PNS Exam 1 pt 1

How many cranial nerves are there?

12 pairs

Nuclei of origin contain the cell bodies of ___

LMN

How many spinal nerves are there?

31 pairs

Anterior rootlets of spinal nerves are ___ and posterior rootlets are ___

motor, sensory

Rami are ___ and rootlets are not

mixed

Somatic nervous system innervates ___ and has both sensory/motor components

skeletal/voluntary muscle

Autonomic nerve system innervates __

glands, smooth muscle, cardiac muscle, erector pili

Sympathetic and parasympathetic nervous system need ___ efferent neurons to reach their target

2

Preganglionic sympathetic cell bodies are located in ___ and they are ___

lateral horn of T1-L2, cholinergic

Postganglionic sympathetic cell bodies are located in ____ and they are ___

sympathetic trunk, adrenergic

Preganglionic parasympathetics have their cell bodies in _____

CN 3, 7, 9, 10, or S2-S4

Preganglionic sympathetics are ____ and preganglionic parasympathetics are ___

short, long

Both parasympathetic neurons are ___ (release ACh)

cholinergic

Splanchnic nerves carry ____ parasympathetic fibers from the pelvis and _____ sympathetic from the sacrum

preganglionic

Afferent fibers have their cells bodies in the ____. Spinal nerves have theirs in the ___ and cranial nerves have theirs in the ___

PNS, DRG, peripheral ganglion

Somatic motor pathways have 2 neurons: ___ and ___

UMN and LMN

UMN cell bodies are in _____ and LMN are in ___

CNS, spinal nerve or nuclei of origin

CN 8 (vestibulocochlear) carries special sensory for what 2 things?

hearing and equilibrium

CN 9 (glossopharyngeal) carries what fibers?

taste from posterior 1/3 of tongue

Somatic sense from ear

Parasympathetic to parotid glands

Innervates stylpharyngeus

CN 10 (vagus) is the most important _____ nerve to visceral structures in the thorax and abdomen

parasympathetic

CN 11 (accessory) supplies somatic motor to what 2 muscles

trapezius and SCM

CN 12 (hypoglossal) carries ___ to tongue muscles

motor (somatic)

CN 1 (olfactory nerve) is a __ neuron pathway

2

Does olfactory nerve synapse in the thalamus?

NO

Where is the cell body of first order bipolar sensory neurons of the olfactory nerve?

superior nasal concha

Are the first order olfactory neurons myelinated?

no

Where are receptors located on olfactory neurons?

olfactory hairs/dendrites

Where do the olfactory 1st order neurons synapse ?

through the cribriform plate to synapse in olfactory glomeruli (bulb) on mitral cells

Axons collect in 10-20 ____ ___ as they travel through the cribriform plate

olfactory nerves

What is the 2nd order sensory neuron of the olfactory nerve?

mitral cells

Where is the cell body of mitral cells?

olfactory buln

Mitral cells send axons ____ in the olfactory tract

posteriorly

The fiber bundle splits at the anterior perforated substance to form what??

medial stria and lateral stria

Do the medial or lateral stria cross?

medial stria cross and go back to olfactory bulb to synapse on opposite bulb

Where does the lateral stria carry fibers to?

primary olfactory cortex

What BA are included in the primary olfactory cortex?

uncus (BA 24): periamygdaloid and prepirigorm areas

Parahippocampal gyrus (BA 28): entorhinal area

What is the additional pathway of the olfactory nerve that carry info from nasal septum to the amygdala (autonomic fxn)?

terminal nerve

What nerve is poorly developed in humans but important for tracking prey?

vomeronasal nerve

What is the loss of smell called?

anosmia

What can cause anosmia?

damage to cribriform plate

In what condition is the medial temporal lobe affected first, affecting smell?

alzheimers

What is CN 2 called?

optic nerve

What are the 3 tunics of the eyeball?

fibrous, vascular, nervous (retina/inner)

What is in the fibrous tunic of the eye?

sclera and cornea

What is in the vascular tunic of the eye?

ciliary body, iris, choroid (lots of blood vessels)

How many layers of the retina are there?

10

What are the 10 layers of the retina?

1. layer of pigmented epithelium

2. photosensitive

3. external limiting membrane

4. outer nuclear layer

5. outer plexiform layer

6. inner nuclear layer

7. inner plexiform layer

8 ganglionic cell layer

9. ganglionic nerve fibers

10. inner limiting membrane

Where is the pigmented layer of the retina?

next to the choroid

What is in the photosensitive layer of the retina?

receptors of rods and cones

What is the purpose of the external limiting membrane?

separates receptors of rods/cones from the cell bodies

What is in the outer nuclear layer?

rod and cone cell bodies

What happens in the outer plexiform layer?

rods and cones synapse with bipolar cells

What is in the inner nuclear layer?

bipolar cell bodies

What happens in the inner plexiform layer?

bipolar cells synapse with ganglion cells

What is in the ganglion cell layer?

ganglion cell bodies

What is in the ganglion nerve fiber layer?

ganglion cell axons (not myelinated)

What is the function of cones?

color and clarity

What are the three types of cones?

red, green, blue

Increased concentration of cones closer to the ___ ____ allows us to see very fine detail

fovea centralis

What causes color blindness?

lack of cones

What is the function of rods?

determine light vs dark

The concentration of rods increases/decreases as you move away from fovea centralis?

increases

How many neurons are in the retinal pathway?

4 neurons from receptor to cortex

Photoreceptors relay info to ____ ___ and they synapse in the outer plexiform layer

bipolar cells (cell bodies in the inner nuclear layer)

Bipolar cells relay info to ___ ___. They synapse in the inner plexiform layer

ganglion cells

Ganglion cell axons converge towards the ___ ___

optic disc (where optic nerve attaches)

Axons leave the optic disc myelinated as the ___ ___

optic nerve

What myelinates the optic nerve?

interfasciular oligodendrocytes

The optic nerve conveys fibers to the ___ ___

optic chiasm

What fibers cross in the optic chiasm?

medial side of retina/ peripheral vision

Where does the optic tract form?

posterior to the optic chiasm

Optic tracts arch around cerebral peduncles and synapse in 1 of 3 places:

lateral geniculate body of thalamus

superior colliculus (tectospinal tract)

pretectal nucleus of midbrain

Where does the optic tract synapse?

BA 17 of occipital lobe along the calcarine sulcus

What would result if there was a lesion of the optic nerve?

lose depth perception (lose sight in one eye)

What would happen if there was a lesion of the optic chiasm?

lose peripheral vision

What would happen if there was a lesion in an optic tract?

lose half visual field

What CN is the light reflex testing?

CN II and II

What should be the consensual reaction of the visual reflex?

opposite pupil slightly constricts

What reflex transitions form far vision to close vision?

accomodation

What is the corneal reflex?

lightly touch cornea and rxn should be to close eyes and pull head back

What is convergence?

eyes move medially when things get closer to the face

Why is it hard to test for just CN II?

it is sensory only so all reflexes involve other CN

What is CN 3?

Oculomotor

What is the somatic supply of oculomotor nerve?

levator palpebrae superioris, superior rectus, medial rectus, inferior rectus, inferior oblique

What is the parasympathetic supply of CN III?

sphincter papillae and ciliaris

What is the nuclei of origin of CN III? Where is it located?

oculomotor nucleus, periaqueductal grey

Where does the oculomotor nucleus receive UMN from?

BA 8, superior collicus, medial longitiduinal fasciculus

What is the somatic pathway of CN III from the oculomotor nerve to the interpeduncular cistern?

LMN from oculomotor nuclei --> nucleus ruber and substantia nigra --> interpeduncular cistern

Once the somatic neurons are in the interpeduncular cistern, they are out of the CNS. What is different about them now?

covered with epineurium

Once in the interpeduncular cistern, the somatic neurons penetrate the dura and travel along the ___ ___ while communicating with the cavernous plexus

cavernous sinus

What is in the cavernous plexus?

postganglionic sympathetic fibers that supply smooth muscle in blood vessels

Where does somatic fibers of CN III exit the skull?

superior orbital fissure

After CN III somatic fibers leave the skull, they split into superior and inferior rami. What do they each supply?

superior: pierces sueprior rects and also supplies the levator palpebrae superioris

inferior: dividies into 3 branches

What do the 3 branches of the inferior rami supply?

medial: medial rectus

central: inferior rectus

lateral: inferior oblique

Where are the cell bodies of preganglionic parasympathetic cell bodies of CN III?

accessory oculomotor nucleus (edinger-westphal)

Do axons of preganglionic parasympathetic neurons follow the same course as the somatic fibers ?

yes, they follow until the inferior ramus

Where do preganglionic parasympathetic fibers synapse?

ciliary ganglion

What do the postganglionic parasympathetic fibers follow when they leave the ciliary ganglion?

ciliary arteries

Postganglionic fibers pierce the sclera and travel along its internal surface to supply what two muscles?

ciliaris (accommodation)

sphincter pupillae (constricts pupil)

What nerve sends some postganglionic sympathetic fibers through the ciliary ganglion to the dilate pupilae?

ophthalmic nerve (V1)