Anatomy Flashcards
What do the arachnoid granulations do?
Fluid passes through SAH into superior sagital sinus
What produces CSF?
Choroid plexuses in the lateral, 3rd & 4th ventricles
Why do you get papilloedema in raised ICP?
Extension of SAH space around optic nerve
What is the venous drainage of the brain?
Superior & inferior sagittal sinuses run backwards
Join the straight sinus to form
Drain into sigmoid sinuses
Drain into internal jugular vein
What structures run in the cavernous sinus?
Oculomotor nerve
Trochlear nerve
Opthalmic branch
Maxillary branch
Internal carotid artery
Abducens nerve
(Mnemonic O Tom Cat)
What’s autoregulation?
Brain maintains constant cerebral blood flow despite changes to systemic BP
Above/below limits this is lost and cerebral blood flow becomes dependent on MAP
How does CO2 act on the brain?
Dilatation of vessels
Rise in pressure
Inc cerebral blood flow
What is the middle cerebral artery a continuation of?
Internal carotid
What are the branches of the middle cerebral artery?
Opthalmic artery
Anterior cerebral artery
What marks the posterior border of the frontal lobe?
Central sulcus
What is the pre-central gyrus important for?
Motor cortex
What is the post-central gyrus important for?
Sensory cortex
What is Broca’s Area responsible for?
Speech production (motor)
What is Wernicke’s area responsible for?
Comprehension
What’s most of the internal area of the brain supplied by?
Anterior cerebral artery
Where does the middle cerebral artery supply?
Largest area- lateral parts of the brain (temporal, parietal, part of frontal lobe)
What does the posterior cerebral artery supply?
Cerebellum
Brainstem
Occipital lobe
What is the function of the lenticulostriate branches?
Blood supply to internal capsule
Infarct to this area = lacunar infarct
What Sx would be seen in an anterior cerebral artery stroke?
Contralateral leg paresis
Disinhibition
What Sx would be seen in an middle cerebral artery stroke of the dominant hemisphere?
Most left hemisphere dominant (opposite to favoured limb)
Face & upper limb hemiparesis
Sensory loss
Homonymous hemianopia
Dysarthria
Receptive aphasia
What Sx would be seen in an anterior cerebral artery stroke of the non-dominant hemisphere?
Face & upper limb hemiparesis
Sensory loss
Neglect
Homonymous hemianopia
Dyspraxia (e.g combing hair)
What Sx would be seen in a lacunar stroke?
Purely motor/sensory defects
What is the function of the internal capsule?
Transmits motor fibres from pre-central gyrus to brainstem
What Sx would be seen in a posterior cerebral artery stroke?
Homonymous hemianopia
Memory impairment
Thalamic syndrome
What Sx would be seen in a brain-stem stroke?
Ipsilateral CN palsy
Contralateral motor & sensory defect below lesion
Cerebellar features: N&V, ataxia, nystagmus
Impaired consciousness
Can have bilateral defects
What is the route of a motor function from the brain to axon?
1) Pre-frontal gyrus
2) Internal capsule
3) Pons
4) Decussation of pyramids
5) Corticospinal tract
6) Anterior horn
7) alpha motor neuron axon
8) Peripheral nerve
What is the Dura made up of?
OUTER: Periosteal layer
INNER: Meningeal layer
What are the 4 infolding of the dura?
-Falx cerebri: Inf to TC, separates hemispheres
- Tentorium Cerebelli: Seperates cerebellum and cerebrum
-Falx Cerebelli: Seperates cerebellar hemispheres
-Diaphragma sellae: Envelopes pituitary gland in sella turcica
What happens between the layers of the Dura?
Venous sinuses - venous blood from brain drains before draining into jugular veins
What are the 3 spaces related to the meninges?
- Extradural: Potential space between skull & dura
- Subdural: Potential space between dura & arachnoid
-Subarachnoid: Between Pia & arachnoid, contains CSF
What is the role of CSF?
- Buoyancy & cushioning
- Maintenance: pH, glucose, electrolytes
-Buffering: Changes in ICP
Describe the lateral ventricles
- C shaped cavities
- Separated by septum pallucidum
-Has 3 horns - ant/post/inf
Where are the 3 horns of the lateral ventricles located?
- Ant = frontal lobes
- Post = Known as occipital horns
- Inf = largest, temporal lobes
Where is the 3rd ventricle located?
Between thalami & hypothalamus
Where is the 4th ventricle located?
Between pons and medulla and cerebellum
What is the route of flow of CSF?
- Lateral ventricles
- Foramen of Monro
- 3rd ventricle
- Aqueduct of Sylvius
- 4th Ventricle
- ## Subarachnoid space via foramen of Magendie and foramen of Lusaka
What is the function of the cerebellum?
Control of pre-programmed:
Motor tasks
Co-ordination of motor functions
Memory
Language processing
Logical reasoning
