Neuroanatomy - Blood supply + ventricular system Flashcards
(23 cards)
Which arteries does the brain receive blood from?
- Internal carotid arteries
- Vertebral arteries
Describe the internal carotid arteries
- Common carotids bifurcate into internal and external
- External supplies the face, scalp, neck, etc
- Internal supplies the brain
- Enters brain via carotid canals
Describe the vertebral arteries
- Branch of the subclavian arteries
- Ascends in the neck through the transverse foramen of the cervical vertebrae
- Enters skull via foramen magnum
- Vertebral arteries fuse at base of brainstem to form the basilar artery
What are the 3 pairs of cerebral arteries
- Posterior cerebral artery
- Middle cerebral artery
- Anterior cerebral artery
What are the 3 pairs of cerebellar arteries
- Posterior inferior cerebellar arteries
- Anterior inferior cerebellar arteries
- Superior cerebellar arteries
What is the arterial circle of willis
- Interconnects the internal carotid and vertebral-basilar system
- Surrounds the optic chiasma and hypothalamus
- Ensures compensation of decreased blood flow If one blood vessel is blocked
What are aneurysms
- Abnormal dilations around the circle of Willis or at points of arterial branching in the brain
- ~ 10% of vascular strokes are caused by rupture of a berry aneurysm
What is the role of the arterial circle
Each cerebral artery supplies a different cerebral hemisphere:
- Anterior cerebral artery - supplies the superior and medial areas of frontal and parietal lobes; supplies the corpus callosum
- Middle cerebral artery - Supplies the lateral areas of the frontal, temporal, and parietal lobes
- Posterior cerebral artery - Supplies the inferior and medial surface of the temporal lobe and the occipital lobe
- Deep arteries and striate arteries supply hemispherical structures
Describe venous drainage of the blood
- All venous blood from the brain drains into the internal jugular veins
- Dural sinuses receive venous blood from the brain and drain directly into the internal jugular
veins respectively - Transverse sinuses transfer blood into the sigmoid sinuses, then the internal jugular
vein
What are the 3 meningeal coverings that surround the CNS and spinal cord
- Dura mater
- Arachnoid mater
- Pia mater
How many layers of dura mater are there?
What do they allow for?
What do they form?
- 2
- Allow for dural infoldings at specific areas
- Form dural sinuses
Describe damage to the dura
- Falx cerebri: a supportive layer that sits between cerebral hemispheres
- Tentorium cerebelli: between occipital lobes and the cerebellum
- Venous dural sinuses lie between dural infoldings
What is the ventricular system?
A series of interconnecting chambers throughout the CNS are present, all derived from the lumen of the neural tube
What are ventricles
Dilations from the central canal containing choroid plexus → Cerebrospinal fluid
How many ventricles are there?
4 ventricles:
- 2 lateral ventricles,
- 3rd ventricle between the thalami
- 4th ventricle lies between the pons (anteriorly) and the cerebellum (posteriorly)
How is the brain formed
Due to the enormous growth and distortion of an elaborate system of ventricles
What is cerebrospinal fluid
A clear, colourless, blood derived fluid that contains glucose and inorganic salts
What does cerebrospinal fluid consist of
- Little protein
- Very few cells
Where is the cerebrospinal fluid produced
Produced in the ventricles by specialised areas of ventricular lining: choroid plexus
What does cerebrospinal fluid provide
- Physical protection for the CNS
- Chemical stability for the CNS
What are arachnoid villi
Extensions of arachnoid matter into dural sinuses predominantly into the superior sagittal sinus
What are the rules of cerebrospinal fluid
- Buoyancy:reducetraction
- Cushioning: dampen trauma
- Transport substances: nutrients, dissolved gases, and the removal of metabolites
- Provides a stable environment
What happens if cerebrospinal fluid flow is blocked
The fluid accumulates upstream of the blockage, leading to a condition called hydrocephalus
