organisation of the brainstem and the cranial nerves

Question 1

define the brainstem

Answer 1

the part of the CNS, exculsive of the cerebellum, that lies between the cerebrum and the spinal cord

Question 2

major divisions of the brainstem *

Answer 2

medulla oblongata
pons
midbrain

Question 3

where does the brainstem sit *

Answer 3

in the posterior cranial fossa

Question 4

list and describe the features at visible from the posterior of the brainstem *

Answer 4

pineal gland - not bilateral, in control of circadian rhythms (light/dark) trained by eyes, control day night release of cortisol

superior colliculus - cause coordinated neck and eye movements, bump on back of brainstem

inferior colliculus - basic survival function - auditory reflex, look towards sound

dorsal columns - in medulla, touch and proprioception - damage cause loss - medial info from leg (gracile), lateral from upper half (cuneate)

4th ventricle - floor of 4th ventricle is in the pons, diamond space

trochlear nerve - CN4, small, supply superior oblique muscle of the eye

Question 5

in imaging what is the roof of the midbrain referred to as

Answer 5

the tectum

Question 6

which nerves don’t arise from in the brainstem *

Answer 6

CN1 and CN 2

Question 7

features that you can see from the anterior of the brainstem *

Answer 7

optic chiasm 
pituitary stalk
mammillary body 
cerebral peduncle 
oculomotor nerve 
trigeminal nerve 
abducens, fascial and vestibulocochlear nerves
pyramids
glossopharyngeal, vagus and accessory nerves 
hypoglossal nerves 
pyramidal decussation

Question 8

describe the location of CN 1 - olfactory nerve *

Answer 8

top of nose

project through skull through Cribiform plate in ethmoid bone - to the olfactory bulb

Question 9

describe path of the optic nerve CN2*

Answer 9

half nerves come from retina, cross over, to back of brain - occipital lobe

Question 10

what is the optic chiasm *

Answer 10

where the cranial nerves cross over

Question 11

where is the pituitary stalk in the brainstem *

Answer 11

in the midline
directly behind the optic chiasm
also called the infundibulum

Question 12

location of the mamillary body *

Answer 12

bilaterally

base of the hypothalamus

Question 13

describe the oculomotor nerve *

Answer 13

CN3
emerge at midline level, just below mamillary body
control eye movement

Question 14

describe the cerebral peduncle *

Answer 14

they are motor fibres - come down from the motor cortex and into the spinal cord - forms part of the cortical spinal tract

Question 15

describe the trigeminal nerve *

Answer 15

only cranial nerve that emerges only from the pons
sensory nerve of the head and neck - 3 divisions - small root next to larger root -some motor functions eg chewing
nuclei is all the way through the brainstem
general somatic afferent

Question 16

describe the abducens, facial and vestibulocochlear nerve *

Answer 16

they emerge at the pontomedullary junction
medially to laterally
abducens - lateral rectus muscle - move eye laterally
fascial - fascial expression
vestibulocochlear - involved in balance and hearing - goes into the inner ear where there is the cochlear and vestibule - special somatic afferent

Question 17

why is the pons called the pons

Answer 17

normally info is all transmitted up amnd down in brain - the pons goes across like a bridge between 2 halves of cerebellum

Question 18

what is bell’s palsy

Answer 18

musculature has lost innervation from the facial nerve usually post infection

Question 19

where do the glossopharyngeal, vagus and accessory nerve originate from and their functions *

Answer 19

the medulla
glossopharyngeal - tongue/pharynx - swallowing and breaking up food
vagus - PNS to whole body
accessory - supply muscle of shoulder and sternocleidomastoid muscle

Question 20

where does the hypoglossal nerve come from and what does it do *

Answer 20

more medially than CN 9, 10, 11 in medulla

supply all muscle under tongue

Question 21

describe the pyramids *

Answer 21

corticospinal tract in medulla

if there is a motor function to do with the corticospinal tract it is called pyramidal symptoms

Question 22

what and where is the pyramidal decussation*

Answer 22

at the base of the medulla

where 95% of the motor fibres cross over - meaning motor function is contralateral

Question 23

why is there functional classification of the CN

Answer 23

because they have some specific functions different to other nerves

Question 24

describe general somatic afferent CN *

Answer 24

this type of nerve is all over body, they are related to the body, they arrive at the CNS - for CN they receive sensation from the skin and mucous membranes in mouth

Question 25

describe general visceral afferent CN *

Answer 25

they receive innervation from the GI, heart, vessels and lungs going to the brain

Question 26

describe general somatic efferent CN *

Answer 26

muscles for eye and tongue movement

Question 27

describe general visceral efferent *

Answer 27

preganglionic PNS - vagus - modulate gut movements

Question 28

describe special somatic afferent *

Answer 28

doesn't apply to whole body | vision, hearing, equilibrium

Question 29

describe special visceral afferent *

Answer 29

smell and taste

Question 30

describe special visceral efferent *

Answer 30

muscles involved in chewing facial expression, swallowing, vocal sounds and turning head - CN11

Question 31

describe the sulcus limitans *

Answer 31

differentiates between the ventral motor and the dorsal sensory

Question 32

rombencephalon *

Answer 32

hind brain

Question 33

summarise where the motor and sensory nuclei are in the brainstem *

Answer 33

motor - medial sensory - lateral [image]

Question 34

where are the different classifications of motor CN nuclei in the brainstem from medial to lateral *

Answer 34

GSE SVE GVE

Question 35

where are the different classifications of sensory CN nuclei in brainstem from medial to lateral

Answer 35

GVA/SVA GSA SSA

Question 36

how is the midbrain recognisable on a transverse image*

Answer 36

general shape - micky mouse - ears are the cerebral peduncles cerebral aqueduct - only in the midbrain substantia nigra - black substance, neuromelanin in dopinergic cells project to basal ganglia, if not present it is responsible for the motor symptoms of Parkinsons inferior colliculus - the roof of the midbrain [image]

Question 37

how is the pons recognisable on a transverse image *

Answer 37

4th ventricle middle cerebral peduncle - where the fibres join to the cerebellum transverse fibres

Question 38

how is the medulla recognisable on a transverse image *

Answer 38

4th ventricle inferior olivary nucleus - high in medulla pyramids

Question 39

how is the LOWER medulla recognisable in a transverse image *

Answer 39

dorsal columns central canal for the spinal cord pyramidal decussation

Question 40

describe lateral medullary syndrome

Answer 40

thrombosis of vertebral artery/posterior inferior cerebella artery - blood clot stop flow into the area vertigo - because vestibular nerve is affected therefore lose balance perception loss of balance because of inferior cerebral peduncle - fibre from spinal cord ipsilateral cerebral ataxia - unsteady on feet hoarseness/difficulty in swallowing - loss innervation to throat because N ambiguous affected ipsilateral loss of pain/thermal sense - face because of spinal nuclei of the peduncle contralateral loss of pain/thermal sense - spinothalamic tract affected horner's syndrome - loss of SNS innervation because sympathetic tract is affected - pinpoint pupil, reduced sweating

Question 41

where are the nuclei for the oculomotor CN *

Answer 41

medial midbrain motor GSE

Question 42

where are the nuclei for the trochlear CN *

Answer 42

medial midbrain lower than oculomotor GSE

Question 43

where is the nuclei for the trigeminal motor nerve *

Answer 43

pons | SVE

Question 44

where is the nuclei for the facial nerve *

Answer 44

pons lower than trigeminal m SVE

Question 45

where is the nuclei for the abducens *

Answer 45

completely in pons | GSE

Question 46

where is the nuclei for the salivatory *

Answer 46

pons and medulla | GVE

Question 47

what makes up the salivatory nuclei *

Answer 47

glossopharyngeal and motor nerve cell bodies

Question 48

where is the nuclei for the vagus nerve *

Answer 48

medulla | GVE

Question 49

where is the ambiguus nuceli *

Answer 49

medulla | SVE

Question 50

what is the ambiguus nuclei *

Answer 50

innervate muscle of pharynx and output of many cranial nerves

Question 51

where is the nuclei for the hypoglossal nerve *

Answer 51

medulla | GSE

Question 52

where is the nuclei for the accessory nerve *

Answer 52

cervical spinal cord | SVE

Question 53

where is the trigeminal nucleus *

Answer 53

GSA | all the way down brain stem

Question 54

where is the vestibulocochlear nucleus *

Answer 54

pons and medulla | SSA

Question 55

where is the solitaries nucleus *

Answer 55

for taste pons and medulla GVA/SVA

Question 56

what is the Edinger Westphal nucleus *

Answer 56

nuclei for PNS innervation of the eye in midbrain GVE