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Flashcards in Central Nervous System Deck (55)
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1
Q

central nervous system divisions

A

brain–>forebrain (cerebrum and diencephalon), midbrain (no subdivisions), and hindbrain (pons and cerebellum, medulla oblongata)
spinal chord

2
Q

spinal chord

A
  • extends from C1 to L1/L2 intervertebral disk
  • does not occupy length of entire vertebral canal (stops growing at age 5)
  • is the distal part of the neural tube and 43-45cm in length
3
Q

end of spinal chord

A

=conus medullaris=cone shaped part @ L1/L2

4
Q

Spinal segment

A

Transverse section that gives rise to dorsal and ventral roots
-not on the equivalent vertebral level due to spinal chord being shorter than vertebral column

5
Q

Lateral horn

A

Only at spinal segment levels T1-L2, where lateral horn contains sympathetic neurons and S2-S4, where it contains parasympathetic neurons

6
Q

which cranial nerves arise from the brainstem?

A

all except I and II

7
Q

which part of the brain is responsible for keeping you alert and connecting parts of the brainstem?

A

reticular formation

eg if you hear a noise or the light turns on while you are sleeping, the sensory info goes to RF and it wakes you up

8
Q

where is the 4th ventricle?

A

partly in the medulla (lower half) and partly in the pons (upper half)

9
Q

pontine nuclei

A

receive motor impulses from cerebrum and pass them to cerebellum

10
Q

what coordinates visual and auditory reflexes?

A

superior colliculus+deep nucleus coordinates visual and inferior colliculus controls some auditory reflexes

11
Q

what is the red nucleus?

A
  • high iron content
  • works with cerebellum to smooth movements
  • w/out function of red nucleus you would have tremors during movements
12
Q

substantia nigra

A
  • produces dopamine
  • if not producing enough–>Parkinson’s
  • resting tremors present (eg pill rolling tremor, can’t hold their head still)
13
Q

cerebellum functions

A

coordinates gross and fine movements
controls balance
lesions in cerebellum–>lost balance and wide gate
-also lose ability to perform fine movements repeatedly

14
Q

what is the white matter in the cerebellum called?

A

arbor vitae

15
Q

what connects the cerebellum to the brainstem?

A

connected to all three parts of brainstem via peduncle pathways (nerve bundles)
superior peduncle (midbrain)
middle peduncle (largest-pons)
inferior cerebral peduncle (medulla)

16
Q

diencephalon

A

includes structures surrounding the 3rd ventricle

-thalamus

17
Q

thalamus

A
  • main part of diencephalon

- relay center for sensory information except smell

18
Q

hypothalamus

A
  • densely packed nuclei
  • main control center for autonomic nervous system
  • controls some emotions and anger, hunger, thirst
  • regulates endocrine system
19
Q

pineal gland

A

-regulates circadian rhythm

20
Q

main function of lobes of brain

A

frontal: motor impulses, judgement, personality, mathematics
almost 2 times as big in females
parietal: receives sensory information (mainly from skin through thalamus)
temporal lobe: memory, auditory sensory info
occipital lobe: vision
–each lobe has an archive and they each send past information to frontal lobe-dreams are product of frontal lobe

21
Q

main function of CSF

A

=cushions and protects nervous system

22
Q

epidural space

subdural space

A

only in spinal chord, mainly fatty tissue
not normal actually spaces but can be in pathological conditions
cushions spinal chord, space where anesthetic substances are injected

23
Q

subarachnoid space

A

=real space b/t arachnoid and pia mater that contains
CSF
-150ml capacity for CSF but 500mL produced/day

24
Q

what is different about the dura mater of the brain from the spinal chord

A

2 layers-periosteal close to bone and meningeal

-usually together but separate to house sinuses (large veins)

25
Q

how is CSF drained?

A

through arachnoid villi in subarachnoid space, which are finger like projections that drain CSF into sinuses (through unidirectional pathways)
-pressure builds up when it can’t be drained-hydrocephalus-and causes coma

26
Q

what happens in severe infection/inflammation of the meninges?
-meningitis

A

unidirectional pathways leak blood back into CSF (the wrong way)

27
Q

where do the cranial nerves pass through?

A
I-cribiform plate
II-optic canal
III-superior orbital fissure
IV-superior orbital fissure
V-superior orbital fissure, rotundum foreman, oval foremen (3 branches-trigemental)
VI-superior orbital fissure
VII and VIII-internal auditory meatus
IX, X, and XI through jugular foregem
XII-hypoglossal canal
28
Q

cranial nerve fibers

A

no cranial nerve to carry sympathetic fibers
only 4 have parasympathetic
motor and sensory
can be mixed

29
Q

optic chiasm

A

optic nerve branches join here and some fibers exchange sides
optic tract continues posteriorly

30
Q

optic tract

A

fibers post. to optic chiasm

send senses to lateral geniculate nucleus

31
Q

why are there vision symptoms w/pituitary tumors?

A

b/c it’s right @ optic chiasm and encroaches on the optic nerve/tract

32
Q

occulomotor III nerve

A

mixed nerve
has motor fibers (supplies extraoccular mm) and parasympathetic fibers (also parasympathetic ganglion “ciliary ganglion”–every cranial nerve that has parasympathetic fibers has a ganglion where a synapse occurs
(constrict pupil)

33
Q

trochlear nerve IV

A

pure motor nerve

supplies 1 of the extraoccular mm

34
Q

Abducens VI

A

pure motor, supplies 1 extraoccular mm

35
Q

how precise are the movements of the eyeball?

A
  • it can move a fraction of a degree
  • 3 cranial nerves control muscles that move it
  • the nerves lose sensitivity after a fraction of a second and it makes a tiny movement that allows light to focus on different parts of the retina
36
Q

trigeminal V nerve

A

3 branches, sensory and motor fibers (sensory ganglion trigeminal ganglion)

  • opthalmic branch V-1: pure general sensory for eyeball (pain, temp, touch)
  • maxillary branch (middle) V-2-pure sensory-nasal cavity, part of skin of the face
  • mandibular branch-teeth and tongue general sense-mixed motor and sensory (deep muscles involved in mastication)
  • V supplies sensory for all areas of the face
37
Q

facial VII nerve

A

mixed sensory, motor, parasympathetic

  • geniculate sensory ganglion
  • sensory fibers mostly for taste
  • motor fibers supply superficial facial mm (for facial expressions)
  • pterygopalatine and submandibular parasympathetic ganglion
  • parasympathetic supply 2 salivary glands, and lacrimal gland (tears)
38
Q

vestibulocochlear VIII

A
  • vestibular branch from vestibular part of inner ear
  • senses balance and equilibrium
  • cochlear branch from cochlea picks up sense from hearing
39
Q

glossopharyngeal IX

A
  • mixed sensory, motor, and parasympathetic
  • ignore motor b/c supplies insignificant muscle
  • sensory superior and inferior ganglion
  • supplies fibers for pharynx and back of tongue (gag reflex)
  • otic parasympathetic ganglion
  • parasympathetic fibers innervate parotid salivary gland
  • some fibers distributed to carotid body and carotid sinus (chemo receptors for blood content and pressure)
40
Q

vagus X nerve

A

only nerve that leaves head and distributes fibers to structures below

  • largest parasympathetic nerve in body and has sensory and motor fibers
  • superior and inferior sensory ganglions
  • motor fibers distributed to pharyngial muscles (pharynx)
  • parasympathetic ganglia (viseral ganglia) located in walls of target organs
  • parasympathetic fibers distribute in thorax (heart, lungs) and organs in abdomen (through celiac plexus and hypogastric plexus)
  • -(many branches, including cardiac branches–>cardiac plexus and then heart)
41
Q

Accessory XI

A

pure motor nerve

-supplies trapezius and sternocleidomastoid

42
Q

Hypoglossal XII nerve

A

pure motor

innervates muscles in the tongue (19)

43
Q

dorsal column-medial lemniscal pathway

A

-ascending sensory pathway, collects fine touch and proprioceptive info
1st order neuron in DRG
2nd order in medulla, crosses body
3rd in thalamus

44
Q

spinocerebellar pathway

A

ascending pathway, connects spinal chord and the cerebellum
1st order in DRG
2nd in dorsal horn–>cerebellum (no decussation)

45
Q

injury to the left sid e of the spinal chord (medial lemniscus pathway)

A
  • if the left side is injured before the decussation, the same side limb will be affected
  • if the injury is above it, the right side will be affected
46
Q

spinothalamic pathway

A
  • ascending pathway for pain and temperature senses from different parts of the body
  • 1st order in DRG
  • 2nd order in dorsal horn
  • deccusation anterior to central canal
  • 3rd order in thalamus
  • there are two (one of each side)
47
Q

syringo myelia (central canal expands)

A

-central canal expands and pushes into spinothalamic pathway–>both sides of the body are effected b/c there is one on each side

48
Q

pyramidal-lateral and ventral corticospinal pathway

A

axons of upper motor neuron pass through cerebral peduncle and pons into medulla

  • all fibers pass through pyramid of medulla, then…
  • 80% of fibers deccusate at the medulla and descend on contralateral side in lateral column as lateral corticospinal tract:
  • the rest of the fibers descend in the anterior column
49
Q

differences in lateral and ventral corticospinal tract

A

axons enter dorsal horn and pass impulse to a second motor neuron in anterior horn of spinal chord which distributes axons to muscles

  • anterior fibers decussate at the spinal chord and synapse to a lower motor neuron in anterior horn
  • lateral supplies mostly mm of limbs
  • anterior supplies mostly mm of torso, head and neck
50
Q

ALS affecting the R side of the spinal chord

A

(injury involved both pathways)
R side limbs movements will be affected b/c lateral has already done decussation
L side trunk mm will be affected

51
Q

white matter in the brain

A
  • comissural fibers connect different hemispheres
  • associated fibers connect different areas of the same hemisphere
  • projection fibers connect cortex to lower brain and spinal chord
52
Q

CSF leaves 4th ventricle how

A

median aperature and lateral aperature x 2

CSF enters subarachnoid space via these 3 openings

53
Q

how is CSF produced

A

choroid plexus produces CSF inside all 4 ventricles from blood plasma from venus sinuses

54
Q

extensions of dura mater

A

falx cerebri partially separates hemispheres
tentorium cerebelli separates cerebellum and occipital lobe
falx cerebelli separates two lobes of cerebellum

main function=to hold venous sinuses

55
Q

extrapyramidal pathways

A

responsible for subconcious control of movement like posture