Neuro Exam 1 - Cranial Nerves

Front 1

1. From which embryologic structure to the cranial nerves develop?

2. Do any of them have sympathetic function?

3. What myelinates the true cranial nerves after they leave the brainstem? What are the exceptions?

Back 1

1. Pharyngeal Arches (brachial arches - gill spaces)

2. No directly sympathetic CN. Sympathetics to the head/face/neck are all controlled by the superior, middle and inferior sympathetic ganglia in the cervical spine (@ the levels of: OA, C1, C2) – know this for OMM.

3. Schwann Cells. EXCEPTIONS are CN I and II, which are outgrowths of the CNS (cerebrum) - Oligodendrocytes

Front 2

1. Where are Motor Nuclei and Sensory nuclei located in the brain stem?

2. What is the dividing line between sensory and motor called?

Back 2

1. Motor - Medial Brain Stem
Sensory - Lateral Brain Stem

2. Sulcus Limitans

Front 3

Where in the brainstem are each of the nuclei located for Cranial Nerves?

Back 3

Blue - Motor Efferents

Yellow - Sensory Afferents

Front 4

1. What is the pathway of the Corticobulbar tract?

2. What is it most important for?

3. What prevents paralysis of these muscles from unilateral decussation?

4. Which two CN do NOT receive bilateral innervation (only contralateral innervation)?

Back 4

1. Corticobulbar Tract: Motor Cortex (precentral gyrus) --> Genu of internal capsule --> Travels in the pyramidal tract (corticobulbar tract) --> motor CN nuclei --> associated motor CN --> Target muscle

2. Speech and Swallowing - Carrier motor messages for these

3. Bilateral Innervation from corticobulbar tract

4. CN VII (muscles of the lower face) and XII (tongue protrusion) [Example: Left pyramidal tract lesions cause right sided facial muscle paralysis or tongue deviation]

Front 5

1. What will upper motor neuron corticobulbar tract lesions do to CN VII? What will it look like?

2. What will lower motor neuron (facial nerve damage) do to the face? What will it look like?

Back 5

1. Loss of innervation below the eyes.

2. Loss of muscles of the contralateral side of the face

Front 6

What is the cause of progressive loss of smell in the elderly?

Back 6

Reduction in number of receptors in the olfactory epithelium

Front 7

1. Where do the axons of the optic tract travel that is responsible for eye movement?

2. Where is the primary relay center for info received from the retina? Where does info go from there?

Back 7

1. The Superior Colliculus of the midbrain

2. Lateral Geniculate Nucleus (LGN) --> Meyer's Loop --> Visual Cortex

Front 8

What two nuclei is CNIII associated with in the Rostral Midbrain?

Back 8

1. Occulomotor Nucleus - motor to the eye mucles
2. Edinger-Westphal Nucleus - Parasympathetic: Accommodation of lens (ciliary muscle) and Constriction of pupil (Sphincter pupilae muscle)

CNIII travels b/w the red nuclei (light circles)

Front 9

1. What is the somatic motor pathway of CN III?

2. What is the Visceral Motor Pathway of CN III (Parasympathetic)?

Back 9

1. Summary: 1. Occulomotor complex --> 2. SOF --> 3. Enters orbit --> 4. Splits into superior and inferior division --> 5. supplies all extraocular muscles except SO4 and LR6 (Superior - levator palpebrae superioris and Superior Rectus; Inferior - Medial and Inferior recti and Inferior Oblique)

2. 1. EW --> 2. SOF --> 3. Ciliary Ganglion (*synapse) --> 4. Ciliary Muscle (accomodation) & Sphinctor Pupillae (pupil dilation)

Front 10

What are the consequences of CN III Damage?

Back 10

Diplopia
Ptosis
Loss of Pupillary reflex
Mydriasis - pupillary dilation
Down and out eye

Front 11

Where is the CN IV nucleus located?

Back 11

1. At the ventral barder of the Periaqueductal grey matter at the level of the inferior colliculus in the caudal midbrain.
2. It within the Medial Longitudinal Fasciculus (MLF)

NOTE: The LEFT trochlear NUCLEUS supplies the RIGHT SO4

Front 12

What are the signs of Trochlea Nerve (CNIV) lesions?

Back 12

Diplopia while looking inferomedially (walking down stairs)
Tilting head toward same shoulder of affected eye

Front 13

1. Where is the Abducens Nucleus Located?

2. What CN fibers run AROUND the abducens nucleus?

3. Where does CN VI (abducens) exit the brainstem?

Back 13

1. Near the midline, in the PONS

2. Facial Nerve fibers

3. Exits at the Ponto-Medullary Junction (most caudal part of pons)

Front 14

What is the result of CN VI injury?

Back 14

Diplopia, Medial Strabismus (eye adduciton)

Front 15

What functions does CNV supply?

Back 15

1. Motor to muscle of mastication
2. ALL sensory to face

Front 16

What is the tract of the Ophthalmic Division of CNV?

Back 16

Front 17

What is the tract of the Maxillary Division of CNV?

Back 17

V2 --> Foramen Rotundum --> Pterygopalatine Fossa --> Infraorbital Canal --> Infraorbital foramen --> Maxillary skin

Front 18

What is the tract of the Mandibular Division of CNV?

Back 18

Lingual - General Sensation to Ant. 2/3 of tongue
Buccal Nerve - Mucosa of mouth & lateral pterygoid muscle
Auriculotemporal Nerve - External auditory meatus and part of Tympanic membrane
Inferior Alveolar Nerve - Lower teeth and gums, Chin and lower lip (mental nerve)

NOTE: sensory to the teeth - dentist inject novacaine into it

Front 19

What are the components of the Trigeminal Nucleus?

Back 19

NOTE: The mesencephalic nucleus, located in the CNS, contains the cell bodies of proprioception from the jaw traveling on V3. --> Runs along the 4th ventricle

These are the only sensory pseudounipolar neurons with Cell Bodies INSIDE of the CNS

Discriminative touch afferents --> Main sensory nucleus of CNV --> Synapse, then Cross --> Join Medial Lemniscus to the Thalamus

Pain & Temperature Afferents --> Trigeminal Ganglion (cell bodies) --> Spinal Nucleus of 5 (*Synapse) --> Spinothalamic

Front 20

What does the facial nerve innervate?

Back 20

1. (Facial Motor Nucleus) Muscle of facial expression AND
a. Stapedius
b. Stylohyoid
c. Posterior Belly of Digastric

2. (Solitary Nucleus) Taste from anterior 2/3 of tongue

3. (Superior and Inferior Salivatory Nuclei) Parasympathetics to Salivary Glands

4. (Trigeminal Nucleus) General Sense from around the ear

Front 21

What is the general sensory pathway that the Facial Nerve (VII) takes to innervate the skin around the ear?

Back 21

General Sensory (skin around ear) --> stylomastoid foramen --> geniculate ganglion (cell bodies) --> internal acoustic meatus --> *synapse in the trigeminal nucleus

- The geniculate ganglion houses the cell bodies for special sensory (taste) & general sensory neurons of CN7.
- These fibers do not synapse at the geniculate ganglion

Front 22

What is the Special Sensory (taste) pathway that the Facial Nerve VII takes to give taste sensation to the anterior 2/3 of the tongue?

Back 22

Special Sensory taste fibers from Ant 2/3 tongue  internal acoustic meatus --> genu --> geniculate ganglion (cell bodies) --> Internal Acoustic Meatus --> Solitary Nucleus (synapse*)

Front 23

What is the CNVII Parasympathetic ANS pathway to the Lacrimal Gland?

Back 23

Front 24

What is the CNVII PANS pathway to the Submandibular and Sublingual Glands?

Back 24

(Should say SUPERIOR SALIVATORY NUCLEUS in the picture)
Superior Salivatory Nucleus –(preganglionic PANS) Chorda Tympany (CN7) --> Internal Acoustic Meatus --> middle ear cavity --> petrotrympanic fissure --> infratemporal fossa --> Joins with lingual V3 --> *synapses in the submandibular ganglion

NOTE: Postganglionic fibers travel on the lingual nerve submandibular & sublingal glands

Front 25

Where are the nuclei of the Vestibulocochlear Nerve (VIII) located?

Back 25

Front 26

Where are the cell bodies of the Primary Sensory Neurons mediating hearing located?

What is the tract that they follow?

Back 26

In the Cochlea

Primary sensory neurons (Hair Cells in Cochlear) --> Cell bodies in the Spiral Ganglion --> travel through the Internal Acoustic Meatus (With the facial nerve) --> To the Cochlear nucleus in the Pons (where they *synapse)

Front 27

Where are the cell bodies of the Primary Sensory Neurons mediating balance located?

What is the tract that they follow?

Back 27

In the Vestibular Ganglion in the bony labyrinth

Primary sensory neurons (Hair Cells) --> Cell bodies in the Vestibular Ganglion --> travel through the Internal Acoustic Meatus (With the facial nerve) --> To the Vestibular nucleus in the Pons (where they *synapse)

Front 28

What are symptoms of Vestibulocochlear Nerve (CNVIII) lesions?

Back 28

Tinnitus, Vertigo (loss of hearing and/or balance)

Front 29

What are the functions of the Glossopharyngeal Nerve (CN IX)?

Back 29

Afferent limb of the gag reflex
Visceral afferents from carotid body & carotid sinus to Solitary Nucleus
General sensation from the pharynx & tonsils
General sensation from posterior 1/3 of the tongue
Taste from the posterior 1/3 of the tongue
Motor to the stylopharyngeous muscle
PANS to the salivary glands (Parotid)

Front 30

What are the nuclei associated with CNIX and what do they do?

Back 30

Sensory information --> Solitary Nucleus (CN10)
All Motor information --> Nucleus Ambiguus (CN 10)
PANS to salivary glands --> Salivatory Nuclei (CN 7)

Front 31

What sensations is the Vagus Nerve (X) responsible for?

Back 31

Parasympathetic - all organs below the neck EXCEPT adrenals and Descending colon

Motor - Pharynx, Larynx, Palatoglossus

General Sensation - External acoustic meatus

Taste - Throat and Epiglottis

Front 32

What are the nuclei associated with the Vagus Nerve (X)?

Back 32

Nucleus Ambiguus - Motor to the muscles in throat

Dorsal Nucleus of the Vagus - Parasympathetics

Solitary Nucleus - Taste & Visceral Sensory

Superior (jugular) Ganglion - cell bodies of sensory afferents from External Auditory Meatus

Inferior (nodose) Ganglion - cell bodies of visceral afferents from the heart, lungs, GI tract & taste from the throat. These fibers *synapse in the nucleus solitarius

Front 33

Where are the nuclei associated with the Vagus Nerve (X) located?

Back 33

Nucleus Ambiguus is a motor nucleus just posterior to the inferior olivary nucleus, in the medulla, which is difficult to see (hence the name).

The dorsal nucleus of the vagus, located in the medulla, contains the preganglionic PANS cell bodies supplying the heart, esophagus, trachea, GI, & abdominal viscera

Solitary Nucleus - ALL TASTE, BARO/CHEMO RECEPTORS, GAG REFLEX (IX), STRETCH RECEPTORS IN GUT

Front 34

What happens if you damage the solitary nucleus?

Back 34

Loss of: Taste, Gag Reflex, Life, Chemo Receptor of Carotid Body and Baroreceptor of Carotid Sinus

Front 35

What are symptoms of CNX lesions?

Back 35

Tachycardia (unopposed Sympathetics)
Hoarseness (recurrent Laryngeal nerve damage)
Deviated Uvula - towards affected side
Difficulty Swallowing

Front 36

Where is the Hypoglossal Nucleus located?

What does CN XII do?

Back 36

Along the midline throughout most of the posterior part of the rostral medulla.

Does motor to all tongue muscles EXCEPT palatoglossus