Intro to neuroscience Flashcards
What constitutes the CNS?
The brain(Cerebrum, Diencephalon (not seen), Cerebellum, Brainstem, Spinal Cord) and the spinal cord
What constitutes the PNS?
All other parts of the nervous system
White matter(CNS)
Axons, supporting cells, and neuronal matrix
Tract(CNS)
A group of traveling together that all do the same thing
Glia(CNS)
The matrix in which the axons reside
Grey matter(CNS)
Neurons and interneurons
Nucleus(CNS)
A collection of cell bodies all involved in the same function
Basal ganglia(CNS)
A collection of nuclei all involved in same function(3-5 nuclei in a group)
Ganglion(PNS)
- A collection of cell bodies all involved in the same function
- The equivalent of a Nucleus from the CNS
What are the types of sensations we can detect?
Touch, temperature, pain, pressure, proprioception, stereognosis
What is stereognosis?
The ability to know something by touch without looking at it
What is proprioception?
- the ability to know where you are in space (conscious proprioception)
- unconscious: knowing that your body exists
rostral
toward the nose, as in the prefrontal portion of the frontal lobe
caudal
toward the tail, as in the most inferior aspect of the spinal cord
anterograde
substance in axon travelling from soma->synapse
retrograde
substance in axon travelling from synapse->soma
T/F: Retrograde flow is directly involved with neurotransmission/synaptic transmission.
false
What is a commissure?
- Fibers connecting equivalent structures in the right side of the brain to the left side
- A white matter pathway
ipsilateral
situated or affecting the same side of the body
contralateral
situated or affecting the opposite side of the body(Most strokes are contralateral)
bilateral
situated or affecting both sides of the body(Bilateral is ideal)
Can we trace neural pathways?
NO: but we can find where activity is associated with (the above) various imaging technique
What is the 3-step procedure for a Golgi Stain?
1) Place the tissue in a fixative that contains potassium dichromate
2) Place tissue in silver nitrate solution
3) cut, dehydrate,&mount tissue
What are the disadvantages of a Golgi Stain?
- incredibly capricious
- sometimes it works and sometimes it doesn’t (not reproducible)
- either works very well or not at all (can get exquisite detailed images)
Golgi vs Ramon Y Cajal: The Debate
- Golgi believed neurons made physical contact (wrong)
* Ramon Y Cajal believed neurons did not make physical contact (correct
Unipolar/pseudounipolar cells [sensory]
- Found in sensory ganglia and one sensory nucleus
- sensory ganglia include dorsal root ganglia,trigeminal ganglion, geniculate ganglion, and sensory ganglia of IX &X
- Both tails are labeled axons, but really they aren’t…(Afferent info comes in one side (serves as dendrite), Efferent info leaves out the other (serves as axon)
multipolar cells (motor)
- Receive info at dendrites, travels into cell body, send info out via axon
- Aka pyramidal cells
Are the cranial nerves part of the CNS?
no
T/F: Any sensory nerve has a ganglion.
T
What are some important neurotransmitters and their main functions
- Acetylcholine—involved in motor function memory (specifically in the frontal lobe)
- Serotonin—involved in various neurologic syndromes
- Epinephrine—aka adrenaline
- Dopamine—involved with Parkinson’s disease
- Gaba-aminobutyric Acid (GABA)
- Glutamic Acid
What are the 5 basic cell types in the CNS? (and their functions?)
•Neuron-make up the majority of the nervous system
-Interneuron-What forms connections between neurons, Make up the bulk of gray matter
•Oligodendrocyte-produce myelin (surrounds most neural fibers)
•Astrocyte-produces matrix in which the nerve cells reside,cuz CNS develops from ectoderm, no connective tissue is present there to develop on (matrix is needed to build on)
•Microglial cell-Phagocytic cell specific to CNS,develop from mesoderm, invades CNS so it can become part of the CNS, does this because up to this point CNS can’t defend itself—now CNS has protection
What cell types in the CNS are derived from ectoderm? From mesoderm?
- Ectoderm: Neuron, Interneuron, Oligodendrocyte, Astrocyte
* Mesoderm: Microglial cell
What is the PNS equivalent to an oligodendrocyte?
Schwann Cell
What does a Schwann cell do?
Produces myelin in the PNS
What is a nerve?
- Think of it as an axial cable in your house
- Nerve is divided into subunits and can segregate function: Each subunit has a different function, Axial cable—one carries TV, other carries internet, etc.
Where are cell bodies contained?
In the grey matter (interneuron)
What are the protrusions of grey matter?
- Dorsal Horn:Sensory—both somatic & visceral (Always afferent)
- Intermediate Horn:Visceral efferent
- Ventral Horn: Somatic efferent
What constitutes the white matter?
- Myelinated fibers
* Contains bundles of axons all doing the same thing
The Dorsal and Ventral Roots combine to form _______
spinal nerve
How many pairs of spinal nerves are there?
•31 pairs Cervical nerves………..8 pairs Thoracic nerves……….12 pairs Lumbar nerves………….5 pairs Sacral nerves…………….5 pairs Coccygeal nerve………..1 pair
What is the cauda equina?
- A bundle of spinal nerves and spinal nerve roots consisting of L2-L5, S1-S5, and C1
- Much branching; named because it resembles a horses tail
What is the innermost wrapping, directly attached to the spinal cord?
• Pia Mater (Absolutely adherent to the spinal cord,very thin; can’t see when you dissect)
What is the middle layer of the spinal cord wrapping?
Arachnoid Mater
What is the outermost wrapping of the spinal cord?
Dura Mater
- very thick layer-so thick that in a fixed cadaver (say a small 100lb person) you can pull on the dura mater layer and sometimes lift whole body
- DURAble
- Outside of dura is connective tissue
What are the spaces between the mater wrappings of the spinal cord?
- Epidural/Extradural space ( bw dura mater and CT)
- Subdural space (bw arachnoid and dura mater)
- Subarachnoid space ( bw pia and arachnoid mater)
What spaces are potential? Which is real?
•Potential spaces: epidural and subdural
•Real space: subarachnoid, contains cerebrospinal fluid (taken during a spinal tap),
normally doesn’t contain a lot of WBC if it does there’s a problem
Where does the spinal cord end in adults?
- Ends at about L1 (pia is attached and ends here as well)
- HOWEVER: arachnoid and dura maters continue (This is useful—in spinal tap don’t have to worry about hitting spinal cord
What is a modality?
In each nerve (cranial or spinal) there are 6 separate sets of functions that can travel
what are 6 sets of functions nerve can travel?
-Motor or efferent
.General Somatic Efferent—to muscles of somatic origin
.General Visceral Efferent—to muscles of splanchnic originn
.Branchial/pharyngeal—to muscles developed from pharyngeal/branchial arch
-Sensory or afferent
.General Somatic Afferent-direct sensation
.General Visceral Afferent—referred sensation
.Special Afferent—sensory from receptors in head
General Somatic Efferent (MOTOR)
- Motor to muscles that developed from somatic mesoderm
- Muscles that are primarily found in the limbs and the trunk, with the esception of the muscles that move the eye and those that move the tongue
- Considered “voluntary” motor
- Via ventral horn
General Visceral Efferent (MOTOR)
- Motor to muscles that developed from splanchnic mesoderm
- Muscles are found throughout the body
- Associated with the autonomic nervous system, considered to be primarily “involuntary” motor
- Via intermediate horn
Special or Pharyngeal (Branchial) Efferent (MOTOR)
- Motor to muscles that developed from the pharyngeal or branchial arches
- Primarily found in the head and face but some are found in the neck (sternocleidomastoid) or upper trunk (trapezius)
- Some are moved voluntarily and some are moved involuntarily
General Somatic Afferent (SENSORY)
- Sensory from receptors in the skin, ligaments and tendons; including sensations of pain, temperature, pressure, touch, proprioception, and stereognosis
- Considered “direct” sensation
- Via dorsal horn
General Visceral Afferent (SENSORY)
•Sensory from receptors in muscles and various sensory organs such as the carotid body and carotid sinus
•Pain associated with this modality is considered to be “referred” pain, E.g. pain in left arm during a heart attack or palm throb from paper cut on finger
..Via dorsal horn
Special Afferent (SENSORY)
- Sensory from receptors in the head
- Sensations include taste, smell, sight, hearing, and balance
- via ?
Where do voluntary (somatic) motor impulses travel through?
- Originate from pyramidal cells in the ventral horn
* Can travel from ventral horn to both dorsal and ventral primary ramus , Somatic muscles in both front and back of body
Can efferent fibers go back to the CNS?
no
Where do autonomic, sympathetic, or visceral motor impulses travel through?
- Originate from the intermediate horn
- Shape of cell body here is round—not pyramidal
- Leaves intermediate horn, travels through ventral root, leaves for a short while, then returns to the ventral root, and then leaves through both the dorsal and ventral ramus (Both front and back of body have blood vessels! Silly goose).
Where do voluntary (somatic) sensory impulses travel through?
- Info comes in dorsal or ventral root to dorsal root ganglion (the bulge) then to the dorsal horn
- The “forky doober” means there is no synapse
- Via a unipolar cell
What runs in a ventral ramus? A dorsal ramus?
•Ventral ramus: any impulse going to or coming from the front of the body
-Visceral motor/sensory and somatic motor/sensory
•Dorsal ramus: any impulse going to or coming from the back of the body
-Visceral motor/sensory and somatic motor/sensory
What goes out of the ventral root?
Somatic efferent and visceral efferent
Where do involuntary (visceral) sensory impulses travel through?
Info comes in dorsal or ventral root to dorsal root ganglion (the bulge) then to the dorsal horn
Which cranial nerves have only 1 modality?
- (I) Olfactory—smell (special sensory)
- (II) Optic—sight (special sensory)
- (IV) Trochlear—somatic motor to superior oblique muscle (an extraocular muscle)
- (VI) Abducens—somatic motor to lateral rectus muscle (an extraocular muscle)
- (VIII) Vestibulocochlear—hearing and balance (special sensory)
- (XI) Accessory—branchial motor to muscles of the pharynx and larynx, sternocleidomastoid and trapezius
- (XII) Hypoglossal—somatic motor to extrinsic and intrinsic muscles of the tongue
Which cranial nerves have 2 modalities?
•(III) Oculomotor
-Somatic motor to 4 of 6 extraocular muscles (superior rectus, inferior rectus, medial rectus, and inferior oblique) and levator palpebrae superioris
-Autonomic para-sympathetic motor to ciliary muscles &constrictor pupillae muscle
•(V) Trigeminal
-Somatic sensory from the majority of the head and neck
-Branchial motor to muscles of mastication (temporalis, masseter, lateral pterygoid, medial pterygoid), mylihyoid, anterior digastric, tensor tympani, tensor veli palatine
Which cranial nerves have the special sensory modality? (not including VII, IX, and X)
I (Olfactory), II (Optic) , VIII (Vestibulocochlear)
Which cranial nerves have the somatic sensory modality? (not including VII, IX, and X)
V (Trigeminal)
Which cranial nerves have the branchial motor modality? (not including VII, IX, and X)
V (Trigeminal), XI (Accessory)
Which cranial nerves have the somatic motor modality?
III (Oculomotor), IV (Trochlear), VI (Abducens),XII (Hypoglossal)
Which cranial nerves have the visceral motor modality? (not including VII, IX, and X)
III (Oculomotor)
Which 4 cranial nerves send out parasympathetic fibers? (not including VII, IX, and X)
- (III) Oculomotor
- (VII) Facial
- (IX) Glossopharengeal
- (X) Vagus
Cranial nerves VII (facial), IX (glossopharangeal), and X (vagus) all have 5 modalities. Which of the 6 possible modalities is not present in these nerves?
somatic motor
What are the specific functions of the various modalities of cranial nerves VII, IX, and X?
the table
Why do cranial nerves VII, IX, and X all have a function in taste? Why not just one nerve?
Embryology; the tongue develops from 4-5 different sources
