Nervous System Flashcards
What does the nervous system do?
master communicator of the body
works with endocrine system
maintains homeostasis
Divisions of the nervous system
- Central Nervous System (CNS)
- Brain and spinal cord
- Integration and command center - Peripheral Nervous System (PNS)
- Divided into sensory (afferent) and motor (efferent) divisions
- Includes 12 pairs of cranial nerves and 31 pairs of spinal nerves
pheripheral nervous system divisions?
somatic nervous system
autonomic nervous system
enteric nervous system
Somatic Nervous System
- “Voluntary” Nervous System
- Sensory neurons throughout the body convey information to the CNS
- All somatic sensory neurons (touch, pressure)
- Includes the special senses (vision, hearing, smell, taste, and equilibrium)
- Motor neurons conduct impulses from the CNS to skeletal muscles only
- Voluntary movements
Autonomic Nervous system
- sensory neurons from viscerl organs (lungs, heart, kidneys) to CNS
- Motor neurons from CNS to cardiac, smooth, muscle and glands - involuntary
2 main divisions of the motor nuerons?
- Sympathetic Division
- Supports exercise or “Fight or Flight” response - Parasympathetic Division
- Rest and Digest activities
The effectors receive innervation from both branches and have opposite actions
Enteric Nervous System
- Sensory neurons monitor chemical changes and stretching of the walls of the GI tract
- Motor neurons control contractions
(peristalsis and segmentations), and
secretions (acid in stomach, hormones, etc.) - Involuntary
Nervous system function
- sensory; monitor changes from inside/outside the body; retrieve stimulus/sensory input
- integration function; interpret sensory info and make decisions
- motor function; generate a response; activate effectors (muscle to contract or organ to secrete)
Neurons
- generate and propagate nerve impulses
- do not replicate like other cells in the body
Neuroglia
- smaller and more plentiful than neurons (25x)
- continually divide throughout life
- cannot transmit nerve impulses
- support, nourish and protect neurons
- “glue” that holds the nervous tissue together
parts of a neuron?
- cell body - contains the nucleus
- dendrites - multiple “little trees”; receiving or input part of neuron
- Axon - propagates nerve impulses to another neuron, muscle or gland
what is a functional classification of neurons?
classified according to the direction of nerve impulses (action potentials) travel with respect to the CNS
What are the functional classifications of neurons?
- sensory (afferent) neurons - away from extremity - nerve impulses travel towards the CNS
- motor (efferent) neurons - effect action of extremity - nerve impulse is carried away from CNS
- Interneurons - within the CNS (between sensory and motor); 90% of neurons - decision makers (integration)
what are the 4 types of neuroglia of the CNS?
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal Cells
What are the 2 types of neuroglia in the PNS?
- Schwann Cells - form the myelin sheath; nerve fiber regeneration
- Satellite Cells - surround the neuron cell bodies in the ganglia
Myelin sheath
- protect and electrically insulate the fiber
- increase the transmission rate of the nerve impulse
Myelin sheath in CNS?
Oligodendrocytes
Myelin sheath in PNS?
Schwann Cells
- nodes of ranvier
- electrical impulses “jump” from node to node
what causes Multiple Sclerosis (MS)?
demyelination
Cell Bodies group together (CNS and PNS)?
PNS - Ganglion
CNS - nucleus
Axons are bundled together (CNS and PNS)?
PNS - nerve
CNS - tract
Gray matter
- contain neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, neuroglia
- gray because no myelin sheath and Nissl bodies in the cell body are gray
- decision makers
white matter
myelinated axons
- high speed travel
resting membrane potential
- build up of negative charges inside membrane
- build up of positive charges outside membrane
- typically -70mV
- cells are “polarized” when they have a membrane potential
potential difference (volts)
- resting is usually negative; excess of positive charges on the outside and negative on the inside
- due to cell being more permeable to potassium than sodium; potassium passes from intercellular fluid to extracellular (leak channels) more readily than sodium from outside to inside
- sodium-potassium pump maintains balance
Ions Channels
- Openings in the membrane that allow specific ions to move across according to the electrochemical gradient
- Channels have “gates” to control the movement of ions
What are the 4 types of ion channels?
- leak channels
- Chemically-gated (or ligand-gated) channels
- mechanically-gated channels
- voltage-gated channels
leak channels
- more potassium leak channels compared to sodium
- membrane more permeable to potassium
- dendrites, cel bodies and axons of all types of neurons
Chemically-gated (ligand-gated) channels
- gates open or close due to a chemical stimulus
- neurotransmitters (acetylcholine) opens channels to allow sodium and calcium ions in and potassium ions out
- dendrites of some sensory neurons (pain receptors)
- dendrites and cell bodies of interneurons and motor neurons
What is the axon hillock?
where the cell body meets the axon
Mechanically-gated channels
- gates open or close channels due to vibrations, stretching and pressure
- found in auditory receptors, internal organ stretch receptors, pressure receptors in skin
If a neuroglia cell doesn’t start with S where is it located?
Central nervous system
cells you need to know functions of are?
schwann cells and oligodendrocytes
- responsible for myelination of axons
study diagram on slide 245
No really go look at it!
Voltage-gated channels
- gates open in response to a change in the resting membrane potential
- these channels participate in the generation and conduction of action potentials in the axons of all types of neurons
where is grey matter located in the brain and spinal cord?
inside of spinal cord, outside of brain
Electrical signals in neurons?
like muscle fibers, neurons are electrically excitable. They communicate with one another using 2 types of electrical signals
what are the 2 types of electrical signals in neurons?
- graded potentials
- action potentials
graded potentials
- Small deviation from the resting membrane potential
- Can cause the cell to be more or less polarized
- Stimulus causes mechanically-gated and chemically-gated channels to open or close
- Graded means the signal varies in size
- Occur mainly in the dendrites and cell bodies
- Localized…only travel for short distances
Action Potentials
- Graded potentials are most often the stimulus for the action potential
- Action potentials can travel long distances without losing the strength of the signal
- Called propagation
- Trigger zone is often the axon hillock
- Nerve impulses travel along an axon
- rapidly occuring in sequence of evets that decrease and reverse the membrane potential and then restore it back to normal
thresholds for action potentials
- needs a threshold level
- According to the all-or-nothing principle, if a stimulus reaches threshold, the action potential is always the same. – A stronger stimulus will not cause a larger impulse, it will just increase the frequency
types of synapses?
chemical and electrical
What is a synapse?
- The site of communication between 2 neurons or between a neuron and an effector cell
- Most synapses between neurons are
axodendritic
Chemical Synapses
- Neurons are close but do not touch
- Space between neurons is called synaptic cleft
- Action potential cannot jump across
- Presynaptic neuron releases a
neurotransmitter - Neurotransmitter diffuses through cytoplasm and binds with the membrane of the postsynaptic neuron
- Chemical stimulus causes the chemically gated channels to open and produces an electric signal in the postsynaptic neuron
- Synaptic delay is approx. 0.5 msec
Electrical synapses
- Action potentials conduct directly between adjacent neurons via channel proteins - tubular connexons
- Common in the brain, visceral smooth muscle, and cardiac muscle
What are the 2 main advantages of electrical synapses?
- faster communication
- synchronization - heart beat, peristalsis
What are the phases of action potential?
depolarizing phase followed by repolarizing phase
What is a synapse?
the site of communication between 2 neurons or between a neutron and an effector cell
most are ago dendritic
1. chemical synapse
2. electrical synapse
chemical synapse
- neurons are close but do not touch
- presynaptic neuron releases a neurotransmitter
- nuerotransmitter diffuses through cytoplasm and binds with the membrane of the postsynaptic neuron
- chemical stimulus causes the chemically gated channels to open and produces an electric signal in the postsynaptic neuron
- synaptic delay of 0.5 ms
what is the synaptic cleft?
space between neurons
electrical synapse
- action potentials conduct directly between adjacent neurons via channel proteins - tubular connexions
- common in the brain, visceral smooth muscle and cardia muscle
what are the 2 main advantage of electrical synapse?
faster communication
synchronization - heartbeat peristalsis
Spinal cord
continuation from the medulla oblongata to the conus medullar is at the disc space between L1 and L2
- filum terminale arises from the conus medullar is and anchors the spinal cord to the coccyx
- contains the major reflex center
where is the cervical enlargement of the spinal cord?
C4-T1
Where is the lumbar enlargement of the spinal cord?
T9-T12
spinal cord protection
cord is completely surrounded by the vertebra
meninges; 3 layers; CSF acts as a shock absorber
intervertebral discs
meninges
spinal meninges are continuous with the cranial meninges
Extend to the level of S2
what is the innermost layer of the meninges?
pia mater
What is the middle layer of the meninges?
arachnoid mater
what is the outermost layer of the meninges?
dura mater
what is the epidural space?
between the dura mater and vertebra
epidural injection - local anaesthetic
what is the subdural space?
between the dura and arachnoid maters
interstitial fluid
what is the subarachnoid space?
between the arachnoid and pia maters
contains CSF (shock absorber)
diagrams slide 285-288
don’t be lazy go look
What vertebral level is a spinal tap performed at in an adult patient?
L3 and L4
avoid spinal cord - go below it
- would insert lower on a child
- prefer L3/4 in an adult as there is less tissue than L4/5
What layer does a spinal tap go to?
subarachnoid space - to access CSF
spinal nerves
31 pairs
- where the nerves exit the spine through the intervertebral foramina
How many nerve pairs in C-spine?
8
How many nerve pairs in T-spine?
12
How many nerve pairs in L-spine?
5
How many nerve pairs in Sacrum?
5
How many nerve pairs in coccyx?
1
spinal nerve positioning
not all segments are aligned with their respective vertebra
roots of lumber, sacral, and coccygeal nerves descend on an angle to exit their respective foramina - cauda equina
spinal nerves formed by 2 roots?
- Posterior (dorsal) root - sensory
- Anterior (ventral) root - motor
all spinal nerves are MIXED
What is the Dorsal root made up of?
contain only axons of sensory neurons
What is the dorsal root ganglion?
collection of cell bodies of sensory neurons
- swelling
diagram slide 296
epidural space
subarachnoid space
Internal anatomy of spinal cord?
white matter - anterior median fissure; posterior median sulcus
Gray matter - “H” or butterfly
what is the difference between a fissure and a sulcus?
fissure is deeper than a sulcus
gray matter in the spinal cavity
posterior dorsal horn
lateral horn
anterior ventral horn
Commissure - cross bar of “H”
Central canal - small hole in the middle of the commissure - extends the entire length go the spinal cord - filled with CSF
Posterior (dorsal) horn (gray matter)
incoming sensory neurons
cell bodies and unmyelinated axons of interneurons
Anterior (ventral) horn (gray matter)
contain somatic motor nuclei
- nerve impulses for contraction of skeletal muscles
what are nuclei of the spinal cord?
clusters of cell bodies in the CNS
Lateral horn (gray matter)
present only in T and L segments
autonomic and enteric motor nuclei
- clusters of cell bodies of motor neurons that regulate the heart, glands and smooth muscle
What is white matter?
myelinated axons
sensory tracts are ascending
motor tracts are descending
What columns are white matter divided into?
posterior (dorsal) column
lateral column
anterior (ventral) column
- these columns contain tracts - bundles of axons in CNS
Posterior column (white matter)
ascending tract (sensory)
Lateral and anterior columns (white matter)
both ascending and descending (sensory and motor)
Study slide 304 and 305 diagrams
good diagram
Nerve plexus
- spinal nerves branch into rami after passing through the intervertebral foramina
- branches of the spinal nerves (anterior rami) do not go directly to the area they supply (except for the intercostal nerves)
what are the different plexus networks?
cervical
brachial
lumbar
sacral
coccygeal
cervical plexus
C1 TO C5
- head, neck, superior part of chest and shoulders
- phrenic nerves arise from the cervical plexus at the levels of C3, C4 and C5
- sternocleidomastoid
- erector spine
- levator scapulae
What do phrenic nerves do in cervical plexus?
supply motor neurons to the diaphragm
C3 to C5 keeps what alive?
the diaphragm
What is referred pain distribution?
C 3, 4, 5
- sensory stimuli from diaphragm often interpreted as pain over shoulder and lower neck
Brachial plexus
- formed by the anterior rami of C5-C8 and T1
what are the major nerves supplied by the brachial plexus?
- musculocutaneous
- axillary
- radial
- median
- ulnar
- long thoracic
wrist drop is damage to what nerve?
radial nerve
what does median nerve damage cause?
median nerve palsy
what does damage to the ulnar nerve cause?
ulnar nerve palsy - last 2 fingers stuck partially bent
What is the lumbar plexus?
- roots from L1-L4
- anterior part of lower limbs
- femoral, obturator, saphenous nerves
What causes winging of the scapula?
damage to the long thoracic nerve
What is the sacral plexus?
- L4 - S4
- sciatic nerve
- posterior part of lower limbs
where does the sciatic nerve branch?
branches into tibial and common fibular nerves at the knee
What are dermatomes?
- area of skin supplied by sensory neurons form a single spinal nerve
- useful to determine neurological levels
What are reflexes?
spinal cord is the integration centre for some reflexes
what are 2 examples of reflexes?
- patellar reflex
- plantar reflex; babinski sign - toes fan out and great toe moves upwards, normal for infant but abnormal for adults
How do you best demonstrate the intervertebral foramina of C-spine?
45 oblique C-spine with 15-20 degree angle (Caudad or Cephalic dependant on AP/PA)
How do you best demonstrate the intervertebral foramina of T-spine?
True lateral
How do you best demonstrate the intervertebral foramina of L-spine?
True lateral
How do you best demonstrate the intervertebral foramina of sacrum?
AP Axial Coccyx
What are the parts of the brain?
- cerebrum
- diencephalon
- brain stem
- cerebellum
What are the parts of the diencephalon?
- thalamus
- hypothalamus
- epithalamus
What are the parts of the brain stem?
- midbrain (mesenceohalon)
- pons
- medulla oblongata
Diagrams slides 329-332
Go learn the parts of the brain
What is the protection of the skull?
skull and meninges
what are the meninges?
- pia mater
- arachnoid mater
- dura mater
what is Pia mater?
adheres tightly to the surface of the brain
- including the gyro and sulci
what is the arachnoid mater?
subarachnoid space
does not adhere tightly to the Pia mater at all times
- forms cisterns
arachnid villi
- finger like extensions that project into the dural venous sinuses
- one way valves that allow CSF into the blood
What sits anterior to the Pons?
clivus - sella turcica - pituitary gland
what is dura mater?
2 layers (spine only has 1)
- periosteal layer (outer)
- meningeal layer (inner)
fused together except where they surround venous sinuses
no epidural space in the brain - there is in the spinal cord
what are the extensions of the dura mater?
falx cerebri
falx cerebelli
tentorium cerebelli
what is the falx cerebri?
- separates the 2 cerebral hemispheres
- in longitudinal fissure
- attaches anteriorly to the crista galli
What is the falx cerebelli?
separates the 2 hemispheres of the cerebellum
what are cisterns of the arachnoid mater?
pockets of CSF
what is tentorium cerebelli?
separates the cerebrum from the cerebellum
Which brain bleed it he most life threatening? subdural, epidural or subarachnoid?
Subarachnoid is most life threatening as it is a ruptured brain aneurism
epidural is arterial is more dangerous than subdural as subdural is venous
Diagrams slide 338 and 339
study them so you don’t fail
Seriously go now
what is located within the sinuses of the brain?
venous blood
What is located within the sinuses of the facial bones?
air
Brain blood flow
the brain represents only 2% of total body weight but receives about 20% of the body’s blood supply and consumes 20% of the O2 and glucose (even when resting)
Where does the internal carotid artery supply the brain?
supplies the anterior and middle parts of the brain
Where does the vertebral artery supply the brain?
supplies the posterior part of the brain
Where does the internal jugular vein drain blood from?
blood drains from the dural venous sinuses and deeper veins into the internal jugular vein
What is the blood brain barrier?
- Tight junctions are formed between the brain tissue and capillaries
- Astrocytes are thought to have an important function
- Semi-permeable membrane
What is the BBB permeable and impermeable to?
- Allows O2, CO2, steroid hormones, alcohol, caffeine, water, and glucose to cross
- Prevents proteins, toxins, most antibiotics from crossing
What may breakdown the BBB?
- Trauma, inflammation, certain toxins may cause a breakdown of the BBB, permitting the passage of normally restricted substances into the brain tissue
What is the BBB’s purpose?
- The BBB protects brain cells from harmful substances and pathogens by serving as a selective barrier to prevent passage of many substances from the blood into the brain
What is the CSF?
- Fluid that continually circulates through the cavities in the brain (ventricles) and spinal cord (central canal) and around the brain and spinal cord in the subarachnoid space
- Mainly water (clear, colourless)
- Contains small amounts of oxygen, glucose, proteins, ions
what are the functions of the CSF?
- Mechanical protection – shock absorber
- Homeostatic Function – pH of CSF affects cerebral blood flow and pulmonary ventilation
- Circulation – minor exchange of nutrients and wastes between the blood and adjacent nervous tissue
where is the CSF produced?
Produced in Choroid Plexus (network of capillaries) in walls of the ventricles
where is the CSF found?
CSF is found in the ventricles, cisterns, subarachnoid space of the brain and spinal cord, and central canal of the spinal cord
where is the CSF reabsorbed
Reabsorbed in the arachnoid villi (stick into the dura venous sinuses)
reabsorption to production ratio
Typically, reabsorption and production are equal
- About 500 ml of CSF produced daily
- About 125 ml of CSF present in the body at any given time
What happens if reabsorption is affected of CSF?
If reabsorption is affected…hydrocephalus
- Infants, the fontanels are open so the skull enlarges
- Adults, the skull is fused, so this becomes a life-threatening condition
What are the lateral ventricles of the brain?
- Lateral Ventricles (2)
- Largest of the ventricles
- C-shaped structures containing CSF
- One in each hemisphere passing through frontal, parietal, temporal, and occipital lobes
- Anterior (Frontal) horn, body, posterior (Occipital) horn, inferior (Temporal) horn
- Anterior/Frontal horns communicate with the Third Ventricle through the interventricular foramina
- Play a crucial role in cushioning the brain
What is the Third ventricle?
- Mid-line, slit-like structure within the diencephalon
- Communicates with the Fourth Ventricle via the Cerebral Aqueduct
What is the Fourth Ventricle?
- Posterior to the Pons (anterior part of the cerebellum)
- Communicates with the subarachnoid space via 3 openings in the roof; Median aperture (1); Lateral apertures (2)
- Becomes the central canal of the spinal cord
diagrams slide 353-358
go look silly, like right now
where does a vp shunt drain to?
ventriculoperitoneal space
- dumps fluid into peritoneal space in the abdomen to be resorbed into the body
How do you obtain image of slide 350
RPO
180 SID
Grid
Small focal spot
75 kVp
Diagram 355 - describe flow of CSF through brain and spinal cord
**** VERY IMPORTANT ******
what does the 4th ventricle become?
central canal of spinal cord
When you are viewing a CT scan you are always viewing it from?
the foot end
what is a cistern?
extra CSF stored
what is the cerebrum (cerebral hemispheres)?
- “Seat of intelligence” - Read, write, speak, make calculations, remember the past, plan for the future
- Superior portion of the brain
- Makes up over 80% of brain mass
- Divided into equal right and left hemispheres by the Longitudinal Fissure
- Each hemisphere acts on sensory and motor functions of the opposite side of the body
- Further divided into Lobes by the bones that cover it; Frontal, Parietal, Temporal, Occipital
cerebrum landmarks in the gray matter?
Gyri, Sulci and fissures
Gyri
Convolutions
- Precentral - anterior central sulcus
- Postcentral - posterior central sulcus
Sulci
Shallow grooves
- lateral
- central
Fissures
Deep grooves
- longitudinal
Diagram 361-362
understand the sulci, gyri and fissures
What is the cerebral cortex?
billions of neurons - gray matter
- gyri, fissures and sulci can be identified on the cortex
what is the basal nuclei?
gray matter deep within the cerebrum
1. caudate nucleus
2. lentiform nucleus
- Subconscious control of skeletal muscle tone
- Coordination of learned movement
- Important in starting, stopping and monitoring movement
- Plays a role in initiating and terminating cognitive processes
where do you find the caudate nucleus?
follows the curve of the lateral ventricle
where do you find the lentiform nucleus?
posterior and lateral to caudate nucleus
Slide 364 identify caudate nucleus and lentiform nucleus
Go - important
What is the white matter of the cerebrum?
Deep to the cortex is white matter composed of tracts of neurons that connect parts of the brain to each other and the spinal cord
what is the corpus callosum?
A bundle of white matter tracts that connects the right and left hemispheres of the cerebrum
what is a tract?
a bundle of axons - CNS
what is a bundle of axons in PNS?
nerves
slide 366 and 368 - be able to label diagram
don’t give up silly
What are the lobes of the cerebrum?
- frontal
- parietal
-occipital
-temporal - insula
What is the frontal lobe?
- Primary motor area is located at the “precentral gyrus” - consciously move skeletal muscle
- Premotor cortex: Learned motor skills
- Broca’s speech area
- Reasoning
What is the Broca’s speech area?
- Typically only on left side
- Speaking
What is the Parietal lobe?
Primary somatic sensory area
- Postcentral gyrus
- Integrate and interpret senses
- Can recognize pain, temperature or a light touch
Area for taste
Wernicke’s Area
What is the wenicke’s area?
Only on left side
General interpretive area
- Interprets the meaning of speech
What is the temporal lobe?
- Also contains Wernicke’s area (left side only)
- Primary olfactory area*
- Primary auditory area
What is the occipital lobe?
primary visual area
What is the insula?
additional area of gustation (taste)
What is the Thalamus?
- relay system*
- The thalamus is located superior to the midbrain and contains nuclei that serve as relay stations for all sensory impulses (except smell) to reach the Primary Sensory Area
- Also transmits information from the cerebellum to the Primary Motor Area
What is the diencephalon?
- Sits on top of brain stem - enclosed by hemispheres
Major structures - Epithalamus
- Pineal gland
- Thalamus (80%)
- Hypothalamus
- Pituitary Gland
Surrounds the 3rd Ventricle
Hypothalamus
- Projecting from the hypothalamus is the hypophysis (or Pituitary Gland)
- It controls the Autonomic Nervous System (ANS).
- It coordinates between nervous and endocrine systems.
- It controls body temperature (measured by blood flowing through it).
- It regulates hunger/thirst
- It regulates circadian rhythms (24-hour clock)
- It regulates emotional and behavioural patterns: Rage, aggression, pain, and pleasure
Epithalamus
Superior and posterior to the thalamus
Superior to the 3rd ventricle
Pineal gland - Secretes melatonin - Promotes sleepiness
habenular nuclei - emotional responses to odours
What is the limbic system?
forms the emotional brain - pleasure, pain, anger, fear and affection
- Encircles upper part of brain stem, inner border of cerebrum, and floor of diencephalon
- Links the conscious, intellectual functions of the cerebral cortex with the unconscious and autonomic functions of the brain stem
- Memory storage and retrieval
- “motivator”
Brain stem
midbrain, pons and medulla oblongata
Midbrain
- Most superior part of brain stem (between Pons and Diencephalon)
- Controls the reflex center for eye movement
- Coordinates head and neck movement in response to visual and auditory stimulus
- The cerebral aqueduct passes through the midbrain connecting the 3rd ventricle with the 4th ventricle
Pons
- Together with the medulla, areas in the pons help control breathing
- Anterior to the 4th Ventricle
White matter in the medulla oblongata?
- Contains ascending and descending tracts to spinal cord
- It has two external bulges called the pyramids formed by the largest motor and sensory tracts in the body.
- Decussation of the pyramids occur (means crosses over) - Right side of the brain controls voluntary movements on the left side of the body
What cranial nerves are associated with the midbrain?
3 and 4
Gray matter of the medulla oblongata
Functions
- Cardiac center adjusts rate & force of heartbeat
- Vasomotor center adjusts blood vessel diameter
- Respiratory centers control rate & depth of breathing
- Reflex centers for coughing, sneezing, gagging, swallowing, vomiting, salivation, sweating, hiccupping, movements of tongue & head
What cranial nerves are associated with the pons?
5-8
What cranial nerves are associated with the gray matter of the medulla oblongata?
8-12
What is the cerebellum?
- occupies the posterior cranial fossa
- cerebellar hemispheres
Are nerves 1 and 2 associated with the brainstem?
no
cerebellum gray matter?
Folia - slender, parallel folds
Cerebellar Nuclei - deep within the white matter
Cerebellum functions
- Regulates posture and balance
Smooths and coordinates contractions of skeletal muscles - Skilled muscular activities
- May have a role in cognition and language processing
What is ataxia?
- Loss of the ability to coordinate movements
- MS, Parkinson’s, tumours,
- ALCOHOL
Cranial Nerves
12 pairs
Part of the PNS
Each has a name and a roman numeral
The number indicates the order from which they arise from the brain, going from anterior to posterior
Some are special sensory nerves only, some are motor nerves only, and some are mixed (both)
Cranial nerve acronyms
Oh, Oh, Oh, To Touch And Feel Very Good Velvet, AH!
Some Say Marry Money But My Brother Says Big Brains Matter Most
What is nerve 1?
Olfactory nerve - sensory
What is nerve 2?
optic nerve - sensory
- Retina - optic foramen- optic nerve - optic chiasm - optic tract - thalamus - visual cortex.
What is nerve 3?
Oculomotor nerve - motor
Midbrain - orbit (superior orbital fissure) - eye
- innervates 4 of 6 intrinsic muscles of eye
- rotates eyes superiorly, inferiorly, or inward, raises eyelid
which cranial nerves control eye movement? where do they pass through?
3, 4 and 6 - they all pass through the superior orbital fissure
