Neurology Flashcards
Explain blood supply to the brain
Anterior supplies medial surface of frontal & parietal lobes
• Middle supplies nearly all of lateral surface
What are the branches of Ant cerebral artery ?
Arteries give off cortical branches (anastomose quite freely on brain surface; blockage may cause cerebral ischemia & infarction) and central branches (pierce brain substance to supply nuclei & tracts) obstruction or hemorrhage usually leads to a ‘stroke’ because the internal capsule has the most vulnerable blood supply
• Hemorrhagic stroke results following rupture of an artery or an aneurysm (Berry aneurysm)
What are the sinuses of the brain
Sup. Sagittal sinus Transverse sinuses Straight sinus Inf sagittal sinus Cavernous sinus Intercavernous sinus Ant & Post Inf petrosal sinus Sigmoid sinus Internal jugular V
Pathophysiology of chemosis
Internal carotid artery & cranial nerves (Ill, IV, Vi & VI) — show in the skull the relationship to the cavernous sinus
• Arterial bleed in the cavernous sinus > sinus enlargement, blood forced into the ophthalmic veins
- exophthalamos and the conjunctiva becomes engorged (chemosis)
What are causes & pathophysiology if extramural hemorrhage
The pterion overlies the anterior branches of the middle meningeal vessels on the internal aspect of the lateral wall of the vault; trauma may result in fracture that may rupture of these vessels causing an intracranial (i.e. extradural ) hemorrhage. Increasing pressure from collecting blood may displace the cerebral cortex causing brainstem compression from herniation.
Clinical association with vault of the skull
The base of the skull seems strong but gets fractured because it has the body connected to it which can deliver a lot of force
• Periosteal (endosteal) layer of dura mater attachment to the floor of the cranium much firmer than to the vault; blow to the head can detach the dura from the vault without bone fracture, whereas a basal fracture usually tears the dura mater and arachnoid mater, resulting in leakage of CSF
Fractures of the anterior cranial fossa
Fractures of the anterior cranial fossa may involve the frontal, ethmoidal and sphenoidal sinuses and cause bleeding and leakage of CSF into the nose or mouth; leakage of CSF implies tearing of the meninges with bacterial access
Anterior basal fractures
Anterior basal fractures may involve the cribriform plate this may result in anosmia due to rupture of nerve fibers of the olfactory bulb; nose blowing causes air in ventricles
Fractures of middle cranial fossa
Fractures of middle cranial fossa may result in bleeding or CSF leakage from the ear and cranial nerve injury (e.g. facial and auditory)
Two extensions of the internal layer between major regions of the brain: of meninges
falx cerebri — stabilizes the cerebral hemispheres laterally. Raised intracranial pressure may result in falcal herniation
2) tentorium cerebelli stabilizes brain vertically separates cerebral /cerebellar compartments. Limits tumor invasion between compartments. Raised intracranial pressure - uncal herniation.
Where does the Dural Venous Sinuses located
natural spaces between periosteal & meningeal layers link venous circulation of brain to systemic veins.
• names & location of major venous sinuses:
- Inferior / Superior Sagittal
- Straight,
- Transverse,
Epidural (potential) space ?
Epidural (potential) space between periosteal layer & skull —extradural (epidural) haemorrhage; NOTE in the skull, the periosteum is part of the dura, while in the spinal canal, the dura is separate from the bone — hence epidurals.
subarachnoid haemorrhage causes
Arachnoid mater separated from the pia mater by subarachoid space which contains CSF
- Tissue strands join arachnoid & pia
- Arachnoid granulations (villi) protrude into the lumina of large venous sinuses
- Major arteries on its inner side; subarachnoid haemorrhage - CSF discoloration
- Berry aneurysms in young people
ligaments from the pia mater stabilize the spinal cord شنواسمها
Denticulate ligaments from the pia mater stabilize the spinal cord
internal hydrocephalus
external hydrocephalus
CSF disturbances overproduction absorption)
(obstruction, or non-
- Blocked intraventricular foramen & stenosis of cerebral aqueduct (internal hydrocephalus or noncommunicating); failure of reabsorption (external hydrocephalus or communicating)
- Abnormalities show up as glucose changes, increased or changed protein content and increased number of cells giving rise to color changes or xanthrochromia.
