Brain Flashcards
Cerebrum
Big part on top
L&R hemispheres
Grey around the hole in the middle and white around that
Grey in patches in the middle of the white
White matter is under the cerebral cortex
Basal ganglia = pockets of grey matter deep in the white matter
Diencephalon
In the middle
Surrounded by cerebrum
Above the brain stem
Cerebellum
Sticking out to the back = little cerebrum – Attached to pons posteriorly
Has more neurons than any other part of the body and non-motor functions (Language, eating, thinking).
It helps to generate smooth + coordinated motions by working with the motor cortex by comparing the motor cortex’s plan to what is actually happening + makes corrections.
Stores learned motor programs : walking, riding a bike, playing an instrument etc.
Brain stem
Connects to the spinal cord - inferior
Sticking down
Lots of white matter tracts
Connects the spinal cord, cranial nerves 3 - 12, and cerebellum to the rest of the brain
Controls many reflexes
Grey Matter: Grey in the middle of the spinal cord with white around that
Patches of grey in the middle of white
Cerebral cortex
Layer of grey matter around the outside of the cerebrum
Where conscious thought occurs - conscious perception of the world, make decisions, + control the body
Areas of the cortex that associate with consiousness
Structures attached to the brain stem
- Midbrain
- Pons
- Medulla Oblongata
Midbrain
- Superior + below the diencephalon
- Lots of white matter tracts
- Connects to come cranial nerves
- Coordinates with basal nucleus (part of cerebrum) to generate smooth motions + other interactions
- Controls the reflexes from eye to ear – Adjusting eye position as head moves & Startle response
Pons
Below the midbrain
Bulges out anteriorly
Cerebellum is connected behind
Many white matter tracts
Connects of other parts of NS
Connects directly to cerebelum
Most cranial nerves
Medulla Oblongata
- Most inferior
- Directly above the brain stem
- Connected to Pons
- Lots of white matter
- A few cranial nerves
- Controls important visceral reflexes
Visceral reflexes the Medulla Oblongata controls
- Cardiovascular control center - controls heart + blood vessels, regulates blood pressure
- Respiratory control center: controlls breathing
- Reflexes for many other things: Swallowing, coughing, sneezing, vomiting
Diencephalon
Where & Components
Where: In the middle of the brain + at the top of the brain stem, surrounded by cerebrum
Components:
1. Thalamus
2. Hypothalmus
3. Epithalimus
Thalamus
- The oval structure on top of the brain stem
- Relay station for incoming signals to the cerebral cortex
- Sensory signals
- Signals from other parts of the brain
- Most signals synapse in the thalamus – doing some processing
- Sends signals to the appropriate part of the cerebral cortex
Hypothalamus
Triangle of tissue inferior + anterior to the thalamus → between the thalamus + pituitary gland
Controls the autonomic nervous system:
* Generates changes in the body in response to emotions
* Psychosomatic
What does the hypothalamus control?
The autonomic nervous system:
* Smooth muscle, glands, adipose
* Critical for homeostasis: Body temp + Water balance
* Regulates Sleep-wake cycle
* Important role in many base emotions: hunger + thirst, pleasure, fear, anger, joy, sexual attraction
* Controls the pituitary gland (responsible for releasing hormones): Acts as a master gland that controls other glands & Acts as a bridge between the CNS and endocrine system
Epithalimus
Positioned posteriorly
Pineal gland: Secretes melatonin & Regulates Sleep-wake cycle
Cerebrum structural components
Gyri: bumps in the cerebral cortex
Sulci: valleys between gyri
Fissures: deeper groves that separate large regions of the brain
Sulci
= valleys between gyri
- Break the cerebral cortex into lobes
- Named after cranial bones above them
- Large Sulci divides the cerebrum into 4 lobes
1. Occipital
2. Parietal
3. Frontal
4. Temporal
Central sulcus
Valley between gyri that separates the frontal from parietal
Porecentral gyrus
Bump just anterior to the central sulcus, frontal lobe
Contains the primary motor complex
Post central gyrus
Bumps just behind the central sulcus - parietal lobe
Lateral sulcus
Valley between gyri separates temporal from frontal + parietal lobes.
Longitudinal fissure
Deeper groove that separates cerebral hemispheres
Transverse fissure
Deeper groove that separates the cerebrum from the cerebellum
Areas of the cortex that correspond to different elements of consciousness
Sensory areas
Motor areas - Priority motor cortex and Homunculus
Premotor cortex
Broca’s Area
Association areas
Sensory areas
Cerebral Cortex
Where we sense the world
* Different senses in different areas for vision, hearing, smell, touch, etc.
* R → L, L →R
Motor Areas
Cerebral Cortex
Consciously plan the movement of skeletal muscle from the frontal lobe.
R → L, L →R
Contains:
- A primary motor complex with a homunculus, Giant pyramidal neurons, and motor neurons\
- Premotor cortex
- Broca’s Area
Primary Motor Complex
In the posterior frontal lobe within the precentral gyrus.
Contains the Homunculus, giant pyramidal neurons, + motor neurons
Homunculus
Primary Motor complex
The body mapped out on primary motor cortex
When neurons in part of the homunculus fire → neurons in that part of the body contract
Giant pyramidal neurons
Neurons from the primary motor cortex that have axons that go down the spinal cord.
Synapses on the motor neuron are in the ventral horn
Motor neurons in the brain…
have axons that exit the spinal cord to control skeletal muscle.
Not a 1-1 relationship between motor neurons + giant neurons
Premotor cortex
helps to plan more complex movements that involve multiple muscle groups with the primary motor cortex.
It coordinates with other parts of the cerebral cortex to incorporate sensory information.
Located in the frontal lobe just anterior of the primary motor control.
Broca’s Area
cerebral cortex
Located in the cerebral cortex, it’s critical for the muscle movements of speech. Does planning for other muscle actions.
Located in the Frontal lobe - inferior to primary motor complex.
Association Areas
cerebral cortex
Where information from multiple sources are considered together.
- Identify characteristics, objects
- Incorporate memory
- What we consider thinking
Sensory areas of the PNS
- Somatosensory cortex
- Homunculus
- Primary visual cortex → spacial mapping
- Auditory cortex
- Olfactory cortex
- Insular cortex → Gustatory cortex, Vestibular cortex, Visceral cortex
Somatosensory cortex
Allows us to consciously perceive our somatic senses.
Senses of body
Touch, temp, pain, limb position (proprioception)
Located in the anterior parietal lobe - post central gyrus
Homunculus
PNS
Right next to the homunculus in the motor cortex and it maps out our body on the cortex.
When neurons in this part of the body light up we sense things in that part of the body
More sensitive parts of the body are disproportionately larger in here
Primary visual cortex
PNS
Where we consciously perceive sight by getting signals from eyes via the thalamus.
Located at the very posterior of the occipital lobe holds spacial mapping.
Sends signals to secondary + tertiary visual cortexs + other visual cortexes for a different aspect of visual color, 3D position, movement, shape.
Spacial Mapping
The position of visual phenomena in the world in front of you from the primary visual cortex.
- Mapped in primary visual cortex
- Center of vision takes up more of the cortex than peripheral
- More sensitive to middle
Auditory cortex
PNS
PNS sensory area that perceives hearing from signals from the ear to the superior temporal lobe - below lateral sulci
(Pitch, loudness, location)
Olfactory cortex
PNS
PNS sensory area that perceives smell from the nose to the temporal lobe - inside lateral sulci.
Insular cortex
PNS
Holds several PNS sensory cortexes deep in the lateral sulci.
* Gustatory cortex
* Vestibular cortex
* Visceral cortex
Visceral Cortex
Part of the PNS’s sensory area within the insular cortex that perceives signals from internal organs.
Have some conscious association
ex: Full bladder, empty stomach
Vestibular cortex
Part of the PNS’s sensory area within the insular cortex that perceives balance from the signals in the ear.
Gustatory cortex
Part of the PNS’s sensory area within the insular cortex that perceives taste via signals from the tongue.
PNS Association Areas
- Sensory association areas
- Multimodal association areas
- Posterior association area
- Limbic association area
Sensory Association Areas
- For a single sense
- Surround sensory area for sense
- Identify more complex concepts: size, shape, + relative position of party
- Identify an object
- Incorporates memory
Multimodal Association Areas
Incorporates info from multiple senses through Information flow and the prefrontal cortex.
Information flow
Part of the multimodal association areas by sending information from a sensory area → to a sensory association area → multimodal association area
Prefrontal cortex
Part of the multimodal association areas that sits at the very anterior frontal cortex and is relatively large in humans. This section of the brain is responsible for:
- Long term planning
- reasoning
- decision making
- working memory
- Important for personality
Phineas Gage, railroad worker that had a pipe go through his skill and changed his personality
Posterior association area
PNS association area that’s a strip in the back of the brain going from across several lobes and sensory areas.
This area puts together a multisensory picture of the world by:
- Language understanding
- Facial recognition
- Locate self in surroundings
Limbic association area
While part of the limbic system, this PNS association area is responsible for the consious regognition of the emotional importance of things. It’s located in the anterior temporal lobe.
White matter tracts
Are in the cerebrum, below the cortex. Responsible for carrying signals between parts of the cortex + between cortex and other parts of the NS
Composed of:
- Association fibers
- Projection fibers
- Commissural fibers → corpus callosum
Association fibers
Part of white matter tracks that go between parts of the cortex in the same hemisphere.
Projection fibers
Part of white matter tracks that go between the cortex + other parts of the NS.
Commissural fibers
Part of white matter tracks that go go between the L + R cerebral hemisphere.
The corpus callosum can be found here as the biggest bundle of commissural fibers.
Corpus callosum
Within white matter tracks as the largest bundle of commissural fibers.
Split brain
Have the corpus callosum cut to treat epilepsy
One side of the brain doesn’t know what the other side is doing
Basal Ganglia
Pockets of grey matter deep within the white matter of the cerebrum around the Diencephalon.
* Communicates directly with parts of the cortex
* Communicates with other parts of the NS through the thalamus
* Has a role in generating smooth movement - inhibits unnecessary movement and memory
* Important in the limbic system
Limbic system
Encompasses many different parts of the brain working together. Such as in many parts of the basal ganglia, parts of the cerebral cortex (Prefrontal cortex + Limbic cortex), and Hypothalamus.
It regulates our emotional response to stimuli and is closely linked to sense of smell.
How does the cerebellum work with the motor cortex?
It compares the motor complexs plan to what’s actually happening and makes corrections
1. Motor cortex sends signals to cerebellum
2. Giant pyramidal neurons synapse in posterior
3. Sends signal to cerebellum
4. Cerebellum gets signals from senses (vestibular + somatic senses)
5. Compares sensory + motor signals
6. Sends signals back to motor cortex
Meninges
Connective tissue membranes that separate the CNS from other tissues + protects it. Goes to the bottom of the vertebral column and surrounds cauda equine (sacrum + lumbar nerves inside the vertebral column)
1. Pia mater
2. Arachnoid mater
3. Dura Mater
Pia mater
The inner layer of meninges
- Soft
- In contact with nervous tissue
- Tightly matches folds in the brain
Arachnoid mater
The middle layer of meninges containing the subarachnoid space.
Is loose and attached to the pia matter by a web-like connective tissue.
Dura Mater
The outer layer of meninges that’s tough and continuous with the periosteum of craneal bone but separates into 2 layers in some places. The inner layer goes down into the transverse fissures, separates hemispheres, separates cerebrum + cerebellum and carries blood back to heart
Also contains dural venous sinuses.
Subarachnoid space
Sits between the arachnoid and pia mater with weblike extensions connecting them and contains cerebral fluid.
Dural Venous Sinuses
Space between the split membrane of dura that gathers blood from the brain and old CSF, then returns it to blood through the jugular vein and into the heart.
Meningies → Brain
Order
Skull → dura → Arachnoid → subarachnoid space - spinal fluid → pia → brain
Epidural space
Space filled with adipose between dura + bones.
Dura doesn’t make contact with bones of the spinal cord
Cerebral Spinal Fluid
properties
- Surrounds the CNS
- Found within meninges and ventricles
- Supports the weight of the brain
- Protects the brain from impact
- Circulates through the brain + spinal cord to deliver gasses + nutrients to brain cells and removes their waste
- Similar to blood in terms of chemical content but is not identical and more stable than blood.
Choroid Plexus
Produces CSF on the roof of each ventricle and has capillary surrounded by ependymal cells.
Fluid in the blood moves out of the capillary to become CSF. Their ependymal cells can pass from blood into CSF to control the content of CSF.
What does CSF circulate through?
- Ventricles + central canal in the middle of CNS
- Subarachroid space - outside CSN
- Movement is driven by the beating of cilia on the ependymal cells
CSF flow path
CSF starts in the L + R lateral ventricles within the cerebrum.
→ Intern ventricular foreman
→ 3rd ventricle (Thin space between 2 halves of the thalamus)
→ Cerebral aqueduct
→ 4th ventricle - posterior pons
→ Option A: Into subarachnoid space
Option B: Down central canal of the spinal cord then it’ll pass into the subarachnoid space in the spinal cord
→ in subarachnoid space moves towards transverse fissure from cerebellum
→ dural venous sinuses
→ return to blood
Blood Brain Barrier
= Tough to move between blood + brain
The brain can’t tolerate fluctuation because neurons need precise ion concentrations. The tight junctions block unnedded substances with the help of capillaries and Astrocytes managing concentrations.
Astrocytes
Help capillaries to maintain blood brain barrier by wrapping their feet around them.
Concussion
= any alteration in brain function from a blow to the head
- They are usually short-lived
- Damage can accumulate from repeated concussions
Contusion
= more severe damage than a concussion with long-term consequences
- Contusions to the brain stem will lead to a coma
Cerebral hemorrhage
= bleeding in the brain
- patient gets progressively worse
Cerebral edema
= swelling in the brain
Cerebrovascular accident (CVA) / Stroke
= blood stops flowing in part of the brain
- Can kill brain tissue
- Can lead to cognitive, motor, and sensory deficits
Hemorrhagic stroke
= blood vessel breaks + bleeding
- very rare
Ischemic Stroke
= blood clot blocks blood vessel in brain
- Clot usually comes from somewhere else in the body
Transient Ischemic Attacks (TIA)
= blood vessel is temporarily blocked
- Fairly common, not that bad
Altimerz
= clusters of misfolded proteins that gather inside + outside neurons
- Leads to dementia - decline in memory, especially short term
- Gets worse as you age
Parkinson’s
= death of dopamine-producing cells in basal ganglia
- Basal ganglia no longer inhibits movement in the cerebral cortex
Ex: Jerky motions + Difficulty walking
- Gets worse as you age
