14_Anatomy Block 3.3 Intro To Cranial Nerves

Front 1

CNI? What is it called when this n is severed? What bone do these nn go through?

Back 1

Olfactory nerve. Anosmia. Pass through the cribriform plate of the ethmoidal bone (both terms mean sieve).

Front 2

CNII? Describe how it courses in to the brain.

Back 2

Optic nerve. Photoreceptor cells send signals to retinal cells --> to optic n --> optic chasm --> to optic tracts --> to lateral geniculate nucleus of the thalamus --> primary visual cortex located in the occipital lobe of cerebrum.

Front 3

Which CNII nerve fibers will decussate at the optic chasm? How can knowing this be helpful diagnostically?

Back 3

Medial optic fibers. If an injury is at the optic n vs the optic tract, pt will experience different symptoms.

Front 4

CNII enters the cranium via ? which is in the ? bone.

Back 4

CNII enters the cranium via OPTIC CANAL which is in the SPHENOID bone.

Front 5

What is immediately posterior to the optic chasm? How is the useful diagnostically?

Back 5

The pituitary gland is immediately posterior to the optic chasm and if there's something wrong with it, there might also be something wrong visually.

Front 6

CNVIII? Serves what?

Back 6

Vestibulocochlear N. Strictly sensory nn that serves the cochlear and vestibular organ.

Front 7

What two nn come together to form CNVIII? Where does it emerge from the cranium?

Back 7

Vestibular and Cochlear nn form CNVIII. It emerges from the Internal Acoustic Meatus (N123)

Front 8

The receptors of the inner ear (cochlea and vestibule) have cell bodies that are located where?

Back 8

The cell bodies are located in ganglia in the inner ear.

Front 9

Damage to CNVIII can result in:

Back 9

Hearing and or balance issues

Front 10

Where do the Oculomotor neurons (CNIII) originate?

Back 10

They originate in the midbrain at the oculomotor nucleus.

Front 11

Describe the course of the CNIII.

Back 11

Originates in midbrain oculomotor nuclease --> passes through cavernous sinus (N103) --> through superior orbital fissure (N4) --> into orbital cavity where it innervates muscles.

Front 12

Label related structures and muscles innervated by CNIII

Back 12

1. Superior Rectus
2. Levator palpebrae superioris muscle
3. Superior oblique muslce
4. Inferior oblique muscle
5. Medial rectus m
6. Inferior rectus m
7. Midbrain
8. Pons
9. Medulla

Front 13

Damage to CNIII presents with what symptoms.

Back 13

Oculumotor n damage presents with ptosis - drooping of the upper eyelid (i.e. levator palpebrae superioris); and the eye deviates laterally bc of the unopposed action of the lateral rectus muscle that is innervated by the Abducent CNVI

Front 14

CNIV innervates what muscle?

Back 14

The superior oblique muscle that travels through a trochlea - hence called the Trochlear N

Front 15

Describe where CNIV originates and its progression toward its insertion.

Back 15

Originates in the trochlear nucleus of the mid brain --> emerges from the DORSAL aspect of the brain stem --> through cavernous sinus --> through superior orbital fissure --> innervates superior oblique

Front 16

What is the CNVI?

Back 16

The Abducent

Front 17

Describe the course of the CNVI.

Back 17

Originates in the abducent nucleus of the brain stem --> emerges at the junction bn the pons and medulla --> passes through cavernous sinus --> pierces optical cavity via the orbital fissure --> innervates the lateral rectus m.

Front 18

Describe the eye movement caused by CNVI

Back 18

The ABducent nerve ABducts the eye.

Front 19

If you see a pt with one eye deviating toward the nose, where might there be an injury (2 things)

Back 19

Trauma to the base of the skull or an aneurism in the cavernous sinus area.

Front 20

CNXI? What does it innervate? (N126)

Back 20

Accessory Nerve. SCM and Trap

Front 21

Describe the course of CNXI (N126)

Back 21

CNXI nerve roots emerge at several locations along the brain stem and coalesce as the ascend and pass through the foremen magnum. The single n now loops around and comes down through the jugular foremen to innervate the SCM and trap.

Front 22

CNXII is called what an innervates what?

Back 22

Hypoglossal N - innervates the Extrinsic m of the tongue.

Front 23

What are the extrinsic muscles of the tongue? (there are four but CNXII only innervates 3)

Back 23

1. Genioglossus
2. Hyoglossus
3. Styloglossus
4. Geniohyoid m* Not innervated by CNXII.

Front 24

Describe the course of the CNXII to the extrinsic tongue muscles.

Back 24

Originates in the hypoglossal nucleus in the medulla. Emerges and passes thru the hypoglossal canal. Runs anterior to the carotid and IJV and runs along the base of the hyoglossus before innervating the extrinsic muscles.

Front 25

CNV1 is? What kind of nerve is it? What tissues does it supply?

Back 25

Ophthalmic Nerve of the trigeminal. It is a purely sensory nerve that receives sensory input from the upper aspects of the face (eye lid, lacrimal gland, anterior portion of the nose, scalp).

Front 26

Describe the course of CNV1

Back 26

Since sensory only it starts at peripheral tissues (e.g. forehead, eyelid, lacrimal gland) --> orbital cavity --> through superior orbital fissure --> to cell bodies in the trigeminal ganglion --> to pons.

Front 27

What is CNV2? What kind of n is it and what tissues does it serve?

Back 27

CNV2 is the Maxillary N. It is a purely sensory n that serves the upper lip/teeth, palate, cheak, etc.

Front 28

Describe the course of CNV2

Back 28

Since it is purely sensory, it starts at the mid face-ish --> enters the cranium via the foremen rotundum (N44) --> to cell bodies in the trigeminal nerve ganglion --> to the pons.

Front 29

What is CNV3? What kind of n is it and what tissues does it serve?

Back 29

CNV3 is the Mandibular division of the Trigeminal. It is both a motor and sensory neuron that supplies the lower jaw.

Front 30

Describe the course of the CNV3

Back 30

The main CNV3 trunk enters the cranial cavity via the foremen ovale. Sensory fibers have nuclei in the trigeminal gangion --> central processes pass to the brainstem (pons).

Front 31

CN VII? Is it S, M or SM?

Back 31

Facial N. Its SM

Front 32

Describe the path of the CNVII

Back 32

It exits the caudal boarder of the pons (bn the pons and medulla) --> enters the petrous division of temporal bone via Internal Acoustic Meatus --> exits petrous via Stylomastoid Foramen --> pass through parotid --> innervates m. of facial expression.

Front 33

Where do the sensory neurons arise in the facial nerve? Where do they go? What is the n called once it gets close to the tongue?

Back 33

The geniculate ganglion neurons go to the anterior 2/3 of the tongue. Called the Chorda Tympani.

Front 34

Facial n innervates this accessory mastication muscle:

Back 34

Buccinator via Buccal Branches

Front 35

This branch of the facial n innervates the Occipital Belly or Occipitofrontalis Muscle

Back 35

The posterior auricular branch.

Front 36

Which n innervates the stapedius and auricular mm?

Back 36

Facial n

Front 37

CNIX? Is S, M, SM?

Back 37

Glossopharyngeal N is a Sensory and Motor neuron.

Front 38

Describe the path of CNIX

Back 38

3-4 roots come off the side of the medulla and enters the jugular foramen

Front 39

Describe the somatic sensory component of the glossopharyngeal n. Hint: there are three major structures.

Back 39

1. Posterior 1/3 of tongue
2. Pharynx (tonsils, soft palate, auditory tubules)
3. Carotid Body and Sinus - monitors lack of O2 and monitors pressure.

Front 40

What is the only motor component of the Glossopharyngeal N? What does damage to this branch result in?

Back 40

Stylopharyngeous m - damage to this branch causes diminished gag reflex.

Front 41

CNX? Is it S, M, SM

Back 41

Vagus is both SM

Front 42

Describe the path of CNX

Back 42

Emerges from the Medulla and exits the cranium through the jugular foramen.

Front 43

In general, the Autonomic Nervous System innervate what?

Back 43

Cardiac m, smooth m, and glands.

Front 44

What is the function of the ANS (3)?
Is it subdivided into parasympathetic and sympathetic divisions?

Back 44

1. Emergency (fight or flight)
2. Maintain homeostatis (rest & digest)
3. Reproduction
Yes, subdivided into para/sympathetic divisions.

Front 45

Recall how the para/sympathetic neurons are set up (see back for diagram). Describe the respective lengths of both.

Back 45

Has a preganglion and postganglion neuron. Parasymp has a long preganglion and a short postganglion.

Front 46

What happens at ganglion?

Back 46

Where the "baton exchange" occurs. Where the presynaptic nerve synapses with the postsynaptic neuron.

Front 47

What are the four parasympathetic ganglion of the head?

Back 47

SPOC Ganglion (Think Star Trek):
1. Submandibular
2. Pterygopalatine
3. Otic
4. Ciliary

Front 48

What CN innervates the smooth muscle of the eye leading to pupil constriction and thickening of the lens (accommodation)? Is this para- or sympathetic?

Back 48

Oculomotor (CNIII). Parasympathetic

Front 49

Describe the path of the parasympathetic portion of the oculomoter neuron

Back 49

Originates in the midbrain at the EDINGER-WESTPHAL nucleus (pre-ganglion) --> travels with occulomoter n through superior orbital fissure --> ciliary ganglion --> short ciliary n (post-ganglion) --> around globe --> sphincter pupillae m (pupil constriction) and ciliary m (lens accommodation for near vision - reading a book during RR).

Front 50

If you have an injury along the parasympathetic n of the occulomoter, what will happen?

Back 50

You'll have a huge an enlarged pupil and pt will have loss of accommodation for near vision.

Front 51

Describe the path of the n that leads to tears. First, what cranial nerve is this?

Back 51

CNVII - Facial.
Starts at Superior Salivatory Nucleus --> emerges with Facial N --> (branch point) --> greater petrosal n --> deep petrosal --> Nerve (Vidian) of Pterygoid Canal --> Pterygopalatine Ganglion --> continues to travel with trigeminal/zygomatical temoral n (CNV) --> lacrimal nn --> lacrimal gland.

Front 52

What do pts complain about with damage to the parasympathic n fibers of CNVII?

Back 52

Dry eyes.

Front 53

What innervates the sublinguinal and submandibular gland? (N132)

Back 53

CNVII - Facial N (parasympathetic)

Front 54

Describe the parasympathetic nerve fiber track (N132) to the salivary glands.

Back 54

Originates at the superior salivatory nucleus --> emerges with facial n --> (branch point) --> chorda tympani --> merges with lingual n (branch of CNV3) greater petrosal --> submandibular ganglion --> submandibular and sublinguinal gland

Front 55

Recall the Bell's Palsy example she used in class and how damage to different areas causes different symptoms. Draw the nerves involved and describe the symptoms.

Back 55

Damage at 1:
a) Facial m paralysis
Damage at 2:
a) and b) loss of taste c) loss of salivation
Damage at 3:
a) b) c) and d) hyperacusis
Damage at 4:
a) b) c) d) and e) loss of tast (palate) 6) loss of lacrimation
**Note - my drawing is a bit off - post submandibular ganlion nerve fibers do not innervate taste bud on tongue.

Front 56

Describe the Otic Ganglion Schema (N124)

Back 56

Originates at the Inferior salivary nucleus in brain stem --> emerges with CNIX (glossal pharyngeal) --> thru tympanic cavity/N --> lesser petrosal --> OTIC Ganglion --> auriculotemporal n --> parotid gland