Central Nervous System

Question 1

central nervous system divisions

Answer 1

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

Question 2

spinal chord

Answer 2

• 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

Question 3

end of spinal chord

Answer 3

=conus medullaris=cone shaped part @ L1/L2

Question 4

Spinal segment

Answer 4

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

Question 5

Lateral horn

Answer 5

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

Question 6

which cranial nerves arise from the brainstem?

Answer 6

all except I and II

Question 7

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

Answer 7

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

Question 8

where is the 4th ventricle?

Answer 8

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

Question 9

pontine nuclei

Answer 9

receive motor impulses from cerebrum and pass them to cerebellum

Question 10

what coordinates visual and auditory reflexes?

Answer 10

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

Question 11

what is the red nucleus?

Answer 11

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

Question 12

substantia nigra

Answer 12

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

Question 13

cerebellum functions

Answer 13

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

Question 14

what is the white matter in the cerebellum called?

Answer 14

arbor vitae

Question 15

what connects the cerebellum to the brainstem?

Answer 15

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

Question 16

diencephalon

Answer 16

includes structures surrounding the 3rd ventricle

-thalamus

Question 17

thalamus

Answer 17

• main part of diencephalon

- relay center for sensory information except smell

Question 18

hypothalamus

Answer 18

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

Question 19

pineal gland

Answer 19

-regulates circadian rhythm

Question 20

main function of lobes of brain

Answer 20

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

Question 21

main function of CSF

Answer 21

=cushions and protects nervous system

Question 22

epidural space

subdural space

Answer 22

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

Question 23

subarachnoid space

Answer 23

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

Question 24

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

Answer 24

2 layers-periosteal close to bone and meningeal

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

Question 25

how is CSF drained?

Answer 25

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

Question 26

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

Answer 26

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

Question 27

where do the cranial nerves pass through?

Answer 27

``` 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 ```

Question 28

cranial nerve fibers

Answer 28

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

Question 29

optic chiasm

Answer 29

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

Question 30

optic tract

Answer 30

fibers post. to optic chiasm | send senses to lateral geniculate nucleus

Question 31

why are there vision symptoms w/pituitary tumors?

Answer 31

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

Question 32

occulomotor III nerve

Answer 32

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)

Question 33

trochlear nerve IV

Answer 33

pure motor nerve | supplies 1 of the extraoccular mm

Question 34

Abducens VI

Answer 34

pure motor, supplies 1 extraoccular mm

Question 35

how precise are the movements of the eyeball?

Answer 35

- 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

Question 36

trigeminal V nerve

Answer 36

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

Question 37

facial VII nerve

Answer 37

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)

Question 38

vestibulocochlear VIII

Answer 38

- vestibular branch from vestibular part of inner ear - senses balance and equilibrium - cochlear branch from cochlea picks up sense from hearing

Question 39

glossopharyngeal IX

Answer 39

- 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)

Question 40

vagus X nerve

Answer 40

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)

Question 41

Accessory XI

Answer 41

pure motor nerve | -supplies trapezius and sternocleidomastoid

Question 42

Hypoglossal XII nerve

Answer 42

pure motor | innervates muscles in the tongue (19)

Question 43

dorsal column-medial lemniscal pathway

Answer 43

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

Question 44

spinocerebellar pathway

Answer 44

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

Question 45

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

Answer 45

- 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

Question 46

spinothalamic pathway

Answer 46

- 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)

Question 47

syringo myelia (central canal expands)

Answer 47

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

Question 48

pyramidal-lateral and ventral corticospinal pathway

Answer 48

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

Question 49

differences in lateral and ventral corticospinal tract

Answer 49

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

Question 50

ALS affecting the R side of the spinal chord

Answer 50

(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

Question 51

white matter in the brain

Answer 51

- comissural fibers connect different hemispheres - associated fibers connect different areas of the same hemisphere - projection fibers connect cortex to lower brain and spinal chord

Question 52

CSF leaves 4th ventricle how

Answer 52

median aperature and lateral aperature x 2 | CSF enters subarachnoid space via these 3 openings

Question 53

how is CSF produced

Answer 53

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

Question 54

extensions of dura mater

Answer 54

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

Question 55

extrapyramidal pathways

Answer 55

responsible for subconcious control of movement like posture