Cranial nerves and ANS

Question 1

CNVII: name? function? test? exit from skull?

Answer 1

(1.) Facial Nerve

(2. ) Sensory = taste to anterior 2/3 tongue (via chorda tympani)
(3. ) Motor = facial expression muscles + platysma
(4. ) PNS = lacrimal, sublingual, submandibular glands

(5. ) Test
- Puff cheek, smile, raise eyebrows, squint
- Sugar, salt, vinegar

(6.) Exit = internal acoustic meatus

Question 2

CNIX: name? function? test? exit from skull?

Answer 2

(1.) Glossopharyngeal

(2. ) Sensory = taste + general sensation to posterior 1/3 of tongue, carotid body + sinus, oropharynx
(3. ) Motor = stylopharyngeus
(4. ) PNS = parotid gland

(5. ) Test = Gag reflex (sensory)
(6. ) Exit = Jugular foramen

Question 3

CNX: name? function? test? exit from skull?

Answer 3

(1.) Vagus

(2. ) Sensory = epiglottis, palate, vocal cords
(3. ) Motor = larynx, pharyngeal constrictors, soft palate
(4. ) PNS = heart, lungs, foregut, midgut

(5. ) Test = Gag reflex
(6. ) Exit = jugular foramen

Question 4

CNXI: name? function? test? exit from skull?

Answer 4

(1. ) Accessory
(2. ) motor = trapezius and sternocleidomastoid

(3. ) Test= Shrug and turn head against resistance
(4. ) Exit = jugular foramen

Question 5

CN XII: name? function? test? exit from skull?

Answer 5

(1. ) Hypoglossal
(2. ) Motor = muscles of the tongue

(3. ) Test = stick tongue out and look for any deviation
(4. ) Exit = hypoglossal canal

Question 6

CNI: name? function? test? exit from skull?

Answer 6

(1. ) Olfactory nerve
(2. ) Sensory = smell

(3. ) Test = Ask pt to smell
(4. ) Exit = Cribriform plate

Question 7

CNII: name? function? test? exit from skull?

Answer 7

(1. ) Optic nerve
(2. ) Sensory = vision

(3. ) Test = Snellen charts for visual acuity, test colour, if pupils constrict with torch or one eye covered
(4. ) Exit = optic canal

Question 8

CNIV: name? function? test? exit from skull?

Answer 8

(1. ) Trochlear
(2. ) Motor = SO

(3. ) Test = Make them follow ‘H’
(4. ) Exit = Superior orbital fissure

Question 9

CNV: name? function? test? exit from skull?

Answer 9

(1.) Trigeminal

(2. ) Sensory = face sensation, anterior 2/3 tongue
(3. ) Motor = muscles of mastication

(4.) Test = Cotton wool on face (sensory test), clench teeth + open jaw against resistance -> feel for temporalis and masseter

(5.) Exit =
Superior orbital fissure = V1
Foramen Rotundum = V2
Foramen Ovale = V3

Question 10

CNVI: name? function? test? exit from skull?

Answer 10

(1. ) Abducens
(2. ) Motor = LR

(3. ) Test = abduct eye
(4. ) Exit = Superior orbital fissure

Question 11

CNVIII: name? function? test? exit from skull?

Answer 11

(1. ) Vestibulococholear
(2. ) Sensory = hear and balance

(3. ) Test = Weber and Rinne tests are performed using tuning fork
(4. ) Exit = internal acoustic meatus

Question 12

CNIII: name? function? test? exit from skull?

Answer 12

(1.) Occulomotor

(2. ) Motor = LPS (open eyelids), IO, SR, IR, MR
(3. ) PNS = pupil constrict

(4. ) Test = follow H
(5. ) Exit = superior orbital fissure

Question 13

What is ANS divided into ? and what is their outflow?

Answer 13

(1. ) Peripheral and sympathetic nervous system
(2. ) PNS outflow = CN3, 7, 9, 10 + S2,3,4
(3. ) SNS outflow = T1 to L2

Question 14

Describe the supply of the PNS outflow

Answer 14

(1. ) CN3 = constrict pupil
(2. ) CN7 = lacrimal, sublingual, submandibular gland
(3. ) CN9 = Parotid gland
(4. ) CN10 = heart, lungs, pharynx, larynx, foregut, midgut

(5.) S2, 3, 4 (pelvic splanchnic nerves) = hindgut (d.colon, rectum etc), uterus, bladder, prostate, testes, urethra.

Question 15

Describe the supply of the SNS outflow?

Answer 15

SNS fibres originate from T1-L2

(1. ) Greater splanchnic nerves (T5-9) = foregut
(2. ) Lesser splanchnic nerves (T10-11) = midgut
(3. ) Least splanchnic nerves (T12) = hindgut

Sympathetic Cervical Trunk arises from T1-L2

(1. ) Comprises of superior, middle and inferior cervical ganglion
(2. ) Inferior cervical ganglion and T1 ganglion may fuse together to form a stellate ganglion.

Question 16

What is Horner’s syndrome?

Answer 16

(1. ) Damage to stellate ganglion can cause Horner’s Syndrome
(2. ) Signs include (unilateral loss of symp innervation):
- No facial sweating (anhidrosis)
- Ptosis
- Constricted pupil (mihosis)

Question 17

Describe the differences between sympathetic and parasympathetic?

Answer 17

Sympathetic - ‘Flight or fight’

(1. ) Dilate pupil
(2. ) Inc HR
(3. ) Inhibit digestion and salivation
(4. ) Stimulate glucose release
(5. ) Vasoconstriction
(6. ) Bronchodilation
(7. ) Relaxes bladder

Parasympathetic - ‘rest + digest’

(1. ) Constrict pupil
(2. ) Dec HR
(3. ) Stimulate digestion + salivation
(4. ) Vasodilation
(5. ) Bronchoconstriction
(6. ) Contracts bladder

Question 18

What is a dermatome?

Answer 18

• area of skin supplied by single sensory nerve
• pain is felt where damage i.e. localised
• dermatome of abdominal wall starts at T5 (epigastrium), T10 (umbillicus), T12 (suprapubic).
• each dermatome starts at the back of the name vertebrae and runs downwards around the trunk

Question 19

What is referred pain?

Answer 19

(1. ) Initiating painful stimulus is felt elsewhere
(2. ) Does not follow dermatome distribution
(3. ) Pain is poorly localised due to ‘sharing of pathways’.

Question 20

Describe referred pain of abdominal organs

Answer 20

Poorly localised pain i.e. pain is felt elsewhere other than where the organ lies

(1. ) Foregut -> Epigastrium = Greater Splanchnic N (T5-9)
(2. ) Midgut -> Umbilical = Lesser Splanchnic N (T10-11)
(3. ) Hindgut -> Suprapubic = Least Splanchnic N (T12)

Question 21

Describe referred pain in appendicitis

Answer 21

Appendicitis usually causes pain that starts in the middle of your tummy before moving towards the lower right side.

(1. ) Early inflammation = umbilical region (midegut referred pain)
(2. ) Late inflammation = right iliac fossa (localised due to parietal peritoneum involvement)

Question 22

Describe referred pain in gallbladder

Answer 22

Pain may be felt in three places

(1. ) Right shoulder = diaphragm aggravated, phrenic nerve -> C3,4,5 [referred pain]
(2. ) Epigastrium = foregut structures, greater splanchnic nerve [referred pain]
(3. ) RUQ = aggravation of abdominal wall and peritoneum, sharp localised pain [dermatome]

Question 23

Describe referred pain in organs adjacent to diaphragm

Answer 23

(1. ) Gallbladder, liver = right shoulder

(2. ) Spleen = left shoulder

Question 24

Describe the route of the phrenic nerve + its motor and sensory innervations

Answer 24

Route

(1. ) Nerve roots at C3, 4, 5
(2. ) Phrenic nerve lies lateral to the vagus nerve
(3. ) Travel in PHront of trachea
(4. ) Passes over subclavian artery (left) + travels with SVC (right_
(5. ) Descends anterior to lungs hilum to diaphragm

Innervation

(1. ) Motor = diaphragm
(2. ) Sensory = central tendon of diaphragm, parietal pleura, pericardium, peritoneum

Question 25

Describe the branches and their supply of the vagus nerve

Answer 25

(1.) Leaves the jugular foramen and branches off into the following:

(2. ) Pharyngeal branch
- forms pharyngeal plexus with CN 9,10,11
- supplies pharyngeal constrictor muscles

(3. ) Superior laryngeal n (branches at the level of ECA and ICA bifurcation)
- Supplies vocal cords
- Internal branch (sensory) supplies larynx mucosa
- external branch supplies cricothyroid muscles

(4. ) Recurrent laryngeal n (branches under R.subclavian A. + Aortic arch)
- Nerve is important for breathing, swallowing, vocalisation
- Sensation to larynx below vocal cords
- Intrinsic muscles (except cricothyroid muscle)

Question 26

Describe the route of the left and right recurrent laryngeal nerves + which one is at more risk in thoracic disease

Answer 26

R.Recurrent Laryngeal Nerve
- Hooks under the right subclavian artery

L.Recurrent Laryngeal Nerve

• Hooks under the aortic arch
• Ascends up to the neck between trachea + oesophagus
• Passes under thyroid gland
• LRLN is at more risk of thoracic disease due to it descending into the thorax area more than the right

Question 27

Describe what would happen in a brainstem stroke in relation to CN9 and 10?

Answer 27

(1. ) CN9 damage = loss of sensation to back of pharynx
(2. ) CN10 damage = loss of sensation to inside of the larynx
(3. ) Effects sensory + motor control of swallowing
(4. ) Larynx opens during swallowing
(5. ) Fluid enters lungs -> infection

Question 28

Describe what you’d expect to see in unilateral and bilateral injury to recurrent laryngeal nerve and left lung tumour?

Answer 28

(1. ) Unilateral injury = hoarseness of voice due to movement of one vocal cord + shortage of breath
(2. ) Bilateral injury = breathing problems, snoring sounds, stridor (hi pitch wheezing), resp distress
(3. ) Left lung tumour = invade left recurrent laryngeal nerve -> cause paralysis of left VC -> hoarseness of voice