Blood Supply Flashcards
Which artery supplies the CEREBRUM/cerebral cortex? the Brainstem & Cerebellum?
- Cerebrum = INTERNAL CAROTID
- Cerebellum + Brainstem = VERTEBROBASILAR
- areas affected during stroke*
What does the internal carotid bifurcate into? Which artery supplies the medial portion of brain, and which lateral?
Anterior & Middle Cerebral Artery
Anterior = Medial portion
MCA = Lateral portion
What does the Vertebrobasilar A. bifurcate into?
What are the main branches of the VERTEBRAL A.?
Posterior Cerebral A.
- Posterior Spinal A.
- Anterior Spinal A.
- PICA (posterior inferior cerebellar A.)
What is referred to as the Anterior circulation of the brain? Posterior?
Anterior = Internal Carotid
Posterior = Vertebrobasilar
Where is the Basilar A. found?
Under pons
What connects the Internal Carotid & Vertebral-Basilar A.?
Posterior COmmunicating A.
Where do 80% of strokes occur? Which branch of this artery is the likely source?
INTERNAL CAROTID
- Middle Cerebral A. is involved most often (lateral aspects of brain)
What is the circle of willis? What is its function?
Connects the Anterior & Posterior Circulation (carotid w/ Vertebrobasilar)
- allows blood to bypass OBSTRUCTION
What supplies DEEP cerebral structures?
Small perforating Arteries
or Ganglionic A.
(base of brain)
What supplies deep structures of diencephalon, hypothalamus, and telencephalon?
MCA branches
= LENTICULOSTRIATES
What are the arteries of the circle of Willis?
- Anterior Communicating A.
- Posterior Communicating A.
- Posterior Cerebral A.
- most people have an incomplete circle
How does the brain receive blood supply? Which structures do these vessels supply?
Perforating Arteries
= supply DEEP CRITICAL structures
- susceptible to diseases:
high blood pressure (renal failure, eye failure, because of tiny vessels)
What is the critical component of the BBB?
ENDOTHELIAL cells with TIGHT JUNCTIONS
What are the supportive cells of the BBB? the WBC (white blood cells) of the brain?
- Astrocytes
2. Microglial Cels
What is the neurovascular unit?
- forms the blood brain barrier
= Astrocytes, Endothelial Cells, Microglial Cells
At what ml of blood do neurons stop generating electrical signals? Necrosis?
- 20 ml
- 10 ml
(normally 55ml)
How is blood flow controlled?
- AUTOREGULATION
- arterial & smooth muscle - Metabolic
= increased neuronal activity
What is the function of the BBB?
= Neurovascular unit
- restricts ionic/fluid movement
- Supplies essential nutrients
- Mediates efflux of waste/toxic products
What are the 4 main components of the BBB?
- Capillary Endothelial cells
- Astrocytes (communicate w/ other cells)
- Pericytes
- Neuronal Processes/Microglial Cells
How does the BBB communicate with other cells?
via Astrocytes
- main barrier is ENDOTHELIAL, everything else adjusts the barrier**
- have a range of receptors & transmitters on the ENDOTHELIAL Cells
What does the valveless Cerebral Vein drain through?
INTERNAL JUGULAR VEIN
What veins connect extracranial veins w/ dural sinuses?
EMISSARY VEINS
Where do the Cerebellar & brainstem veins drain into?
Great Vein of Galen
How do the Superficial Veins get to the Transverse Sinus? (4)
- Superficial Veins
- Superior Sagital Sinus
- Confluence of Sinuses **
- Transverse Sinus
How do the Deep Veins get to the Transverse Sinus? (6)
- Deep Veins
- Internal Cerebral V
- GREAT VEIN OF GALEN
- Straight Sinus
- CONFLUENCE OF SINUSES**
- Transverse sinus
Where do both the superficial and deep veins drain?
Confluence of sinuses –> TRANSVERSE SINUS
- venous blood is connected
Is there an epidural space typically? What usually is found here? what forms the 2 layers
NO!
- Middle Meningeal A.
- if trauma = blood fills & creates EPIDURAL hematoma
- 2 layers = DURA + SKULL
What is the term for blood pushing away the dura from the skull by a hematoma?
HERNIATION
What is a subdural hematoma?
Blood outside the skull
