Neuroanatomy Flashcards
the midbrain
- mesencephalon
- divided into tectum and the cerebral peduncle
- tectum
- superior and inferior colliculi
- cerebral peduncle
- tegmentum dorsally
- crus cerebri ventrally
- tegmentum and crura are divided by the substantia negra
the forebrain
- prosencephalon
- composed of
- diencephalon
- thalamus
- hypothalamus
- telancephalon
- cerebral cortex
- basal ganglia
- diencephalon
main cortices found in the frontal lobe
- primary motor cortex
- prefrontal cortex
main things found in the temporal lobes
- primary auditory cortex
- wernicke’s
- hippocampus
- amygdala
main things found in the perietal lobes
- primary somatosensory cortex
main things found in the occipital lobe
- primary visual cortex
- visual association cortex
which sulcus seperates the temporal lobe from the parietal and frontal lobes?
the lateral sulcus
what is the insula
the floor of the lateral sulcus
opercula overly the insula and are like the ‘lips’ that form the channel into the insula
two layers of dura mater
- endosteal
- lines skull
- meningeal
- envelopes entire CNS
what is the dura lying in the longitudinal fissure called?
the falx cerebri
tentorium cerebelli
dura forming thick roof to the cerebellum
contains the straight sinus which attaches to the falx cerebri
transverse sinuses
sinuses that run along the attachment of the tentorium cerebelli to the occipital bone
the diaphragm sellae
this is a small dural fold that makes a roof for the pituitary fossa (the sella turcica)
falx cerebelli
sickle shaped reflection of dura seperating the lobes of the cerebellum
sigmoid sinus
curly sinues that drains the blood from the transverse sinuses into the jugular
summarise sinuses
cisterna ambiens
this is a system of cisterns that encircles the midbrain
where are the pontine cistern, the cerebellomedullary cistern and the interpeduncular cistern
extradural hemmorhage
- between skull and dura
- strips skull of dura and compresses brain
- hemorrhages from meningeal arteries
subdural hemorrhage
- between the dura and the arachnoid
- crescent shaped CT
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subarachnoid hemorrhage
- blood between the arachnoid and the pia
- bood fills sulci locally to injury
- head injury or rupture of berry aneurism
- thunderclap headache
- high mortality rate
intracerebral hemorrhage
- rupture of small vessels/microaneurisms
- classical location is in the internal capsule
- often caused by high blood pressure
amaurosis fugax
- temporary loss of vision in one eye
- carotid plaque breaks off and occludes central retinal artery
- this is a warning of an impending stroke
3 contributing elements of the blood brain barrier
- the endothelial cells of the capillaries
- the basement membrane of the pia
- the astrocytic end feet
what layer are the arteries and veins on the surface of the brain in?
- within trabeculae within the subarachnoid space
how much of brain blood supply is supplied by internal carotids and the vertebral arteries
- internal carotids supply 80% of total blood supply
- these supply the anterior and middle parts of the brain
- the vertebral arteries supply 20% of total blood supply
- they supply the posterior cerebrum and the cerebellum
draw the circle of willis
what is the anterior circulation of the brain
- it’s the circulation supplied by:
- anterior cerebral artery
- middle cerebral artery
what is the posterior circulation of the brain
- it’s the circulation supplied by:
- AICA
- PICA
- Basilar artery
- Pontine arteries
- Superior cerebellar artery
- Posterior cerebral artery
describe the blood supply territories of the brain
how does the internal carotid enter the skull
- it doesn’t enter the foramen lacerum itself
- it enters through the carotid foramen and then passes through the carotid canal in the petrous temporal bone
- the carotid canal ends deep to the foramen lacerum
- therefore it looks like it comes out the foramen lacerum in a dead skull
the vertebral arteries
- vertebral arteris arise from the first part of the subclavian
- enter the skull through the foramen magnum
external cerebral veins drain where
into the dural venous sinuses
what is the great cerebral vein and where does it drain into
- great cerebral vein of galen
- drains deep structures of the brain into the straight sinus
what can be found in the cavernous sinus
- 5 cranial nerves
- oculomotor
- abducens
- trochlear
- opthalmic (V1)
- maxillary (V2)
- the internal carotid can also be found in it
where is CSF produced
- in the choroid plexus in the ventricles
- the largest aggregation of choroid plexus is in the lateral ventricles
- it passes out through the foramen of magendie and luschka into the sub arachnoid space (cerebellomedullary cistern)
- then it can spread in the subarachnoid space and bathe the rest of the brain
which cells line the ventricles
- ependymal cells
- these constitute the CSF brain barrier
Foramina of the skull and which cranial nerves leave through them
parasympathetic fibres to the orbit
- PS fibres from CN III
- Originate from the Edinger-Westphal nucleus in the midbrain
- They travel to the cilliary ganglion
- Cilliary ganglion has fibres that innervate:
- ciliary muscle (acomodation)
- sphincter pupillae
- PS fibres from CN VII leave the middle ear and travel to the orbit where they innervate the lacrimal duct
sympathetic fibres to the orbit
- arise from T1
- moves through stellate ganglion of sympathetic trunk
- this is the most superior ganglion in the sympathetic trunk and in most people it is two fused together
- these fibres supply the dilator pupillae muscle
what are the cerebral peduncles?
part of the midbrain that link the remainder of the brainstem to the thalami and thereby, the cerebrum. They are the most anterior structure in the midbrain and contain the large ascending and descending tracts that run to and from the cerebrum
Medullary pyramids
- elongated swellings marking the position of underlying fibres that pass from the cerebrum to the cord
- THIS IS THE CORTICOSPINAL TRACT
medullary ventrolateral sulcus
very slight sulcus that is continuous with the same sulcus in the spinal cord
it’s on the lateral border of the pyramid on each side
medullary olive
- lateral to the ventrolateral sulcus
- underneith is the inferior olivary nucleus
- this has something to do with movement
cerebellar peduncles
- Inferior: to the medulla
- middle: to the pons
- superior: to the midbrain
midbrain auditory processing
inferior colliculi >inferior brachium > medial geniculate nucleus
- inferior colliculi on posterior aspect of midbrain (tectum)
- inferior brachium is a nerve pathway
- medial geniculate nucleus is in the thalamus
- so not midbrain
visual processing in the midbrain
superior colliculi > superior brachium > lateral geniculate nuclei
- superior colliculi on posterior of the midbrain (tectum)
- superior brachium is a nerve pathway
- lateral geniculat nuclei are in the thalamus
- so not midbrain
what is the pinneal gland
this is a small gland just above the colliculi
it produces melatonin
where do the cranial nerves come off the brainstem?
what are the external folds of the cerebellum called?
these are folia
how is the cerebellum divided
- two hemispheres joined by a vermis
- three lobes
- Anterior lobe
- Posterior lobe
- Folliculo nodular lobe
- very difficult to see but basically it’s behind the brainstem, inferior to the peduncles
- it’s basically two structures called the flocculus and the nodule.
- this lobe is concerned with vestibular info
- Two important fissures
- Primary fissure is the big one
- horizontal fissure is the slightly less obvious one in the posterior lobe
draw out the diagram of the connections of the cerebellum
the rhomboid fossa
- the flood of the 4th ventricle
- little diamond shaped depression in the back of the pons and medulla
- the gracile and cuneate tubercles (dorsal) limit it posteriorly (below it)
- has a median sulcus
- medullary striae splits it into a top and bottom half
- facial colliculus is a rounded swelling in the fossa
- this is just above the striae
medullary striae
- stripe across the rhomboid fossa
- they’re fibres that pass from the pons to the cerebellum
- these fibres divide the rhomboid fossa into a rostral pontine half and a caudal medullary half
what’s in the caudal part of the rhomboid fossa?
- hypoglossal trigone
- medially
- Vagal trigone
- intermediately
- Vestibular trigone
- laterally
- trigone basically means a rectangular layer that overlies the nucleus
obex
most inferior point of the rhomboid fossa
area postrema
- chemoreceptive trigger for the emetic response
- there’s no bb barrier here or it’s weaker or something
- it’s rostrolateral to the obex
third ventricle
- lies between the two halves of the thalamus
- it’s just above the chiasma
- has an IV foramen (of munro) that is the only communication between the lateral ventricles and the rest of the ventricular system
paracentral lobule
- medial U shaped gyrus
- contains representations of the lower limb in the motor and somatosensory cortices
cingulate gyrus
runs above the corpus callosum
cingulate sulcus seperates this from the rest of the hemisphere
parieto-occipital sulcus
forms a Y with the calcarine sulcus
the primary visual cortex is in the walls of the calcarine sulcus
difference in cross section of primary motor cortex and primary somatosensory cortex
- PMC grey matter is twice as thick as that of the PSC
- more cells
Parts of the corpus callossum
- Genu - anterior curved end
- Rostrum - leads down from genu
- Body - central main curve
- Splenium - rounded posterior
remember the corpus calossum spoons the fornix which spoons the thalamus
the fornix
- bundle of white matter below the corpus calossum body
- it connects the hippocampus to the diencephalon
- columns:
- anterior AND posterior extensions of the fornix
- anteriorly they extend vertically downwards to the mamillary bodies
- commissure:
- connects the two fornices/hippocampi
anterior commissure
- just infront of the anterior columns of the fornix
- connects the temporal lobes and olfactory structures of both sides
septum pellucidum
- thin sheets of glia that seperate the anterior horns of the left and right lateral ventricles
- it is between the corpus calossum and the fornix
three main types of fibres
- Association fibres
- connecting two cortical regions of the same hemisphere
- Commissural fibres
- connecting regions of different hemispheres
- Projection fibres
- connecting the cortex with sub-cortical structures
to which hemisphere of the brain is language usually confined
it’s confined to the dominant hemisphere which is usually the left
what does the limbic system include?
- cingulaete gyrus
- hippocampal formation
- parahippocampal gyrus
- anterior perforated substance
- septal nuclei
- uncus
- amygdala
what is the parahippocampal gyrus
- it is in continuity with the cingulate gyrus
- it is part of the temporal lobe
uncus
a hook shaped region at the anterior portion of the temporal lobe
cingulum
bundle of association fibres that run in the cingulate gyrus
fimbria
connection from the hippocampus to the fornix
ventricles
label this coronal section of brain
include white matter tracts between the bits of basal ganglia
name the two white matter tracts:
- between the internal and external globus pallidus
- between the external globus pallidus and the putamen
- the medial medullary lamina
- the lateral medullary lamina
how many cervical, thoracic, lumbar and sacral vertebrae are there?
- 7 cervical
- 12 thoracic
- 5 lumbar
- 5 fused sacral
- coccyx is formed by 4 rudimentary vertebrae
label this lumbar vertebrae
label this lumbar vertebrae (2)
differences between cervical, thoracic and lumbar vertebrae
intervertebral disks
- nucleus pulposus surrounded by an annulus fibrosus
- nucleus pulposus = gel
- proteoglycan
- collagen gel
- Annulus fibrosus
- concentric layers of collagen
- herneation = annulus fibrosus no longer contains nucleus pulposus
- herneation of the disc can narrow the intervertebral foramen and cause compression of the nerve root
label this diagram
conus medullaris
this is where the spinal cord ends and becomes the cauda aquina
it is usually around the level of L1/L2
spinal cord segments and how many there are in each section (cervical, thoracic etc)
- a spinal cord segment is an area of spinal cord from which a pair of spinal nerves is given off
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
describe how spinal nerves leave the spinal cord
- ventral and dorsal roots join in the intervertebral foramen to form the spinal nerve
- immediately when the spinal nerve emerges from the foramen it splits into the anterior and posterior rami
- anterior and posterior rami each contain both motor and sensory fibres
- length of nerve roots increases as you descend the spinal cord
filum terminale
delicate strand of fibrous tissue, about 20 cm in length, proceeding downward from the apex of the conus medullaris. It is one of the modifications of pia mater
