PNS Exam 1

How many pairs of cranial nerves?

12 pairs

T/F Nuclei of origin contain LMN and have motor function

True

T/F Nuclei of termination have sensory function and house cell bodies of 2nd order sensory neurons

True

T/F Cranial nerves can be compromised where they exit the skull

False- can NOT

How many pairs of of spinal nerves are there?

31 pairs

Spinal nerves are attached to the CNS by___

1. Anterior rootlet

2. Posterior rootlet

How many neurons does it take to get from CNS to muscle?

1 neuron

How many neurons does it take to get from cerebral cortex to muscle?

2 neurons

T/F Every peripheral nerve has a postganglionic sympathetic neuron

True

In sympathetic nervous system, preganglionic sympathetic neurons are carried at what level?

T1-L2

Sympathetic NS uses what pathway?

Adrenergic pathway- Ach is used

Two efferent neurons are used to reach target in Sympathetic NS, what are they called?

1. Preganglionic sympathetic neuron (short)

2. Postganglionic sympathetic neuron (long)

   Ach released first then NE released

What are the two main structures that carry sympathetic innervation?

1. Sympathetic trunk

2. Splanchnic nerves

There are two efferent neurons used to reach target in parasympathetic NS, what are they?

1. Preganglionic neuron (long)

2. Postganglionic neuron (short)

   Ach released

What pathway is parasympathetic NS apart of?

cholinergic “Ach released at both”

Splachnic nervers are located where?

located and effect pelvis

Where are the cell bodies for visceral afferent neurons located?

Dorsal root ganglion or C.N. ganglion

Which CN doesn’t go through the thalamus?

Olfactory nerve

What CN’s have NO motor components?

Olfactory nerve

Optic nerve

What nerves carry preganglionic parasympathetic neurons?

CN 3,7,9,10

S2,S3, S4

What CN has two special senses?

Vestibulocochlear nerve (CN 8)

What two special senses does CN 8 have?

Hearing

Equillibrium

Where is hearing integrated from CN 8?

transverse temporal gyrus

Where is equillibrium integrated from CN 8?

cerebellum

What special sense does glossopharyngeal nerve hold?

supplies taste from posterior 1/3 of tongue

T/F Glossopharyngeal provides general sensory to the ear?

True

Where does the glossopharyngeal nerve carry parasympathetics to?

Parotid glands

What muscle does CN 9 innervate?

Stylopharyngeus

What is the longest cranial nerve?

vagus nerve

Vagus is the most important___

parasympathetic nerve

Vagus nerve provides parasympathetic innervation where?

thorax and abdomen

Does accessory nerve have sensory or motor function?

Motor

What muscles are innervated by CN 11?

SCM and Trapezius

Does hypoglossal nerve have motor or sensory function?

Motor

What CN provides innervation to almost all tongue muscles?

Hypoglossal nerve

What is the skull opening for CN 8?

Internal acoustic meatus

What is the skull opening for CN 9,10,11?

Jugular foramen

What is the skull opening for CN 12?

Hypoglossal canal

What are the two neurons from cerebral cortex to target in somatic motor pathway?

1. UMN

2. LMN

What are the two types of upper motor neurons?

1. Pyramidal

2. Extrapyramidal

What is the cell body location of a pyramidal neuron?

cerebral cortex

What is the cell body location of an extrapyramidal neuron?

brain stem

What are the synapse locations of upper motor neurons?

1. Anterior horn of gray matter

2. CN nucleus of origin

T/F UMN are completely within the CNS

True

Where are the cell bodies located in a LMN?

1. Anterior horn of gray matter

2. CN nucleus of origin

What is the course of a LMN?

into the PNS and then carried to named nerve

How many neurons in the somatic sensory pathway?

3

What is the general pathway of the somatic sensory pathway?

1. 1st order goes thorugh IVF into posterior gray horn

2. 2nd order crosses sides→goes to thalamus

3. 3rd order integrated into cortex (CNS)

What does the IVF contain?

primary sensory axons

LMN travel through here

Where are olfactory neurons found?

superior nasal cavity- between supporting cells

What cells are affected by Covid-19 and are important for smell?

supporting cells

T/F Supporting cells have no olfactory receptors

True

What type of neurons are olfactory neurons?

Bipolar

Where do olfactory hairs go through?

cribriform plate

Where do olfactory neurons synapse?

Olfactory bulb

How many olfactory nerves are formed/collected on axons?

10-20

T/F Myelinated olfactory axons pass through cribriform plate

Unmyelinated

What do olfactory neurons synapse on in the olfactory bulb?

mitral cells

What are mitral cells?

secondary sensory neurons

Cell bodies in bulb

Where do mitral cells send axons?

posteriorly in olfactory tract

Fiber bundle (olfactory tract) splits where?

Anterior perforated substance

What does olfactory tract split into?

Medial and Lateral stria

Where do medial stria fibers cross?

in anterior commissure

travel to opposite bulb

Where are lateral stria fibers carried?

primary olfactory cortex (medial side of temporal lobe)

What two structures relating to olfaction are in the uncus?

1. Periamygdaloid area

2. Prepiriform area

What structure is in the secondary olfactory cortex?

entorhinal area in parahippocampal gyrus

What structure does the sensory olfactory pathway NOT synapse in?

Thalamus

What nerve is important for tracking prey?

Vomeronasal nerve

What is anosmia?

inability to smell

T/F Olfactory neurons can regenrate

True

Skull fractures can lead to CSF leakage which can cause a ____which is different from mucus

Halo sign

What are the three layers of the eyeball (external and internal)?

1. Fibrous

2. Vascular

3. Retina

What makes up the fibrous tunic?

1. Sclera

2. Cornea

What is the vascular tunic made up of?

1. Ciliary body

2. Iris

3. Choroid- loaded with BV

What are the 10 retinal layers?

1. Pigmented layer

2. Photosensitive outer segments

3. External limiting membrane

4. Outer nuclear layer

5. Outer plexiform layer

6. Inner nuclear layer

7. Inner plexiform layer

8. Ganglion cell layer

9. Nerve fiber layer

10. Internal limiting layer

What retinal layer has rod/cone receptors?

Photosensitive outer segments

What layer has rod/cone cell bodies?

Outer nuclear layer

Where do photoreceptors synapse on ganglion cells?

outer plexiform layer

Where are bipolar cell bodies found?

Inner nuclear layer

Where do bipolar cells synapse on ganglion cells?

Inner plexiform layer

Where do axons from ganglion cell layer go?

to nerve fiber layer to then leave eye through optic nerve

What are cones?

allow us to see in fine detail

1. Red

2. Green

3. Blue

T/F Cones require light?

True

T/F Cones decrease concentration closer to fovea

False- increased

What is fovea centralis?

point of clearest vision

When unmyelinated axons leave the eyeball and enter optic nerve they become __

myelinated

What cells form myelin?

interfascicular oligodendrocytes

Where do fibers from optic nerve go to?

optic chiasm

Which fibers cross over in the optic chiasm?

1. axons from medial side of retina

2. Fibers carrying peripheral visual field info

Where do fibers from optic tract synapse?

1. Lateral geniculate nucleus- largest # and then relayed to occipital lob

2. Superior colliculus- vision reflex information relayed to tectospinal tract

3. Pretectal nucleus of midbrain

If there was a lesion involving the optic nerve, what would it cause?

loss of depth perception

If there was a lesion involving the optic tract, what would it cause?

loss of ½ of visual field

If there is a lesion involving optic chiasm, what would it cause?

loss of peripheral vision

narrowing of visual field “tunnel vision”

What CN are involved in light reflexes?

CN II-CN III

What is a direct light reflex?

eye with light shown in will constrict

What is a consensual light reflex?

when light is shown, opposite eye will constrict

What is a corneal reflex?

touch cornea to look for response- CN 5- CN 7

What is convergence?

eyes converge as objects get closer

What is accomodation?

eyes can adapt from objects far to close

T/F Light reflexes use afferent component only

True