Topography of the brain Flashcards
Identify the labels
Which foramen do some of these arteries go through?
Internal Carotid Arteries:
- enter the skull through the carotid canal (Foramen Lacerum) to supply the brain
Vertebral arteries:
- branches of the subclavian artery
- enter the skull through the foramen magnum to supply the brain
The ‘Circle of ______’ is the vascular structure that plays a central role in cerebral blood supply
Identify the arteries that make up the circle
Circle of Willis
Complete the statement about the Circle of Willis
Branches of the Internal carotid artery join with ____________ and with the ____________ (branch of the basilar artery) to form a continuous circle at the base of the brain.
Branches of the ICA join with those of the opposite side and with the Posterior Cerebral Artery (branch of the basilar artery) via the PComA to form a continuous circle at the base of the brain.
Why is the circle of willis an important protective structure of the brain?
Protects against vaso-occlusion of large arteries
As it provides alternative routes
Heres a lovely diagram of the bottom of the brain
Identify the arteries of the COW
Which branches of the ICA are important in supplying the brain?
The ICA gives branches – the anterior (ACA), middle cerebral (MCA) and posterior communicating arteries (PComA).
The ACA and the MCA supply a large part of the cerebral hemispheres
The 2 vertebral arteries join together to form a basilar artery on the ventral surface of the brainstem
The system that is formed supplies what areas of the brain?
What is the fate of this basilar artery?
The vertebro-basilar system gives branches that supply the brainstem and cerebellum
The basilar artery finally ends at the level of the midbrain by dividing into two Posterior cerebral arteries (PCA) which supplies the posterior part of the cerebral hemispheres
Cerebral blood supply can be split into 3 territories
What are these?
Identify the areas below
Anterior cerebral:
- Medial aspect of cerebral hemispheres excluding Occipital lobe.
Middle cerebral:
- Lateral aspect of cerebral hemispheres
Posterior cerebral:
- Inferior aspect of cerebral hemispheres and Occipital lobe
Give an overview of the venous drainage of the brain
Superficial & deep veins of the brain drain into venous sinuses which lie between 2 layers of dura mater
The dural venous sinuses join together to ultimately drain into the Internal Jugular Veins
Bit aids but identify the veins n stuff
Shown below is the cavernous sinus.
What structures pass through/near it?
Identify the labels
CN III
CN IV
CN V1
CN V2
CN VI
Internal jugular
Pituitary gland
From what embryonic layer does the neural tube develop?
(dorsal) surface ectoderm
What is the fate of the cranial end of the neural tube (embryology)?
Cranial end of the tube forms vesicles each of which develops into different parts of the brain
Describe the formation of the primary and secondary vesicles in embryology
As soon as the neural tube forms, it divides into 3 primary vesicles - the prosencephalon (forebrain), mesencephalon (midbrain) and rhombencephalon (hindbrain)
From these - the secondary vesicles develop
These develop into the adult brain
What are the parts of the brainstem
Midbrain
Pons
Medulla
What nervey stuff is in the brainstem?
- Cranial nerves III – XII
- Tracts from spinal cord
- Vital centres - eg: cardiorespiratory centre
You know the drill
Yellow = nerves
Red = areas n stuff
What are the functions of the brainstem?
Pathway for fibre tracts running between higher & lower centres.
Brainstem nucleii are involved with 10 of the 12 cranial nerves, so innervation of head & neck.
Brainstem centres produce the rigidly programmed automatic behaviours essential for survival.
Which cranial nerves leave from each part of the brainstem?
Midbrain:
- III to IV
Pons:
- V to VIII
Medulla:
- IX to XII
What is the relation between the brainstem and the cerebellum?
Cerebellum and brainstem are connected by Cerebellar peduncles of which there are 3 pairs (6)
Superior, Middle & Inferior cerebellar peduncles leaving from the Midbrain, Pons & medulla respectively
Each level joins and they leave as one big daddy peduncle. You can not differentiate them on a cadaver
Identify the labels on the medulla’s surface
The arrow without the label is pointing at the daddy peduncle (you can see the individual peduncles)
What is the cavity within the medulla?
The 4th (IV) ventricle
(located in the Superior medulla)
Why are the pyramids of the medulla an important feature?
Decussation of pyramids
There is a crossing over of motor fibres from each hemisphere of the brain as they enter the medulla
What are the olives of the medulla?
The olives contain the inferior olivary nucleus
The superior olivary nucleus is in the pons
Identify the nerves leaving the Pons
What cavity lies posterior to the Pons?
IV ventricle
Which peduncle originates on the pons’ surface?
The middle cerebellar peduncle
Identify the parts of the posterior midbrain
What function is associated with each?
Corpora quadrigemina:
- superior (visual) & inferior (auditory) colliculus
Identify the parts of the anterior midbrain
Note that CN IV originates on the posterior surface but kinda comes round
What embryological structure develops into the midbrain?
Mesencephalon
What cavity is located within the midbrain?
Cerebral aqueduct
(connects III & IV ventricles)
Describe the structure of the cerebellum
- Right and left hemispheres separated by Vermis
- Each hemisphere has an anterior, posterior and flocculonodular lobe
- Surface has sulci and folia
- Three cerebellar peduncles connect it to brainstem
Identify the parts of the diagram of the cerebellum
Arborvitae - tree like white matter structure
Where is the diencephalon?
What does it develop from?
Deep within the cerebral hemispheres - around the III ventricle
Diencephalon develops from the diencephalic vesicle (part of the forebrain vesicle)
What structures make up the diencephalon?
Thalamus
Hypothalamus
Infundibulum (stalk of the pituitary)
Epithalamus (pineal gland)
What tissue makes up most of the diencephalon?
Mainly grey matter
Identify the parts of the diencephalon
What is the purpose of the thalamus?
It is basically the relay centre for all sensory information that is going to the cerebral hemispheres
(The only exception to this is SMELL)
In the thalamus, sensory triage takes place - so it decides how important/relevant it is
Identify the labels
Describe the functional structure of the thalamus and how it works
Contains groups of nuclei - Anterior, Medial and lateral
The lateral group is the sensory relay bit - it has different areas for different sensory info from different parts
There is also the Lateral geniculate body, which sticks out the lateral group - this is where the optic tract synapses in the visual pathway
Do the thing
What does the hypothalamus do?
Main visceral control centre & is essential for control of homeostasis
Controls:
- Autonomic control
- Body temp
- Food intake
- Water balance & thirst
- Sleep-wake cycle
- Endocrine system function
