hns Flashcards
skull anterior view
mandible maxilla zygoma frontal nasal bone
lateral voew
frontal pariental occipital temparol sphenoid bone
what is the weak spot
pterion
inferior
occipital
temparol
mandilble
posterior
parietal
occipital
what is the suture between them
lamboid
adult superior
coronal suture
saggital sutire
lamboid suture
superior of neonatal
unfused bone- anteterior fonatanelle
function
not fused so flexible incase bc is tight
cranial base
anterior cranial fossa - frontal lobe
middle cf- temparol lobe
posterior cf- cerebullum/brain step
whats formaina
holes in skull
optic canal
optic nerve pass through
on the side of teh skull
superior orbital fissure
control extrisic mussle of eye
foramenal rotundum
maxilalry divion of trigemial nerve passes out of
foramen overly
madibullar divission of tgmn
cranial nerve examination
functionality of cranial nerve
what are cranial nerve
pairs of nerves taht connect brain to different part of the
on trunk e.g. nose eye mouth
how many are there
12
what is the order based on
anatomical location
front to back
which nerves are not originaated from brain stem
1 2
olfactury and optic nerve
where are the nuclie of cn 3 and 4
mid brain
where are the nuclie of cn 5 6 7 8
within pons
where are the nuclie of cn 9 to 12
medulla oblongata
what to do before examination
1) introduce you and position
2) explain purpose
3) state patient exposure and position
4) wash hands
olfactory nerve CN1 function
specialised sensory nerve transmit info relating to smell
anatomical course
where are the olfactory receptors
nasal epithelium, their axons forming the olfactory nerves
where do the nerves enter from
which enter the intra-cranial cavity by passing through the cribriform plate in the ethmoid bone.
what part of teh brain is smell deboted to
temparol lobe
how does it get there from the ethmoid bone
primary olfactory cortex in the temporal lobe
Test
1) ask if they have noticed changes in taste or smell
2) test smell of each nostril with strong smell, such as mint or vanilla. The patient’s eyes should be shut when carrying out the testing.
what is loss in smell called
anosmia
Temporary anosmia can be caused by
blocked nose from a common cold and other upper respiratory tract infections.
Permanent anosmia has many causes such as
severe head injuries, or tumours that run along the olfactory nerves intracranial path. Also progressive anosmia may occur in neuro degenerative diseases, such as Alzheimer’s disease and some other brain disorders (such as multiple sclerosis).
Optic Nerve (CN II) tests for
Testing Pupillary Light Reflex
function
pupillary light reflex is a reflex that controls the size of the pupils in response to changes in the strength of light that lands on the retina of the eye
how many afferent and efferent limbs
Each pupillary light reflex has an afferent limb (optic nerve) and two efferent limbs (parasympathetic fibres along the oculomotor nerves).
Anatomical course
Light travels through the pupil of the eye and is turned into impulses by rods and cones of the photo-receptor layer of the retina. impulses are the transmitted from the retina through the intracranial cavity to the brain by the optic nerve (CN II) through the optic canal. These impulses then pass through the visual pathway within the brain to the primary visual cortex where we appreciate the vision.
pupillary light reflex
takes a different and shorter path than the whole visual pathway, as the reflex does not require our appreciation of the light, it works independent of our thought and command.
pupillary light reflex pathway
he optic nerve is the afferent limb of the pupillary light reflex, sending the sensory impulses via mid brain nuclei to trigger motor impulses through parasympathetic axons running along the oculomotor nerves (efferent limb) to innervate the pupillary sphincter muscles in the eye leading to pupillary constriction (miosis) of both the ipsilateral pupil (same side) and the contralateral pupil (other side).
direct pupillary reflex but also a consensual pupillary light reflex.
Testing
Ask the patient to look at a distant target
Inspect the pupils for size, shape and colour and any presence of ptosis (drooping of eye lid)
Shine one eye with a penlight - observe for the pupillary constriction in the same eye (ipsilateral)
Take away the light for a few seconds
Shine the penlight in the same eye - observe the pupillary constriction in the other eye (consensual)
clinical revelance
Direct and consensual pupillary light reflexes are tested to assess the integrity the function of both optic and oculomotor nerves.
what is abnormal caused by
An Abnormal pupillary reflex can be caused by optic nerve damage, oculomotor nerve damage, brainstem injury, and depressant drugs.
Anisocoria
is a condition characterised by an unequal size of the eyes’ pupils
Remember to inspect the size and shape of the pupils before testing the direct and consensual light reflexes with a pen torch.
