Neuroanatomy 1 Flashcards
What is the term for back?
dorsal
What is the term for front?
ventral
What is the difference between cranial and rostral?
Cranial is towards the head, rostral is towards the beak/nose - rostral is used more in neuroanatomy
What term is used for ‘towards the tail’?
caudal
What are the 3 embryonic divisions of the brain?
Forebrain (prosencephalon)
Midbrain (mesencephalon)
Hindbrain (rhombencephalon)
What is the forebrain divided into? (embryologically)
Cerebrum (telencephalon)
diencephalon
What is the hindbrain divided into? (embryologically)
Pons and cerebellum (metencephalon)
Medulla oblongata (myelencephalon)
What is white matter made up of?
Nerve cell axons
Myelin sheaths cause white apperance
What is grey matter made up of?
Mostly nerve cell bodies
Also other nervous system cell or unmyelinated axons
Where is grey matter found in the brain?
Outer surface of the cerebrum mostly, some spots found deeper which are large groups of nuclei
Where is grey matter found in the spinal cord?
H-shape in the center
What is the cortex?
Outer part of the cerebrum and cerebellum - mainly grey matter
What is a nucleus? in neuroanatomy
Groups of functionally similar or anatomically related cells are collectively called a nucleus
What is a tract?
A pathway of nerve fibres
can include a single group with no synapses from start to finish or may be multiple nerve fibres that synapse along the tract
What is a fossa?
Indentation or shallow depression
What is a foramen?
Opening, hole or passage
What is the longitudinal fissure?
separates left and right hemispheres
large groove
What is the vermis?
Joins/separates two halves of cerebellum
What parts of the brain make up the brain stem?
Midbrain, pons and medulla
What is in the diencephalon?
mostly thalamus and hypothalamus
How can the brain be broadly separated into 4 parts?
Cerebrum
Cerebellum
Diencephalon
Brainstem
What is the cerebrum?
Largest part of the brain
Has a left and right hemisphere
What is the brainstem?
It connects the cerebrum and diencephalon and spinal cord
Where is the primary auditory complex?
temporal lobe
processes auditory information
What is in the temporal lobe?
Contains primary auditory complex and hippocampus(memory formation)
Amygdala
Wernicke’s area
Where is the hippocampus? What is it involved in?
In the temporal lobe, medial and inferiorly
Involved in the formation of memories
Where is the primary somatosensory cortex? What is it involved in?
In the parietal lobe
Involved in processing sensory information
Where is the primary visual cortex?
Occipital lobe
Processes visual information
What is the broad function of the cerebellum?
Helps maintain posture and balance
Corrects fine movements
What are gyri?
Folds/ridges that stick out on the brain surface
What are sulci?
Furrows or grooves in between the gyri
What and where is the central sulcus?
Runs in coronal plane, spans both hemispheres
Separates frontal and parietal lobes
What and where is the lateral sulcus?
Separates the temporal lobe from the frontal and parietal lobes
Runs in the transverse plane, one on each hemisphere
What structures mostly make up the brainstem?
Pons, medulla, midbrain
What is the insula?
Part of the cerebral cortex that is only seen by opening the lateral sulcus - covered by the opercula
What covers the insula?
the opercula - latin for lips
Parts of frontal, parietal and temporal lobes
What is the corpus callosum?
large bundle of white matter that connects the two hemispheres (fibre)
What are the olfactory tracts? What view of the brain can they be identified from?
Nerve fibres from nasal cavity
they run along inferior surface of the frontal lobes on both sides
Identified from below
What are the optic nerves? What view of the brain can they be identified from?
Nerves from retinas of the eyes
On inferior surface of the frontal lobe, pass posteriorly and medially to a point where they partly cross over (optic chiasm)
What is the optic chiasm?
Where the optic nerves partly cross over
What are the rounded structures found just behind the optic chiasm and pituitary gland?
Mammillary bodies
Part of the diencephalon
Located on the most inferior surface
What are the crus cerebri?
‘feet of the brain’
Pillars of white matter near the mammillary bodies
Connect rest of the brain to the brainstem
Part of the cerebral peduncles
What part of the (embryological) brain is the cerebral peduncles part of?
The midbrain
What is the fossa between the cerebral peduncles called?
Interpeduncular
On brain specimens may have layer of arachnoid mater covering it
What is the most superior part of the brainstem that contains crus cerebri?
The midbrain
Describe the pons
Large, bulbous, central part of the brainstem
Describe the medulla oblongata
Most inferior part of the brainstem
Tapers down to become the spinal cord inferiorly
What connects the two hemispheres of the cerebellum?
the central ‘vermis’
What is the cerebrum made up of?
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
Limbic system
What are the main parts of the frontal lobe?
Primary motor cortex (posteriorly)
Premotor cortex
Prefrontal cortex
Broca’s area
Where is the primary motor cortex?
Immediately anterior to central sulcus
Most posterior part of the frontal lobe
What is the function of the primary motor cortex?
Execution of motor function (movement)
Where is the premotor cortex?
Between primary motor cortex and prefrontal cortex.
In the frontal lobe
What is the function of the premotor cortex?
Preparation and planning of movements
Where is the prefrontal cortex?
Anterior to the premotor cortex
Most anterior part of the frontal lobe
What is the function of the prefrontal cortex?
Involved in
personality
behaviour
problem solving
impulse control and inhibition
social and sexual behaviour
Where is Broca’s area and what is it involved in?
Found at inferior frontal lobe of the dominant hemisphere
Important for spoken language production
What is the parietal lobe made up of?
Primary somatosensory cortex
Secondary somatosensory cortex
Where is the parietal lobe located?
Central sulcus is anterior to it
Parietooccipital fissure is posterior to it
What is the primary somatosensory cortex responsible for?
Interpretation of sensory information
What are the dominant and non- dominant parietal lobe responsible for?
Dominant important for perception and language and mathematical operations
Non-dominant important for visuospatial functions
Where is the amygdala, what is it responsible for?
Located deep in the temporal lobe
Has a role in the perception of fear
Where is Wernicke’s area and what is it responsible for?
Most superior and posterior part of the dominant temporal lobe
Important for understanding and coordinating spoken language
What is the most posterior part of the cerebrum?
The occipital lobe
What is the limbic system?
Group of structures
Involved in emotion, memory and behaviour
It has influence over the endocrine functions and parts are specifically related to sensations of fear pleasure and rewarding behaviours
Where is the limbic system?
Group of structures found in medial margins of the hemispheres
Includes hippocampus, amygdala, and parts of the cortex and diencephalon
What is the occipital lobe made up of?
Visual association cortex
Primary visual cortex
What is homunculus?
A pictorial mapping of the different gyri (in slices of brain) that represent specific body parts
e.g. homunculus for motor and sensory cortices
Very relevant when the brain is affected in lateral aspect
What are the layers of tissue that envelop the brain and spinal cord?
The meninges
The dura mater
Arachnoid mater
Pia mater
What is the dura mater?
Outermost layer of meninges
Fibrous, thick, doesn’t stretch
What is the arachnoid mater?
Middle layer of meninges
Much thinner than dura and more flexible
Resembles a spider’s web
What is the pia mater?
The innermost layer of the meninges
So thin it can’t be seen by the naked eye
Lies on the surface of the brain
What are the two layers of the dura mater?
Outer, endosteal layer - adherent to interior of the skull
Inner, meningeal layer - sometimes separates from endosteal layer and folds down into the brain to separate parts
What is the falx cerebri?
A double layer of folded dura in the longitudinal fissure
Separates the two cerebral hemispheres
What separates occipital lobe from the cerebellum?
Tentorium cerebelli
A double layer of folded dura
What separates the two lobes of the cerebellum?
Falx cerebelli
A double layer of folded dura
Much less pronounced
What are the small channels (where the two layers of dura separate or meningeal layer folds) filled with? What are they called?
Filled with venous blood
Called dural venous sinuses
What are 7 of the dural venous sinuses?
Superior sagittal sinus
Inferior sagittal sinus
Straight sinus
Transverse sinus
Sigmoid sinus
Confluence of sinuses
Cavernous sinuses
Which dural venous sinus is formed in the space between two layer of dura and runs superiorly along the top of the brain in the sagittal plane?
Superior saggital sinus
Which dural venous sinus is a smaller(shorter) version of the superior sagittal sinus? How is it formed?
Where is it?
Inferior sagittal sinus
Formed in fold of flax cerebri in the longitudinal fissure
Lies inferiorly to SSS, lies on top of the corpus callosum
Which dural venous sinus connects the inferior sagittal sinus to the confluence of sinuses?
Where is it found?
Straight sinus
Where the falx cerebri connects to the tentorium cerebelli posteriorly
What are the transverse sinuses? Where are they found?
Dural venous sinuses
Found on both lateral aspects
Extending from the tentorium cerebelli, around the side of the skull
Sigmoid sinuses connect to them, they connect to confluence
Which dural venous sinuses connect to the jugular vein to allow draining of venous blood from the brain?
What do they connect to?
Sigmoid sinuses
s- shaped
Connected to transverse sinuses to internal jugular vein
Where is the confluence of dural venous sinuses located in the brain?
Straight meets transverse meets superior saggital sinuses
Most posterior aspect of skull
Where are the cavernous (dural venous) sinuses located? What passes through them?
Found anteriorly either side of the sella turcica of the sphenoid bone
Internal carotid artery passes through it alongside some important nerves
Where and what is the subarachnoid space?
Between the arachnoid and pia mater
Contains cerebrospinal fluid and has the arteries that supply the brain in it
What are cisterns?
Spaces where the arachnoid mater spans across two gyri and cover a sulcus, leaving a sealed space filled with CSF - this is the cistern
How does the pia mater help in forming the blood brain barrier?
Blood vessels pass from subarachnoid space into the brain
Part of the pia mater goes with them
Pia fuses with the endothelial cells of the capillaries
Forms blood brain barrier
What 4 features of the blood brain barrier allow it to limit the passage of molecules into the brain and spinal cord?
Endothelial cells - tightly bonded together
Basement membrane of capillaries in brain and cord lack fenestrations found elsewhere in the body
Pericytes - regulate blood flow and permeability
Astrocytes have end feet that also wrap around capillaries - restrict flow of certain molecules
What is meningitis?
Inflammation of the meninges
Often viral(more mild) or bacterial(much more serious)
Diagnosed by taking a CSF sample from the subarachnoid space of the lumbar region of the spine (a lumbar puncture)
What are the 3 main types of intrameningeal bleeding?
Extradural haemorrhage - blood is inside the skull but outside the dura - bulges as it can’t spread out, arterial and often due to trauma
Subdural haematoma - blood is deep to the dura but superficial to the arachnoid, blood can spread out as they arent adhered to each other - venous blood often from bridging veins connecting sinuses and brain
Subarachnoid haemorrhage - deep to the arachnoid, superficial to the pia - leaks into subarachnoid cisterns - arterial usually, classicly presents as a sudden onset of a severe headache
What 2 pairs of arteries supply the brain?
What % of the brain do they supply?
Internal carotid arteries - 80%
Vertebral arteries - 20% mostly posterior parts
What arteries meet to form the circle of Willis/cerebral arterial circle?
Internal carotid arteries
Vertebral arteries
What artery is formed from the union of the to vertebral arteries in the brain?
What small arteries come off it to supply the brainstem?
Basilar arteries
Pontine arteries
What do the pontine arteries supply?
Where do they branch from?
Brainstem
Basilar artery
How are posterior cerebral arteries l/r formed?
By the bifurcation of the basilar artery
How are the middle cerebral arteries l/r formed?
Where do they pass into?
Continuation of internal carotid arteries after entering the skull
They pass into the lateral sulcus
How are the anterior cerebral arteries formed?
Where do they pass into?
Branch of the internal carotid arteries as they enter the skull
They pass anteriorly and wrap backwards over the corpus callosum
Which arteries join the posterior cerebral to the middle cerebral arteries?
posterior communicating arteries l/r
What artery joins the l/r anterior cerebral arteries?
anterior communicating artery
What are the 3 pairs of cerebellar arteries?
anterior inferior cerebellar arteries
posterior inferior cerebellar arteries
superior cerebellar arteries
What is the difference between dural sinuses and veins?
Veins are a distinct vascular tube
Dural sinuses are formed between layers of the meninges
Which area of the brain does the anterior cerebral artery supply?
Medial aspects of the frontal and parietal lobes
Strip of cortex on the superior aspect.
Includes motor and somatosensory cortex responsible for lower limbs
Some anterior structures of the diencephalon
Which part of the brain does the middle cerebral artery supply?
Supply the vast majority of the lateral aspects and deep parts of the hemispheres
Includes parts of the motor and somatosensory cortices responsible for the face, arms and trunk
And the internal capsule (transmits all fibres to and from the cortices)
Some of the structures of the diencephalon
Which parts of the brain does the posterior cerebral artery supply?
Mainly supply the occipital lobe
Also a small portion of the inferior temporal lobe
Which part of the brain does the basilar artery supply?
Supplies part of the circle of Willis
Gives off small branches to supply the pons
SO disruption to the basilar artery can threaten function of all ascending and descending fibres including motor control and sensation from the neck down
Which parts of the brain do the (anterior inferior, posterior inferior, superior) cerebellar arteries supply?
Mainly the cerebellum
Also parts of the brainstem alongside the basilar artery
How can blood supply to the brain be divided into anterior and posterior circulation?
Anterior - anterior and middle cerebral arteries
Posterior - posterior cerebral, basilar, cerebellar arteries
What are the two types of stroke?
Ischaemic - obstruction of a vessel
Haemorrhagic - reupture of a blood vessel leading to compression of structures/accumulation of blood
What is a berry aneurysm?
Aneurysm - deformities in arterial vessel walls - they balloon and are prone to rupture
Berry aneurysms - found in sides of cerebral arteries (have characteristic appearance)
Asymptomatic until they rupture - subarachnoid haemorrhage most often happens.
Symptoms may inc severe, sudden-onset headache, vomiting, reduction i nconscious level
What is the pathway of venous blood from braincells to internal jugular veins?
(Smaller) internal cerebral veins to…
External cerebral veins (larger) to…
Dural venous sinuses to…
sigmoid sinuses become internal jugular veins
What is the other route for venous blood to take out of the brain, other than the internal jugulars?
Drain into emissary veins that cross the endosteal layer of the dura and drain the venous blood into bones of the skull
Where is the cavernous sinus found?
Behind the orbit on both sides
What passes through the cavernous sinus?
So what can happen when it gets inflamed?
Internal carotid artery, CN III, IV, V1, V2, VI
Some venous blood drains from face, any infections easily access it…
Lead to meningitis or thrombosis
What does venous sinus thrombosis cause?
Blood clot in the dural sinuses
Drainage of venous blood is compromised
Increase in intercranial pressure
Headache and potentially devastating compression of intercranial structures
How many ventricles are there in the brain?
4
Pair is 1 and 2 - lateral ventricles
What is the subarachnoid space continuous with in the brain?
The ventricles
Spinal cord
What is the purpose of CSF?
Surrounds the brain in subarachnoid space - degree of physical protection
Mechanism for transfer of substances in and out of brain tissue
Where is CSF produced?
specialised cells called the choroid plexus
CSF then flows into lateral ventricles
What does the interventricular foramen connect?
Lateral ventricles and 3rd ventricles
aka foramen of monroe
What does the third ventricle separate?
The two sides of the diencephalon
What connects the 3rd and 4th ventricles?
Cerebral aqueduct
aka aqueduct of sylvius (dont use)
Where is the 4th ventricle located?
Diamond shaped
Posterior to the brainstem
Anterior to the cerebellum
How does CSF leave the ventricle system?
