organisation of brainstem and cranial nerves

Question 1

define brainstem and divisions and location

Answer 1

part of CNS between cerebrum and spinal cord -in posterior cranial fossa

Question 2

posterior part of brainstem DIAGRAM

Answer 2

pineal gland in midbrain important for circadium rhythm superior coliiculus for coordinate neck and eye movement, inferior for auditory reflex only one nerve emerges from posterior part- CN 4 (trocheal nerve- superior oblique) pons has 4th ventricles, and medulla has dorsal columns

Question 3

anterior part of brainstem DIAGRAM- all nerves, function, and talk about cerebral pundles

Answer 3

has nearly all cranial nerves- CN1 is olfactory nerves , CN2 is optic nerve where optic chiasm is just below is pituitary stalk/infundibulum, and then mamillary body at base of hypothalamus CN3 is last nerve in midbrain (ocular muscles + pupil constriction) cerebral peduncle is corticospinal tract only the trigeminal nerve is at pons (sensory for head and neck+ motor for mastication muscles), at pontomedullary junction is next 3 (6,7,8) nerves- abducens (lateral eye movement), facial (muscles of facial expression+ sensory for taste in tongue+ subman/subling glands+ lacrimation) and vestibulocochlear (balance and hearing) nerve in medulla is glossopharyngeal (swallowing, taste/sensation in tongue+ parotid gland), vagus ( swallowing, cough, laryngeal muscles+ viscera) and accessory nerve (SCM+ traps), and hypoglossal nerve (nearly all muscles of tongue)

pyramids- cerebral peduncle is tract, which is hidden in pons, and emerges out as pyramids pyramidal decussation- where tract crosses over, hence right side of cortex controls left side

Question 4

functional classification in head (same as rest of body)+ nerves

Answer 4

general somatic afferent (sensory from skin/mucous membranes) general visceral afferent (sensory from GI, heart etc) general somatic efferent (eye and tongue muscles) general visceral efferent (preganglionic PNS)

GSA- 5

GSE- oculomotor, trochlear, abducens, hypoglossal

GVE- salivatory nuclei

Question 5

functional classification in head (different from rest of body)+ nerves

Answer 5

special somatic afferent (vision and hearing) special visceral afferent (smell and taste) special visceral event (muscles for chewing, face, swallowing, turning head)

SSA- 8

SVE- nucleus solitarus

Question 6

location of nerves on efferent side DIAGRAM

Answer 6

midbrain has oculomotor and trochlear nerve, and edinger westphal nucleus (PNS innervation of eye) pons has trigeminal, abducens and facial nerves (nuclei are in pons) salivatory nuclei are in pons and medulla medulla has vagus, and hypoglossal nerve, and nucleus ambigus cervical spinal cord has spinal cord

Question 7

location of nerves on afferent side DIAGRAM

Answer 7

nucleus solitarus is important for sensing smell/taste trigeminal nuclei (general somatic afferent) is across all level special somatic afferent is nuclei of vestibulocochlear hence nuclei tend to be at levels from where nerves emerge

Question 8

brainstem at level of midbrain DIAGRAM: what is between the mickey mice, what membrane, and what nerve

Answer 8

should have inverted mickey mouse shapes, with ears being cerebral peduncle cerebral aqueduct ONLY found at midbrain level also a dark substantia nigra present, and inferior colliculus

between mickey mouses is interpenducular fossa- membrane covers this area: trochlear nerve is here

Question 9

brainstem at level of Pons DIAGRAM

Answer 9

transverse fibres and 4th ventricle (mostly at pons) present here

Question 10

brainstem at level of medulla DIAGRAM

Answer 10

pyramids and wavy shape of the inferior olivary nucleus

Question 11

brainstem at level of lower medulla DIAGRAM

Answer 11

should see dorsal column, start of central canal of spinal cord, and pyramidal decussation (fibres crossing over)

Question 12

what is lateral medullary syndrome and symptoms

Answer 12

thrombosis (clot) of vertebral artery or PICA causes vertigo (unstable), ataxia (movement problems), loss of pain/temp in face and limbs, horners syndrome (loss SNS control eg no sweating in eye) and swallowing issues

Question 13

brain of lateral medullary syndrome DIAGRAM

Answer 13

vestibular nuclei- vertigo inferior cerebella penduncle (fibres coming up from cord)- ataxia trigeminal- lost of pain/temp SNS tract- loss of SNS innervation to eye nucleus ambigus- swallowing problems spinothalamic tract- contralateral (one side of body) loss of pain/temp

Question 14

function of brainstem

Answer 14

cardiorespiratory centre

cranial nerves

NT production (dopa from nigra, NA from LOCUS COERULEUS)

integrates visual, auditory and motor systems

Question 15

bells palsy vs stroke

Answer 15

bells palsy is lower motor neurone disease- whole of half of face gone: because only one lower motor neurone

stroke is upper motor neurone disease- half of half face is affected: there are 2 upper motor neurones, thus other upper motor neurone can compensate

Question 16

aneurysm to PCA- what nerve affected andresults

Answer 16

when aneurysm of posterior communicating, oculomotor- leads to dilated pupil

Question 17

where is loecus coreulus

Answer 17

part of pons

Question 18

what supplies thalamus

Answer 18

PCA

Question 19

if hypthalamus damaged, which hormone affected first

Answer 19

vasopressin

Question 20

what doesnt occur with more pain stimulation

Answer 20

AMPLITUDE of receptor activation, as A.P’s are all the same

Question 21

internuclear opthalmoplegia- what part affected, and what kind of patients- what happens

Answer 21

medial leminiscus fasciculus- affects MS patient: one eye moves, one doesn’t

Question 22

DIAGRAM 5 vesicles

Answer 22

pons is in 4th vesicle

Question 23

what part of brain is affected in hungtingtons and what NT affected

Answer 23

caudate nucleus due to less GABA activity

Question 24

where is vermis and paravermis

Answer 24

in spinocerebellum

Question 25

what contains commisural fibres

Answer 25

not just corpus callosum, or pyramidal decussation and optic chiasm

Question 26

what occurs in a thalamic stroke

Answer 26

burning pain is one side of body- also leads to visual field loss

Question 27

where does lateral inhibition of neural units occur

Answer 27

dorsal horn