Blood Supply, Hemorrhage, and Herniation Flashcards
What are the parts of the internal carotid artery?
Cervical, petrous, cavernous, and cerebral parts
What is the cervical part of the ICA?
Bifurcation to the carotid canal
What is the petrous part of ICA?
Carotid canal in the petrous part of the temporal bone upward and medially above the foramen lacerum
What is the cavernous part of ICA?
In the cavernous sinus
What surrounds the cavernous part of the ICA?
Sympathetic plexus and CNs III, IV, V1, and VI
What are the parts of the vertebral artery?
Cervical, atlantic, and intracranial parts
What is the cervical part of the vertebral artery?
Transverse foramina of first 6 cervical vertebrae
What is the atlantic part of the vertebral artery?
Perforates the dura and arachnoid mater; passes through foramen magnum
What is the intracranial part of the vertebral artery?
In the cranium; unite with other side at caudal border of pons to form the basilar artery
What arteries make up the Circle of Willis?
2 anterior cerebral, 2 ICA, 2 posterior cerebral, anterior communicating, and 2 posterior communicating
What percentage of lesions to nerves come from issues with the vasculature?
50%
What does the anterior cerebral artery supply?
Supplies most of the medial and superior surface of the frontal and parietal lobes
What does the middle cerebral artery supply?
Supplies lateral surface of frontal and parietal lobes and the superior part of temporal lobe
What does the posterior cerebral artery supply?
Supplies the occipital lobe and the inferior temporal lobe
What is the epidural space?
Potential space between cranium and periosteal dura
What is the subdural space?
Potential space between dura and arachnoid mater
What is the subarachnoid space?
Real space between the arachnoid and pia mater; contains CSF, arteries, and veins
What are some causes of herniation syndromes?
Hemorrhage, mass/tumor, trauma, abscess, infection, and/or metabolic conditions
What is the supratentorial compartment?
Above the tentorium and divided into right and left by the falx cerebri
What is the infratentorial compartment?
Below the tentorium cerebelli
What is the tentorial notch?
Continuation of the supra and infratentorial compartment
What is a subfalcine (cingulate, falcine, falx) herniation?
Occurs in supratentorial compartment; displaces brain tissue under the falx cerebri; may compress anterior cerebral artery, frontal lobe, parietal lobe; may evolve into a transtentorial herniation
What is a transtentorial (central) herniation?
Brain is displaced downward toward tentorial notch; compromises the upper brainstem, CN III, and possibly lower structures; may also compress basilar artery and posterior cerebral arteries; results in decorticate and decerebrate rigidity
What is a uncal herniation?
Uncus and usually portions of parahippocampal gyrus are extruded over the edge of tentorium cerebelli and through the tentorial notch; impinges on the brain
What is a tonsilar herniation?
Herniation of cerebellar tonsils through the foramen magnum; leads to compression of the medulla and upper cervical spinal cord
In a epidural hematoma, where does it bleed into? What is the common site this occurs? What is the source of the bleeding? What are the clinical signs? What is the treatment?
Bleeds Into: epidural space between skull and dura mater
Common Site: fracture of squamous temporal bone or pterion
Source: middle meningeal artery
Signs: momentary unconsciousness followed by lucid period of hours to 1-2 days then unconsciousness
Treatment: surgical
In a subdural hematoma, where does it bleed into? What is the occurrence that causes this to happen? What is the source of the bleeding? What are the clinical signs? What is the treatment?
Bleeds Into: between dura and arachnoid mater
Occurrence: head strikes fixed object or during an assault
Source: venous, usually cortical veins opening into superior sagittal sinus
Signs: slower accumulation of blood due to pressure and often self-limiting
Treatment: surgical
For a subarachnoid hemorrhage, when is this commonly found? What is the source of the bleeding? What are the clinical signs?
Commonly Found: severe head injury, but more common in rupture of aneurysm
Source: arterial bleeding from cerebral arteries
Signs: massive bleeding into CSF compartment due to arterial source with headaches and deteriorating level of consciousness
What is a intracerebral (subpial) hemorrhage? What is the source? What are the clinical signs?
Bleeding within brain substance (stroke); can be a complication in 2-3% of all head injuries
Source: middle cerebral artery
Signs: hypertension or degenerative arterial disease (commonly seen at autopsy
What is vertebral basilar insufficiency?
Reduced blood flow from the vertebral arteries during extreme hyperextension of the head and extreme head rotation (Bow-Hunter’s Syndrome)
What is subclavian steal syndrome?
Blood from one vertebral artery goes back down the other vertebral artery to the subclavian; happens when there is an occlusion of the subclavian artery proximal to where the vertebral artery comes off; blood is stolen to supply the upper extremities
