Anatomy and Physiology: Brain, CNS, Spinal Cord

What are the subdivisions of the brain?

• Cerebrum (largest)

• Diencephalon

• Cerebellum

• Brain Stem

What is the function of the Cerebellum?

• balance, posture

• fine tuning motor function: timing and details, normal walking gait

• sensory feedback leads to motor coordination

What are the sections of the Diencephalon?

• Thalamus: all senses (except for smell) travel thru the thalamus

• Hypothalamus: maintains homeostasis (temp, thirst)

• Epithalamus/pineal gland: makes melatonin (sleep-wake cycle)

What is the function of the thalamus in the diencephalon?

• to send info to appropriate cortex for interpretation

• to send info for all senses EXCEPT SIGHT

• to get info from spinal cord and brain

What is the function of the hypothalamus in the diencephalon?

• helps with communication between nervous system and endocrine system

• deals with heart rate, food/water intake, temp, sleep-wake, menstruation

• releases hormones (communicates with endocrine system

What is the role of the pituitary gland in the diencephalon?

• releases hormones

• connected to hypothalamus

What are the bumps called on the cerebrum (largest subdivision of the brain)?

Gyri

What are the grooves between the gyri called on the cerebrum (largest subdivision of the brain)?

Sulci

What is the left hemisphere of the brain GENERALLY used for?

logical tasks

What is the right hemisphere of the brain GENERALLY used for?

creative, non-language tasks (like piano)

What is gray matter (cerebrum)?

the cell bodies and dendrites of MOTOR NEURONS. Gray matter is the superficial layer of of the spaghetti gyri.

What is white matter (cerebrum)?

specific nerve tracts (collections of nerves with similar functions). It is deep to gray matter.

What are some examples of tracts that make up white matter?

• Association tracts: a nerve connects 1 gyri to another gyri in the same hemisphere

• Commissural tracts: nerves connect the right hemisphere to the left hemisphere

• Projection tracts: nerves connect the cerebrum to some other place throughout the brain or spinal cord.

What are the lobes of the cerebrum (larges subdivision of the brain)?

• Frontal lobe

• Parietal lobe

• Temporal lobe

• Occipital lobe

• Insular lobe

What does the frontal lobe do (cerebrum)

• thinking, reasoning

• emotions, personality

• speech (Broca’s area)

What are some cortices in the frontal lobe of the cerebrum?

• Motor cortex: movement of skeletal muscles

• Broca’s motor speech area: speech production, language processing

• Prefrontal cortex: behavior, motivation, goal setting

What does the parietal lobe do in the cerebrum?

• touch, pressure, temp (sensory stuff)

• some taste stuff

What does the temporal lobe in the cerebrum do?

• hearing/sound sensory input

• Wernicke’s area: speech/language understanding

• some taste

• primary smell sensing area

• memory

What is Broca’s and Wernicke’s aphasia?

• Broca’s aphasia: slow, poorly articulated speech; speech understanding isn’t impaired

• Wernicke’s aphasia: fast speech, word salad; spoken/written comprehension is destroyed

What does the occipital lobe do in the cerebrum?

• visual processing (stating and moving objects)spatial orientation

• color, speed, direction of a moving object
  

What does the Insular lobe do in the cerebrum?

• smell memory

• has basal nuclei/basal ganglia (cluster of nuclei deep in the brain)

What are basal nuclei/ganglia?

• areas of gray matter

• deep in the brain

• works with motor cortex to start motions

• prohibits muscles from moving that aren’t needed for a particular action (subconscious muscle control like swinging my arms when I’m walking)

If the basal nuclei/ganglia arean’t working properly, what are the conditions that can arise?

• Chorea: jerky movements without purpose

• Athetosis: slow (non jerky) movements

What is gray matter called in the CEREBELLUM?

cortex; superficial

What is white matter called in the CEREBELLUM?

arbor vitae; deep(looks a bit like a shrub)

What is Ataxia (it’s a sign, not a disease)?

damage to cerebellum or sensory structure that causes clumsy, unbalanced movements. Can cause intention tremors (tremors during movement)

What is the limbic system?

• “emotional brain”

• reward/punishment

• visceral responses??

What are the structures that make up the limbic system?

• amygdala

• hippocampus

• thalamus

What and where is the amygdala (part of limbic system)?

• helps identify danger

• within temporal lobe

• love, fear, rage, anxiety

• storage of short-term memories

What and where is the hippocampus?

• smell and sound memories

• spatial orientation

• in cerebral cortex

• compares past and present threats to decide if there is possible danger

What are the sections of the brainstem?

• midbrain: made of basal nuclei, has motor tracts

• medulla oblongata: regulates heart rate, breathing, sneezing, vomit, BP

• pons: bridge between medulla and midbrain

What are the three sections of gray matter in the spinal cord?

• posterior horn: sensory neurons

• anterior horn: motor neurons

• lateral horn: sympathetic neurons (thoracic and lumbar vertebrae ONLY!)

What are the two sections of white matter in the spinal cord?

• Ascending tracts: gets sensory info to the brain thru sensory neurons in the posterior horn

• Descending tracts: motor info moves down the spinal cord through motor neurons int the anterior horn

What and where is the spinal cord?

• from the brain to L1 vertebra

• in vertebral column in vertebra

• made of gray and white matter

• central canal has CSF and is the very center of the spinal cord

What are components of a reflex arc?

• sensory neuron

• effector (skeletal muscle)

• receptor (on the skin?)

• control center/ interneuron

What are some examples of a reflex arc?

• knee jerk

• poop and pee

• everyone’s reflex arcs present the same (we all react the same to a medical hammer to our knee; everyone’s knee jerks up)

What are the meninges?

connective tissue around the brain and spinal cord

What are the three layers of the meninges?

• Dura mater

• Arachnoid mater

• Pia mater

Where is the dura mater, and what does it do?

• most superficial layer

• attaches to the interior of the skull

• has 2 layers:

  • periosteal layer: superficial layer on the surface of cranial bones

  • meningeal layer: fused with periosteal layer, but where it seperates it creates sinuses or “dural spaces”

where is the arachnoid mater, and what does it do?

• middle meninges layer

• looks like a cobweb appearance

• made of collagen and elastic fibers

• subarachnoid space: spinal fluid in cerebral arteries and veins??

What is the pia mater and what does it do?

• deepest layer of the meninges

• attaches to brain tissue

• helps form spinal fluid

What are the functions of the meninges?

• covers and projects brain

• creates cerebrospinal fluid

• keeps brain and spinal cord from moving too much

• protects blood vessels

What are hematomas?

They are brain injuries affecting layers of the meninges. They’re caused by too much pressure in the skull, head injuries, or vessel rupture

• Epidural hematoma: blood between skull and dura mater

• Subdural hematoma: blood between arachnoid and dura mater

Where is cerebrosional fluid (CSF) found?

• around brain and spinal cord

• in subarachnoid space and ventricles

• CAN cross the blood brain barrier (BBB)

Where does cerebrospinal fluid come from?

blood plasma; made by choroid plexus (ependymal cells, capillaries)

• HAS: Oxygen, ions, glucose

• DOESN”T have: blood cells, plasma proteins, platelets

What makes up the blood-brain barrier (BBB)?

• blood capillary wall

• pia mater

• ependymal cells

What is the function of the blood brain barrier (BBB)?

to allow certain things to get to the brain, and to keep other things out. Water, glucose, oxygen, carbon dioxide, alcohol, caffein, nicotine, and some anesthetics can all cross the BBB

What are ventricles in the brain?

• there are 4

• deep in the brain

• lateral ventricles (2), 3rd ventricle, 4th ventricle

• circulate cerebrospinal fluid

What is the flow of cerebrospinal fluid?

1.) CSF made in the lateral ventricle/choroid plexus

2.) moves to 3rd ventricle

3.) moves to the cerebral aqueduct

4.) moves to the 4th ventricle

5.) some CSF moves down spinal cord; most ends up in the subarachnoid space

What is hydrocephalus?

• excess CSF

• causes big/ distorted head

• causes pressure in the skull in adults because their skull can’t expand like young childrens’ can

• a shunt is placed to relieve the excess pressure

What is a stroke?

bleeding arteries or blocked brain tissues causes brain cells to die from lack of oxygen.

What are the types of strokes?

• Thrombotic: plaque build-up in arteries

• Transient Ischemic Attach (TIA): fleeting blockage in an artery (can resolve on it’s own)

• Embolic: blood clot lodges in vessel

• Hemorrhagic: from increased BP, head trauma, or ruptured aneurysm

What are the symptoms of a stroke?

• weak/paralyzed limbs

• sensory loss (vision, pain, temp sensation)

• symptoms can vary by the artery affected

What are the risk factors for a stroke?

• hx or high BP

• smoking

• diabetes

• decreased heart function

What are the types of concussions?

• Mild: no loss of consciousness, decreased attention, loss of memory of event

• Classical cerebral: unconsciousness, amnesia

• Mild diffuse: coma lasting up to 24 hours

• Moderate diffuse: most never recover

• Severe diffuse: primary brainstem injury, widespread damage; often lethal

What is Alzheimer’s Disease?

Proteins collect in CNS neurons causing memory loss. There isn’t enough acetylcholine in the synapse to properly relay messages between neurons. It’s a progressive disease where more and more of the brain is affected

What is Epilepsy?

Irregular, recurrent electrical discharges in the brain (seizures). Causes motor, sensory, and psychological malfunctions. Can be caused by stroke, head trauma, or disease. Nowadays, there are really good anticonvulsants that limit the effect of seizures.

What is Amyotrophic lateral sclerosis?

A genetic disorder that causes muscle weakness and muscle atrophy. The motor neuron system breaks down which eventually causes paralysis. Physical therapy can help.

What is multiple sclerosis?

It’s an autoimmune disease that causes demyelination of axons. There is a decreased number of myelin-making cells. There are more females than males with MS. Immunosuppressants can help because they reduce inflammation.

What is Myasthenia Gravis?

It’s caused by a decrease in acetylcholine receptors OR acetylcholine receptors that aren’t working right. This causes nerve impulses to not get through and causes unpredictable muscle weakness.