellum, and inner ear

this vessel is formed by the merging of the vertebral arteries

middle cerebral artery

the artery that supplies lateral cerebral cortex and anterior temporal lobes

strokes here can affect face, arm and language use

anterior cerebral artery

the arteries that supply oxygen to most medial portions of frontal lobes and superior medial parietal lobes

strokes here can affect leg use

stroke

rapid loss of brain tissue and function as a result of disruption of the blood supply to the brain

transient ischemic attack (TIA)

“mini stroke”

same wide-range of possible symptoms as a stroke, but symptoms are only temporary

ischemia

lack of oxygen arising from a restriction in blood supply

ischemic stroke

a stroke resulting from restriction of blood flow into a region of brain tissue

thrombus

a clot, or atherosclerotic plaque, that forms in place within a blood vessel obstructing blood flow

can close off blood flow at the place it forms or may break apart to form an embolus

embolus

a moving clot that then lodges in a small vessel

carotid stenosis

abnormal narrowing of the carotid artery, often caused by atherosclerotic plaque formation

hemorrhage

bleeding, the loss of blood from the circulatory system

hemorrhagic stroke

a stroke resulting from blood bleeding into the brain, damaging tissue

aneurysm

a localized, blood-filled bulge of blood vessel

subarachnoid hemorrhage

bleeding that occurs between the arachnoid and the pial meningeal layers

this is the space where the CSF flows around the brain and the spinal cord, the space that is also filled with spiderweb-like protrusions of the arachnoid mater

intracerebral hemorrhage

bleeding that occurs within the brain tissue itself

this would be below the pia mater

intraventricular hemorrhage

bleeding that occurs from vessels along the ventricles

the bleeding in this case would be directed into the ventricles

tPA

drug made from tissue plasminogen activator, a protein involved in the breakdown of blood clots

used to treat ischemic stroke if within 3 hours of symptom onset

venous malformation

a general term for congenital vascular anomalies

the anomalies- unusual formation- can involve only veins or veins and arteries

often increase the patient’s risk of bleeding in the brain and/or abnormal oxygen delivery to the brain tissue

arteriovenous malformation (AVM)

a vascular malformation that is a tangle of abnormal blood vessels connecting arteries and veins in the brain

has increased risk of bleeding and decreases normal oxygen flow to local tissue (no capillary bed for gas exchange)

venous thrombosis

a blood clot that forms within a vein

in the brain, this may occur in the large venous sinuses and block off blood flow out of the brain, which frequently is fatal

bridging veins

veins that drain the neural tissue and puncture (“bridge”) through the dura mater to drain into the venous sinuses

they may tear with trauma and bleed to cause a subdural hematoma

have a higher risk of rupturing from trauma from a fall in patients who suffer from alcoholism

long term alcoholism both weakens the vein vessel walls throughout the body and shrinks the brain, which puts greater stress on them specifically

hematoma

a solid swelling of clotted blood within the tissues, which can be located anywhere in the body

also called a bruise when in/under the skin

in the brain: causes local mass effects, such as compressing and injuring surrounding brain tissue like a brain tumor can

subdural hematoma

bleeding that occurs below the dura- between the dura and the brain (or spinal cord), resulting in a build up of blood that compresses the brain (or spinal cord)

this type usually comes from trauma, like a fall that tears the bridging veins

compared to epidural hematomas, these usually have a slower onset, as lower pressure venous blood is usually involved

epidural hematoma

bleeding that occurs between the skull and the dura (or spinal column and dura), resulting in a build-up of blood that compresses the brain (or spinal cord)

this type usually develops from trauma, especially in conjunction with a skull fracture

compared to subdural hematomas, these tend to have a faster and more serious onset, as higher-pressure arterial blood is usually involved

traumatic brain injury (TBI)

damage to the brain as a result of external physical force

common term: concussion

coup/contra coup injury

results from focal injury or whiplash, in which the side of the brain directly hit and the opposite side are both damaged

diffuse shearing injury

rapid acceleration/deceleration forces separates cell bodies and axons, causing widespread brain injury

phineas gage

a man who had a train spike shoot through his frontal cortex in an accident

survived but was emotionally disturbed from that point forward

blood brain barrier

a filtering mechanism of the capillaries that carry blood to the brain and spinal cord tissue, blocking the passage of certain substances (i.e., infectious agents, immune cells, some drugs)

meningitis

viral or bacterial infection of the meninges

symptoms: rash, stiff neck, headache, vomiting, mental status change

encephalitis

usually viral (herpes) infection of brain tissue

symptoms: personality changes, seizures, weakness

measles

childhood infection caused by a virus

used to be common, can be prevented with vaccine now

symptoms: appear 7-14 days after contact and include high fever, cough, runny nose, and watery eyes- rash appears 3-5 days after the first symptoms

vaccine does NOT cause autism, but measles itself DOES cause neurological complications

subacute sclerosing panencephalitis (SSPE)

history of primary measles infection, followed by an asymptomatic period that lasts 7 years on average, but can range from 1 month to 27 years

after this period, progressive neurological deterioration occurs, characterized by behavior change, intellectual problems, myoclonic seizures, blindness, ataxia, and eventually death

death can occur in 1-3 years but can be faster or slower, fastest within 3 months

rabies

virus that enters the brain by following peripheral nerves, causing diffuse brain swelling

symptoms: headaches, fever, rages, inability to swallow water, coma, and death

prion

infectious protein molecules

creutzfeld-jakob disease (CJD)/transmissible spongiform encephalopathy

commonly known as mad cow disease

prional infection kills of brain cells, creating numerous lacunae (“lakes”) in the brain tissue

symptoms: dementia and problems with coordination

encephalopathy

means disorder or disease of the brain

in modern usage, does not refer to a single disease, but rather to a syndrome of global brain dysfunction

this syndrome can be caused by many different illnesses

cysticercosis

condition resulting from infection with the pork tapeworm

symptoms: headache, stroke-like effects, brain swelling, risk of death

brain tumor

any intracranial growth created by abnormal and uncontrolled cell division, normally either in the brain itself (e.g., neurons, glial cells, lymphatic tissue, blood vessels), in the cranial nerves (e.g., myelin-producing Schwann cells), in the brain envelopes (e.g. meninges), skull, pituitary and pineal gland, or spread from cancers primarily locaed in other organs (e.g., metastatic tumors)

any type can cause damage either through direct damage to the surrounding tissue or through a mass effect- in which the pressure squishes down parts of the brain

holoprosencephaly

a congenital disorder caused by the failure of the embryonic forebrain to sufficiently divide into the double lobes of the cerebral hemispheres

the result is a single lobed frontal brain structure usually with severe skull and facial defects

autism

diffuse developmental disorder that impairs social interaction and communication

epilepsy

chronic neurological disorder that is characterized by recurring seizures

neurodegeneration

progressive loss of structure or function of neurons, including death of neurons

dementia

progressive decline in cognitive function due to damage or disease in the brain

atrophy

loss of cells

alzheimers disease

the most common form of dementia, characterized by loss of memory, cognitive abilities, and widespread neurodegeneration

different diagnosis

a systematic method of diagnosing a disorder

mental status

psychological and behavioral functioning determined through observation and questioning

edema

swelling due to excess fluid

sclerosis

scarring

commonly seen in chronic epilepsy and long term M.S.

multiple sclerosis (M.S.)

an autoimmune disease in which the patient’s immune system attacks myelin in the brain and spinal cord, causing lesions and symptoms that shift over time and eventually lead to sclerosis

x-ray

2d structural image created by differential radiation absorption in different tissues

useful for imaging skull fracture, foreign objects