Week 1 Control Q&A copy 2utf Flashcards
What is the palpebral fissure?
Palpebral fissure (area between 2 eyelids
Which eyelid is bigger and more mobile?
upper
What are the canthus? How many?
commissures: medial and lateral
What is the lacrimal caruncle?
red bit
what is the lacrimal papilla?
the bit close to medial canthus with punctum (hole): upper and lower lids
how do tears enter the lacriaml sac?
via the punctum (holes) into superior and inferior lacrimal canals
what is the sclera
white bit of eye
where is the canal of schlemm
sclero-corneal jct (limbus)
what part of the eye is avascula
cornea
a small bit of sclera is usually visible above or below iris?
below
what is the fibrous tunic?
outer layer of eye: sclera and cornea; cts with dural covering of optic nerve
where is the optic nerve on the retina?
medial (more nasal than the fovea is)
what is the lamina cribosa? What does it do?
where sclera is perforated by emerging nerve fibres. is a mesh-like structure that allows optic nerve to pass through sclera. It helps to maintain pressure inside vs outside the eye.
wht is the vascular tunic?
choroid, ciliary body, iris
what does the choroid do?
absorb excess light, so not reflected within eye ball
what is the macula and fovea? Where?
The macula is important for high-acuity, central vision. More lateral than optic disc. No bipolar/ganglion cells here, so light gets directly to photoreceptors.
what is the blind spot
optic disc (optic nerve head)
other than the nerve, what comes out of the optic disc?
cenral retinal artery and vein, which branch in quadrants
what happens with central retinal artery occlusion
unilateral vision loss. Painless
how much refraction is done by cornea?
two thirds
what is the hyaloid fossa?
the depression of the vitreous where the lens sits of the vitreous body
what are zonule fibres?
make up suspensory ligament. Tension in the zonule fibres flattens the anterior surface of the lens. Contraction of the ciliary muscle increases the refractive power of the lens because it makes suspensory ligaments floppy and the lens more fat (greater optic power of lens).
anterior and posterior segments vs chambers of the eye?
segments are the large bits, separated by lens, and the anterior segment has anterior and posterior chambers, separated by the iris.
how does aqueous humor flow?
Aqueous humour flows from capillaries in ciliary process of cilliary body, out behind iris, through pupil, in front of iris, through trabecular meshwork, to the sinus venosus sclera (or canal of Schlemm).
which muscle does not attach to the tendinous ring? Where instead?
inferior oblique: nasal orbital bone (floor of)
what is the visual pathway?
Optic nerve ˆ chiasm ˆ optic tract ˆ LGN (thalamus) ˆ optic radiations ˆ primary visual cortex
which sulcus in occipital lobe contains visual cortex?
calcarine
where is the fovea represented in the occipital lobe
pole
what is hemianopia
loss of half visual field
What is the significance of PITS?
inferior visual field processed above calcarine fissure (parietal), superior visual field processed below calcarine fissure (temporal)
Why might a loss of sympathetic innervation cause mild drooping (ptosis) of the eyelid?
Ê loss of SYM innervation of the superior tarsal muscle eg HornerÕs
Why might more of the sclera be visible in anxiety states or hyperthyroidism?
a.ÊÊÊÊ Due to SYM innervation that raises the eyelid (anxiety) due to proptosis (eye popping forwards) in hyperthyroidism.
Would selective disease of the rods or cones be most likely to affect night vision?
rods
What is myopia and what does it have to do with the antero-posterior length of the eye?
a.ÊÊÊÊ Short sightedness. Due to long eyeball, so that rays of light converge before the lens.
What is the normal intraocular pressure and upper limit of normal?
10-21 mmHg
What anatomical changes occur in glaucoma (seen clinically, by fundoscopy)?
a.ÊÊÊÊ Increased cup:disc ratio (>0.4), paler disc due to atrophy of the neural tissue
What are the clinical features of a complete third nerve palsy?
a.ÊÊÊÊ Eye is down and out (due to actions of the trochlear and abducens, which are still working when the oculomotor nerve is not working). Also complete ptosis (70%).
In 3rd nerve palsy: is the puil dilated or constricted?
dilated
If a patient has hemianopia, is the lesion anterior or posterior to the optic chiasm?
a.ÊÊÊÊ After. If before, you would just lose an entire eye
Why might Goliath not have seen David and his slingshot? (Clue: growth hormone)
Acromegaly _ tumour of pituitary, so have bitemporal hemianopia.
Discuss the anatomical basis of the pupillary light and accommodation reflexes.
Light: afferent information from a single eye, to midbrain, efferent information returns to both eyes. Cross at edinger-westphal nucleus. PARA CN3. Accommodation/Near reflex: small pupil, accommodation of lens (bulge), convergence of eyes on nose. PARA.
What are the meninges?
coverings of barin: dura - arachnoid - pia
Speak about the attachments of the meninges
The dura is tightly adherent to the periosteum lining the skull. Hence, the dura is usually left behind when the brain is removed from the skull. The arachnoid is only loosely attached to the dura and remains with the brain. So usually the membranes you can see on the brain are the arachnoid and pia. Pia covers every gyrus and sulcus like a layer of Ôshrink wrappingÕ.
Where is CSF?
ventricles, central canal, sub-arachnoid space
what are the arachnoid trabeculae?
delicate strands connective tissue- extend between the arachnoid and pia. They suspend the brain like puppet strings as it ÔfloatsÕ in a layer of CSF.
Where are the major blood vessels located within the brain?
Blood vessels within the subarachnoid space. Arachnoid is transparent so you can see vessels in the subarachoid space. Leak or trauma (more likely aneurism than trauma) = haemorrhage.
what are the 3 major divisions of the brain?
cerebrum, cerebellum, brainstem
what is the crack between the 2 hemispheres?
longitudinal fissure with falx cerebri (dura).
how do the dura reduce movement of brain in skull?
falx cerebri: reduces side-to-side movement of brain. Tentorium cerebelli: limits superior-inferior movements of the brain within the skull.
what is the corpus callosum
a major bundle of white matter linking the two hemispheres.
what is the crack between Cb and cerebrum?
transverse fissure
what is the tentorium cerebelli?
dural fold - forms a roof over the posterior cranial fossa
what is the hole in the dura for the brain stem
tentorial hiatus
in which direction is there no dura to stop brain movement?
anterior-posterior
where is the vermis?
midline of cerebellum; 2 Cb hemis on eitehr side
what is the arbor vitae?
inside the Cb: tree-like, branching pattern of the white matter
does the cerebellum have gyri and sulci?
Cb has folia and fissures (cf. gyri and sulci in the cerebrum), which oriented transversely.
where are the tonsils? Clinical signifiance?
posterior Cb. Lobules of Cb. presses on the medulla during high intracranial pressure and causes death (presses on respiratory and cardiac centres of medulla).
which embryological structure do the brain/spinal cord develop from?
neural tube
what is CSF produced by
choroid plexus in each ventricle
how does CSF flow?
2x lateral (with frontal, occipital and temporal horns) separated by septum pellucidum ˆ interventricular foramen (Y shaped from front) ˆ 3rd ventricle (2 thalamus connected through hole) ˆ cerebral aqueduct ˆ 4th ventricle (between brain stem and Cb)ˆ 2x medial foramen of majendie, 2x lateral foramen ˆ Sub-arachnoid space ˆ arachnoid villi/granulations to reabsorb into dural sinuses and back into bloodstream
In which view do the ventricles look like a Y shape?
coronal
which CNs are PARA
3,7,9,10
what is ptosis vs proptosis?
Ptosis (droopy eyelid) vs proptosis (pop out eye)
what are the internal and external parts of the oculomotor nerve specialised for?
internal: motor; external: PARA. Suregery/ICP damages outer first. Ischemia damages internal first
Why do ruptured brain aneurysms cause bleeding into the subarachnoid space?
a.ÊÊÊÊ Because vessels located here. Not usually trauma of these vessels (because protected a bit), so usually haemorrhage due to aneurysm (ballooning of vessel wall, which is weak and can rupture
What happens to the subarachnoid space in places where the skull bone is at a distance from the surface of the brain (e.g. between medulla and cerebellum)?
Lots CSF there
Why is this useful if a CSF sample is needed but a lumbar puncture cannot be done?
a.ÊÊÊÊ Can sample CSF here
How might the arrangement of the dural partitions make the anterior and posterior poles of the brain more susceptible to damage in traumatic head injury?
a.ÊÊÊÊ Anterior-posterior movement of brain within skull
A stroke in the left cerebral hemisphere might cause weakness on which side of the body?
right
A stroke in the left cerebellar hemisphere might cause ataxia (inco-ordination) on which side of the body?
left
In advanced raised intracranial pressure the tonsils may herniate through the foramen magnum and cause death by compressing which part of the brain stem?
medulla (resp centre)
What happens to the ventricular system if there is a focal obstruction?
hydrocephalus
Symptoms of hydrocephalus and how to treat?
a.ÊÊÊÊ Child: enlarged head, bulging fontanelle; Adult: headache, vomit, nausea, seizure; Shunt to bypass obstruction and allow flow of CSF
what part of the brain stem has pyramids?
medulla
what part of the brain stem has olives? Where are olives located?
medulla. Olives = oval swellings just above and lateral to the pyramids on each side (upper medulla).
what is the meaning of the pons?
bridge; bridges two Cb hemis
what is the importance of the ventral median fissure of the medulla?
contains basilar artery
Where are the peduncles of the midbrain?
Above the pons = the two cerebral peduncles of the midbrain, which resemble two Roman pillars, separated by a gap. The gap is the interpeduncular fossa (Latin: ditch
in which fossa is the oculomotor nerve? Where does it emerge
interpeduncular fossa. Emerges between the cerebral peduncles.
what is the tectum?
tectum is the posterior area of the midbrain (Latin: tectum, roof). There are four elevations (2x superior and inferior colliculi) of the tectum.
what is the importance of the superior and inferior collicular?
visual (superior) and auditory (inferior) reflexes. Eyes above ears, so superior is about vision and inferior about audition. The superior colliculus is not part of the main visual pathway, but the inferior colliculus is part of the main auditory pathway.